330 lines
6.8 KiB
C
330 lines
6.8 KiB
C
/*
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* sortextable.c: Sort the kernel's exception table
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*
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* Copyright 2011 - 2012 Cavium, Inc.
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*
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* Based on code taken from recortmcount.c which is:
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*
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* Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
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* Licensed under the GNU General Public License, version 2 (GPLv2).
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*
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* Restructured to fit Linux format, as well as other updates:
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* Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
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*/
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/*
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* Strategy: alter the vmlinux file in-place.
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*/
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <getopt.h>
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#include <elf.h>
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#include <fcntl.h>
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#include <setjmp.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <tools/be_byteshift.h>
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#include <tools/le_byteshift.h>
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#ifndef EM_AARCH64
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#define EM_AARCH64 183
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#endif
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static int fd_map; /* File descriptor for file being modified. */
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static int mmap_failed; /* Boolean flag. */
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static void *ehdr_curr; /* current ElfXX_Ehdr * for resource cleanup */
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static struct stat sb; /* Remember .st_size, etc. */
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static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */
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/* setjmp() return values */
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enum {
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SJ_SETJMP = 0, /* hardwired first return */
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SJ_FAIL,
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SJ_SUCCEED
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};
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/* Per-file resource cleanup when multiple files. */
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static void
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cleanup(void)
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{
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if (!mmap_failed)
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munmap(ehdr_curr, sb.st_size);
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close(fd_map);
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}
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static void __attribute__((noreturn))
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fail_file(void)
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{
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cleanup();
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longjmp(jmpenv, SJ_FAIL);
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}
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static void __attribute__((noreturn))
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succeed_file(void)
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{
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cleanup();
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longjmp(jmpenv, SJ_SUCCEED);
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}
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/*
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* Get the whole file as a programming convenience in order to avoid
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* malloc+lseek+read+free of many pieces. If successful, then mmap
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* avoids copying unused pieces; else just read the whole file.
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* Open for both read and write.
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*/
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static void *mmap_file(char const *fname)
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{
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void *addr;
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fd_map = open(fname, O_RDWR);
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if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
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perror(fname);
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fail_file();
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}
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if (!S_ISREG(sb.st_mode)) {
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fprintf(stderr, "not a regular file: %s\n", fname);
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fail_file();
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}
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addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED,
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fd_map, 0);
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if (addr == MAP_FAILED) {
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mmap_failed = 1;
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fprintf(stderr, "Could not mmap file: %s\n", fname);
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fail_file();
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}
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return addr;
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}
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static uint64_t r8be(const uint64_t *x)
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{
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return get_unaligned_be64(x);
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}
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static uint32_t rbe(const uint32_t *x)
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{
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return get_unaligned_be32(x);
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}
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static uint16_t r2be(const uint16_t *x)
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{
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return get_unaligned_be16(x);
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}
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static uint64_t r8le(const uint64_t *x)
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{
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return get_unaligned_le64(x);
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}
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static uint32_t rle(const uint32_t *x)
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{
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return get_unaligned_le32(x);
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}
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static uint16_t r2le(const uint16_t *x)
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{
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return get_unaligned_le16(x);
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}
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static void w8be(uint64_t val, uint64_t *x)
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{
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put_unaligned_be64(val, x);
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}
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static void wbe(uint32_t val, uint32_t *x)
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{
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put_unaligned_be32(val, x);
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}
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static void w2be(uint16_t val, uint16_t *x)
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{
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put_unaligned_be16(val, x);
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}
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static void w8le(uint64_t val, uint64_t *x)
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{
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put_unaligned_le64(val, x);
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}
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static void wle(uint32_t val, uint32_t *x)
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{
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put_unaligned_le32(val, x);
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}
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static void w2le(uint16_t val, uint16_t *x)
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{
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put_unaligned_le16(val, x);
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}
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static uint64_t (*r8)(const uint64_t *);
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static uint32_t (*r)(const uint32_t *);
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static uint16_t (*r2)(const uint16_t *);
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static void (*w8)(uint64_t, uint64_t *);
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static void (*w)(uint32_t, uint32_t *);
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static void (*w2)(uint16_t, uint16_t *);
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typedef void (*table_sort_t)(char *, int);
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/* 32 bit and 64 bit are very similar */
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#include "sortextable.h"
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#define SORTEXTABLE_64
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#include "sortextable.h"
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static int compare_relative_table(const void *a, const void *b)
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{
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int32_t av = (int32_t)r(a);
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int32_t bv = (int32_t)r(b);
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if (av < bv)
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return -1;
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if (av > bv)
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return 1;
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return 0;
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}
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static void sort_relative_table(char *extab_image, int image_size)
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{
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int i;
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/*
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* Do the same thing the runtime sort does, first normalize to
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* being relative to the start of the section.
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*/
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i = 0;
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while (i < image_size) {
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uint32_t *loc = (uint32_t *)(extab_image + i);
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w(r(loc) + i, loc);
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i += 4;
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}
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qsort(extab_image, image_size / 8, 8, compare_relative_table);
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/* Now denormalize. */
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i = 0;
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while (i < image_size) {
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uint32_t *loc = (uint32_t *)(extab_image + i);
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w(r(loc) - i, loc);
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i += 4;
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}
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}
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static void
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do_file(char const *const fname)
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{
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table_sort_t custom_sort;
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Elf32_Ehdr *ehdr = mmap_file(fname);
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ehdr_curr = ehdr;
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switch (ehdr->e_ident[EI_DATA]) {
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default:
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fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
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ehdr->e_ident[EI_DATA], fname);
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fail_file();
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break;
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case ELFDATA2LSB:
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r = rle;
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r2 = r2le;
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r8 = r8le;
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w = wle;
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w2 = w2le;
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w8 = w8le;
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break;
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case ELFDATA2MSB:
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r = rbe;
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r2 = r2be;
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r8 = r8be;
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w = wbe;
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w2 = w2be;
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w8 = w8be;
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break;
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} /* end switch */
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if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
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|| r2(&ehdr->e_type) != ET_EXEC
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|| ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
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fprintf(stderr, "unrecognized ET_EXEC file %s\n", fname);
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fail_file();
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}
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custom_sort = NULL;
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switch (r2(&ehdr->e_machine)) {
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default:
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fprintf(stderr, "unrecognized e_machine %d %s\n",
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r2(&ehdr->e_machine), fname);
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fail_file();
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break;
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case EM_386:
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case EM_X86_64:
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case EM_S390:
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custom_sort = sort_relative_table;
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break;
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case EM_ARM:
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case EM_AARCH64:
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case EM_MIPS:
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break;
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} /* end switch */
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switch (ehdr->e_ident[EI_CLASS]) {
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default:
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fprintf(stderr, "unrecognized ELF class %d %s\n",
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ehdr->e_ident[EI_CLASS], fname);
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fail_file();
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break;
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case ELFCLASS32:
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if (r2(&ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
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|| r2(&ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
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fprintf(stderr,
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"unrecognized ET_EXEC file: %s\n", fname);
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fail_file();
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}
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do32(ehdr, fname, custom_sort);
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break;
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case ELFCLASS64: {
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Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
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if (r2(&ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
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|| r2(&ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
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fprintf(stderr,
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"unrecognized ET_EXEC file: %s\n", fname);
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fail_file();
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}
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do64(ghdr, fname, custom_sort);
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break;
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}
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} /* end switch */
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cleanup();
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}
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int
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main(int argc, char *argv[])
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{
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int n_error = 0; /* gcc-4.3.0 false positive complaint */
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int i;
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if (argc < 2) {
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fprintf(stderr, "usage: sortextable vmlinux...\n");
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return 0;
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}
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/* Process each file in turn, allowing deep failure. */
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for (i = 1; i < argc; i++) {
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char *file = argv[i];
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int const sjval = setjmp(jmpenv);
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switch (sjval) {
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default:
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fprintf(stderr, "internal error: %s\n", file);
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exit(1);
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break;
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case SJ_SETJMP: /* normal sequence */
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/* Avoid problems if early cleanup() */
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fd_map = -1;
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ehdr_curr = NULL;
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mmap_failed = 1;
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do_file(file);
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break;
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case SJ_FAIL: /* error in do_file or below */
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++n_error;
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break;
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case SJ_SUCCEED: /* premature success */
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/* do nothing */
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break;
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} /* end switch */
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}
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return !!n_error;
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}
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