arch/x86/net/bpf_jit_comp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * BPF JIT compiler
   4  *
   5  * Copyright (C) 2011-2013 Eric Dumazet (eric.dumazet@gmail.com)
   6  * Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   7  */
   8 #include <linux/netdevice.h>
   9 #include <linux/filter.h>
  10 #include <linux/if_vlan.h>
  11 #include <linux/bpf.h>
  12 #include <linux/memory.h>
  13 #include <linux/sort.h>
  14 #include <asm/extable.h>
  15 #include <asm/set_memory.h>
  16 #include <asm/nospec-branch.h>
  17 #include <asm/text-patching.h>
  18
  19 static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
  20 {
  21         if (len == 1)
  22                 *ptr = bytes;
  23         else if (len == 2)
  24                 *(u16 *)ptr = bytes;
  25         else {
  26                 *(u32 *)ptr = bytes;
  27                 barrier();
  28         }
  29         return ptr + len;
  30 }
  31
  32 #define EMIT(bytes, len) \
  33         do { prog = emit_code(prog, bytes, len); } while (0)
  34
  35 #define EMIT1(b1)               EMIT(b1, 1)
  36 #define EMIT2(b1, b2)           EMIT((b1) + ((b2) << 8), 2)
  37 #define EMIT3(b1, b2, b3)       EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
  38 #define EMIT4(b1, b2, b3, b4)   EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
  39
  40 #define EMIT1_off32(b1, off) \
  41         do { EMIT1(b1); EMIT(off, 4); } while (0)
  42 #define EMIT2_off32(b1, b2, off) \
  43         do { EMIT2(b1, b2); EMIT(off, 4); } while (0)
  44 #define EMIT3_off32(b1, b2, b3, off) \
  45         do { EMIT3(b1, b2, b3); EMIT(off, 4); } while (0)
  46 #define EMIT4_off32(b1, b2, b3, b4, off) \
  47         do { EMIT4(b1, b2, b3, b4); EMIT(off, 4); } while (0)
  48
  49 #ifdef CONFIG_X86_KERNEL_IBT
  50 #define EMIT_ENDBR()    EMIT(gen_endbr(), 4)
  51 #else
  52 #define EMIT_ENDBR()
  53 #endif
  54
  55 static bool is_imm8(int value)
  56 {
  57         return value <= 127 && value >= -128;
  58 }
  59
  60 static bool is_simm32(s64 value)
  61 {
  62         return value == (s64)(s32)value;
  63 }
  64
  65 static bool is_uimm32(u64 value)
  66 {
  67         return value == (u64)(u32)value;
  68 }
  69
  70 /* mov dst, src */
  71 #define EMIT_mov(DST, SRC)                                                               \
  72         do {                                                                             \
  73                 if (DST != SRC)                                                          \
  74                         EMIT3(add_2mod(0x48, DST, SRC), 0x89, add_2reg(0xC0, DST, SRC)); \
  75         } while (0)
  76
  77 static int bpf_size_to_x86_bytes(int bpf_size)
  78 {
  79         if (bpf_size == BPF_W)
  80                 return 4;
  81         else if (bpf_size == BPF_H)
  82                 return 2;
  83         else if (bpf_size == BPF_B)
  84                 return 1;
  85         else if (bpf_size == BPF_DW)
  86                 return 4; /* imm32 */
  87         else
  88                 return 0;
  89 }
  90
  91 /*
  92  * List of x86 cond jumps opcodes (. + s8)
  93  * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
  94  */
  95 #define X86_JB  0x72
  96 #define X86_JAE 0x73
  97 #define X86_JE  0x74
  98 #define X86_JNE 0x75
  99 #define X86_JBE 0x76
 100 #define X86_JA  0x77
 101 #define X86_JL  0x7C
 102 #define X86_JGE 0x7D
 103 #define X86_JLE 0x7E
 104 #define X86_JG  0x7F
 105
 106 /* Pick a register outside of BPF range for JIT internal work */
 107 #define AUX_REG (MAX_BPF_JIT_REG + 1)
 108 #define X86_REG_R9 (MAX_BPF_JIT_REG + 2)
 109
 110 /*
 111  * The following table maps BPF registers to x86-64 registers.
 112  *
 113  * x86-64 register R12 is unused, since if used as base address
 114  * register in load/store instructions, it always needs an
 115  * extra byte of encoding and is callee saved.
 116  *
 117  * x86-64 register R9 is not used by BPF programs, but can be used by BPF
 118  * trampoline. x86-64 register R10 is used for blinding (if enabled).
 119  */
 120 static const int reg2hex[] = {
 121         [BPF_REG_0] = 0,  /* RAX */
 122         [BPF_REG_1] = 7,  /* RDI */
 123         [BPF_REG_2] = 6,  /* RSI */
 124         [BPF_REG_3] = 2,  /* RDX */
 125         [BPF_REG_4] = 1,  /* RCX */
 126         [BPF_REG_5] = 0,  /* R8  */
 127         [BPF_REG_6] = 3,  /* RBX callee saved */
 128         [BPF_REG_7] = 5,  /* R13 callee saved */
 129         [BPF_REG_8] = 6,  /* R14 callee saved */
 130         [BPF_REG_9] = 7,  /* R15 callee saved */
 131         [BPF_REG_FP] = 5, /* RBP readonly */
 132         [BPF_REG_AX] = 2, /* R10 temp register */
 133         [AUX_REG] = 3,    /* R11 temp register */
 134         [X86_REG_R9] = 1, /* R9 register, 6th function argument */
 135 };
 136
 137 static const int reg2pt_regs[] = {
 138         [BPF_REG_0] = offsetof(struct pt_regs, ax),
 139         [BPF_REG_1] = offsetof(struct pt_regs, di),
 140         [BPF_REG_2] = offsetof(struct pt_regs, si),
 141         [BPF_REG_3] = offsetof(struct pt_regs, dx),
 142         [BPF_REG_4] = offsetof(struct pt_regs, cx),
 143         [BPF_REG_5] = offsetof(struct pt_regs, r8),
 144         [BPF_REG_6] = offsetof(struct pt_regs, bx),
 145         [BPF_REG_7] = offsetof(struct pt_regs, r13),
 146         [BPF_REG_8] = offsetof(struct pt_regs, r14),
 147         [BPF_REG_9] = offsetof(struct pt_regs, r15),
 148 };
 149
 150 /*
 151  * is_ereg() == true if BPF register 'reg' maps to x86-64 r8..r15
 152  * which need extra byte of encoding.
 153  * rax,rcx,...,rbp have simpler encoding
 154  */
 155 static bool is_ereg(u32 reg)
 156 {
 157         return (1 << reg) & (BIT(BPF_REG_5) |
 158                              BIT(AUX_REG) |
 159                              BIT(BPF_REG_7) |
 160                              BIT(BPF_REG_8) |
 161                              BIT(BPF_REG_9) |
 162                              BIT(X86_REG_R9) |
 163                              BIT(BPF_REG_AX));
 164 }
 165
 166 /*
 167  * is_ereg_8l() == true if BPF register 'reg' is mapped to access x86-64
 168  * lower 8-bit registers dil,sil,bpl,spl,r8b..r15b, which need extra byte
 169  * of encoding. al,cl,dl,bl have simpler encoding.
 170  */
 171 static bool is_ereg_8l(u32 reg)
 172 {
 173         return is_ereg(reg) ||
 174             (1 << reg) & (BIT(BPF_REG_1) |
 175                           BIT(BPF_REG_2) |
 176                           BIT(BPF_REG_FP));
 177 }
 178
 179 static bool is_axreg(u32 reg)
 180 {
 181         return reg == BPF_REG_0;
 182 }
 183
 184 /* Add modifiers if 'reg' maps to x86-64 registers R8..R15 */
 185 static u8 add_1mod(u8 byte, u32 reg)
 186 {
 187         if (is_ereg(reg))
 188                 byte |= 1;
 189         return byte;
 190 }
 191
 192 static u8 add_2mod(u8 byte, u32 r1, u32 r2)
 193 {
 194         if (is_ereg(r1))
 195                 byte |= 1;
 196         if (is_ereg(r2))
 197                 byte |= 4;
 198         return byte;
 199 }
 200
 201 /* Encode 'dst_reg' register into x86-64 opcode 'byte' */
 202 static u8 add_1reg(u8 byte, u32 dst_reg)
 203 {
 204         return byte + reg2hex[dst_reg];
 205 }
 206
 207 /* Encode 'dst_reg' and 'src_reg' registers into x86-64 opcode 'byte' */
 208 static u8 add_2reg(u8 byte, u32 dst_reg, u32 src_reg)
 209 {
 210         return byte + reg2hex[dst_reg] + (reg2hex[src_reg] << 3);
 211 }
 212
 213 /* Some 1-byte opcodes for binary ALU operations */
 214 static u8 simple_alu_opcodes[] = {
 215         [BPF_ADD] = 0x01,
 216         [BPF_SUB] = 0x29,
 217         [BPF_AND] = 0x21,
 218         [BPF_OR] = 0x09,
 219         [BPF_XOR] = 0x31,
 220         [BPF_LSH] = 0xE0,
 221         [BPF_RSH] = 0xE8,
 222         [BPF_ARSH] = 0xF8,
 223 };
 224
 225 static void jit_fill_hole(void *area, unsigned int size)
 226 {
 227         /* Fill whole space with INT3 instructions */
 228         memset(area, 0xcc, size);
 229 }
 230
 231 int bpf_arch_text_invalidate(void *dst, size_t len)
 232 {
 233         return IS_ERR_OR_NULL(text_poke_set(dst, 0xcc, len));
 234 }
 235
 236 struct jit_context {
 237         int cleanup_addr; /* Epilogue code offset */
 238
 239         /*
 240          * Program specific offsets of labels in the code; these rely on the
 241          * JIT doing at least 2 passes, recording the position on the first
 242          * pass, only to generate the correct offset on the second pass.
 243          */
 244         int tail_call_direct_label;
 245         int tail_call_indirect_label;
 246 };
 247
 248 /* Maximum number of bytes emitted while JITing one eBPF insn */
 249 #define BPF_MAX_INSN_SIZE       128
 250 #define BPF_INSN_SAFETY         64
 251
 252 /* Number of bytes emit_patch() needs to generate instructions */
 253 #define X86_PATCH_SIZE          5
 254 /* Number of bytes that will be skipped on tailcall */
 255 #define X86_TAIL_CALL_OFFSET    (11 + ENDBR_INSN_SIZE)
 256
 257 static void push_callee_regs(u8 **pprog, bool *callee_regs_used)
 258 {
 259         u8 *prog = *pprog;
 260
 261         if (callee_regs_used[0])
 262                 EMIT1(0x53);         /* push rbx */
 263         if (callee_regs_used[1])
 264                 EMIT2(0x41, 0x55);   /* push r13 */
 265         if (callee_regs_used[2])
 266                 EMIT2(0x41, 0x56);   /* push r14 */
 267         if (callee_regs_used[3])
 268                 EMIT2(0x41, 0x57);   /* push r15 */
 269         *pprog = prog;
 270 }
 271
 272 static void pop_callee_regs(u8 **pprog, bool *callee_regs_used)
 273 {
 274         u8 *prog = *pprog;
 275
 276         if (callee_regs_used[3])
 277                 EMIT2(0x41, 0x5F);   /* pop r15 */
 278         if (callee_regs_used[2])
 279                 EMIT2(0x41, 0x5E);   /* pop r14 */
 280         if (callee_regs_used[1])
 281                 EMIT2(0x41, 0x5D);   /* pop r13 */
 282         if (callee_regs_used[0])
 283                 EMIT1(0x5B);         /* pop rbx */
 284         *pprog = prog;
 285 }
 286
 287 /*
 288  * Emit x86-64 prologue code for BPF program.
 289  * bpf_tail_call helper will skip the first X86_TAIL_CALL_OFFSET bytes
 290  * while jumping to another program
 291  */
 292 static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf,
 293                           bool tail_call_reachable, bool is_subprog)
 294 {
 295         u8 *prog = *pprog;
 296
 297         /* BPF trampoline can be made to work without these nops,
 298          * but let's waste 5 bytes for now and optimize later
 299          */
 300         EMIT_ENDBR();
 301         memcpy(prog, x86_nops[5], X86_PATCH_SIZE);
 302         prog += X86_PATCH_SIZE;
 303         if (!ebpf_from_cbpf) {
 304                 if (tail_call_reachable && !is_subprog)
 305                         EMIT2(0x31, 0xC0); /* xor eax, eax */
 306                 else
 307                         EMIT2(0x66, 0x90); /* nop2 */
 308         }
 309         EMIT1(0x55);             /* push rbp */
 310         EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */
 311
 312         /* X86_TAIL_CALL_OFFSET is here */
 313         EMIT_ENDBR();
 314
 315         /* sub rsp, rounded_stack_depth */
 316         if (stack_depth)
 317                 EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8));
 318         if (tail_call_reachable)
 319                 EMIT1(0x50);         /* push rax */
 320         *pprog = prog;
 321 }
 322
 323 static int emit_patch(u8 **pprog, void *func, void *ip, u8 opcode)
 324 {
 325         u8 *prog = *pprog;
 326         s64 offset;
 327
 328         offset = func - (ip + X86_PATCH_SIZE);
 329         if (!is_simm32(offset)) {
 330                 pr_err("Target call %p is out of range\n", func);
 331                 return -ERANGE;
 332         }
 333         EMIT1_off32(opcode, offset);
 334         *pprog = prog;
 335         return 0;
 336 }
 337
 338 static int emit_call(u8 **pprog, void *func, void *ip)
 339 {
 340         return emit_patch(pprog, func, ip, 0xE8);
 341 }
 342
 343 static int emit_jump(u8 **pprog, void *func, void *ip)
 344 {
 345         return emit_patch(pprog, func, ip, 0xE9);
 346 }
 347
 348 static int __bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
 349                                 void *old_addr, void *new_addr)
 350 {
 351         const u8 *nop_insn = x86_nops[5];
 352         u8 old_insn[X86_PATCH_SIZE];
 353         u8 new_insn[X86_PATCH_SIZE];
 354         u8 *prog;
 355         int ret;
 356
 357         memcpy(old_insn, nop_insn, X86_PATCH_SIZE);
 358         if (old_addr) {
 359                 prog = old_insn;
 360                 ret = t == BPF_MOD_CALL ?
 361                       emit_call(&prog, old_addr, ip) :
 362                       emit_jump(&prog, old_addr, ip);
 363                 if (ret)
 364                         return ret;
 365         }
 366
 367         memcpy(new_insn, nop_insn, X86_PATCH_SIZE);
 368         if (new_addr) {
 369                 prog = new_insn;
 370                 ret = t == BPF_MOD_CALL ?
 371                       emit_call(&prog, new_addr, ip) :
 372                       emit_jump(&prog, new_addr, ip);
 373                 if (ret)
 374                         return ret;
 375         }
 376
 377         ret = -EBUSY;
 378         mutex_lock(&text_mutex);
 379         if (memcmp(ip, old_insn, X86_PATCH_SIZE))
 380                 goto out;
 381         ret = 1;
 382         if (memcmp(ip, new_insn, X86_PATCH_SIZE)) {
 383                 text_poke_bp(ip, new_insn, X86_PATCH_SIZE, NULL);
 384                 ret = 0;
 385         }
 386 out:
 387         mutex_unlock(&text_mutex);
 388         return ret;
 389 }
 390
 391 int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
 392                        void *old_addr, void *new_addr)
 393 {
 394         if (!is_kernel_text((long)ip) &&
 395             !is_bpf_text_address((long)ip))
 396                 /* BPF poking in modules is not supported */
 397                 return -EINVAL;
 398
 399         /*
 400          * See emit_prologue(), for IBT builds the trampoline hook is preceded
 401          * with an ENDBR instruction.
 402          */
 403         if (is_endbr(*(u32 *)ip))
 404                 ip += ENDBR_INSN_SIZE;
 405
 406         return __bpf_arch_text_poke(ip, t, old_addr, new_addr);
 407 }
 408
 409 #define EMIT_LFENCE()   EMIT3(0x0F, 0xAE, 0xE8)
 410
 411 static void emit_indirect_jump(u8 **pprog, int reg, u8 *ip)
 412 {
 413         u8 *prog = *pprog;
 414
 415 #ifdef CONFIG_RETPOLINE
 416         if (cpu_feature_enabled(X86_FEATURE_RETPOLINE_LFENCE)) {
 417                 EMIT_LFENCE();
 418                 EMIT2(0xFF, 0xE0 + reg);
 419         } else if (cpu_feature_enabled(X86_FEATURE_RETPOLINE)) {
 420                 OPTIMIZER_HIDE_VAR(reg);
 421                 emit_jump(&prog, &__x86_indirect_thunk_array[reg], ip);
 422         } else
 423 #endif
 424         EMIT2(0xFF, 0xE0 + reg);
 425
 426         *pprog = prog;
 427 }
 428
 429 /*
 430  * Generate the following code:
 431  *
 432  * ... bpf_tail_call(void *ctx, struct bpf_array *array, u64 index) ...
 433  *   if (index >= array->map.max_entries)
 434  *     goto out;
 435  *   if (tail_call_cnt++ >= MAX_TAIL_CALL_CNT)
 436  *     goto out;
 437  *   prog = array->ptrs[index];
 438  *   if (prog == NULL)
 439  *     goto out;
 440  *   goto *(prog->bpf_func + prologue_size);
 441  * out:
 442  */
 443 static void emit_bpf_tail_call_indirect(u8 **pprog, bool *callee_regs_used,
 444                                         u32 stack_depth, u8 *ip,
 445                                         struct jit_context *ctx)
 446 {
 447         int tcc_off = -4 - round_up(stack_depth, 8);
 448         u8 *prog = *pprog, *start = *pprog;
 449         int offset;
 450
 451         /*
 452          * rdi - pointer to ctx
 453          * rsi - pointer to bpf_array
 454          * rdx - index in bpf_array
 455          */
 456
 457         /*
 458          * if (index >= array->map.max_entries)
 459          *      goto out;
 460          */
 461         EMIT2(0x89, 0xD2);                        /* mov edx, edx */
 462         EMIT3(0x39, 0x56,                         /* cmp dword ptr [rsi + 16], edx */
 463               offsetof(struct bpf_array, map.max_entries));
 464
 465         offset = ctx->tail_call_indirect_label - (prog + 2 - start);
 466         EMIT2(X86_JBE, offset);                   /* jbe out */
 467
 468         /*
 469          * if (tail_call_cnt++ >= MAX_TAIL_CALL_CNT)
 470          *      goto out;
 471          */
 472         EMIT2_off32(0x8B, 0x85, tcc_off);         /* mov eax, dword ptr [rbp - tcc_off] */
 473         EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT);     /* cmp eax, MAX_TAIL_CALL_CNT */
 474
 475         offset = ctx->tail_call_indirect_label - (prog + 2 - start);
 476         EMIT2(X86_JAE, offset);                   /* jae out */
 477         EMIT3(0x83, 0xC0, 0x01);                  /* add eax, 1 */
 478         EMIT2_off32(0x89, 0x85, tcc_off);         /* mov dword ptr [rbp - tcc_off], eax */
 479
 480         /* prog = array->ptrs[index]; */
 481         EMIT4_off32(0x48, 0x8B, 0x8C, 0xD6,       /* mov rcx, [rsi + rdx * 8 + offsetof(...)] */
 482                     offsetof(struct bpf_array, ptrs));
 483
 484         /*
 485          * if (prog == NULL)
 486          *      goto out;
 487          */
 488         EMIT3(0x48, 0x85, 0xC9);                  /* test rcx,rcx */
 489
 490         offset = ctx->tail_call_indirect_label - (prog + 2 - start);
 491         EMIT2(X86_JE, offset);                    /* je out */
 492
 493         pop_callee_regs(&prog, callee_regs_used);
 494
 495         EMIT1(0x58);                              /* pop rax */
 496         if (stack_depth)
 497                 EMIT3_off32(0x48, 0x81, 0xC4,     /* add rsp, sd */
 498                             round_up(stack_depth, 8));
 499
 500         /* goto *(prog->bpf_func + X86_TAIL_CALL_OFFSET); */
 501         EMIT4(0x48, 0x8B, 0x49,                   /* mov rcx, qword ptr [rcx + 32] */
 502               offsetof(struct bpf_prog, bpf_func));
 503         EMIT4(0x48, 0x83, 0xC1,                   /* add rcx, X86_TAIL_CALL_OFFSET */
 504               X86_TAIL_CALL_OFFSET);
 505         /*
 506          * Now we're ready to jump into next BPF program
 507          * rdi == ctx (1st arg)
 508          * rcx == prog->bpf_func + X86_TAIL_CALL_OFFSET
 509          */
 510         emit_indirect_jump(&prog, 1 /* rcx */, ip + (prog - start));
 511
 512         /* out: */
 513         ctx->tail_call_indirect_label = prog - start;
 514         *pprog = prog;
 515 }
 516
 517 static void emit_bpf_tail_call_direct(struct bpf_jit_poke_descriptor *poke,
 518                                       u8 **pprog, u8 *ip,
 519                                       bool *callee_regs_used, u32 stack_depth,
 520                                       struct jit_context *ctx)
 521 {
 522         int tcc_off = -4 - round_up(stack_depth, 8);
 523         u8 *prog = *pprog, *start = *pprog;
 524         int offset;
 525
 526         /*
 527          * if (tail_call_cnt++ >= MAX_TAIL_CALL_CNT)
 528          *      goto out;
 529          */
 530         EMIT2_off32(0x8B, 0x85, tcc_off);             /* mov eax, dword ptr [rbp - tcc_off] */
 531         EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT);         /* cmp eax, MAX_TAIL_CALL_CNT */
 532
 533         offset = ctx->tail_call_direct_label - (prog + 2 - start);
 534         EMIT2(X86_JAE, offset);                       /* jae out */
 535         EMIT3(0x83, 0xC0, 0x01);                      /* add eax, 1 */
 536         EMIT2_off32(0x89, 0x85, tcc_off);             /* mov dword ptr [rbp - tcc_off], eax */
 537
 538         poke->tailcall_bypass = ip + (prog - start);
 539         poke->adj_off = X86_TAIL_CALL_OFFSET;
 540         poke->tailcall_target = ip + ctx->tail_call_direct_label - X86_PATCH_SIZE;
 541         poke->bypass_addr = (u8 *)poke->tailcall_target + X86_PATCH_SIZE;
 542
 543         emit_jump(&prog, (u8 *)poke->tailcall_target + X86_PATCH_SIZE,
 544                   poke->tailcall_bypass);
 545
 546         pop_callee_regs(&prog, callee_regs_used);
 547         EMIT1(0x58);                                  /* pop rax */
 548         if (stack_depth)
 549                 EMIT3_off32(0x48, 0x81, 0xC4, round_up(stack_depth, 8));
 550
 551         memcpy(prog, x86_nops[5], X86_PATCH_SIZE);
 552         prog += X86_PATCH_SIZE;
 553
 554         /* out: */
 555         ctx->tail_call_direct_label = prog - start;
 556
 557         *pprog = prog;
 558 }
 559
 560 static void bpf_tail_call_direct_fixup(struct bpf_prog *prog)
 561 {
 562         struct bpf_jit_poke_descriptor *poke;
 563         struct bpf_array *array;
 564         struct bpf_prog *target;
 565         int i, ret;
 566
 567         for (i = 0; i < prog->aux->size_poke_tab; i++) {
 568                 poke = &prog->aux->poke_tab[i];
 569                 if (poke->aux && poke->aux != prog->aux)
 570                         continue;
 571
 572                 WARN_ON_ONCE(READ_ONCE(poke->tailcall_target_stable));
 573
 574                 if (poke->reason != BPF_POKE_REASON_TAIL_CALL)
 575                         continue;
 576
 577                 array = container_of(poke->tail_call.map, struct bpf_array, map);
 578                 mutex_lock(&array->aux->poke_mutex);
 579                 target = array->ptrs[poke->tail_call.key];
 580                 if (target) {
 581                         ret = __bpf_arch_text_poke(poke->tailcall_target,
 582                                                    BPF_MOD_JUMP, NULL,
 583                                                    (u8 *)target->bpf_func +
 584                                                    poke->adj_off);
 585                         BUG_ON(ret < 0);
 586                         ret = __bpf_arch_text_poke(poke->tailcall_bypass,
 587                                                    BPF_MOD_JUMP,
 588                                                    (u8 *)poke->tailcall_target +
 589                                                    X86_PATCH_SIZE, NULL);
 590                         BUG_ON(ret < 0);
 591                 }
 592                 WRITE_ONCE(poke->tailcall_target_stable, true);
 593                 mutex_unlock(&array->aux->poke_mutex);
 594         }
 595 }
 596
 597 static void emit_mov_imm32(u8 **pprog, bool sign_propagate,
 598                            u32 dst_reg, const u32 imm32)
 599 {
 600         u8 *prog = *pprog;
 601         u8 b1, b2, b3;
 602
 603         /*
 604          * Optimization: if imm32 is positive, use 'mov %eax, imm32'
 605          * (which zero-extends imm32) to save 2 bytes.
 606          */
 607         if (sign_propagate && (s32)imm32 < 0) {
 608                 /* 'mov %rax, imm32' sign extends imm32 */
 609                 b1 = add_1mod(0x48, dst_reg);
 610                 b2 = 0xC7;
 611                 b3 = 0xC0;
 612                 EMIT3_off32(b1, b2, add_1reg(b3, dst_reg), imm32);
 613                 goto done;
 614         }
 615
 616         /*
 617          * Optimization: if imm32 is zero, use 'xor %eax, %eax'
 618          * to save 3 bytes.
 619          */
 620         if (imm32 == 0) {
 621                 if (is_ereg(dst_reg))
 622                         EMIT1(add_2mod(0x40, dst_reg, dst_reg));
 623                 b2 = 0x31; /* xor */
 624                 b3 = 0xC0;
 625                 EMIT2(b2, add_2reg(b3, dst_reg, dst_reg));
 626                 goto done;
 627         }
 628
 629         /* mov %eax, imm32 */
 630         if (is_ereg(dst_reg))
 631                 EMIT1(add_1mod(0x40, dst_reg));
 632         EMIT1_off32(add_1reg(0xB8, dst_reg), imm32);
 633 done:
 634         *pprog = prog;
 635 }
 636
 637 static void emit_mov_imm64(u8 **pprog, u32 dst_reg,
 638                            const u32 imm32_hi, const u32 imm32_lo)
 639 {
 640         u8 *prog = *pprog;
 641
 642         if (is_uimm32(((u64)imm32_hi << 32) | (u32)imm32_lo)) {
 643                 /*
 644                  * For emitting plain u32, where sign bit must not be
 645                  * propagated LLVM tends to load imm64 over mov32
 646                  * directly, so save couple of bytes by just doing
 647                  * 'mov %eax, imm32' instead.
 648                  */
 649                 emit_mov_imm32(&prog, false, dst_reg, imm32_lo);
 650         } else {
 651                 /* movabsq %rax, imm64 */
 652                 EMIT2(add_1mod(0x48, dst_reg), add_1reg(0xB8, dst_reg));
 653                 EMIT(imm32_lo, 4);
 654                 EMIT(imm32_hi, 4);
 655         }
 656
 657         *pprog = prog;
 658 }
 659
 660 static void emit_mov_reg(u8 **pprog, bool is64, u32 dst_reg, u32 src_reg)
 661 {
 662         u8 *prog = *pprog;
 663
 664         if (is64) {
 665                 /* mov dst, src */
 666                 EMIT_mov(dst_reg, src_reg);
 667         } else {
 668                 /* mov32 dst, src */
 669                 if (is_ereg(dst_reg) || is_ereg(src_reg))
 670                         EMIT1(add_2mod(0x40, dst_reg, src_reg));
 671                 EMIT2(0x89, add_2reg(0xC0, dst_reg, src_reg));
 672         }
 673
 674         *pprog = prog;
 675 }
 676
 677 /* Emit the suffix (ModR/M etc) for addressing *(ptr_reg + off) and val_reg */
 678 static void emit_insn_suffix(u8 **pprog, u32 ptr_reg, u32 val_reg, int off)
 679 {
 680         u8 *prog = *pprog;
 681
 682         if (is_imm8(off)) {
 683                 /* 1-byte signed displacement.
 684                  *
 685                  * If off == 0 we could skip this and save one extra byte, but
 686                  * special case of x86 R13 which always needs an offset is not
 687                  * worth the hassle
 688                  */
 689                 EMIT2(add_2reg(0x40, ptr_reg, val_reg), off);
 690         } else {
 691                 /* 4-byte signed displacement */
 692                 EMIT1_off32(add_2reg(0x80, ptr_reg, val_reg), off);
 693         }
 694         *pprog = prog;
 695 }
 696
 697 /*
 698  * Emit a REX byte if it will be necessary to address these registers
 699  */
 700 static void maybe_emit_mod(u8 **pprog, u32 dst_reg, u32 src_reg, bool is64)
 701 {
 702         u8 *prog = *pprog;
 703
 704         if (is64)
 705                 EMIT1(add_2mod(0x48, dst_reg, src_reg));
 706         else if (is_ereg(dst_reg) || is_ereg(src_reg))
 707                 EMIT1(add_2mod(0x40, dst_reg, src_reg));
 708         *pprog = prog;
 709 }
 710
 711 /*
 712  * Similar version of maybe_emit_mod() for a single register
 713  */
 714 static void maybe_emit_1mod(u8 **pprog, u32 reg, bool is64)
 715 {
 716         u8 *prog = *pprog;
 717
 718         if (is64)
 719                 EMIT1(add_1mod(0x48, reg));
 720         else if (is_ereg(reg))
 721                 EMIT1(add_1mod(0x40, reg));
 722         *pprog = prog;
 723 }
 724
 725 /* LDX: dst_reg = *(u8*)(src_reg + off) */
 726 static void emit_ldx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off)
 727 {
 728         u8 *prog = *pprog;
 729
 730         switch (size) {
 731         case BPF_B:
 732                 /* Emit 'movzx rax, byte ptr [rax + off]' */
 733                 EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB6);
 734                 break;
 735         case BPF_H:
 736                 /* Emit 'movzx rax, word ptr [rax + off]' */
 737                 EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB7);
 738                 break;
 739         case BPF_W:
 740                 /* Emit 'mov eax, dword ptr [rax+0x14]' */
 741                 if (is_ereg(dst_reg) || is_ereg(src_reg))
 742                         EMIT2(add_2mod(0x40, src_reg, dst_reg), 0x8B);
 743                 else
 744                         EMIT1(0x8B);
 745                 break;
 746         case BPF_DW:
 747                 /* Emit 'mov rax, qword ptr [rax+0x14]' */
 748                 EMIT2(add_2mod(0x48, src_reg, dst_reg), 0x8B);
 749                 break;
 750         }
 751         emit_insn_suffix(&prog, src_reg, dst_reg, off);
 752         *pprog = prog;
 753 }
 754
 755 /* STX: *(u8*)(dst_reg + off) = src_reg */
 756 static void emit_stx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off)
 757 {
 758         u8 *prog = *pprog;
 759
 760         switch (size) {
 761         case BPF_B:
 762                 /* Emit 'mov byte ptr [rax + off], al' */
 763                 if (is_ereg(dst_reg) || is_ereg_8l(src_reg))
 764                         /* Add extra byte for eregs or SIL,DIL,BPL in src_reg */
 765                         EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x88);
 766                 else
 767                         EMIT1(0x88);
 768                 break;
 769         case BPF_H:
 770                 if (is_ereg(dst_reg) || is_ereg(src_reg))
 771                         EMIT3(0x66, add_2mod(0x40, dst_reg, src_reg), 0x89);
 772                 else
 773                         EMIT2(0x66, 0x89);
 774                 break;
 775         case BPF_W:
 776                 if (is_ereg(dst_reg) || is_ereg(src_reg))
 777                         EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x89);
 778                 else
 779                         EMIT1(0x89);
 780                 break;
 781         case BPF_DW:
 782                 EMIT2(add_2mod(0x48, dst_reg, src_reg), 0x89);
 783                 break;
 784         }
 785         emit_insn_suffix(&prog, dst_reg, src_reg, off);
 786         *pprog = prog;
 787 }
 788
 789 static int emit_atomic(u8 **pprog, u8 atomic_op,
 790                        u32 dst_reg, u32 src_reg, s16 off, u8 bpf_size)
 791 {
 792         u8 *prog = *pprog;
 793
 794         EMIT1(0xF0); /* lock prefix */
 795
 796         maybe_emit_mod(&prog, dst_reg, src_reg, bpf_size == BPF_DW);
 797
 798         /* emit opcode */
 799         switch (atomic_op) {
 800         case BPF_ADD:
 801         case BPF_AND:
 802         case BPF_OR:
 803         case BPF_XOR:
 804                 /* lock *(u32/u64*)(dst_reg + off) <op>= src_reg */
 805                 EMIT1(simple_alu_opcodes[atomic_op]);
 806                 break;
 807         case BPF_ADD | BPF_FETCH:
 808                 /* src_reg = atomic_fetch_add(dst_reg + off, src_reg); */
 809                 EMIT2(0x0F, 0xC1);
 810                 break;
 811         case BPF_XCHG:
 812                 /* src_reg = atomic_xchg(dst_reg + off, src_reg); */
 813                 EMIT1(0x87);
 814                 break;
 815         case BPF_CMPXCHG:
 816                 /* r0 = atomic_cmpxchg(dst_reg + off, r0, src_reg); */
 817                 EMIT2(0x0F, 0xB1);
 818                 break;
 819         default:
 820                 pr_err("bpf_jit: unknown atomic opcode %02x\n", atomic_op);
 821                 return -EFAULT;
 822         }
 823
 824         emit_insn_suffix(&prog, dst_reg, src_reg, off);
 825
 826         *pprog = prog;
 827         return 0;
 828 }
 829
 830 bool ex_handler_bpf(const struct exception_table_entry *x, struct pt_regs *regs)
 831 {
 832         u32 reg = x->fixup >> 8;
 833
 834         /* jump over faulting load and clear dest register */
 835         *(unsigned long *)((void *)regs + reg) = 0;
 836         regs->ip += x->fixup & 0xff;
 837         return true;
 838 }
 839
 840 static void detect_reg_usage(struct bpf_insn *insn, int insn_cnt,
 841                              bool *regs_used, bool *tail_call_seen)
 842 {
 843         int i;
 844
 845         for (i = 1; i <= insn_cnt; i++, insn++) {
 846                 if (insn->code == (BPF_JMP | BPF_TAIL_CALL))
 847                         *tail_call_seen = true;
 848                 if (insn->dst_reg == BPF_REG_6 || insn->src_reg == BPF_REG_6)
 849                         regs_used[0] = true;
 850                 if (insn->dst_reg == BPF_REG_7 || insn->src_reg == BPF_REG_7)
 851                         regs_used[1] = true;
 852                 if (insn->dst_reg == BPF_REG_8 || insn->src_reg == BPF_REG_8)
 853                         regs_used[2] = true;
 854                 if (insn->dst_reg == BPF_REG_9 || insn->src_reg == BPF_REG_9)
 855                         regs_used[3] = true;
 856         }
 857 }
 858
 859 static void emit_nops(u8 **pprog, int len)
 860 {
 861         u8 *prog = *pprog;
 862         int i, noplen;
 863
 864         while (len > 0) {
 865                 noplen = len;
 866
 867                 if (noplen > ASM_NOP_MAX)
 868                         noplen = ASM_NOP_MAX;
 869
 870                 for (i = 0; i < noplen; i++)
 871                         EMIT1(x86_nops[noplen][i]);
 872                 len -= noplen;
 873         }
 874
 875         *pprog = prog;
 876 }
 877
 878 #define INSN_SZ_DIFF (((addrs[i] - addrs[i - 1]) - (prog - temp)))
 879
 880 static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image,
 881                   int oldproglen, struct jit_context *ctx, bool jmp_padding)
 882 {
 883         bool tail_call_reachable = bpf_prog->aux->tail_call_reachable;
 884         struct bpf_insn *insn = bpf_prog->insnsi;
 885         bool callee_regs_used[4] = {};
 886         int insn_cnt = bpf_prog->len;
 887         bool tail_call_seen = false;
 888         bool seen_exit = false;
 889         u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY];
 890         int i, excnt = 0;
 891         int ilen, proglen = 0;
 892         u8 *prog = temp;
 893         int err;
 894
 895         detect_reg_usage(insn, insn_cnt, callee_regs_used,
 896                          &tail_call_seen);
 897
 898         /* tail call's presence in current prog implies it is reachable */
 899         tail_call_reachable |= tail_call_seen;
 900
 901         emit_prologue(&prog, bpf_prog->aux->stack_depth,
 902                       bpf_prog_was_classic(bpf_prog), tail_call_reachable,
 903                       bpf_prog->aux->func_idx != 0);
 904         push_callee_regs(&prog, callee_regs_used);
 905
 906         ilen = prog - temp;
 907         if (rw_image)
 908                 memcpy(rw_image + proglen, temp, ilen);
 909         proglen += ilen;
 910         addrs[0] = proglen;
 911         prog = temp;
 912
 913         for (i = 1; i <= insn_cnt; i++, insn++) {
 914                 const s32 imm32 = insn->imm;
 915                 u32 dst_reg = insn->dst_reg;
 916                 u32 src_reg = insn->src_reg;
 917                 u8 b2 = 0, b3 = 0;
 918                 u8 *start_of_ldx;
 919                 s64 jmp_offset;
 920                 u8 jmp_cond;
 921                 u8 *func;
 922                 int nops;
 923
 924                 switch (insn->code) {
 925                         /* ALU */
 926                 case BPF_ALU | BPF_ADD | BPF_X:
 927                 case BPF_ALU | BPF_SUB | BPF_X:
 928                 case BPF_ALU | BPF_AND | BPF_X:
 929                 case BPF_ALU | BPF_OR | BPF_X:
 930                 case BPF_ALU | BPF_XOR | BPF_X:
 931                 case BPF_ALU64 | BPF_ADD | BPF_X:
 932                 case BPF_ALU64 | BPF_SUB | BPF_X:
 933                 case BPF_ALU64 | BPF_AND | BPF_X:
 934                 case BPF_ALU64 | BPF_OR | BPF_X:
 935                 case BPF_ALU64 | BPF_XOR | BPF_X:
 936                         maybe_emit_mod(&prog, dst_reg, src_reg,
 937                                        BPF_CLASS(insn->code) == BPF_ALU64);
 938                         b2 = simple_alu_opcodes[BPF_OP(insn->code)];
 939                         EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg));
 940                         break;
 941
 942                 case BPF_ALU64 | BPF_MOV | BPF_X:
 943                 case BPF_ALU | BPF_MOV | BPF_X:
 944                         emit_mov_reg(&prog,
 945                                      BPF_CLASS(insn->code) == BPF_ALU64,
 946                                      dst_reg, src_reg);
 947                         break;
 948
 949                         /* neg dst */
 950                 case BPF_ALU | BPF_NEG:
 951                 case BPF_ALU64 | BPF_NEG:
 952                         maybe_emit_1mod(&prog, dst_reg,
 953                                         BPF_CLASS(insn->code) == BPF_ALU64);
 954                         EMIT2(0xF7, add_1reg(0xD8, dst_reg));
 955                         break;
 956
 957                 case BPF_ALU | BPF_ADD | BPF_K:
 958                 case BPF_ALU | BPF_SUB | BPF_K:
 959                 case BPF_ALU | BPF_AND | BPF_K:
 960                 case BPF_ALU | BPF_OR | BPF_K:
 961                 case BPF_ALU | BPF_XOR | BPF_K:
 962                 case BPF_ALU64 | BPF_ADD | BPF_K:
 963                 case BPF_ALU64 | BPF_SUB | BPF_K:
 964                 case BPF_ALU64 | BPF_AND | BPF_K:
 965                 case BPF_ALU64 | BPF_OR | BPF_K:
 966                 case BPF_ALU64 | BPF_XOR | BPF_K:
 967                         maybe_emit_1mod(&prog, dst_reg,
 968                                         BPF_CLASS(insn->code) == BPF_ALU64);
 969
 970                         /*
 971                          * b3 holds 'normal' opcode, b2 short form only valid
 972                          * in case dst is eax/rax.
 973                          */
 974                         switch (BPF_OP(insn->code)) {
 975                         case BPF_ADD:
 976                                 b3 = 0xC0;
 977                                 b2 = 0x05;
 978                                 break;
 979                         case BPF_SUB:
 980                                 b3 = 0xE8;
 981                                 b2 = 0x2D;
 982                                 break;
 983                         case BPF_AND:
 984                                 b3 = 0xE0;
 985                                 b2 = 0x25;
 986                                 break;
 987                         case BPF_OR:
 988                                 b3 = 0xC8;
 989                                 b2 = 0x0D;
 990                                 break;
 991                         case BPF_XOR:
 992                                 b3 = 0xF0;
 993                                 b2 = 0x35;
 994                                 break;
 995                         }
 996
 997                         if (is_imm8(imm32))
 998                                 EMIT3(0x83, add_1reg(b3, dst_reg), imm32);
 999                         else if (is_axreg(dst_reg))
1000                                 EMIT1_off32(b2, imm32);
1001                         else
1002                                 EMIT2_off32(0x81, add_1reg(b3, dst_reg), imm32);
1003                         break;
1004
1005                 case BPF_ALU64 | BPF_MOV | BPF_K:
1006                 case BPF_ALU | BPF_MOV | BPF_K:
1007                         emit_mov_imm32(&prog, BPF_CLASS(insn->code) == BPF_ALU64,
1008                                        dst_reg, imm32);
1009                         break;
1010
1011                 case BPF_LD | BPF_IMM | BPF_DW:
1012                         emit_mov_imm64(&prog, dst_reg, insn[1].imm, insn[0].imm);
1013                         insn++;
1014                         i++;
1015                         break;
1016
1017                         /* dst %= src, dst /= src, dst %= imm32, dst /= imm32 */
1018                 case BPF_ALU | BPF_MOD | BPF_X:
1019                 case BPF_ALU | BPF_DIV | BPF_X:
1020                 case BPF_ALU | BPF_MOD | BPF_K:
1021                 case BPF_ALU | BPF_DIV | BPF_K:
1022                 case BPF_ALU64 | BPF_MOD | BPF_X:
1023                 case BPF_ALU64 | BPF_DIV | BPF_X:
1024                 case BPF_ALU64 | BPF_MOD | BPF_K:
1025                 case BPF_ALU64 | BPF_DIV | BPF_K: {
1026                         bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
1027
1028                         if (dst_reg != BPF_REG_0)
1029                                 EMIT1(0x50); /* push rax */
1030                         if (dst_reg != BPF_REG_3)
1031                                 EMIT1(0x52); /* push rdx */
1032
1033                         if (BPF_SRC(insn->code) == BPF_X) {
1034                                 if (src_reg == BPF_REG_0 ||
1035                                     src_reg == BPF_REG_3) {
1036                                         /* mov r11, src_reg */
1037                                         EMIT_mov(AUX_REG, src_reg);
1038                                         src_reg = AUX_REG;
1039                                 }
1040                         } else {
1041                                 /* mov r11, imm32 */
1042                                 EMIT3_off32(0x49, 0xC7, 0xC3, imm32);
1043                                 src_reg = AUX_REG;
1044                         }
1045
1046                         if (dst_reg != BPF_REG_0)
1047                                 /* mov rax, dst_reg */
1048                                 emit_mov_reg(&prog, is64, BPF_REG_0, dst_reg);
1049
1050                         /*
1051                          * xor edx, edx
1052                          * equivalent to 'xor rdx, rdx', but one byte less
1053                          */
1054                         EMIT2(0x31, 0xd2);
1055
1056                         /* div src_reg */
1057                         maybe_emit_1mod(&prog, src_reg, is64);
1058                         EMIT2(0xF7, add_1reg(0xF0, src_reg));
1059
1060                         if (BPF_OP(insn->code) == BPF_MOD &&
1061                             dst_reg != BPF_REG_3)
1062                                 /* mov dst_reg, rdx */
1063                                 emit_mov_reg(&prog, is64, dst_reg, BPF_REG_3);
1064                         else if (BPF_OP(insn->code) == BPF_DIV &&
1065                                  dst_reg != BPF_REG_0)
1066                                 /* mov dst_reg, rax */
1067                                 emit_mov_reg(&prog, is64, dst_reg, BPF_REG_0);
1068
1069                         if (dst_reg != BPF_REG_3)
1070                                 EMIT1(0x5A); /* pop rdx */
1071                         if (dst_reg != BPF_REG_0)
1072                                 EMIT1(0x58); /* pop rax */
1073                         break;
1074                 }
1075
1076                 case BPF_ALU | BPF_MUL | BPF_K:
1077                 case BPF_ALU64 | BPF_MUL | BPF_K:
1078                         maybe_emit_mod(&prog, dst_reg, dst_reg,
1079                                        BPF_CLASS(insn->code) == BPF_ALU64);
1080
1081                         if (is_imm8(imm32))
1082                                 /* imul dst_reg, dst_reg, imm8 */
1083                                 EMIT3(0x6B, add_2reg(0xC0, dst_reg, dst_reg),
1084                                       imm32);
1085                         else
1086                                 /* imul dst_reg, dst_reg, imm32 */
1087                                 EMIT2_off32(0x69,
1088                                             add_2reg(0xC0, dst_reg, dst_reg),
1089                                             imm32);
1090                         break;
1091
1092                 case BPF_ALU | BPF_MUL | BPF_X:
1093                 case BPF_ALU64 | BPF_MUL | BPF_X:
1094                         maybe_emit_mod(&prog, src_reg, dst_reg,
1095                                        BPF_CLASS(insn->code) == BPF_ALU64);
1096
1097                         /* imul dst_reg, src_reg */
1098                         EMIT3(0x0F, 0xAF, add_2reg(0xC0, src_reg, dst_reg));
1099                         break;
1100
1101                         /* Shifts */
1102                 case BPF_ALU | BPF_LSH | BPF_K:
1103                 case BPF_ALU | BPF_RSH | BPF_K:
1104                 case BPF_ALU | BPF_ARSH | BPF_K:
1105                 case BPF_ALU64 | BPF_LSH | BPF_K:
1106                 case BPF_ALU64 | BPF_RSH | BPF_K:
1107                 case BPF_ALU64 | BPF_ARSH | BPF_K:
1108                         maybe_emit_1mod(&prog, dst_reg,
1109                                         BPF_CLASS(insn->code) == BPF_ALU64);
1110
1111                         b3 = simple_alu_opcodes[BPF_OP(insn->code)];
1112                         if (imm32 == 1)
1113                                 EMIT2(0xD1, add_1reg(b3, dst_reg));
1114                         else
1115                                 EMIT3(0xC1, add_1reg(b3, dst_reg), imm32);
1116                         break;
1117
1118                 case BPF_ALU | BPF_LSH | BPF_X:
1119                 case BPF_ALU | BPF_RSH | BPF_X:
1120                 case BPF_ALU | BPF_ARSH | BPF_X:
1121                 case BPF_ALU64 | BPF_LSH | BPF_X:
1122                 case BPF_ALU64 | BPF_RSH | BPF_X:
1123                 case BPF_ALU64 | BPF_ARSH | BPF_X:
1124
1125                         /* Check for bad case when dst_reg == rcx */
1126                         if (dst_reg == BPF_REG_4) {
1127                                 /* mov r11, dst_reg */
1128                                 EMIT_mov(AUX_REG, dst_reg);
1129                                 dst_reg = AUX_REG;
1130                         }
1131
1132                         if (src_reg != BPF_REG_4) { /* common case */
1133                                 EMIT1(0x51); /* push rcx */
1134
1135                                 /* mov rcx, src_reg */
1136                                 EMIT_mov(BPF_REG_4, src_reg);
1137                         }
1138
1139                         /* shl %rax, %cl | shr %rax, %cl | sar %rax, %cl */
1140                         maybe_emit_1mod(&prog, dst_reg,
1141                                         BPF_CLASS(insn->code) == BPF_ALU64);
1142
1143                         b3 = simple_alu_opcodes[BPF_OP(insn->code)];
1144                         EMIT2(0xD3, add_1reg(b3, dst_reg));
1145
1146                         if (src_reg != BPF_REG_4)
1147                                 EMIT1(0x59); /* pop rcx */
1148
1149                         if (insn->dst_reg == BPF_REG_4)
1150                                 /* mov dst_reg, r11 */
1151                                 EMIT_mov(insn->dst_reg, AUX_REG);
1152                         break;
1153
1154                 case BPF_ALU | BPF_END | BPF_FROM_BE:
1155                         switch (imm32) {
1156                         case 16:
1157                                 /* Emit 'ror %ax, 8' to swap lower 2 bytes */
1158                                 EMIT1(0x66);
1159                                 if (is_ereg(dst_reg))
1160                                         EMIT1(0x41);
1161                                 EMIT3(0xC1, add_1reg(0xC8, dst_reg), 8);
1162
1163                                 /* Emit 'movzwl eax, ax' */
1164                                 if (is_ereg(dst_reg))
1165                                         EMIT3(0x45, 0x0F, 0xB7);
1166                                 else
1167                                         EMIT2(0x0F, 0xB7);
1168                                 EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
1169                                 break;
1170                         case 32:
1171                                 /* Emit 'bswap eax' to swap lower 4 bytes */
1172                                 if (is_ereg(dst_reg))
1173                                         EMIT2(0x41, 0x0F);
1174                                 else
1175                                         EMIT1(0x0F);
1176                                 EMIT1(add_1reg(0xC8, dst_reg));
1177                                 break;
1178                         case 64:
1179                                 /* Emit 'bswap rax' to swap 8 bytes */
1180                                 EMIT3(add_1mod(0x48, dst_reg), 0x0F,
1181                                       add_1reg(0xC8, dst_reg));
1182                                 break;
1183                         }
1184                         break;
1185
1186                 case BPF_ALU | BPF_END | BPF_FROM_LE:
1187                         switch (imm32) {
1188                         case 16:
1189                                 /*
1190                                  * Emit 'movzwl eax, ax' to zero extend 16-bit
1191                                  * into 64 bit
1192                                  */
1193                                 if (is_ereg(dst_reg))
1194                                         EMIT3(0x45, 0x0F, 0xB7);
1195                                 else
1196                                         EMIT2(0x0F, 0xB7);
1197                                 EMIT1(add_2reg(0xC0, dst_reg, dst_reg));
1198                                 break;
1199                         case 32:
1200                                 /* Emit 'mov eax, eax' to clear upper 32-bits */
1201                                 if (is_ereg(dst_reg))
1202                                         EMIT1(0x45);
1203                                 EMIT2(0x89, add_2reg(0xC0, dst_reg, dst_reg));
1204                                 break;
1205                         case 64:
1206                                 /* nop */
1207                                 break;
1208                         }
1209                         break;
1210
1211                         /* speculation barrier */
1212                 case BPF_ST | BPF_NOSPEC:
1213                         if (boot_cpu_has(X86_FEATURE_XMM2))
1214                                 EMIT_LFENCE();
1215                         break;
1216
1217                         /* ST: *(u8*)(dst_reg + off) = imm */
1218                 case BPF_ST | BPF_MEM | BPF_B:
1219                         if (is_ereg(dst_reg))
1220                                 EMIT2(0x41, 0xC6);
1221                         else
1222                                 EMIT1(0xC6);
1223                         goto st;
1224                 case BPF_ST | BPF_MEM | BPF_H:
1225                         if (is_ereg(dst_reg))
1226                                 EMIT3(0x66, 0x41, 0xC7);
1227                         else
1228                                 EMIT2(0x66, 0xC7);
1229                         goto st;
1230                 case BPF_ST | BPF_MEM | BPF_W:
1231                         if (is_ereg(dst_reg))
1232                                 EMIT2(0x41, 0xC7);
1233                         else
1234                                 EMIT1(0xC7);
1235                         goto st;
1236                 case BPF_ST | BPF_MEM | BPF_DW:
1237                         EMIT2(add_1mod(0x48, dst_reg), 0xC7);
1238
1239 st:                     if (is_imm8(insn->off))
1240                                 EMIT2(add_1reg(0x40, dst_reg), insn->off);
1241                         else
1242                                 EMIT1_off32(add_1reg(0x80, dst_reg), insn->off);
1243
1244                         EMIT(imm32, bpf_size_to_x86_bytes(BPF_SIZE(insn->code)));
1245                         break;
1246
1247                         /* STX: *(u8*)(dst_reg + off) = src_reg */
1248                 case BPF_STX | BPF_MEM | BPF_B:
1249                 case BPF_STX | BPF_MEM | BPF_H:
1250                 case BPF_STX | BPF_MEM | BPF_W:
1251                 case BPF_STX | BPF_MEM | BPF_DW:
1252                         emit_stx(&prog, BPF_SIZE(insn->code), dst_reg, src_reg, insn->off);
1253                         break;
1254
1255                         /* LDX: dst_reg = *(u8*)(src_reg + off) */
1256                 case BPF_LDX | BPF_MEM | BPF_B:
1257                 case BPF_LDX | BPF_PROBE_MEM | BPF_B:
1258                 case BPF_LDX | BPF_MEM | BPF_H:
1259                 case BPF_LDX | BPF_PROBE_MEM | BPF_H:
1260                 case BPF_LDX | BPF_MEM | BPF_W:
1261                 case BPF_LDX | BPF_PROBE_MEM | BPF_W:
1262                 case BPF_LDX | BPF_MEM | BPF_DW:
1263                 case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
1264                         if (BPF_MODE(insn->code) == BPF_PROBE_MEM) {
1265                                 /* Though the verifier prevents negative insn->off in BPF_PROBE_MEM
1266                                  * add abs(insn->off) to the limit to make sure that negative
1267                                  * offset won't be an issue.
1268                                  * insn->off is s16, so it won't affect valid pointers.
1269                                  */
1270                                 u64 limit = TASK_SIZE_MAX + PAGE_SIZE + abs(insn->off);
1271                                 u8 *end_of_jmp1, *end_of_jmp2;
1272
1273                                 /* Conservatively check that src_reg + insn->off is a kernel address:
1274                                  * 1. src_reg + insn->off >= limit
1275                                  * 2. src_reg + insn->off doesn't become small positive.
1276                                  * Cannot do src_reg + insn->off >= limit in one branch,
1277                                  * since it needs two spare registers, but JIT has only one.
1278                                  */
1279
1280                                 /* movabsq r11, limit */
1281                                 EMIT2(add_1mod(0x48, AUX_REG), add_1reg(0xB8, AUX_REG));
1282                                 EMIT((u32)limit, 4);
1283                                 EMIT(limit >> 32, 4);
1284                                 /* cmp src_reg, r11 */
1285                                 maybe_emit_mod(&prog, src_reg, AUX_REG, true);
1286                                 EMIT2(0x39, add_2reg(0xC0, src_reg, AUX_REG));
1287                                 /* if unsigned '<' goto end_of_jmp2 */
1288                                 EMIT2(X86_JB, 0);
1289                                 end_of_jmp1 = prog;
1290
1291                                 /* mov r11, src_reg */
1292                                 emit_mov_reg(&prog, true, AUX_REG, src_reg);
1293                                 /* add r11, insn->off */
1294                                 maybe_emit_1mod(&prog, AUX_REG, true);
1295                                 EMIT2_off32(0x81, add_1reg(0xC0, AUX_REG), insn->off);
1296                                 /* jmp if not carry to start_of_ldx
1297                                  * Otherwise ERR_PTR(-EINVAL) + 128 will be the user addr
1298                                  * that has to be rejected.
1299                                  */
1300                                 EMIT2(0x73 /* JNC */, 0);
1301                                 end_of_jmp2 = prog;
1302
1303                                 /* xor dst_reg, dst_reg */
1304                                 emit_mov_imm32(&prog, false, dst_reg, 0);
1305                                 /* jmp byte_after_ldx */
1306                                 EMIT2(0xEB, 0);
1307
1308                                 /* populate jmp_offset for JB above to jump to xor dst_reg */
1309                                 end_of_jmp1[-1] = end_of_jmp2 - end_of_jmp1;
1310                                 /* populate jmp_offset for JNC above to jump to start_of_ldx */
1311                                 start_of_ldx = prog;
1312                                 end_of_jmp2[-1] = start_of_ldx - end_of_jmp2;
1313                         }
1314                         emit_ldx(&prog, BPF_SIZE(insn->code), dst_reg, src_reg, insn->off);
1315                         if (BPF_MODE(insn->code) == BPF_PROBE_MEM) {
1316                                 struct exception_table_entry *ex;
1317                                 u8 *_insn = image + proglen + (start_of_ldx - temp);
1318                                 s64 delta;
1319
1320                                 /* populate jmp_offset for JMP above */
1321                                 start_of_ldx[-1] = prog - start_of_ldx;
1322
1323                                 if (!bpf_prog->aux->extable)
1324                                         break;
1325
1326                                 if (excnt >= bpf_prog->aux->num_exentries) {
1327                                         pr_err("ex gen bug\n");
1328                                         return -EFAULT;
1329                                 }
1330                                 ex = &bpf_prog->aux->extable[excnt++];
1331
1332                                 delta = _insn - (u8 *)&ex->insn;
1333                                 if (!is_simm32(delta)) {
1334                                         pr_err("extable->insn doesn't fit into 32-bit\n");
1335                                         return -EFAULT;
1336                                 }
1337                                 /* switch ex to rw buffer for writes */
1338                                 ex = (void *)rw_image + ((void *)ex - (void *)image);
1339
1340                                 ex->insn = delta;
1341
1342                                 ex->data = EX_TYPE_BPF;
1343
1344                                 if (dst_reg > BPF_REG_9) {
1345                                         pr_err("verifier error\n");
1346                                         return -EFAULT;
1347                                 }
1348                                 /*
1349                                  * Compute size of x86 insn and its target dest x86 register.
1350                                  * ex_handler_bpf() will use lower 8 bits to adjust
1351                                  * pt_regs->ip to jump over this x86 instruction
1352                                  * and upper bits to figure out which pt_regs to zero out.
1353                                  * End result: x86 insn "mov rbx, qword ptr [rax+0x14]"
1354                                  * of 4 bytes will be ignored and rbx will be zero inited.
1355                                  */
1356                                 ex->fixup = (prog - start_of_ldx) | (reg2pt_regs[dst_reg] << 8);
1357                         }
1358                         break;
1359
1360                 case BPF_STX | BPF_ATOMIC | BPF_W:
1361                 case BPF_STX | BPF_ATOMIC | BPF_DW:
1362                         if (insn->imm == (BPF_AND | BPF_FETCH) ||
1363                             insn->imm == (BPF_OR | BPF_FETCH) ||
1364                             insn->imm == (BPF_XOR | BPF_FETCH)) {
1365                                 bool is64 = BPF_SIZE(insn->code) == BPF_DW;
1366                                 u32 real_src_reg = src_reg;
1367                                 u32 real_dst_reg = dst_reg;
1368                                 u8 *branch_target;
1369
1370                                 /*
1371                                  * Can't be implemented with a single x86 insn.
1372                                  * Need to do a CMPXCHG loop.
1373                                  */
1374
1375                                 /* Will need RAX as a CMPXCHG operand so save R0 */
1376                                 emit_mov_reg(&prog, true, BPF_REG_AX, BPF_REG_0);
1377                                 if (src_reg == BPF_REG_0)
1378                                         real_src_reg = BPF_REG_AX;
1379                                 if (dst_reg == BPF_REG_0)
1380                                         real_dst_reg = BPF_REG_AX;
1381
1382                                 branch_target = prog;
1383                                 /* Load old value */
1384                                 emit_ldx(&prog, BPF_SIZE(insn->code),
1385                                          BPF_REG_0, real_dst_reg, insn->off);
1386                                 /*
1387                                  * Perform the (commutative) operation locally,
1388                                  * put the result in the AUX_REG.
1389                                  */
1390                                 emit_mov_reg(&prog, is64, AUX_REG, BPF_REG_0);
1391                                 maybe_emit_mod(&prog, AUX_REG, real_src_reg, is64);
1392                                 EMIT2(simple_alu_opcodes[BPF_OP(insn->imm)],
1393                                       add_2reg(0xC0, AUX_REG, real_src_reg));
1394                                 /* Attempt to swap in new value */
1395                                 err = emit_atomic(&prog, BPF_CMPXCHG,
1396                                                   real_dst_reg, AUX_REG,
1397                                                   insn->off,
1398                                                   BPF_SIZE(insn->code));
1399                                 if (WARN_ON(err))
1400                                         return err;
1401                                 /*
1402                                  * ZF tells us whether we won the race. If it's
1403                                  * cleared we need to try again.
1404                                  */
1405                                 EMIT2(X86_JNE, -(prog - branch_target) - 2);
1406                                 /* Return the pre-modification value */
1407                                 emit_mov_reg(&prog, is64, real_src_reg, BPF_REG_0);
1408                                 /* Restore R0 after clobbering RAX */
1409                                 emit_mov_reg(&prog, true, BPF_REG_0, BPF_REG_AX);
1410                                 break;
1411                         }
1412
1413                         err = emit_atomic(&prog, insn->imm, dst_reg, src_reg,
1414                                           insn->off, BPF_SIZE(insn->code));
1415                         if (err)
1416                                 return err;
1417                         break;
1418
1419                         /* call */
1420                 case BPF_JMP | BPF_CALL:
1421                         func = (u8 *) __bpf_call_base + imm32;
1422                         if (tail_call_reachable) {
1423                                 EMIT3_off32(0x48, 0x8B, 0x85,
1424                                             -(bpf_prog->aux->stack_depth + 8));
1425                                 if (!imm32 || emit_call(&prog, func, image + addrs[i - 1] + 7))
1426                                         return -EINVAL;
1427                         } else {
1428                                 if (!imm32 || emit_call(&prog, func, image + addrs[i - 1]))
1429                                         return -EINVAL;
1430                         }
1431                         break;
1432
1433                 case BPF_JMP | BPF_TAIL_CALL:
1434                         if (imm32)
1435                                 emit_bpf_tail_call_direct(&bpf_prog->aux->poke_tab[imm32 - 1],
1436                                                           &prog, image + addrs[i - 1],
1437                                                           callee_regs_used,
1438                                                           bpf_prog->aux->stack_depth,
1439                                                           ctx);
1440                         else
1441                                 emit_bpf_tail_call_indirect(&prog,
1442                                                             callee_regs_used,
1443                                                             bpf_prog->aux->stack_depth,
1444                                                             image + addrs[i - 1],
1445                                                             ctx);
1446                         break;
1447
1448                         /* cond jump */
1449                 case BPF_JMP | BPF_JEQ | BPF_X:
1450                 case BPF_JMP | BPF_JNE | BPF_X:
1451                 case BPF_JMP | BPF_JGT | BPF_X:
1452                 case BPF_JMP | BPF_JLT | BPF_X:
1453                 case BPF_JMP | BPF_JGE | BPF_X:
1454                 case BPF_JMP | BPF_JLE | BPF_X:
1455                 case BPF_JMP | BPF_JSGT | BPF_X:
1456                 case BPF_JMP | BPF_JSLT | BPF_X:
1457                 case BPF_JMP | BPF_JSGE | BPF_X:
1458                 case BPF_JMP | BPF_JSLE | BPF_X:
1459                 case BPF_JMP32 | BPF_JEQ | BPF_X:
1460                 case BPF_JMP32 | BPF_JNE | BPF_X:
1461                 case BPF_JMP32 | BPF_JGT | BPF_X:
1462                 case BPF_JMP32 | BPF_JLT | BPF_X:
1463                 case BPF_JMP32 | BPF_JGE | BPF_X:
1464                 case BPF_JMP32 | BPF_JLE | BPF_X:
1465                 case BPF_JMP32 | BPF_JSGT | BPF_X:
1466                 case BPF_JMP32 | BPF_JSLT | BPF_X:
1467                 case BPF_JMP32 | BPF_JSGE | BPF_X:
1468                 case BPF_JMP32 | BPF_JSLE | BPF_X:
1469                         /* cmp dst_reg, src_reg */
1470                         maybe_emit_mod(&prog, dst_reg, src_reg,
1471                                        BPF_CLASS(insn->code) == BPF_JMP);
1472                         EMIT2(0x39, add_2reg(0xC0, dst_reg, src_reg));
1473                         goto emit_cond_jmp;
1474
1475                 case BPF_JMP | BPF_JSET | BPF_X:
1476                 case BPF_JMP32 | BPF_JSET | BPF_X:
1477                         /* test dst_reg, src_reg */
1478                         maybe_emit_mod(&prog, dst_reg, src_reg,
1479                                        BPF_CLASS(insn->code) == BPF_JMP);
1480                         EMIT2(0x85, add_2reg(0xC0, dst_reg, src_reg));
1481                         goto emit_cond_jmp;
1482
1483                 case BPF_JMP | BPF_JSET | BPF_K:
1484                 case BPF_JMP32 | BPF_JSET | BPF_K:
1485                         /* test dst_reg, imm32 */
1486                         maybe_emit_1mod(&prog, dst_reg,
1487                                         BPF_CLASS(insn->code) == BPF_JMP);
1488                         EMIT2_off32(0xF7, add_1reg(0xC0, dst_reg), imm32);
1489                         goto emit_cond_jmp;
1490
1491                 case BPF_JMP | BPF_JEQ | BPF_K:
1492                 case BPF_JMP | BPF_JNE | BPF_K:
1493                 case BPF_JMP | BPF_JGT | BPF_K:
1494                 case BPF_JMP | BPF_JLT | BPF_K:
1495                 case BPF_JMP | BPF_JGE | BPF_K:
1496                 case BPF_JMP | BPF_JLE | BPF_K:
1497                 case BPF_JMP | BPF_JSGT | BPF_K:
1498                 case BPF_JMP | BPF_JSLT | BPF_K:
1499                 case BPF_JMP | BPF_JSGE | BPF_K:
1500                 case BPF_JMP | BPF_JSLE | BPF_K:
1501                 case BPF_JMP32 | BPF_JEQ | BPF_K:
1502                 case BPF_JMP32 | BPF_JNE | BPF_K:
1503                 case BPF_JMP32 | BPF_JGT | BPF_K:
1504                 case BPF_JMP32 | BPF_JLT | BPF_K:
1505                 case BPF_JMP32 | BPF_JGE | BPF_K:
1506                 case BPF_JMP32 | BPF_JLE | BPF_K:
1507                 case BPF_JMP32 | BPF_JSGT | BPF_K:
1508                 case BPF_JMP32 | BPF_JSLT | BPF_K:
1509                 case BPF_JMP32 | BPF_JSGE | BPF_K:
1510                 case BPF_JMP32 | BPF_JSLE | BPF_K:
1511                         /* test dst_reg, dst_reg to save one extra byte */
1512                         if (imm32 == 0) {
1513                                 maybe_emit_mod(&prog, dst_reg, dst_reg,
1514                                                BPF_CLASS(insn->code) == BPF_JMP);
1515                                 EMIT2(0x85, add_2reg(0xC0, dst_reg, dst_reg));
1516                                 goto emit_cond_jmp;
1517                         }
1518
1519                         /* cmp dst_reg, imm8/32 */
1520                         maybe_emit_1mod(&prog, dst_reg,
1521                                         BPF_CLASS(insn->code) == BPF_JMP);
1522
1523                         if (is_imm8(imm32))
1524                                 EMIT3(0x83, add_1reg(0xF8, dst_reg), imm32);
1525                         else
1526                                 EMIT2_off32(0x81, add_1reg(0xF8, dst_reg), imm32);
1527
1528 emit_cond_jmp:          /* Convert BPF opcode to x86 */
1529                         switch (BPF_OP(insn->code)) {
1530                         case BPF_JEQ:
1531                                 jmp_cond = X86_JE;
1532                                 break;
1533                         case BPF_JSET:
1534                         case BPF_JNE:
1535                                 jmp_cond = X86_JNE;
1536                                 break;
1537                         case BPF_JGT:
1538                                 /* GT is unsigned '>', JA in x86 */
1539                                 jmp_cond = X86_JA;
1540                                 break;
1541                         case BPF_JLT:
1542                                 /* LT is unsigned '<', JB in x86 */
1543                                 jmp_cond = X86_JB;
1544                                 break;
1545                         case BPF_JGE:
1546                                 /* GE is unsigned '>=', JAE in x86 */
1547                                 jmp_cond = X86_JAE;
1548                                 break;
1549                         case BPF_JLE:
1550                                 /* LE is unsigned '<=', JBE in x86 */
1551                                 jmp_cond = X86_JBE;
1552                                 break;
1553                         case BPF_JSGT:
1554                                 /* Signed '>', GT in x86 */
1555                                 jmp_cond = X86_JG;
1556                                 break;
1557                         case BPF_JSLT:
1558                                 /* Signed '<', LT in x86 */
1559                                 jmp_cond = X86_JL;
1560                                 break;
1561                         case BPF_JSGE:
1562                                 /* Signed '>=', GE in x86 */
1563                                 jmp_cond = X86_JGE;
1564                                 break;
1565                         case BPF_JSLE:
1566                                 /* Signed '<=', LE in x86 */
1567                                 jmp_cond = X86_JLE;
1568                                 break;
1569                         default: /* to silence GCC warning */
1570                                 return -EFAULT;
1571                         }
1572                         jmp_offset = addrs[i + insn->off] - addrs[i];
1573                         if (is_imm8(jmp_offset)) {
1574                                 if (jmp_padding) {
1575                                         /* To keep the jmp_offset valid, the extra bytes are
1576                                          * padded before the jump insn, so we subtract the
1577                                          * 2 bytes of jmp_cond insn from INSN_SZ_DIFF.
1578                                          *
1579                                          * If the previous pass already emits an imm8
1580                                          * jmp_cond, then this BPF insn won't shrink, so
1581                                          * "nops" is 0.
1582                                          *
1583                                          * On the other hand, if the previous pass emits an
1584                                          * imm32 jmp_cond, the extra 4 bytes(*) is padded to
1585                                          * keep the image from shrinking further.
1586                                          *
1587                                          * (*) imm32 jmp_cond is 6 bytes, and imm8 jmp_cond
1588                                          *     is 2 bytes, so the size difference is 4 bytes.
1589                                          */
1590                                         nops = INSN_SZ_DIFF - 2;
1591                                         if (nops != 0 && nops != 4) {
1592                                                 pr_err("unexpected jmp_cond padding: %d bytes\n",
1593                                                        nops);
1594                                                 return -EFAULT;
1595                                         }
1596                                         emit_nops(&prog, nops);
1597                                 }
1598                                 EMIT2(jmp_cond, jmp_offset);
1599                         } else if (is_simm32(jmp_offset)) {
1600                                 EMIT2_off32(0x0F, jmp_cond + 0x10, jmp_offset);
1601                         } else {
1602                                 pr_err("cond_jmp gen bug %llx\n", jmp_offset);
1603                                 return -EFAULT;
1604                         }
1605
1606                         break;
1607
1608                 case BPF_JMP | BPF_JA:
1609                         if (insn->off == -1)
1610                                 /* -1 jmp instructions will always jump
1611                                  * backwards two bytes. Explicitly handling
1612                                  * this case avoids wasting too many passes
1613                                  * when there are long sequences of replaced
1614                                  * dead code.
1615                                  */
1616                                 jmp_offset = -2;
1617                         else
1618                                 jmp_offset = addrs[i + insn->off] - addrs[i];
1619
1620                         if (!jmp_offset) {
1621                                 /*
1622                                  * If jmp_padding is enabled, the extra nops will
1623                                  * be inserted. Otherwise, optimize out nop jumps.
1624                                  */
1625                                 if (jmp_padding) {
1626                                         /* There are 3 possible conditions.
1627                                          * (1) This BPF_JA is already optimized out in
1628                                          *     the previous run, so there is no need
1629                                          *     to pad any extra byte (0 byte).
1630                                          * (2) The previous pass emits an imm8 jmp,
1631                                          *     so we pad 2 bytes to match the previous
1632                                          *     insn size.
1633                                          * (3) Similarly, the previous pass emits an
1634                                          *     imm32 jmp, and 5 bytes is padded.
1635                                          */
1636                                         nops = INSN_SZ_DIFF;
1637                                         if (nops != 0 && nops != 2 && nops != 5) {
1638                                                 pr_err("unexpected nop jump padding: %d bytes\n",
1639                                                        nops);
1640                                                 return -EFAULT;
1641                                         }
1642                                         emit_nops(&prog, nops);
1643                                 }
1644                                 break;
1645                         }
1646 emit_jmp:
1647                         if (is_imm8(jmp_offset)) {
1648                                 if (jmp_padding) {
1649                                         /* To avoid breaking jmp_offset, the extra bytes
1650                                          * are padded before the actual jmp insn, so
1651                                          * 2 bytes is subtracted from INSN_SZ_DIFF.
1652                                          *
1653                                          * If the previous pass already emits an imm8
1654                                          * jmp, there is nothing to pad (0 byte).
1655                                          *
1656                                          * If it emits an imm32 jmp (5 bytes) previously
1657                                          * and now an imm8 jmp (2 bytes), then we pad
1658                                          * (5 - 2 = 3) bytes to stop the image from
1659                                          * shrinking further.
1660                                          */
1661                                         nops = INSN_SZ_DIFF - 2;
1662                                         if (nops != 0 && nops != 3) {
1663                                                 pr_err("unexpected jump padding: %d bytes\n",
1664                                                        nops);
1665                                                 return -EFAULT;
1666                                         }
1667                                         emit_nops(&prog, INSN_SZ_DIFF - 2);
1668                                 }
1669                                 EMIT2(0xEB, jmp_offset);
1670                         } else if (is_simm32(jmp_offset)) {
1671                                 EMIT1_off32(0xE9, jmp_offset);
1672                         } else {
1673                                 pr_err("jmp gen bug %llx\n", jmp_offset);
1674                                 return -EFAULT;
1675                         }
1676                         break;
1677
1678                 case BPF_JMP | BPF_EXIT:
1679                         if (seen_exit) {
1680                                 jmp_offset = ctx->cleanup_addr - addrs[i];
1681                                 goto emit_jmp;
1682                         }
1683                         seen_exit = true;
1684                         /* Update cleanup_addr */
1685                         ctx->cleanup_addr = proglen;
1686                         pop_callee_regs(&prog, callee_regs_used);
1687                         EMIT1(0xC9);         /* leave */
1688                         EMIT1(0xC3);         /* ret */
1689                         break;
1690
1691                 default:
1692                         /*
1693                          * By design x86-64 JIT should support all BPF instructions.
1694                          * This error will be seen if new instruction was added
1695                          * to the interpreter, but not to the JIT, or if there is
1696                          * junk in bpf_prog.
1697                          */
1698                         pr_err("bpf_jit: unknown opcode %02x\n", insn->code);
1699                         return -EINVAL;
1700                 }
1701
1702                 ilen = prog - temp;
1703                 if (ilen > BPF_MAX_INSN_SIZE) {
1704                         pr_err("bpf_jit: fatal insn size error\n");
1705                         return -EFAULT;
1706                 }
1707
1708                 if (image) {
1709                         /*
1710                          * When populating the image, assert that:
1711                          *
1712                          *  i) We do not write beyond the allocated space, and
1713                          * ii) addrs[i] did not change from the prior run, in order
1714                          *     to validate assumptions made for computing branch
1715                          *     displacements.
1716                          */
1717                         if (unlikely(proglen + ilen > oldproglen ||
1718                                      proglen + ilen != addrs[i])) {
1719                                 pr_err("bpf_jit: fatal error\n");
1720                                 return -EFAULT;
1721                         }
1722                         memcpy(rw_image + proglen, temp, ilen);
1723                 }
1724                 proglen += ilen;
1725                 addrs[i] = proglen;
1726                 prog = temp;
1727         }
1728
1729         if (image && excnt != bpf_prog->aux->num_exentries) {
1730                 pr_err("extable is not populated\n");
1731                 return -EFAULT;
1732         }
1733         return proglen;
1734 }
1735
1736 static void save_regs(const struct btf_func_model *m, u8 **prog, int nr_args,
1737                       int stack_size)
1738 {
1739         int i;
1740         /* Store function arguments to stack.
1741          * For a function that accepts two pointers the sequence will be:
1742          * mov QWORD PTR [rbp-0x10],rdi
1743          * mov QWORD PTR [rbp-0x8],rsi
1744          */
1745         for (i = 0; i < min(nr_args, 6); i++)
1746                 emit_stx(prog, bytes_to_bpf_size(m->arg_size[i]),
1747                          BPF_REG_FP,
1748                          i == 5 ? X86_REG_R9 : BPF_REG_1 + i,
1749                          -(stack_size - i * 8));
1750 }
1751
1752 static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_args,
1753                          int stack_size)
1754 {
1755         int i;
1756
1757         /* Restore function arguments from stack.
1758          * For a function that accepts two pointers the sequence will be:
1759          * EMIT4(0x48, 0x8B, 0x7D, 0xF0); mov rdi,QWORD PTR [rbp-0x10]
1760          * EMIT4(0x48, 0x8B, 0x75, 0xF8); mov rsi,QWORD PTR [rbp-0x8]
1761          */
1762         for (i = 0; i < min(nr_args, 6); i++)
1763                 emit_ldx(prog, bytes_to_bpf_size(m->arg_size[i]),
1764                          i == 5 ? X86_REG_R9 : BPF_REG_1 + i,
1765                          BPF_REG_FP,
1766                          -(stack_size - i * 8));
1767 }
1768
1769 static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog,
1770                            struct bpf_tramp_link *l, int stack_size,
1771                            int run_ctx_off, bool save_ret)
1772 {
1773         u8 *prog = *pprog;
1774         u8 *jmp_insn;
1775         int ctx_cookie_off = offsetof(struct bpf_tramp_run_ctx, bpf_cookie);
1776         struct bpf_prog *p = l->link.prog;
1777         u64 cookie = l->cookie;
1778
1779         /* mov rdi, cookie */
1780         emit_mov_imm64(&prog, BPF_REG_1, (long) cookie >> 32, (u32) (long) cookie);
1781
1782         /* Prepare struct bpf_tramp_run_ctx.
1783          *
1784          * bpf_tramp_run_ctx is already preserved by
1785          * arch_prepare_bpf_trampoline().
1786          *
1787          * mov QWORD PTR [rbp - run_ctx_off + ctx_cookie_off], rdi
1788          */
1789         emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_1, -run_ctx_off + ctx_cookie_off);
1790
1791         /* arg1: mov rdi, progs[i] */
1792         emit_mov_imm64(&prog, BPF_REG_1, (long) p >> 32, (u32) (long) p);
1793         /* arg2: lea rsi, [rbp - ctx_cookie_off] */
1794         EMIT4(0x48, 0x8D, 0x75, -run_ctx_off);
1795
1796         if (emit_call(&prog,
1797                       p->aux->sleepable ? __bpf_prog_enter_sleepable :
1798                       __bpf_prog_enter, prog))
1799                         return -EINVAL;
1800         /* remember prog start time returned by __bpf_prog_enter */
1801         emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0);
1802
1803         /* if (__bpf_prog_enter*(prog) == 0)
1804          *      goto skip_exec_of_prog;
1805          */
1806         EMIT3(0x48, 0x85, 0xC0);  /* test rax,rax */
1807         /* emit 2 nops that will be replaced with JE insn */
1808         jmp_insn = prog;
1809         emit_nops(&prog, 2);
1810
1811         /* arg1: lea rdi, [rbp - stack_size] */
1812         EMIT4(0x48, 0x8D, 0x7D, -stack_size);
1813         /* arg2: progs[i]->insnsi for interpreter */
1814         if (!p->jited)
1815                 emit_mov_imm64(&prog, BPF_REG_2,
1816                                (long) p->insnsi >> 32,
1817                                (u32) (long) p->insnsi);
1818         /* call JITed bpf program or interpreter */
1819         if (emit_call(&prog, p->bpf_func, prog))
1820                 return -EINVAL;
1821
1822         /*
1823          * BPF_TRAMP_MODIFY_RETURN trampolines can modify the return
1824          * of the previous call which is then passed on the stack to
1825          * the next BPF program.
1826          *
1827          * BPF_TRAMP_FENTRY trampoline may need to return the return
1828          * value of BPF_PROG_TYPE_STRUCT_OPS prog.
1829          */
1830         if (save_ret)
1831                 emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
1832
1833         /* replace 2 nops with JE insn, since jmp target is known */
1834         jmp_insn[0] = X86_JE;
1835         jmp_insn[1] = prog - jmp_insn - 2;
1836
1837         /* arg1: mov rdi, progs[i] */
1838         emit_mov_imm64(&prog, BPF_REG_1, (long) p >> 32, (u32) (long) p);
1839         /* arg2: mov rsi, rbx <- start time in nsec */
1840         emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6);
1841         /* arg3: lea rdx, [rbp - run_ctx_off] */
1842         EMIT4(0x48, 0x8D, 0x55, -run_ctx_off);
1843         if (emit_call(&prog,
1844                       p->aux->sleepable ? __bpf_prog_exit_sleepable :
1845                       __bpf_prog_exit, prog))
1846                         return -EINVAL;
1847
1848         *pprog = prog;
1849         return 0;
1850 }
1851
1852 static void emit_align(u8 **pprog, u32 align)
1853 {
1854         u8 *target, *prog = *pprog;
1855
1856         target = PTR_ALIGN(prog, align);
1857         if (target != prog)
1858                 emit_nops(&prog, target - prog);
1859
1860         *pprog = prog;
1861 }
1862
1863 static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond)
1864 {
1865         u8 *prog = *pprog;
1866         s64 offset;
1867
1868         offset = func - (ip + 2 + 4);
1869         if (!is_simm32(offset)) {
1870                 pr_err("Target %p is out of range\n", func);
1871                 return -EINVAL;
1872         }
1873         EMIT2_off32(0x0F, jmp_cond + 0x10, offset);
1874         *pprog = prog;
1875         return 0;
1876 }
1877
1878 static int invoke_bpf(const struct btf_func_model *m, u8 **pprog,
1879                       struct bpf_tramp_links *tl, int stack_size,
1880                       int run_ctx_off, bool save_ret)
1881 {
1882         int i;
1883         u8 *prog = *pprog;
1884
1885         for (i = 0; i < tl->nr_links; i++) {
1886                 if (invoke_bpf_prog(m, &prog, tl->links[i], stack_size,
1887                                     run_ctx_off, save_ret))
1888                         return -EINVAL;
1889         }
1890         *pprog = prog;
1891         return 0;
1892 }
1893
1894 static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog,
1895                               struct bpf_tramp_links *tl, int stack_size,
1896                               int run_ctx_off, u8 **branches)
1897 {
1898         u8 *prog = *pprog;
1899         int i;
1900
1901         /* The first fmod_ret program will receive a garbage return value.
1902          * Set this to 0 to avoid confusing the program.
1903          */
1904         emit_mov_imm32(&prog, false, BPF_REG_0, 0);
1905         emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
1906         for (i = 0; i < tl->nr_links; i++) {
1907                 if (invoke_bpf_prog(m, &prog, tl->links[i], stack_size, run_ctx_off, true))
1908                         return -EINVAL;
1909
1910                 /* mod_ret prog stored return value into [rbp - 8]. Emit:
1911                  * if (*(u64 *)(rbp - 8) !=  0)
1912                  *      goto do_fexit;
1913                  */
1914                 /* cmp QWORD PTR [rbp - 0x8], 0x0 */
1915                 EMIT4(0x48, 0x83, 0x7d, 0xf8); EMIT1(0x00);
1916
1917                 /* Save the location of the branch and Generate 6 nops
1918                  * (4 bytes for an offset and 2 bytes for the jump) These nops
1919                  * are replaced with a conditional jump once do_fexit (i.e. the
1920                  * start of the fexit invocation) is finalized.
1921                  */
1922                 branches[i] = prog;
1923                 emit_nops(&prog, 4 + 2);
1924         }
1925
1926         *pprog = prog;
1927         return 0;
1928 }
1929
1930 static bool is_valid_bpf_tramp_flags(unsigned int flags)
1931 {
1932         if ((flags & BPF_TRAMP_F_RESTORE_REGS) &&
1933             (flags & BPF_TRAMP_F_SKIP_FRAME))
1934                 return false;
1935
1936         /*
1937          * BPF_TRAMP_F_RET_FENTRY_RET is only used by bpf_struct_ops,
1938          * and it must be used alone.
1939          */
1940         if ((flags & BPF_TRAMP_F_RET_FENTRY_RET) &&
1941             (flags & ~BPF_TRAMP_F_RET_FENTRY_RET))
1942                 return false;
1943
1944         return true;
1945 }
1946
1947 /* Example:
1948  * __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev);
1949  * its 'struct btf_func_model' will be nr_args=2
1950  * The assembly code when eth_type_trans is executing after trampoline:
1951  *
1952  * push rbp
1953  * mov rbp, rsp
1954  * sub rsp, 16                     // space for skb and dev
1955  * push rbx                        // temp regs to pass start time
1956  * mov qword ptr [rbp - 16], rdi   // save skb pointer to stack
1957  * mov qword ptr [rbp - 8], rsi    // save dev pointer to stack
1958  * call __bpf_prog_enter           // rcu_read_lock and preempt_disable
1959  * mov rbx, rax                    // remember start time in bpf stats are enabled
1960  * lea rdi, [rbp - 16]             // R1==ctx of bpf prog
1961  * call addr_of_jited_FENTRY_prog
1962  * movabsq rdi, 64bit_addr_of_struct_bpf_prog  // unused if bpf stats are off
1963  * mov rsi, rbx                    // prog start time
1964  * call __bpf_prog_exit            // rcu_read_unlock, preempt_enable and stats math
1965  * mov rdi, qword ptr [rbp - 16]   // restore skb pointer from stack
1966  * mov rsi, qword ptr [rbp - 8]    // restore dev pointer from stack
1967  * pop rbx
1968  * leave
1969  * ret
1970  *
1971  * eth_type_trans has 5 byte nop at the beginning. These 5 bytes will be
1972  * replaced with 'call generated_bpf_trampoline'. When it returns
1973  * eth_type_trans will continue executing with original skb and dev pointers.
1974  *
1975  * The assembly code when eth_type_trans is called from trampoline:
1976  *
1977  * push rbp
1978  * mov rbp, rsp
1979  * sub rsp, 24                     // space for skb, dev, return value
1980  * push rbx                        // temp regs to pass start time
1981  * mov qword ptr [rbp - 24], rdi   // save skb pointer to stack
1982  * mov qword ptr [rbp - 16], rsi   // save dev pointer to stack
1983  * call __bpf_prog_enter           // rcu_read_lock and preempt_disable
1984  * mov rbx, rax                    // remember start time if bpf stats are enabled
1985  * lea rdi, [rbp - 24]             // R1==ctx of bpf prog
1986  * call addr_of_jited_FENTRY_prog  // bpf prog can access skb and dev
1987  * movabsq rdi, 64bit_addr_of_struct_bpf_prog  // unused if bpf stats are off
1988  * mov rsi, rbx                    // prog start time
1989  * call __bpf_prog_exit            // rcu_read_unlock, preempt_enable and stats math
1990  * mov rdi, qword ptr [rbp - 24]   // restore skb pointer from stack
1991  * mov rsi, qword ptr [rbp - 16]   // restore dev pointer from stack
1992  * call eth_type_trans+5           // execute body of eth_type_trans
1993  * mov qword ptr [rbp - 8], rax    // save return value
1994  * call __bpf_prog_enter           // rcu_read_lock and preempt_disable
1995  * mov rbx, rax                    // remember start time in bpf stats are enabled
1996  * lea rdi, [rbp - 24]             // R1==ctx of bpf prog
1997  * call addr_of_jited_FEXIT_prog   // bpf prog can access skb, dev, return value
1998  * movabsq rdi, 64bit_addr_of_struct_bpf_prog  // unused if bpf stats are off
1999  * mov rsi, rbx                    // prog start time
2000  * call __bpf_prog_exit            // rcu_read_unlock, preempt_enable and stats math
2001  * mov rax, qword ptr [rbp - 8]    // restore eth_type_trans's return value
2002  * pop rbx
2003  * leave
2004  * add rsp, 8                      // skip eth_type_trans's frame
2005  * ret                             // return to its caller
2006  */
2007 int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end,
2008                                 const struct btf_func_model *m, u32 flags,
2009                                 struct bpf_tramp_links *tlinks,
2010                                 void *orig_call)
2011 {
2012         int ret, i, nr_args = m->nr_args;
2013         int regs_off, ip_off, args_off, stack_size = nr_args * 8, run_ctx_off;
2014         struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
2015         struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
2016         struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN];
2017         u8 **branches = NULL;
2018         u8 *prog;
2019         bool save_ret;
2020
2021         /* x86-64 supports up to 6 arguments. 7+ can be added in the future */
2022         if (nr_args > 6)
2023                 return -ENOTSUPP;
2024
2025         if (!is_valid_bpf_tramp_flags(flags))
2026                 return -EINVAL;
2027
2028         /* Generated trampoline stack layout:
2029          *
2030          * RBP + 8         [ return address  ]
2031          * RBP + 0         [ RBP             ]
2032          *
2033          * RBP - 8         [ return value    ]  BPF_TRAMP_F_CALL_ORIG or
2034          *                                      BPF_TRAMP_F_RET_FENTRY_RET flags
2035          *
2036          *                 [ reg_argN        ]  always
2037          *                 [ ...             ]
2038          * RBP - regs_off  [ reg_arg1        ]  program's ctx pointer
2039          *
2040          * RBP - args_off  [ args count      ]  always
2041          *
2042          * RBP - ip_off    [ traced function ]  BPF_TRAMP_F_IP_ARG flag
2043          *
2044          * RBP - run_ctx_off [ bpf_tramp_run_ctx ]
2045          */
2046
2047         /* room for return value of orig_call or fentry prog */
2048         save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET);
2049         if (save_ret)
2050                 stack_size += 8;
2051
2052         regs_off = stack_size;
2053
2054         /* args count  */
2055         stack_size += 8;
2056         args_off = stack_size;
2057
2058         if (flags & BPF_TRAMP_F_IP_ARG)
2059                 stack_size += 8; /* room for IP address argument */
2060
2061         ip_off = stack_size;
2062
2063         stack_size += (sizeof(struct bpf_tramp_run_ctx) + 7) & ~0x7;
2064         run_ctx_off = stack_size;
2065
2066         if (flags & BPF_TRAMP_F_SKIP_FRAME) {
2067                 /* skip patched call instruction and point orig_call to actual
2068                  * body of the kernel function.
2069                  */
2070                 if (is_endbr(*(u32 *)orig_call))
2071                         orig_call += ENDBR_INSN_SIZE;
2072                 orig_call += X86_PATCH_SIZE;
2073         }
2074
2075         prog = image;
2076
2077         EMIT_ENDBR();
2078         EMIT1(0x55);             /* push rbp */
2079         EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */
2080         EMIT4(0x48, 0x83, 0xEC, stack_size); /* sub rsp, stack_size */
2081         EMIT1(0x53);             /* push rbx */
2082
2083         /* Store number of arguments of the traced function:
2084          *   mov rax, nr_args
2085          *   mov QWORD PTR [rbp - args_off], rax
2086          */
2087         emit_mov_imm64(&prog, BPF_REG_0, 0, (u32) nr_args);
2088         emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -args_off);
2089
2090         if (flags & BPF_TRAMP_F_IP_ARG) {
2091                 /* Store IP address of the traced function:
2092                  * mov rax, QWORD PTR [rbp + 8]
2093                  * sub rax, X86_PATCH_SIZE
2094                  * mov QWORD PTR [rbp - ip_off], rax
2095                  */
2096                 emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, 8);
2097                 EMIT4(0x48, 0x83, 0xe8, X86_PATCH_SIZE);
2098                 emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -ip_off);
2099         }
2100
2101         save_regs(m, &prog, nr_args, regs_off);
2102
2103         if (flags & BPF_TRAMP_F_CALL_ORIG) {
2104                 /* arg1: mov rdi, im */
2105                 emit_mov_imm64(&prog, BPF_REG_1, (long) im >> 32, (u32) (long) im);
2106                 if (emit_call(&prog, __bpf_tramp_enter, prog)) {
2107                         ret = -EINVAL;
2108                         goto cleanup;
2109                 }
2110         }
2111
2112         if (fentry->nr_links)
2113                 if (invoke_bpf(m, &prog, fentry, regs_off, run_ctx_off,
2114                                flags & BPF_TRAMP_F_RET_FENTRY_RET))
2115                         return -EINVAL;
2116
2117         if (fmod_ret->nr_links) {
2118                 branches = kcalloc(fmod_ret->nr_links, sizeof(u8 *),
2119                                    GFP_KERNEL);
2120                 if (!branches)
2121                         return -ENOMEM;
2122
2123                 if (invoke_bpf_mod_ret(m, &prog, fmod_ret, regs_off,
2124                                        run_ctx_off, branches)) {
2125                         ret = -EINVAL;
2126                         goto cleanup;
2127                 }
2128         }
2129
2130         if (flags & BPF_TRAMP_F_CALL_ORIG) {
2131                 restore_regs(m, &prog, nr_args, regs_off);
2132
2133                 /* call original function */
2134                 if (emit_call(&prog, orig_call, prog)) {
2135                         ret = -EINVAL;
2136                         goto cleanup;
2137                 }
2138                 /* remember return value in a stack for bpf prog to access */
2139                 emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8);
2140                 im->ip_after_call = prog;
2141                 memcpy(prog, x86_nops[5], X86_PATCH_SIZE);
2142                 prog += X86_PATCH_SIZE;
2143         }
2144
2145         if (fmod_ret->nr_links) {
2146                 /* From Intel 64 and IA-32 Architectures Optimization
2147                  * Reference Manual, 3.4.1.4 Code Alignment, Assembly/Compiler
2148                  * Coding Rule 11: All branch targets should be 16-byte
2149                  * aligned.
2150                  */
2151                 emit_align(&prog, 16);
2152                 /* Update the branches saved in invoke_bpf_mod_ret with the
2153                  * aligned address of do_fexit.
2154                  */
2155                 for (i = 0; i < fmod_ret->nr_links; i++)
2156                         emit_cond_near_jump(&branches[i], prog, branches[i],
2157                                             X86_JNE);
2158         }
2159
2160         if (fexit->nr_links)
2161                 if (invoke_bpf(m, &prog, fexit, regs_off, run_ctx_off, false)) {
2162                         ret = -EINVAL;
2163                         goto cleanup;
2164                 }
2165
2166         if (flags & BPF_TRAMP_F_RESTORE_REGS)
2167                 restore_regs(m, &prog, nr_args, regs_off);
2168
2169         /* This needs to be done regardless. If there were fmod_ret programs,
2170          * the return value is only updated on the stack and still needs to be
2171          * restored to R0.
2172          */
2173         if (flags & BPF_TRAMP_F_CALL_ORIG) {
2174                 im->ip_epilogue = prog;
2175                 /* arg1: mov rdi, im */
2176                 emit_mov_imm64(&prog, BPF_REG_1, (long) im >> 32, (u32) (long) im);
2177                 if (emit_call(&prog, __bpf_tramp_exit, prog)) {
2178                         ret = -EINVAL;
2179                         goto cleanup;
2180                 }
2181         }
2182         /* restore return value of orig_call or fentry prog back into RAX */
2183         if (save_ret)
2184                 emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, -8);
2185
2186         EMIT1(0x5B); /* pop rbx */
2187         EMIT1(0xC9); /* leave */
2188         if (flags & BPF_TRAMP_F_SKIP_FRAME)
2189                 /* skip our return address and return to parent */
2190                 EMIT4(0x48, 0x83, 0xC4, 8); /* add rsp, 8 */
2191         EMIT1(0xC3); /* ret */
2192         /* Make sure the trampoline generation logic doesn't overflow */
2193         if (WARN_ON_ONCE(prog > (u8 *)image_end - BPF_INSN_SAFETY)) {
2194                 ret = -EFAULT;
2195                 goto cleanup;
2196         }
2197         ret = prog - (u8 *)image;
2198
2199 cleanup:
2200         kfree(branches);
2201         return ret;
2202 }
2203
2204 static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs)
2205 {
2206         u8 *jg_reloc, *prog = *pprog;
2207         int pivot, err, jg_bytes = 1;
2208         s64 jg_offset;
2209
2210         if (a == b) {
2211                 /* Leaf node of recursion, i.e. not a range of indices
2212                  * anymore.
2213                  */
2214                 EMIT1(add_1mod(0x48, BPF_REG_3));       /* cmp rdx,func */
2215                 if (!is_simm32(progs[a]))
2216                         return -1;
2217                 EMIT2_off32(0x81, add_1reg(0xF8, BPF_REG_3),
2218                             progs[a]);
2219                 err = emit_cond_near_jump(&prog,        /* je func */
2220                                           (void *)progs[a], prog,
2221                                           X86_JE);
2222                 if (err)
2223                         return err;
2224
2225                 emit_indirect_jump(&prog, 2 /* rdx */, prog);
2226
2227                 *pprog = prog;
2228                 return 0;
2229         }
2230
2231         /* Not a leaf node, so we pivot, and recursively descend into
2232          * the lower and upper ranges.
2233          */
2234         pivot = (b - a) / 2;
2235         EMIT1(add_1mod(0x48, BPF_REG_3));               /* cmp rdx,func */
2236         if (!is_simm32(progs[a + pivot]))
2237                 return -1;
2238         EMIT2_off32(0x81, add_1reg(0xF8, BPF_REG_3), progs[a + pivot]);
2239
2240         if (pivot > 2) {                                /* jg upper_part */
2241                 /* Require near jump. */
2242                 jg_bytes = 4;
2243                 EMIT2_off32(0x0F, X86_JG + 0x10, 0);
2244         } else {
2245                 EMIT2(X86_JG, 0);
2246         }
2247         jg_reloc = prog;
2248
2249         err = emit_bpf_dispatcher(&prog, a, a + pivot,  /* emit lower_part */
2250                                   progs);
2251         if (err)
2252                 return err;
2253
2254         /* From Intel 64 and IA-32 Architectures Optimization
2255          * Reference Manual, 3.4.1.4 Code Alignment, Assembly/Compiler
2256          * Coding Rule 11: All branch targets should be 16-byte
2257          * aligned.
2258          */
2259         emit_align(&prog, 16);
2260         jg_offset = prog - jg_reloc;
2261         emit_code(jg_reloc - jg_bytes, jg_offset, jg_bytes);
2262
2263         err = emit_bpf_dispatcher(&prog, a + pivot + 1, /* emit upper_part */
2264                                   b, progs);
2265         if (err)
2266                 return err;
2267
2268         *pprog = prog;
2269         return 0;
2270 }
2271
2272 static int cmp_ips(const void *a, const void *b)
2273 {
2274         const s64 *ipa = a;
2275         const s64 *ipb = b;
2276
2277         if (*ipa > *ipb)
2278                 return 1;
2279         if (*ipa < *ipb)
2280                 return -1;
2281         return 0;
2282 }
2283
2284 int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs)
2285 {
2286         u8 *prog = image;
2287
2288         sort(funcs, num_funcs, sizeof(funcs[0]), cmp_ips, NULL);
2289         return emit_bpf_dispatcher(&prog, 0, num_funcs - 1, funcs);
2290 }
2291
2292 struct x64_jit_data {
2293         struct bpf_binary_header *rw_header;
2294         struct bpf_binary_header *header;
2295         int *addrs;
2296         u8 *image;
2297         int proglen;
2298         struct jit_context ctx;
2299 };
2300
2301 #define MAX_PASSES 20
2302 #define PADDING_PASSES (MAX_PASSES - 5)
2303
2304 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
2305 {
2306         struct bpf_binary_header *rw_header = NULL;
2307         struct bpf_binary_header *header = NULL;
2308         struct bpf_prog *tmp, *orig_prog = prog;
2309         struct x64_jit_data *jit_data;
2310         int proglen, oldproglen = 0;
2311         struct jit_context ctx = {};
2312         bool tmp_blinded = false;
2313         bool extra_pass = false;
2314         bool padding = false;
2315         u8 *rw_image = NULL;
2316         u8 *image = NULL;
2317         int *addrs;
2318         int pass;
2319         int i;
2320
2321         if (!prog->jit_requested)
2322                 return orig_prog;
2323
2324         tmp = bpf_jit_blind_constants(prog);
2325         /*
2326          * If blinding was requested and we failed during blinding,
2327          * we must fall back to the interpreter.
2328          */
2329         if (IS_ERR(tmp))
2330                 return orig_prog;
2331         if (tmp != prog) {
2332                 tmp_blinded = true;
2333                 prog = tmp;
2334         }
2335
2336         jit_data = prog->aux->jit_data;
2337         if (!jit_data) {
2338                 jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
2339                 if (!jit_data) {
2340                         prog = orig_prog;
2341                         goto out;
2342                 }
2343                 prog->aux->jit_data = jit_data;
2344         }
2345         addrs = jit_data->addrs;
2346         if (addrs) {
2347                 ctx = jit_data->ctx;
2348                 oldproglen = jit_data->proglen;
2349                 image = jit_data->image;
2350                 header = jit_data->header;
2351                 rw_header = jit_data->rw_header;
2352                 rw_image = (void *)rw_header + ((void *)image - (void *)header);
2353                 extra_pass = true;
2354                 padding = true;
2355                 goto skip_init_addrs;
2356         }
2357         addrs = kvmalloc_array(prog->len + 1, sizeof(*addrs), GFP_KERNEL);
2358         if (!addrs) {
2359                 prog = orig_prog;
2360                 goto out_addrs;
2361         }
2362
2363         /*
2364          * Before first pass, make a rough estimation of addrs[]
2365          * each BPF instruction is translated to less than 64 bytes
2366          */
2367         for (proglen = 0, i = 0; i <= prog->len; i++) {
2368                 proglen += 64;
2369                 addrs[i] = proglen;
2370         }
2371         ctx.cleanup_addr = proglen;
2372 skip_init_addrs:
2373
2374         /*
2375          * JITed image shrinks with every pass and the loop iterates
2376          * until the image stops shrinking. Very large BPF programs
2377          * may converge on the last pass. In such case do one more
2378          * pass to emit the final image.
2379          */
2380         for (pass = 0; pass < MAX_PASSES || image; pass++) {
2381                 if (!padding && pass >= PADDING_PASSES)
2382                         padding = true;
2383                 proglen = do_jit(prog, addrs, image, rw_image, oldproglen, &ctx, padding);
2384                 if (proglen <= 0) {
2385 out_image:
2386                         image = NULL;
2387                         if (header) {
2388                                 bpf_arch_text_copy(&header->size, &rw_header->size,
2389                                                    sizeof(rw_header->size));
2390                                 bpf_jit_binary_pack_free(header, rw_header);
2391                         }
2392                         /* Fall back to interpreter mode */
2393                         prog = orig_prog;
2394                         if (extra_pass) {
2395                                 prog->bpf_func = NULL;
2396                                 prog->jited = 0;
2397                                 prog->jited_len = 0;
2398                         }
2399                         goto out_addrs;
2400                 }
2401                 if (image) {
2402                         if (proglen != oldproglen) {
2403                                 pr_err("bpf_jit: proglen=%d != oldproglen=%d\n",
2404                                        proglen, oldproglen);
2405                                 goto out_image;
2406                         }
2407                         break;
2408                 }
2409                 if (proglen == oldproglen) {
2410                         /*
2411                          * The number of entries in extable is the number of BPF_LDX
2412                          * insns that access kernel memory via "pointer to BTF type".
2413                          * The verifier changed their opcode from LDX|MEM|size
2414                          * to LDX|PROBE_MEM|size to make JITing easier.
2415                          */
2416                         u32 align = __alignof__(struct exception_table_entry);
2417                         u32 extable_size = prog->aux->num_exentries *
2418                                 sizeof(struct exception_table_entry);
2419
2420                         /* allocate module memory for x86 insns and extable */
2421                         header = bpf_jit_binary_pack_alloc(roundup(proglen, align) + extable_size,
2422                                                            &image, align, &rw_header, &rw_image,
2423                                                            jit_fill_hole);
2424                         if (!header) {
2425                                 prog = orig_prog;
2426                                 goto out_addrs;
2427                         }
2428                         prog->aux->extable = (void *) image + roundup(proglen, align);
2429                 }
2430                 oldproglen = proglen;
2431                 cond_resched();
2432         }
2433
2434         if (bpf_jit_enable > 1)
2435                 bpf_jit_dump(prog->len, proglen, pass + 1, image);
2436
2437         if (image) {
2438                 if (!prog->is_func || extra_pass) {
2439                         /*
2440                          * bpf_jit_binary_pack_finalize fails in two scenarios:
2441                          *   1) header is not pointing to proper module memory;
2442                          *   2) the arch doesn't support bpf_arch_text_copy().
2443                          *
2444                          * Both cases are serious bugs and justify WARN_ON.
2445                          */
2446                         if (WARN_ON(bpf_jit_binary_pack_finalize(prog, header, rw_header))) {
2447                                 /* header has been freed */
2448                                 header = NULL;
2449                                 goto out_image;
2450                         }
2451
2452                         bpf_tail_call_direct_fixup(prog);
2453                 } else {
2454                         jit_data->addrs = addrs;
2455                         jit_data->ctx = ctx;
2456                         jit_data->proglen = proglen;
2457                         jit_data->image = image;
2458                         jit_data->header = header;
2459                         jit_data->rw_header = rw_header;
2460                 }
2461                 prog->bpf_func = (void *)image;
2462                 prog->jited = 1;
2463                 prog->jited_len = proglen;
2464         } else {
2465                 prog = orig_prog;
2466         }
2467
2468         if (!image || !prog->is_func || extra_pass) {
2469                 if (image)
2470                         bpf_prog_fill_jited_linfo(prog, addrs + 1);
2471 out_addrs:
2472                 kvfree(addrs);
2473                 kfree(jit_data);
2474                 prog->aux->jit_data = NULL;
2475         }
2476 out:
2477         if (tmp_blinded)
2478                 bpf_jit_prog_release_other(prog, prog == orig_prog ?
2479                                            tmp : orig_prog);
2480         return prog;
2481 }
2482
2483 bool bpf_jit_supports_kfunc_call(void)
2484 {
2485         return true;
2486 }
2487
2488 void *bpf_arch_text_copy(void *dst, void *src, size_t len)
2489 {
2490         if (text_poke_copy(dst, src, len) == NULL)
2491                 return ERR_PTR(-EINVAL);
2492         return dst;
2493 }