On 29/10/2021 07:50, Lexi Shao wrote: > 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> I tested this and it has removed the $ symbols from kallsyms where I saw them before. Reviewed-by: James Clark <james.clark@xxxxxxx> > --- > 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) { >
