Commit a79f248b authored by David Daney's avatar David Daney Committed by H. Peter Anvin

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

Using this build-time sort saves time booting as we don't have to burn
cycles sorting the exception table.
Signed-off-by: default avatarDavid Daney <david.daney@cavium.com>
Link: http://lkml.kernel.org/r/1334872799-14589-2-git-send-email-ddaney.cavm@gmail.comSigned-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent e816b57a
......@@ -9,3 +9,4 @@ unifdef
ihex2fw
recordmcount
docproc
sortextable
......@@ -13,6 +13,7 @@ hostprogs-$(CONFIG_LOGO) += pnmtologo
hostprogs-$(CONFIG_VT) += conmakehash
hostprogs-$(CONFIG_IKCONFIG) += bin2c
hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable
always := $(hostprogs-y) $(hostprogs-m)
......
/*
* sortextable.c: Sort the kernel's exception table
*
* Copyright 2011 Cavium, Inc.
*
* Based on code taken from recortmcount.c which is:
*
* Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
* Licensed under the GNU General Public License, version 2 (GPLv2).
*
* Restructured to fit Linux format, as well as other updates:
* Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
*/
/*
* Strategy: alter the vmlinux file in-place.
*/
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <getopt.h>
#include <elf.h>
#include <fcntl.h>
#include <setjmp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static int fd_map; /* File descriptor for file being modified. */
static int mmap_failed; /* Boolean flag. */
static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */
static struct stat sb; /* Remember .st_size, etc. */
static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */
/* setjmp() return values */
enum {
SJ_SETJMP = 0, /* hardwired first return */
SJ_FAIL,
SJ_SUCCEED
};
/* Per-file resource cleanup when multiple files. */
static void
cleanup(void)
{
if (!mmap_failed)
munmap(ehdr_curr, sb.st_size);
close(fd_map);
}
static void __attribute__((noreturn))
fail_file(void)
{
cleanup();
longjmp(jmpenv, SJ_FAIL);
}
static void __attribute__((noreturn))
succeed_file(void)
{
cleanup();
longjmp(jmpenv, SJ_SUCCEED);
}
/*
* Get the whole file as a programming convenience in order to avoid
* malloc+lseek+read+free of many pieces. If successful, then mmap
* avoids copying unused pieces; else just read the whole file.
* Open for both read and write.
*/
static void *mmap_file(char const *fname)
{
void *addr;
fd_map = open(fname, O_RDWR);
if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
perror(fname);
fail_file();
}
if (!S_ISREG(sb.st_mode)) {
fprintf(stderr, "not a regular file: %s\n", fname);
fail_file();
}
addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED,
fd_map, 0);
if (addr == MAP_FAILED) {
mmap_failed = 1;
fprintf(stderr, "Could not mmap file: %s\n", fname);
fail_file();
}
return addr;
}
/* w8rev, w8nat, ...: Handle endianness. */
static uint64_t w8rev(uint64_t const x)
{
return ((0xff & (x >> (0 * 8))) << (7 * 8))
| ((0xff & (x >> (1 * 8))) << (6 * 8))
| ((0xff & (x >> (2 * 8))) << (5 * 8))
| ((0xff & (x >> (3 * 8))) << (4 * 8))
| ((0xff & (x >> (4 * 8))) << (3 * 8))
| ((0xff & (x >> (5 * 8))) << (2 * 8))
| ((0xff & (x >> (6 * 8))) << (1 * 8))
| ((0xff & (x >> (7 * 8))) << (0 * 8));
}
static uint32_t w4rev(uint32_t const x)
{
return ((0xff & (x >> (0 * 8))) << (3 * 8))
| ((0xff & (x >> (1 * 8))) << (2 * 8))
| ((0xff & (x >> (2 * 8))) << (1 * 8))
| ((0xff & (x >> (3 * 8))) << (0 * 8));
}
static uint32_t w2rev(uint16_t const x)
{
return ((0xff & (x >> (0 * 8))) << (1 * 8))
| ((0xff & (x >> (1 * 8))) << (0 * 8));
}
static uint64_t w8nat(uint64_t const x)
{
return x;
}
static uint32_t w4nat(uint32_t const x)
{
return x;
}
static uint32_t w2nat(uint16_t const x)
{
return x;
}
static uint64_t (*w8)(uint64_t);
static uint32_t (*w)(uint32_t);
static uint32_t (*w2)(uint16_t);
/* 32 bit and 64 bit are very similar */
#include "sortextable.h"
#define SORTEXTABLE_64
#include "sortextable.h"
static void
do_file(char const *const fname)
{
Elf32_Ehdr *const ehdr = mmap_file(fname);
ehdr_curr = ehdr;
w = w4nat;
w2 = w2nat;
w8 = w8nat;
switch (ehdr->e_ident[EI_DATA]) {
static unsigned int const endian = 1;
default:
fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
ehdr->e_ident[EI_DATA], fname);
fail_file();
break;
case ELFDATA2LSB:
if (*(unsigned char const *)&endian != 1) {
/* main() is big endian, file.o is little endian. */
w = w4rev;
w2 = w2rev;
w8 = w8rev;
}
break;
case ELFDATA2MSB:
if (*(unsigned char const *)&endian != 0) {
/* main() is little endian, file.o is big endian. */
w = w4rev;
w2 = w2rev;
w8 = w8rev;
}
break;
} /* end switch */
if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
|| w2(ehdr->e_type) != ET_EXEC
|| ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
fprintf(stderr, "unrecognized ET_EXEC file %s\n", fname);
fail_file();
}
switch (w2(ehdr->e_machine)) {
default:
fprintf(stderr, "unrecognized e_machine %d %s\n",
w2(ehdr->e_machine), fname);
fail_file();
break;
case EM_386:
case EM_MIPS:
case EM_X86_64:
break;
} /* end switch */
switch (ehdr->e_ident[EI_CLASS]) {
default:
fprintf(stderr, "unrecognized ELF class %d %s\n",
ehdr->e_ident[EI_CLASS], fname);
fail_file();
break;
case ELFCLASS32:
if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
|| w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
fprintf(stderr,
"unrecognized ET_EXEC file: %s\n", fname);
fail_file();
}
do32(ehdr, fname);
break;
case ELFCLASS64: {
Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
|| w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
fprintf(stderr,
"unrecognized ET_EXEC file: %s\n", fname);
fail_file();
}
do64(ghdr, fname);
break;
}
} /* end switch */
cleanup();
}
int
main(int argc, char *argv[])
{
int n_error = 0; /* gcc-4.3.0 false positive complaint */
int i;
if (argc < 2) {
fprintf(stderr, "usage: sortextable vmlinux...\n");
return 0;
}
/* Process each file in turn, allowing deep failure. */
for (i = 1; i < argc; i++) {
char *file = argv[i];
int const sjval = setjmp(jmpenv);
switch (sjval) {
default:
fprintf(stderr, "internal error: %s\n", file);
exit(1);
break;
case SJ_SETJMP: /* normal sequence */
/* Avoid problems if early cleanup() */
fd_map = -1;
ehdr_curr = NULL;
mmap_failed = 1;
do_file(file);
break;
case SJ_FAIL: /* error in do_file or below */
++n_error;
break;
case SJ_SUCCEED: /* premature success */
/* do nothing */
break;
} /* end switch */
}
return !!n_error;
}
/*
* 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;
}
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