arch/s390/kernel/traps.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  S390 version
   4  *    Copyright IBM Corp. 1999, 2000
   5  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
   6  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
   7  *
   8  *  Derived from "arch/i386/kernel/traps.c"
   9  *    Copyright (C) 1991, 1992 Linus Torvalds
  10  */
  11
  12 /*
  13  * 'Traps.c' handles hardware traps and faults after we have saved some
  14  * state in 'asm.s'.
  15  */
  16 #include "asm/irqflags.h"
  17 #include "asm/ptrace.h"
  18 #include <linux/kprobes.h>
  19 #include <linux/kdebug.h>
  20 #include <linux/randomize_kstack.h>
  21 #include <linux/extable.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/sched.h>
  24 #include <linux/sched/debug.h>
  25 #include <linux/mm.h>
  26 #include <linux/slab.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/cpu.h>
  29 #include <linux/entry-common.h>
  30 #include <asm/asm-extable.h>
  31 #include <asm/fpu/api.h>
  32 #include <asm/vtime.h>
  33 #include "entry.h"
  34
  35 static inline void __user *get_trap_ip(struct pt_regs *regs)
  36 {
  37         unsigned long address;
  38
  39         if (regs->int_code & 0x200)
  40                 address = current->thread.trap_tdb.data[3];
  41         else
  42                 address = regs->psw.addr;
  43         return (void __user *) (address - (regs->int_code >> 16));
  44 }
  45
  46 int is_valid_bugaddr(unsigned long addr)
  47 {
  48         return 1;
  49 }
  50
  51 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  52 {
  53         if (user_mode(regs)) {
  54                 force_sig_fault(si_signo, si_code, get_trap_ip(regs));
  55                 report_user_fault(regs, si_signo, 0);
  56         } else {
  57                 if (!fixup_exception(regs))
  58                         die(regs, str);
  59         }
  60 }
  61
  62 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  63 {
  64         if (notify_die(DIE_TRAP, str, regs, 0,
  65                        regs->int_code, si_signo) == NOTIFY_STOP)
  66                 return;
  67         do_report_trap(regs, si_signo, si_code, str);
  68 }
  69 NOKPROBE_SYMBOL(do_trap);
  70
  71 void do_per_trap(struct pt_regs *regs)
  72 {
  73         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
  74                 return;
  75         if (!current->ptrace)
  76                 return;
  77         force_sig_fault(SIGTRAP, TRAP_HWBKPT,
  78                 (void __force __user *) current->thread.per_event.address);
  79 }
  80 NOKPROBE_SYMBOL(do_per_trap);
  81
  82 static void default_trap_handler(struct pt_regs *regs)
  83 {
  84         if (user_mode(regs)) {
  85                 report_user_fault(regs, SIGSEGV, 0);
  86                 force_exit_sig(SIGSEGV);
  87         } else
  88                 die(regs, "Unknown program exception");
  89 }
  90
  91 #define DO_ERROR_INFO(name, signr, sicode, str) \
  92 static void name(struct pt_regs *regs)          \
  93 {                                               \
  94         do_trap(regs, signr, sicode, str);      \
  95 }
  96
  97 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
  98               "addressing exception")
  99 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
 100               "execute exception")
 101 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
 102               "fixpoint divide exception")
 103 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
 104               "fixpoint overflow exception")
 105 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
 106               "HFP overflow exception")
 107 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
 108               "HFP underflow exception")
 109 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
 110               "HFP significance exception")
 111 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
 112               "HFP divide exception")
 113 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
 114               "HFP square root exception")
 115 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
 116               "operand exception")
 117 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
 118               "privileged operation")
 119 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
 120               "special operation exception")
 121 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
 122               "transaction constraint exception")
 123
 124 static inline void do_fp_trap(struct pt_regs *regs, __u32 fpc)
 125 {
 126         int si_code = 0;
 127         /* FPC[2] is Data Exception Code */
 128         if ((fpc & 0x00000300) == 0) {
 129                 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
 130                 if (fpc & 0x8000) /* invalid fp operation */
 131                         si_code = FPE_FLTINV;
 132                 else if (fpc & 0x4000) /* div by 0 */
 133                         si_code = FPE_FLTDIV;
 134                 else if (fpc & 0x2000) /* overflow */
 135                         si_code = FPE_FLTOVF;
 136                 else if (fpc & 0x1000) /* underflow */
 137                         si_code = FPE_FLTUND;
 138                 else if (fpc & 0x0800) /* inexact */
 139                         si_code = FPE_FLTRES;
 140         }
 141         do_trap(regs, SIGFPE, si_code, "floating point exception");
 142 }
 143
 144 static void translation_specification_exception(struct pt_regs *regs)
 145 {
 146         /* May never happen. */
 147         panic("Translation-Specification Exception");
 148 }
 149
 150 static void illegal_op(struct pt_regs *regs)
 151 {
 152         __u8 opcode[6];
 153         __u16 __user *location;
 154         int is_uprobe_insn = 0;
 155         int signal = 0;
 156
 157         location = get_trap_ip(regs);
 158
 159         if (user_mode(regs)) {
 160                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
 161                         return;
 162                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
 163                         if (current->ptrace)
 164                                 force_sig_fault(SIGTRAP, TRAP_BRKPT, location);
 165                         else
 166                                 signal = SIGILL;
 167 #ifdef CONFIG_UPROBES
 168                 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
 169                         is_uprobe_insn = 1;
 170 #endif
 171                 } else
 172                         signal = SIGILL;
 173         }
 174         /*
 175          * We got either an illegal op in kernel mode, or user space trapped
 176          * on a uprobes illegal instruction. See if kprobes or uprobes picks
 177          * it up. If not, SIGILL.
 178          */
 179         if (is_uprobe_insn || !user_mode(regs)) {
 180                 if (notify_die(DIE_BPT, "bpt", regs, 0,
 181                                3, SIGTRAP) != NOTIFY_STOP)
 182                         signal = SIGILL;
 183         }
 184         if (signal)
 185                 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
 186 }
 187 NOKPROBE_SYMBOL(illegal_op);
 188
 189 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 190               "specification exception");
 191
 192 static void vector_exception(struct pt_regs *regs)
 193 {
 194         int si_code, vic;
 195
 196         if (!MACHINE_HAS_VX) {
 197                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
 198                 return;
 199         }
 200
 201         /* get vector interrupt code from fpc */
 202         save_fpu_regs();
 203         vic = (current->thread.fpu.fpc & 0xf00) >> 8;
 204         switch (vic) {
 205         case 1: /* invalid vector operation */
 206                 si_code = FPE_FLTINV;
 207                 break;
 208         case 2: /* division by zero */
 209                 si_code = FPE_FLTDIV;
 210                 break;
 211         case 3: /* overflow */
 212                 si_code = FPE_FLTOVF;
 213                 break;
 214         case 4: /* underflow */
 215                 si_code = FPE_FLTUND;
 216                 break;
 217         case 5: /* inexact */
 218                 si_code = FPE_FLTRES;
 219                 break;
 220         default: /* unknown cause */
 221                 si_code = 0;
 222         }
 223         do_trap(regs, SIGFPE, si_code, "vector exception");
 224 }
 225
 226 static void data_exception(struct pt_regs *regs)
 227 {
 228         save_fpu_regs();
 229         if (current->thread.fpu.fpc & FPC_DXC_MASK)
 230                 do_fp_trap(regs, current->thread.fpu.fpc);
 231         else
 232                 do_trap(regs, SIGILL, ILL_ILLOPN, "data exception");
 233 }
 234
 235 static void space_switch_exception(struct pt_regs *regs)
 236 {
 237         /* Set user psw back to home space mode. */
 238         if (user_mode(regs))
 239                 regs->psw.mask |= PSW_ASC_HOME;
 240         /* Send SIGILL. */
 241         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
 242 }
 243
 244 static void monitor_event_exception(struct pt_regs *regs)
 245 {
 246         if (user_mode(regs))
 247                 return;
 248
 249         switch (report_bug(regs->psw.addr - (regs->int_code >> 16), regs)) {
 250         case BUG_TRAP_TYPE_NONE:
 251                 fixup_exception(regs);
 252                 break;
 253         case BUG_TRAP_TYPE_WARN:
 254                 break;
 255         case BUG_TRAP_TYPE_BUG:
 256                 die(regs, "monitor event");
 257                 break;
 258         }
 259 }
 260
 261 void kernel_stack_overflow(struct pt_regs *regs)
 262 {
 263         bust_spinlocks(1);
 264         printk("Kernel stack overflow.\n");
 265         show_regs(regs);
 266         bust_spinlocks(0);
 267         panic("Corrupt kernel stack, can't continue.");
 268 }
 269 NOKPROBE_SYMBOL(kernel_stack_overflow);
 270
 271 static void __init test_monitor_call(void)
 272 {
 273         int val = 1;
 274
 275         if (!IS_ENABLED(CONFIG_BUG))
 276                 return;
 277         asm volatile(
 278                 "       mc      0,0\n"
 279                 "0:     xgr     %0,%0\n"
 280                 "1:\n"
 281                 EX_TABLE(0b,1b)
 282                 : "+d" (val));
 283         if (!val)
 284                 panic("Monitor call doesn't work!\n");
 285 }
 286
 287 void __init trap_init(void)
 288 {
 289         local_mcck_enable();
 290         test_monitor_call();
 291 }
 292
 293 static void (*pgm_check_table[128])(struct pt_regs *regs);
 294
 295 void noinstr __do_pgm_check(struct pt_regs *regs)
 296 {
 297         unsigned int trapnr;
 298         irqentry_state_t state;
 299
 300         regs->int_code = S390_lowcore.pgm_int_code;
 301         regs->int_parm_long = S390_lowcore.trans_exc_code;
 302
 303         state = irqentry_enter(regs);
 304
 305         if (user_mode(regs)) {
 306                 update_timer_sys();
 307                 if (!static_branch_likely(&cpu_has_bear)) {
 308                         if (regs->last_break < 4096)
 309                                 regs->last_break = 1;
 310                 }
 311                 current->thread.last_break = regs->last_break;
 312         }
 313
 314         if (S390_lowcore.pgm_code & 0x0200) {
 315                 /* transaction abort */
 316                 current->thread.trap_tdb = S390_lowcore.pgm_tdb;
 317         }
 318
 319         if (S390_lowcore.pgm_code & PGM_INT_CODE_PER) {
 320                 if (user_mode(regs)) {
 321                         struct per_event *ev = &current->thread.per_event;
 322
 323                         set_thread_flag(TIF_PER_TRAP);
 324                         ev->address = S390_lowcore.per_address;
 325                         ev->cause = S390_lowcore.per_code_combined;
 326                         ev->paid = S390_lowcore.per_access_id;
 327                 } else {
 328                         /* PER event in kernel is kprobes */
 329                         __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
 330                         do_per_trap(regs);
 331                         goto out;
 332                 }
 333         }
 334
 335         if (!irqs_disabled_flags(regs->psw.mask))
 336                 trace_hardirqs_on();
 337         __arch_local_irq_ssm(regs->psw.mask & ~PSW_MASK_PER);
 338
 339         trapnr = regs->int_code & PGM_INT_CODE_MASK;
 340         if (trapnr)
 341                 pgm_check_table[trapnr](regs);
 342 out:
 343         local_irq_disable();
 344         irqentry_exit(regs, state);
 345 }
 346
 347 /*
 348  * The program check table contains exactly 128 (0x00-0x7f) entries. Each
 349  * line defines the function to be called corresponding to the program check
 350  * interruption code.
 351  */
 352 static void (*pgm_check_table[128])(struct pt_regs *regs) = {
 353         [0x00]          = default_trap_handler,
 354         [0x01]          = illegal_op,
 355         [0x02]          = privileged_op,
 356         [0x03]          = execute_exception,
 357         [0x04]          = do_protection_exception,
 358         [0x05]          = addressing_exception,
 359         [0x06]          = specification_exception,
 360         [0x07]          = data_exception,
 361         [0x08]          = overflow_exception,
 362         [0x09]          = divide_exception,
 363         [0x0a]          = overflow_exception,
 364         [0x0b]          = divide_exception,
 365         [0x0c]          = hfp_overflow_exception,
 366         [0x0d]          = hfp_underflow_exception,
 367         [0x0e]          = hfp_significance_exception,
 368         [0x0f]          = hfp_divide_exception,
 369         [0x10]          = do_dat_exception,
 370         [0x11]          = do_dat_exception,
 371         [0x12]          = translation_specification_exception,
 372         [0x13]          = special_op_exception,
 373         [0x14]          = default_trap_handler,
 374         [0x15]          = operand_exception,
 375         [0x16]          = default_trap_handler,
 376         [0x17]          = default_trap_handler,
 377         [0x18]          = transaction_exception,
 378         [0x19]          = default_trap_handler,
 379         [0x1a]          = default_trap_handler,
 380         [0x1b]          = vector_exception,
 381         [0x1c]          = space_switch_exception,
 382         [0x1d]          = hfp_sqrt_exception,
 383         [0x1e ... 0x37] = default_trap_handler,
 384         [0x38]          = do_dat_exception,
 385         [0x39]          = do_dat_exception,
 386         [0x3a]          = do_dat_exception,
 387         [0x3b]          = do_dat_exception,
 388         [0x3c]          = default_trap_handler,
 389         [0x3d]          = do_secure_storage_access,
 390         [0x3e]          = do_non_secure_storage_access,
 391         [0x3f]          = do_secure_storage_violation,
 392         [0x40]          = monitor_event_exception,
 393         [0x41 ... 0x7f] = default_trap_handler,
 394 };
 395
 396 #define COND_TRAP(x) asm(                       \
 397         ".weak " __stringify(x) "\n\t"          \
 398         ".set  " __stringify(x) ","             \
 399         __stringify(default_trap_handler))
 400
 401 COND_TRAP(do_secure_storage_access);
 402 COND_TRAP(do_non_secure_storage_access);
 403 COND_TRAP(do_secure_storage_violation);