1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Kernel module help for PPC64.
3 Copyright (C) 2001, 2003 Rusty Russell IBM Corporation.
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/module.h>
10 #include <linux/elf.h>
11 #include <linux/moduleloader.h>
12 #include <linux/err.h>
13 #include <linux/vmalloc.h>
14 #include <linux/ftrace.h>
15 #include <linux/bug.h>
16 #include <linux/uaccess.h>
17 #include <linux/kernel.h>
18 #include <asm/module.h>
19 #include <asm/firmware.h>
20 #include <asm/code-patching.h>
21 #include <linux/sort.h>
22 #include <asm/setup.h>
23 #include <asm/sections.h>
26 /* FIXME: We don't do .init separately. To do this, we'd need to have
27 a separate r2 value in the init and core section, and stub between
30 Using a magic allocator which places modules within 32MB solves
31 this, and makes other things simpler. Anton?
34 #ifdef PPC64_ELF_ABI_v2
36 static func_desc_t func_desc(unsigned long addr)
45 /* PowerPC64 specific values for the Elf64_Sym st_other field. */
46 #define STO_PPC64_LOCAL_BIT 5
47 #define STO_PPC64_LOCAL_MASK (7 << STO_PPC64_LOCAL_BIT)
48 #define PPC64_LOCAL_ENTRY_OFFSET(other) \
49 (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
51 static unsigned int local_entry_offset(const Elf64_Sym *sym)
53 /* sym->st_other indicates offset to local entry point
54 * (otherwise it will assume r12 is the address of the start
55 * of function and try to derive r2 from it). */
56 return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
60 static func_desc_t func_desc(unsigned long addr)
62 return *(struct func_desc *)addr;
64 static unsigned int local_entry_offset(const Elf64_Sym *sym)
69 void *dereference_module_function_descriptor(struct module *mod, void *ptr)
71 if (ptr < (void *)mod->arch.start_opd ||
72 ptr >= (void *)mod->arch.end_opd)
75 return dereference_function_descriptor(ptr);
79 static unsigned long func_addr(unsigned long addr)
81 return func_desc(addr).addr;
84 static unsigned long stub_func_addr(func_desc_t func)
89 #define STUB_MAGIC 0x73747562 /* stub */
91 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
92 the kernel itself). But on PPC64, these need to be used for every
93 jump, actually, to reset r2 (TOC+0x8000). */
94 struct ppc64_stub_entry
96 /* 28 byte jump instruction sequence (7 instructions). We only
97 * need 6 instructions on ABIv2 but we always allocate 7 so
98 * so we don't have to modify the trampoline load instruction. */
100 /* Used by ftrace to identify stubs */
102 /* Data for the above code */
103 func_desc_t funcdata;
107 * PPC64 uses 24 bit jumps, but we need to jump into other modules or
108 * the kernel which may be further. So we jump to a stub.
110 * For ELFv1 we need to use this to set up the new r2 value (aka TOC
111 * pointer). For ELFv2 it's the callee's responsibility to set up the
112 * new r2, but for both we need to save the old r2.
114 * We could simply patch the new r2 value and function pointer into
115 * the stub, but it's significantly shorter to put these values at the
116 * end of the stub code, and patch the stub address (32-bits relative
117 * to the TOC ptr, r2) into the stub.
119 static u32 ppc64_stub_insns[] = {
120 PPC_RAW_ADDIS(_R11, _R2, 0),
121 PPC_RAW_ADDI(_R11, _R11, 0),
122 /* Save current r2 value in magic place on the stack. */
123 PPC_RAW_STD(_R2, _R1, R2_STACK_OFFSET),
124 PPC_RAW_LD(_R12, _R11, 32),
125 #ifdef PPC64_ELF_ABI_v1
126 /* Set up new r2 from function descriptor */
127 PPC_RAW_LD(_R2, _R11, 40),
133 /* Count how many different 24-bit relocations (different symbol,
135 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
137 unsigned int i, r_info, r_addend, _count_relocs;
139 /* FIXME: Only count external ones --RR */
143 for (i = 0; i < num; i++)
144 /* Only count 24-bit relocs, others don't need stubs */
145 if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
146 (r_info != ELF64_R_SYM(rela[i].r_info) ||
147 r_addend != rela[i].r_addend)) {
149 r_info = ELF64_R_SYM(rela[i].r_info);
150 r_addend = rela[i].r_addend;
153 return _count_relocs;
156 static int relacmp(const void *_x, const void *_y)
158 const Elf64_Rela *x, *y;
160 y = (Elf64_Rela *)_x;
161 x = (Elf64_Rela *)_y;
163 /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
164 * make the comparison cheaper/faster. It won't affect the sorting or
165 * the counting algorithms' performance
167 if (x->r_info < y->r_info)
169 else if (x->r_info > y->r_info)
171 else if (x->r_addend < y->r_addend)
173 else if (x->r_addend > y->r_addend)
179 /* Get size of potential trampolines required. */
180 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
181 const Elf64_Shdr *sechdrs)
183 /* One extra reloc so it's always 0-addr terminated */
184 unsigned long relocs = 1;
187 /* Every relocated section... */
188 for (i = 1; i < hdr->e_shnum; i++) {
189 if (sechdrs[i].sh_type == SHT_RELA) {
190 pr_debug("Found relocations in section %u\n", i);
191 pr_debug("Ptr: %p. Number: %Lu\n",
192 (void *)sechdrs[i].sh_addr,
193 sechdrs[i].sh_size / sizeof(Elf64_Rela));
195 /* Sort the relocation information based on a symbol and
196 * addend key. This is a stable O(n*log n) complexity
197 * alogrithm but it will reduce the complexity of
198 * count_relocs() to linear complexity O(n)
200 sort((void *)sechdrs[i].sh_addr,
201 sechdrs[i].sh_size / sizeof(Elf64_Rela),
202 sizeof(Elf64_Rela), relacmp, NULL);
204 relocs += count_relocs((void *)sechdrs[i].sh_addr,
206 / sizeof(Elf64_Rela));
210 #ifdef CONFIG_DYNAMIC_FTRACE
211 /* make the trampoline to the ftrace_caller */
213 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
214 /* an additional one for ftrace_regs_caller */
219 pr_debug("Looks like a total of %lu stubs, max\n", relocs);
220 return relocs * sizeof(struct ppc64_stub_entry);
223 /* Still needed for ELFv2, for .TOC. */
224 static void dedotify_versions(struct modversion_info *vers,
227 struct modversion_info *end;
229 for (end = (void *)vers + size; vers < end; vers++)
230 if (vers->name[0] == '.') {
231 memmove(vers->name, vers->name+1, strlen(vers->name));
236 * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
237 * seem to be defined (value set later).
239 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
243 for (i = 1; i < numsyms; i++) {
244 if (syms[i].st_shndx == SHN_UNDEF) {
245 char *name = strtab + syms[i].st_name;
246 if (name[0] == '.') {
247 if (strcmp(name+1, "TOC.") == 0)
248 syms[i].st_shndx = SHN_ABS;
255 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
257 unsigned int symindex)
259 unsigned int i, numsyms;
262 syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
263 numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
265 for (i = 1; i < numsyms; i++) {
266 if (syms[i].st_shndx == SHN_ABS
267 && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
273 bool module_init_section(const char *name)
275 /* We don't handle .init for the moment: always return false. */
279 int module_frob_arch_sections(Elf64_Ehdr *hdr,
286 /* Find .toc and .stubs sections, symtab and strtab */
287 for (i = 1; i < hdr->e_shnum; i++) {
288 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
289 me->arch.stubs_section = i;
290 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) {
291 me->arch.toc_section = i;
292 if (sechdrs[i].sh_addralign < 8)
293 sechdrs[i].sh_addralign = 8;
295 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
296 dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
299 if (sechdrs[i].sh_type == SHT_SYMTAB)
300 dedotify((void *)hdr + sechdrs[i].sh_offset,
301 sechdrs[i].sh_size / sizeof(Elf64_Sym),
303 + sechdrs[sechdrs[i].sh_link].sh_offset);
306 if (!me->arch.stubs_section) {
307 pr_err("%s: doesn't contain .stubs.\n", me->name);
311 /* If we don't have a .toc, just use .stubs. We need to set r2
312 to some reasonable value in case the module calls out to
313 other functions via a stub, or if a function pointer escapes
314 the module by some means. */
315 if (!me->arch.toc_section)
316 me->arch.toc_section = me->arch.stubs_section;
318 /* Override the stubs size */
319 sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
323 #ifdef CONFIG_MPROFILE_KERNEL
325 static u32 stub_insns[] = {
326 PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
327 PPC_RAW_ADDIS(_R12, _R12, 0),
328 PPC_RAW_ADDI(_R12, _R12, 0),
334 * For mprofile-kernel we use a special stub for ftrace_caller() because we
335 * can't rely on r2 containing this module's TOC when we enter the stub.
337 * That can happen if the function calling us didn't need to use the toc. In
338 * that case it won't have setup r2, and the r2 value will be either the
339 * kernel's toc, or possibly another modules toc.
341 * To deal with that this stub uses the kernel toc, which is always accessible
342 * via the paca (in r13). The target (ftrace_caller()) is responsible for
343 * saving and restoring the toc before returning.
345 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
351 memcpy(entry->jump, stub_insns, sizeof(stub_insns));
353 /* Stub uses address relative to kernel toc (from the paca) */
354 reladdr = addr - kernel_toc_addr();
355 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
356 pr_err("%s: Address of %ps out of range of kernel_toc.\n",
357 me->name, (void *)addr);
361 entry->jump[1] |= PPC_HA(reladdr);
362 entry->jump[2] |= PPC_LO(reladdr);
364 /* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */
365 entry->funcdata = func_desc(addr);
366 entry->magic = STUB_MAGIC;
371 static bool is_mprofile_ftrace_call(const char *name)
373 if (!strcmp("_mcount", name))
375 #ifdef CONFIG_DYNAMIC_FTRACE
376 if (!strcmp("ftrace_caller", name))
378 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
379 if (!strcmp("ftrace_regs_caller", name))
387 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
394 static bool is_mprofile_ftrace_call(const char *name)
401 * r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the
402 * value maximum span in an instruction which uses a signed offset). Round down
403 * to a 256 byte boundary for the odd case where we are setting up r2 without a
406 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
408 return (sechdrs[me->arch.toc_section].sh_addr & ~0xfful) + 0x8000;
411 /* Patch stub to reference function and correct r2 value. */
412 static inline int create_stub(const Elf64_Shdr *sechdrs,
413 struct ppc64_stub_entry *entry,
422 if (is_mprofile_ftrace_call(name))
423 return create_ftrace_stub(entry, addr, me);
425 for (i = 0; i < ARRAY_SIZE(ppc64_stub_insns); i++) {
426 if (patch_instruction(&entry->jump[i],
427 ppc_inst(ppc64_stub_insns[i])))
431 /* Stub uses address relative to r2. */
432 reladdr = (unsigned long)entry - my_r2(sechdrs, me);
433 if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
434 pr_err("%s: Address %p of stub out of range of %p.\n",
435 me->name, (void *)reladdr, (void *)my_r2);
438 pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
440 if (patch_instruction(&entry->jump[0],
441 ppc_inst(entry->jump[0] | PPC_HA(reladdr))))
444 if (patch_instruction(&entry->jump[1],
445 ppc_inst(entry->jump[1] | PPC_LO(reladdr))))
448 // func_desc_t is 8 bytes if ABIv2, else 16 bytes
449 desc = func_desc(addr);
450 for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) {
451 if (patch_instruction(((u32 *)&entry->funcdata) + i,
452 ppc_inst(((u32 *)(&desc))[i])))
456 if (patch_instruction(&entry->magic, ppc_inst(STUB_MAGIC)))
462 /* Create stub to jump to function described in this OPD/ptr: we need the
463 stub to set up the TOC ptr (r2) for the function. */
464 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
469 struct ppc64_stub_entry *stubs;
470 unsigned int i, num_stubs;
472 num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
474 /* Find this stub, or if that fails, the next avail. entry */
475 stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
476 for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
477 if (WARN_ON(i >= num_stubs))
480 if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
481 return (unsigned long)&stubs[i];
484 if (!create_stub(sechdrs, &stubs[i], addr, me, name))
487 return (unsigned long)&stubs[i];
490 /* We expect a noop next: if it is, replace it with instruction to
492 static int restore_r2(const char *name, u32 *instruction, struct module *me)
494 u32 *prev_insn = instruction - 1;
496 if (is_mprofile_ftrace_call(name))
500 * Make sure the branch isn't a sibling call. Sibling calls aren't
501 * "link" branches and they don't return, so they don't need the r2
502 * restore afterwards.
504 if (!instr_is_relative_link_branch(ppc_inst(*prev_insn)))
507 if (*instruction != PPC_RAW_NOP()) {
508 pr_err("%s: Expected nop after call, got %08x at %pS\n",
509 me->name, *instruction, instruction);
513 /* ld r2,R2_STACK_OFFSET(r1) */
514 if (patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC)))
520 int apply_relocate_add(Elf64_Shdr *sechdrs,
522 unsigned int symindex,
527 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
529 unsigned long *location;
532 pr_debug("Applying ADD relocate section %u to %u\n", relsec,
533 sechdrs[relsec].sh_info);
535 /* First time we're called, we can fix up .TOC. */
536 if (!me->arch.toc_fixed) {
537 sym = find_dot_toc(sechdrs, strtab, symindex);
538 /* It's theoretically possible that a module doesn't want a
539 * .TOC. so don't fail it just for that. */
541 sym->st_value = my_r2(sechdrs, me);
542 me->arch.toc_fixed = true;
545 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
546 /* This is where to make the change */
547 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
549 /* This is the symbol it is referring to */
550 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
551 + ELF64_R_SYM(rela[i].r_info);
553 pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
554 location, (long)ELF64_R_TYPE(rela[i].r_info),
555 strtab + sym->st_name, (unsigned long)sym->st_value,
556 (long)rela[i].r_addend);
558 /* `Everything is relative'. */
559 value = sym->st_value + rela[i].r_addend;
561 switch (ELF64_R_TYPE(rela[i].r_info)) {
564 *(u32 *)location = value;
569 *(unsigned long *)location = value;
573 *(unsigned long *)location = my_r2(sechdrs, me);
577 /* Subtract TOC pointer */
578 value -= my_r2(sechdrs, me);
579 if (value + 0x8000 > 0xffff) {
580 pr_err("%s: bad TOC16 relocation (0x%lx)\n",
584 *((uint16_t *) location)
585 = (*((uint16_t *) location) & ~0xffff)
589 case R_PPC64_TOC16_LO:
590 /* Subtract TOC pointer */
591 value -= my_r2(sechdrs, me);
592 *((uint16_t *) location)
593 = (*((uint16_t *) location) & ~0xffff)
597 case R_PPC64_TOC16_DS:
598 /* Subtract TOC pointer */
599 value -= my_r2(sechdrs, me);
600 if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
601 pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
605 *((uint16_t *) location)
606 = (*((uint16_t *) location) & ~0xfffc)
610 case R_PPC64_TOC16_LO_DS:
611 /* Subtract TOC pointer */
612 value -= my_r2(sechdrs, me);
613 if ((value & 3) != 0) {
614 pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
618 *((uint16_t *) location)
619 = (*((uint16_t *) location) & ~0xfffc)
623 case R_PPC64_TOC16_HA:
624 /* Subtract TOC pointer */
625 value -= my_r2(sechdrs, me);
626 value = ((value + 0x8000) >> 16);
627 *((uint16_t *) location)
628 = (*((uint16_t *) location) & ~0xffff)
633 /* FIXME: Handle weak symbols here --RR */
634 if (sym->st_shndx == SHN_UNDEF ||
635 sym->st_shndx == SHN_LIVEPATCH) {
636 /* External: go via stub */
637 value = stub_for_addr(sechdrs, value, me,
638 strtab + sym->st_name);
641 if (!restore_r2(strtab + sym->st_name,
642 (u32 *)location + 1, me))
645 value += local_entry_offset(sym);
647 /* Convert value to relative */
648 value -= (unsigned long)location;
649 if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
650 pr_err("%s: REL24 %li out of range!\n",
651 me->name, (long int)value);
655 /* Only replace bits 2 through 26 */
656 value = (*(uint32_t *)location & ~0x03fffffc)
657 | (value & 0x03fffffc);
659 if (patch_instruction((u32 *)location, ppc_inst(value)))
665 /* 64 bits relative (used by features fixups) */
666 *location = value - (unsigned long)location;
670 /* 32 bits relative (used by relative exception tables) */
671 /* Convert value to relative */
672 value -= (unsigned long)location;
673 if (value + 0x80000000 > 0xffffffff) {
674 pr_err("%s: REL32 %li out of range!\n",
675 me->name, (long int)value);
678 *(u32 *)location = value;
681 case R_PPC64_TOCSAVE:
683 * Marker reloc indicates we don't have to save r2.
684 * That would only save us one instruction, so ignore
691 * Optimize ELFv2 large code model entry point if
692 * the TOC is within 2GB range of current location.
694 value = my_r2(sechdrs, me) - (unsigned long)location;
695 if (value + 0x80008000 > 0xffffffff)
698 * Check for the large code model prolog sequence:
702 if ((((uint32_t *)location)[0] & ~0xfffc) != PPC_RAW_LD(_R2, _R12, 0))
704 if (((uint32_t *)location)[1] != PPC_RAW_ADD(_R2, _R2, _R12))
707 * If found, replace it with:
708 * addis r2, r12, (.TOC.-func)@ha
709 * addi r2, r2, (.TOC.-func)@l
711 ((uint32_t *)location)[0] = PPC_RAW_ADDIS(_R2, _R12, PPC_HA(value));
712 ((uint32_t *)location)[1] = PPC_RAW_ADDI(_R2, _R2, PPC_LO(value));
715 case R_PPC64_REL16_HA:
716 /* Subtract location pointer */
717 value -= (unsigned long)location;
718 value = ((value + 0x8000) >> 16);
719 *((uint16_t *) location)
720 = (*((uint16_t *) location) & ~0xffff)
724 case R_PPC64_REL16_LO:
725 /* Subtract location pointer */
726 value -= (unsigned long)location;
727 *((uint16_t *) location)
728 = (*((uint16_t *) location) & ~0xffff)
733 pr_err("%s: Unknown ADD relocation: %lu\n",
735 (unsigned long)ELF64_R_TYPE(rela[i].r_info));
743 #ifdef CONFIG_DYNAMIC_FTRACE
744 int module_trampoline_target(struct module *mod, unsigned long addr,
745 unsigned long *target)
747 struct ppc64_stub_entry *stub;
748 func_desc_t funcdata;
751 if (!within_module_core(addr, mod)) {
752 pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name);
756 stub = (struct ppc64_stub_entry *)addr;
758 if (copy_from_kernel_nofault(&magic, &stub->magic,
760 pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
764 if (magic != STUB_MAGIC) {
765 pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name);
769 if (copy_from_kernel_nofault(&funcdata, &stub->funcdata,
771 pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
775 *target = stub_func_addr(funcdata);
780 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
782 mod->arch.tramp = stub_for_addr(sechdrs,
783 (unsigned long)ftrace_caller,
786 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
787 mod->arch.tramp_regs = stub_for_addr(sechdrs,
788 (unsigned long)ftrace_regs_caller,
790 "ftrace_regs_caller");
791 if (!mod->arch.tramp_regs)
795 if (!mod->arch.tramp)