From b1a9651d48b42f3eddf095123c09f93e4df23060 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 1 Jun 2023 21:09:58 +0900 Subject: [PATCH] modpost: refactor find_fromsym() and find_tosym() find_fromsym() and find_tosym() are similar - both of them iterate in the .symtab section and return the nearest symbol. The difference between them is that find_tosym() allows a negative distance, but the distance must be less than 20. Factor out the common part into find_nearest_sym(). Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers --- scripts/mod/modpost.c | 89 +++++++++++++++++++-------------------------------- 1 file changed, 33 insertions(+), 56 deletions(-) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 5a5e802..32d56ef 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1075,79 +1075,56 @@ static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym) return !is_mapping_symbol(name); } -/** - * Find symbol based on relocation record info. - * In some cases the symbol supplied is a valid symbol so - * return refsym. If is_valid_name() == true, we assume this is a valid symbol. - * In other cases the symbol needs to be looked up in the symbol table - * based on section and address. - * **/ -static Elf_Sym *find_tosym(struct elf_info *elf, Elf64_Sword addr, - Elf_Sym *relsym) +/* Look up the nearest symbol based on the section and the address */ +static Elf_Sym *find_nearest_sym(struct elf_info *elf, Elf_Addr addr, + unsigned int secndx, bool allow_negative, + Elf_Addr min_distance) { Elf_Sym *sym; Elf_Sym *near = NULL; - Elf64_Sword distance = 20; - Elf64_Sword d; - unsigned int relsym_secindex; - - if (is_valid_name(elf, relsym)) - return relsym; + Elf_Addr distance; - /* - * Strive to find a better symbol name, but the resulting name may not - * match the symbol referenced in the original code. - */ - relsym_secindex = get_secindex(elf, relsym); for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) { - if (get_secindex(elf, sym) != relsym_secindex) - continue; - if (ELF_ST_TYPE(sym->st_info) == STT_SECTION) + if (get_secindex(elf, sym) != secndx) continue; if (!is_valid_name(elf, sym)) continue; - if (sym->st_value == addr) - return sym; - /* Find a symbol nearby - addr are maybe negative */ - d = sym->st_value - addr; - if (d < 0) - d = addr - sym->st_value; - if (d < distance) { - distance = d; + + if (addr >= sym->st_value) + distance = addr - sym->st_value; + else if (allow_negative) + distance = sym->st_value - addr; + else + continue; + + if (distance <= min_distance) { + min_distance = distance; near = sym; } + + if (min_distance == 0) + break; } - /* We need a close match */ - if (distance < 20) - return near; - else - return NULL; + return near; } -/* - * Find symbols before or equal addr and after addr - in the section sec. - * If we find two symbols with equal offset prefer one with a valid name. - * The ELF format may have a better way to detect what type of symbol - * it is, but this works for now. - **/ static Elf_Sym *find_fromsym(struct elf_info *elf, Elf_Addr addr, unsigned int secndx) { - Elf_Sym *sym; - Elf_Sym *near = NULL; - Elf_Addr distance = ~0; + return find_nearest_sym(elf, addr, secndx, false, ~0); +} - for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) { - if (get_secindex(elf, sym) != secndx) - continue; - if (!is_valid_name(elf, sym)) - continue; - if (sym->st_value <= addr && addr - sym->st_value <= distance) { - distance = addr - sym->st_value; - near = sym; - } - } - return near; +static Elf_Sym *find_tosym(struct elf_info *elf, Elf_Addr addr, Elf_Sym *sym) +{ + /* If the supplied symbol has a valid name, return it */ + if (is_valid_name(elf, sym)) + return sym; + + /* + * Strive to find a better symbol name, but the resulting name may not + * match the symbol referenced in the original code. + */ + return find_nearest_sym(elf, addr, get_secindex(elf, sym), true, 20); } static bool is_executable_section(struct elf_info *elf, unsigned int secndx) -- 2.7.4