Arm modules contains mapping symbols(e.g. $a $d) which are ignored in module_kallsyms_on_each_symbol. However, these symbols are still displayed when catting /proc/kallsyms. This confuses tools(e.g. perf) that resolves kernel symbols with address using information from /proc/kallsyms. See discussion in Link: https://lore.kernel.org/all/c7dfbd17-85fd-b914-b90f-082abc64c9d1@xxxxxxx/ Being left out in vmlinux(see scripts/kallsyms.c is_ignored_symbol) and kernelspace API implies that these symbols are not used in any cases. So we can ignore them in the first place by not adding them to module kallsyms. Signed-off-by: Lexi Shao <shaolexi@xxxxxxxxxx> --- kernel/module.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 5c26a76e800b..b30cbbe144c7 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2662,16 +2662,22 @@ static char elf_type(const Elf_Sym *sym, const struct load_info *info) return '?'; } -static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs, - unsigned int shnum, unsigned int pcpundx) +static inline int is_arm_mapping_symbol(const char *str); +static bool is_core_symbol(const Elf_Sym *src, const struct load_info *info) { const Elf_Shdr *sec; + const Elf_Shdr *sechdrs = info->sechdrs; + unsigned int shnum = info->hdr->e_shnum; + unsigned int pcpundx = info->index.pcpu; if (src->st_shndx == SHN_UNDEF || src->st_shndx >= shnum || !src->st_name) return false; + if (is_arm_mapping_symbol(&info->strtab[src->st_name])) + return false; + #ifdef CONFIG_KALLSYMS_ALL if (src->st_shndx == pcpundx) return true; @@ -2714,8 +2720,7 @@ static void layout_symtab(struct module *mod, struct load_info *info) /* Compute total space required for the core symbols' strtab. */ for (ndst = i = 0; i < nsrc; i++) { if (i == 0 || is_livepatch_module(mod) || - is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum, - info->index.pcpu)) { + is_core_symbol(src+i, info)) { strtab_size += strlen(&info->strtab[src[i].st_name])+1; ndst++; } @@ -2778,8 +2783,7 @@ static void add_kallsyms(struct module *mod, const struct load_info *info) for (ndst = i = 0; i < mod->kallsyms->num_symtab; i++) { mod->kallsyms->typetab[i] = elf_type(src + i, info); if (i == 0 || is_livepatch_module(mod) || - is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum, - info->index.pcpu)) { + is_core_symbol(src+i, info)) { mod->core_kallsyms.typetab[ndst] = mod->kallsyms->typetab[i]; dst[ndst] = src[i]; @@ -4246,8 +4250,7 @@ static const char *find_kallsyms_symbol(struct module *mod, * We ignore unnamed symbols: they're uninformative * and inserted at a whim. */ - if (*kallsyms_symbol_name(kallsyms, i) == '\0' - || is_arm_mapping_symbol(kallsyms_symbol_name(kallsyms, i))) + if (*kallsyms_symbol_name(kallsyms, i) == '\0') continue; if (thisval <= addr && thisval > bestval) { -- 2.12.3
