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scripts: Add sortextable to sort the kernel's exception table.

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Using this build-time sort saves time booting as we don't have to burn
cycles sorting the exception table.

Signed-off-by: David Daney <david.daney@cavium.com>
Link: http://lkml.kernel.org/r/1334872799-14589-2-git-send-email-ddaney.cavm@gmail.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
David Daney 2012-04-19 14:59:55 -07:00 • committed by H. Peter Anvin
parent e816b57a33
commit a79f248b9b
4 changed files with 441 additions and 0 deletions
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168
scripts/sortextable.h Normal file
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/*
* sortextable.h
*
* Copyright 2011 Cavium, Inc.
*
* Some of this code was taken out of recordmcount.h written by:
*
* Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
* Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
*
*
* Licensed under the GNU General Public License, version 2 (GPLv2).
*/
#undef extable_ent_size
#undef compare_extable
#undef do_func
#undef Elf_Addr
#undef Elf_Ehdr
#undef Elf_Shdr
#undef Elf_Rel
#undef Elf_Rela
#undef Elf_Sym
#undef ELF_R_SYM
#undef Elf_r_sym
#undef ELF_R_INFO
#undef Elf_r_info
#undef ELF_ST_BIND
#undef ELF_ST_TYPE
#undef fn_ELF_R_SYM
#undef fn_ELF_R_INFO
#undef uint_t
#undef _w
#ifdef SORTEXTABLE_64
# define extable_ent_size 16
# define compare_extable compare_extable_64
# define do_func do64
# define Elf_Addr Elf64_Addr
# define Elf_Ehdr Elf64_Ehdr
# define Elf_Shdr Elf64_Shdr
# define Elf_Rel Elf64_Rel
# define Elf_Rela Elf64_Rela
# define Elf_Sym Elf64_Sym
# define ELF_R_SYM ELF64_R_SYM
# define Elf_r_sym Elf64_r_sym
# define ELF_R_INFO ELF64_R_INFO
# define Elf_r_info Elf64_r_info
# define ELF_ST_BIND ELF64_ST_BIND
# define ELF_ST_TYPE ELF64_ST_TYPE
# define fn_ELF_R_SYM fn_ELF64_R_SYM
# define fn_ELF_R_INFO fn_ELF64_R_INFO
# define uint_t uint64_t
# define _w w8
#else
# define extable_ent_size 8
# define compare_extable compare_extable_32
# define do_func do32
# define Elf_Addr Elf32_Addr
# define Elf_Ehdr Elf32_Ehdr
# define Elf_Shdr Elf32_Shdr
# define Elf_Rel Elf32_Rel
# define Elf_Rela Elf32_Rela
# define Elf_Sym Elf32_Sym
# define ELF_R_SYM ELF32_R_SYM
# define Elf_r_sym Elf32_r_sym
# define ELF_R_INFO ELF32_R_INFO
# define Elf_r_info Elf32_r_info
# define ELF_ST_BIND ELF32_ST_BIND
# define ELF_ST_TYPE ELF32_ST_TYPE
# define fn_ELF_R_SYM fn_ELF32_R_SYM
# define fn_ELF_R_INFO fn_ELF32_R_INFO
# define uint_t uint32_t
# define _w w
#endif
static int compare_extable(const void *a, const void *b)
{
const uint_t *aa = a;
const uint_t *bb = b;
if (_w(*aa) < _w(*bb))
return -1;
if (_w(*aa) > _w(*bb))
return 1;
return 0;
}
static void
do_func(Elf_Ehdr *const ehdr, char const *const fname)
{
Elf_Shdr *shdr;
Elf_Shdr *shstrtab_sec;
Elf_Shdr *strtab_sec = NULL;
Elf_Shdr *symtab_sec = NULL;
Elf_Shdr *extab_sec = NULL;
Elf_Sym *sym;
Elf_Sym *sort_needed_sym;
Elf_Shdr *sort_needed_sec;
uint32_t *sort_done_location;
const char *secstrtab;
const char *strtab;
int i;
int idx;
shdr = (Elf_Shdr *)((void *)ehdr + _w(ehdr->e_shoff));
shstrtab_sec = shdr + w2(ehdr->e_shstrndx);
secstrtab = (const char *)ehdr + _w(shstrtab_sec->sh_offset);
for (i = 0; i < w2(ehdr->e_shnum); i++) {
idx = w(shdr[i].sh_name);
if (strcmp(secstrtab + idx, "__ex_table") == 0)
extab_sec = shdr + i;
if (strcmp(secstrtab + idx, ".symtab") == 0)
symtab_sec = shdr + i;
if (strcmp(secstrtab + idx, ".strtab") == 0)
strtab_sec = shdr + i;
}
if (strtab_sec == NULL) {
fprintf(stderr, "no .strtab in file: %s\n", fname);
fail_file();
}
if (symtab_sec == NULL) {
fprintf(stderr, "no .symtab in file: %s\n", fname);
fail_file();
}
if (extab_sec == NULL) {
fprintf(stderr, "no __ex_table in file: %s\n", fname);
fail_file();
}
strtab = (const char *)ehdr + _w(strtab_sec->sh_offset);
/* Sort the table in place */
qsort((void *)ehdr + _w(extab_sec->sh_offset),
(_w(extab_sec->sh_size) / extable_ent_size),
extable_ent_size, compare_extable);
/* find main_extable_sort_needed */
sort_needed_sym = NULL;
for (i = 0; i < _w(symtab_sec->sh_size) / sizeof(Elf_Sym); i++) {
sym = (void *)ehdr + _w(symtab_sec->sh_offset);
sym += i;
if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
continue;
idx = w(sym->st_name);
if (strcmp(strtab + idx, "main_extable_sort_needed") == 0) {
sort_needed_sym = sym;
break;
}
}
if (sort_needed_sym == NULL) {
fprintf(stderr,
"no main_extable_sort_needed symbol in file: %s\n",
fname);
fail_file();
}
sort_needed_sec = &shdr[w2(sort_needed_sym->st_shndx)];
sort_done_location = (void *)ehdr +
_w(sort_needed_sec->sh_offset) +
_w(sort_needed_sym->st_value) -
_w(sort_needed_sec->sh_addr);
printf("sort done marker at %lx\n",
(unsigned long) (_w(sort_needed_sec->sh_offset) +
_w(sort_needed_sym->st_value) -
_w(sort_needed_sec->sh_addr)));
/* We sorted it, clear the flag. */
*sort_done_location = 0;
}