Messages in this thread Patch in this message | | | Date | Sun, 30 Oct 2022 10:15:22 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 0/5] x86/kallsyms: Fix the call-thunk kallsyms fail |
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On Fri, Oct 28, 2022 at 09:40:22PM +0200, Peter Zijlstra wrote: > Hi all, > > As reported here: > > https://lkml.kernel.org/r/202210241614.2ae4c1f5-yujie.liu@intel.com > > The kallsyms change for call-thunks doesn't really work out as expected. These > patches revert that change and propose an alternative.
Robot found it needed the below; have folded back and pushed out again.
--- diff --git a/tools/objtool/check.c b/tools/objtool/check.c index cf743520a786..55066c493570 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3479,7 +3479,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, if (func && insn_func(insn) && func != insn_func(insn)->pfunc) { /* Ignore KCFI type preambles, which always fall through */ - if (!strncmp(func->name, "__cfi_", 6)) + if (!strncmp(func->name, "__cfi_", 6) || + !strncmp(func->name, "__pfx_", 6)) return 0; WARN("%s() falls through to next function %s()", @@ -4042,6 +4043,7 @@ static int add_prefix_symbol(struct objtool_file *file, struct symbol *func, for (;;) { struct instruction *prev = list_prev_entry(insn, list); + u64 offset; if (&prev->list == &file->insn_list) break; @@ -4049,11 +4051,13 @@ static int add_prefix_symbol(struct objtool_file *file, struct symbol *func, if (prev->type != INSN_NOP) break; - insn = prev; - if (func->offset - prev->offset == opts.prefix) { - elf_create_prefix_symbol(file->elf, func, -opts.prefix); + offset = func->offset - prev->offset; + if (offset >= opts.prefix) { + if (offset == opts.prefix) + elf_create_prefix_symbol(file->elf, func, opts.prefix); break; } + insn = prev; } return 0; diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 9fbdad7a565d..3d636d12d679 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -822,7 +822,7 @@ elf_create_section_symbol(struct elf *elf, struct section *sec) static int elf_add_string(struct elf *elf, struct section *strtab, char *str); struct symbol * -elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long addend) +elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size) { struct symbol *sym = calloc(1, sizeof(*sym)); size_t namelen = strlen(orig->name) + sizeof("__pfx_"); @@ -840,7 +840,8 @@ elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long addend) sym->sym.st_name = elf_add_string(elf, NULL, name); sym->sym.st_info = orig->sym.st_info; - sym->sym.st_value = orig->sym.st_value + addend; + sym->sym.st_value = orig->sym.st_value - size; + sym->sym.st_size = size; sym = __elf_create_symbol(elf, sym); if (sym) diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index 9e3bd4717a11..b6974e3173aa 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -146,7 +146,7 @@ static inline bool has_multiple_files(struct elf *elf) struct elf *elf_open_read(const char *name, int flags); struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr); -struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long addend); +struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size); int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset, unsigned int type, struct symbol *sym, s64 addend);
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