/*
* sortextable.c: Sort the kernel's exception table
*
* Copyright 2011 - 2012 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>
#include <tools/be_byteshift.h>
#include <tools/le_byteshift.h>
#ifndef EM_ARCOMPACT
#define EM_ARCOMPACT 93
#endif
#ifndef EM_AARCH64
#define EM_AARCH64 183
#endif
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);
}
/*
* 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;
}
static uint64_t r8be(const uint64_t *x)
{
return get_unaligned_be64(x);
}
static uint32_t rbe(const uint32_t *x)
{
return get_unaligned_be32(x);
}
static uint16_t r2be(const uint16_t *x)
{
return get_unaligned_be16(x);
}
static uint64_t r8le(const uint64_t *x)
{
return get_unaligned_le64(x);
}
static uint32_t rle(const uint32_t *x)
{
return get_unaligned_le32(x);
}
static uint16_t r2le(const uint16_t *x)
{
return get_unaligned_le16(x);
}
static void w8be(uint64_t val, uint64_t *x)
{
put_unaligned_be64(val, x);
}
static void wbe(uint32_t val, uint32_t *x)
{
put_unaligned_be32(val, x);
}
static void w2be(uint16_t val, uint16_t *x)
{
put_unaligned_be16(val, x);
}
static void w8le(uint64_t val, uint64_t *x)
{
put_unaligned_le64(val, x);
}
static void wle(uint32_t val, uint32_t *x)
{
put_unaligned_le32(val, x);
}
static void w2le(uint16_t val, uint16_t *x)
{
put_unaligned_le16(val, x);
}
static uint64_t (*r8)(const uint64_t *);
static uint32_t (*r)(const uint32_t *);
static uint16_t (*r2)(const uint16_t *);
static void (*w8)(uint64_t, uint64_t *);
static void (*w)(uint32_t, uint32_t *);
static void (*w2)(uint16_t, uint16_t *);
typedef void (*table_sort_t)(char *, int);
/*
* Move reserved section indices SHN_LORESERVE..SHN_HIRESERVE out of
* the way to -256..-1, to avoid conflicting with real section
* indices.
*/
#define SPECIAL(i) ((i) - (SHN_HIRESERVE + 1))
static inline int is_shndx_special(unsigned int i)
{
return i != SHN_XINDEX && i >= SHN_LORESERVE && i <= SHN_HIRESERVE;
}
/* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
static inline unsigned int get_secindex(unsigned int shndx,
unsigned int sym_offs,
const Elf32_Word *symtab_shndx_start)
{
if (is_shndx_special(shndx))
return SPECIAL(shndx);
if (shndx != SHN_XINDEX)
return shndx;
return r(&symtab_shndx_start[sym_offs]);
}
/* 32 bit and 64 bit are very similar */
#include "sortextable.h"
#define SORTEXTABLE_64
#include "sortextable.h"
static int compare_relative_table(const void *a, const void *b)
{
int32_t av = (int32_t)r(a);
int32_t bv = (int32_t)r(b);
if (av < bv)
return -1;
if (av > bv)
return 1;
return 0;
}
static void sort_relative_table(char *extab_image, int image_size)
{
int i;
/*
* Do the same thing the runtime sort does, first normalize to
* being relative to the start of the section.
*/
i = 0;
while (i < image_size) {
uint32_t *loc = (uint32_t *)(extab_image + i);
w(r(loc) + i, loc);
i += 4;
}
qsort(extab_image, image_size / 8, 8, compare_relative_table);
/* Now denormalize. */
i = 0;
while (i < image_size) {
uint32_t *loc = (uint32_t *)(extab_image + i);
w(r(loc) - i, loc);
i += 4;
}
}
static void
do_file(char const *const fname)
{
table_sort_t custom_sort;
Elf32_Ehdr *ehdr = mmap_file(fname);
ehdr_curr = ehdr;
switch (ehdr->e_ident[EI_DATA]) {
default:
fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
ehdr->e_ident[EI_DATA], fname);
fail_file();
break;
case ELFDATA2LSB:
r = rle;
r2 = r2le;
r8 = r8le;
w = wle;
w2 = w2le;
w8 = w8le;
break;
case ELFDATA2MSB:
r = rbe;
r2 = r2be;
r8 = r8be;
w = wbe;
w2 = w2be;
w8 = w8be;
break;
} /* end switch */
if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
|| r2(&ehdr->e_type) != ET_EXEC
|| ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
fprintf(stderr, "unrecognized ET_EXEC file %s\n", fname);
fail_file();
}
custom_sort = NULL;
switch (r2(&ehdr->e_machine)) {
default:
fprintf(stderr, "unrecognized e_machine %d %s\n",
r2(&ehdr->e_machine), fname);
fail_file();
break;
case EM_386:
case EM_X86_64:
case EM_S390:
custom_sort = sort_relative_table;
break;
case EM_ARCOMPACT:
case EM_ARM:
case EM_AARCH64:
case EM_MIPS:
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 (r2(&ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
|| r2(&ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
fprintf(stderr,
"unrecognized ET_EXEC file: %s\n", fname);
fail_file();
}
do32(ehdr, fname, custom_sort);
break;
case ELFCLASS64: {
Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
if (r2(&ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
|| r2(&ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
fprintf(stderr,
"unrecognized ET_EXEC file: %s\n", fname);
fail_file();
}
do64(ghdr, fname, custom_sort);
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;
}
