[PATCH v4 10/21] modpost: simplify find_elf_symbol()

Masahiro Yamada
2023-05-13T20:46:18Z

I do not know why commit 157c23c80eed ("kbuild: use simpler section
mismatch warnings in modpost") is only applicable to find_elf_symbol2().

Simplify find_elf_symbol() based on find_elf_symbol2().

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

scripts/mod/modpost.c | 64 +++++++++----------------------------------
1 file changed, 13 insertions(+), 51 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 3b7b78e69137..b4fa9e0be4d1 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1117,57 +1117,7 @@ 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 st_name != 0 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_elf_symbol(struct elf_info *elf, Elf64_Sword addr,
- Elf_Sym *relsym)
-{
- Elf_Sym *sym;
- Elf_Sym *near = NULL;
- Elf64_Sword distance = 20;
- Elf64_Sword d;
- unsigned int relsym_secindex;
-
- if (relsym->st_name != 0)
- return relsym;
-
- 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)
- 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;
- near = sym;
- }
- }
- /* We need a close match */
- if (distance < 20)
- return near;
- else
- return NULL;
-}
-
-/*
- * 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.
- **/
+/* Look up the nearest symbol based on the section and the address */
static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr,
unsigned int secndx)
{
@@ -1178,6 +1128,8 @@ static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr,
for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
if (get_secindex(elf, sym) != secndx)
continue;
+ if (ELF_ST_TYPE(sym->st_info) == STT_SECTION)
+ continue;
if (!is_valid_name(elf, sym))
continue;
if (sym->st_value <= addr && addr - sym->st_value <= distance) {
@@ -1188,6 +1140,16 @@ static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr,
return near;
}

+static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf_Addr addr, Elf_Sym *sym)
+{
+ /* If the supplied symbol is valid, return it */
+ if (sym->st_name != 0)
+ return sym;
+
+ /* Otherwise, look up a better symbol */
+ return find_elf_symbol2(elf, addr, get_secindex(elf, sym));
+}
+
static bool is_executable_section(struct elf_info *elf, unsigned int secndx)
{
if (secndx > elf->num_sections)
--
2.39.2