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modpost: Optimize symbol search from linear to binary search

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[ Upstream commit 4074532758 ]

Modify modpost to use binary search for converting addresses back
into symbol references.  Previously it used linear search.

This change saves a few seconds of wall time for defconfig builds,
but can save several minutes on allyesconfigs.

Before:
$ make LLVM=1 -j128 allyesconfig vmlinux -s KCFLAGS="-Wno-error"
$ time scripts/mod/modpost -M -m -a -N -o vmlinux.symvers vmlinux.o
198.38user 1.27system 3:19.71elapsed

After:
$ make LLVM=1 -j128 allyesconfig vmlinux -s KCFLAGS="-Wno-error"
$ time scripts/mod/modpost -M -m -a -N -o vmlinux.symvers vmlinux.o
11.91user 0.85system 0:12.78elapsed

Signed-off-by: Jack Brennen <jbrennen@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Stable-dep-of: 1102f9f85b ("modpost: do not make find_tosym() return NULL")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jack Brennen
2023-09-26 08:40:44 -04:00
committed by Greg Kroah-Hartman
parent 55ed6c4778
commit 2bc92c61c5
4 changed files with 232 additions and 66 deletions
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25
scripts/mod/modpost.h
View File

@@ -10,6 +10,7 @@
#include <fcntl.h>
#include <unistd.h>
#include <elf.h>
#include "../../include/linux/module_symbol.h"
#include "list.h"
#include "elfconfig.h"
@@ -128,6 +129,8 @@ struct elf_info {
* take shndx from symtab_shndx_start[N] instead */
Elf32_Word *symtab_shndx_start;
Elf32_Word *symtab_shndx_stop;
struct symsearch *symsearch;
};
/* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
@@ -154,6 +157,28 @@ static inline unsigned int get_secindex(const struct elf_info *info,
return index;
}
/*
* If there's no name there, ignore it; likewise, ignore it if it's
* one of the magic symbols emitted used by current tools.
*
* Internal symbols created by tools should be ignored by modpost.
*/
static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym)
{
const char *name = elf->strtab + sym->st_name;
if (!name || !strlen(name))
return 0;
return !is_mapping_symbol(name);
}
/* symsearch.c */
void symsearch_init(struct elf_info *elf);
void symsearch_finish(struct elf_info *elf);
Elf_Sym *symsearch_find_nearest(struct elf_info *elf, Elf_Addr addr,
unsigned int secndx, bool allow_negative,
Elf_Addr min_distance);
/* file2alias.c */
void handle_moddevtable(struct module *mod, struct elf_info *info,
Elf_Sym *sym, const char *symname);