[PATCH v2 03/10] modpost: remove useless export_from_sec()

From: Masahiro Yamada
Date: Tue Apr 05 2022 - 16:10:51 EST


With commit 1743694eb235 ("modpost: stop symbol preloading for
modversion CRC") applied, now export_from_sec() is useless.

handle_symbol() is called for every symbol in the ELF.

When 'symname' does not start with "__ksymtab", export_from_sec() is
called, and the returned value is stored in 'export'.

It is used in the last part of handle_symbol():

if (strstarts(symname, "__ksymtab_")) {
name = symname + strlen("__ksymtab_");
sym_add_exported(name, mod, export);
}

'export' is used only when 'symname' starts with "__ksymtab_".

So, the value returned by export_from_sec() is never used.

Remove useless export_from_sec(). This makes further cleanups possible.

I put the temporary code:

export = export_unknown;

Otherwise, I would get the compiler warning:

warning: 'export' may be used uninitialized in this function [-Wmaybe-uninitialized]

This is apparently false positive because

if (strstarts(symname, "__ksymtab_")

... is a stronger condition than:

if (strstarts(symname, "__ksymtab")

Anyway, this part will be cleaned up by the next commit.

Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
---

Changes in v2:
- Fix compiler warning

scripts/mod/modpost.c | 17 ++---------------
scripts/mod/modpost.h | 4 ----
2 files changed, 2 insertions(+), 19 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index ed9d056d2108..eebb32689816 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -369,16 +369,6 @@ static enum export export_from_secname(struct elf_info *elf, unsigned int sec)
return export_unknown;
}

-static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
-{
- if (sec == elf->export_sec)
- return export_plain;
- else if (sec == elf->export_gpl_sec)
- return export_gpl;
- else
- return export_unknown;
-}
-
static const char *namespace_from_kstrtabns(const struct elf_info *info,
const Elf_Sym *sym)
{
@@ -576,10 +566,7 @@ static int parse_elf(struct elf_info *info, const char *filename)
fatal("%s has NOBITS .modinfo\n", filename);
info->modinfo = (void *)hdr + sechdrs[i].sh_offset;
info->modinfo_len = sechdrs[i].sh_size;
- } else if (strcmp(secname, "__ksymtab") == 0)
- info->export_sec = i;
- else if (strcmp(secname, "__ksymtab_gpl") == 0)
- info->export_gpl_sec = i;
+ }

if (sechdrs[i].sh_type == SHT_SYMTAB) {
unsigned int sh_link_idx;
@@ -703,7 +690,7 @@ static void handle_symbol(struct module *mod, struct elf_info *info,
if (strstarts(symname, "__ksymtab"))
export = export_from_secname(info, get_secindex(info, sym));
else
- export = export_from_sec(info, get_secindex(info, sym));
+ export = export_unknown;

switch (sym->st_shndx) {
case SHN_COMMON:
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 0c47ff95c0e2..a85dcec3669a 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -25,7 +25,6 @@
#define Elf_Sym Elf32_Sym
#define Elf_Addr Elf32_Addr
#define Elf_Sword Elf64_Sword
-#define Elf_Section Elf32_Half
#define ELF_ST_BIND ELF32_ST_BIND
#define ELF_ST_TYPE ELF32_ST_TYPE

@@ -40,7 +39,6 @@
#define Elf_Sym Elf64_Sym
#define Elf_Addr Elf64_Addr
#define Elf_Sword Elf64_Sxword
-#define Elf_Section Elf64_Half
#define ELF_ST_BIND ELF64_ST_BIND
#define ELF_ST_TYPE ELF64_ST_TYPE

@@ -138,8 +136,6 @@ struct elf_info {
Elf_Shdr *sechdrs;
Elf_Sym *symtab_start;
Elf_Sym *symtab_stop;
- Elf_Section export_sec;
- Elf_Section export_gpl_sec;
char *strtab;
char *modinfo;
unsigned int modinfo_len;
--
2.32.0