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: 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
H. Peter Anvin
parent
e816b57a33
commit
a79f248b9b
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@ -9,3 +9,4 @@ unifdef
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ihex2fw
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recordmcount
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docproc
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sortextable
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@ -13,6 +13,7 @@ hostprogs-$(CONFIG_LOGO) += pnmtologo
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hostprogs-$(CONFIG_VT) += conmakehash
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hostprogs-$(CONFIG_IKCONFIG) += bin2c
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hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
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hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable
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always := $(hostprogs-y) $(hostprogs-m)
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@ -0,0 +1,271 @@
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/*
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* sortextable.c: Sort the kernel's exception table
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*
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* Copyright 2011 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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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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/* w8rev, w8nat, ...: Handle endianness. */
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static uint64_t w8rev(uint64_t const x)
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{
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return ((0xff & (x >> (0 * 8))) << (7 * 8))
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| ((0xff & (x >> (1 * 8))) << (6 * 8))
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| ((0xff & (x >> (2 * 8))) << (5 * 8))
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| ((0xff & (x >> (3 * 8))) << (4 * 8))
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| ((0xff & (x >> (4 * 8))) << (3 * 8))
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| ((0xff & (x >> (5 * 8))) << (2 * 8))
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| ((0xff & (x >> (6 * 8))) << (1 * 8))
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| ((0xff & (x >> (7 * 8))) << (0 * 8));
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}
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static uint32_t w4rev(uint32_t const x)
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{
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return ((0xff & (x >> (0 * 8))) << (3 * 8))
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| ((0xff & (x >> (1 * 8))) << (2 * 8))
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| ((0xff & (x >> (2 * 8))) << (1 * 8))
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| ((0xff & (x >> (3 * 8))) << (0 * 8));
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}
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static uint32_t w2rev(uint16_t const x)
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{
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return ((0xff & (x >> (0 * 8))) << (1 * 8))
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| ((0xff & (x >> (1 * 8))) << (0 * 8));
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}
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static uint64_t w8nat(uint64_t const x)
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{
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return x;
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}
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static uint32_t w4nat(uint32_t const x)
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{
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return x;
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}
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static uint32_t w2nat(uint16_t const x)
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{
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return x;
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}
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static uint64_t (*w8)(uint64_t);
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static uint32_t (*w)(uint32_t);
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static uint32_t (*w2)(uint16_t);
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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 void
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do_file(char const *const fname)
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{
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Elf32_Ehdr *const ehdr = mmap_file(fname);
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ehdr_curr = ehdr;
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w = w4nat;
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w2 = w2nat;
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w8 = w8nat;
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switch (ehdr->e_ident[EI_DATA]) {
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static unsigned int const endian = 1;
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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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if (*(unsigned char const *)&endian != 1) {
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/* main() is big endian, file.o is little endian. */
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w = w4rev;
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w2 = w2rev;
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w8 = w8rev;
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}
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break;
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case ELFDATA2MSB:
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if (*(unsigned char const *)&endian != 0) {
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/* main() is little endian, file.o is big endian. */
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w = w4rev;
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w2 = w2rev;
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w8 = w8rev;
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}
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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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|| w2(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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switch (w2(ehdr->e_machine)) {
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default:
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fprintf(stderr, "unrecognized e_machine %d %s\n",
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w2(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_MIPS:
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case EM_X86_64:
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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 (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
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|| w2(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);
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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 (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
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|| w2(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);
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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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@ -0,0 +1,168 @@
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/*
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* sortextable.h
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*
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* Copyright 2011 Cavium, Inc.
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*
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* Some of this code was taken out of recordmcount.h written by:
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*
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* Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
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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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* Licensed under the GNU General Public License, version 2 (GPLv2).
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*/
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#undef extable_ent_size
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#undef compare_extable
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#undef do_func
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#undef Elf_Addr
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#undef Elf_Ehdr
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#undef Elf_Shdr
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#undef Elf_Rel
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#undef Elf_Rela
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#undef Elf_Sym
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#undef ELF_R_SYM
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#undef Elf_r_sym
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#undef ELF_R_INFO
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#undef Elf_r_info
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#undef ELF_ST_BIND
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#undef ELF_ST_TYPE
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#undef fn_ELF_R_SYM
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#undef fn_ELF_R_INFO
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#undef uint_t
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#undef _w
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#ifdef SORTEXTABLE_64
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# define extable_ent_size 16
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# define compare_extable compare_extable_64
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# define do_func do64
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# define Elf_Addr Elf64_Addr
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# define Elf_Ehdr Elf64_Ehdr
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# define Elf_Shdr Elf64_Shdr
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# define Elf_Rel Elf64_Rel
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# define Elf_Rela Elf64_Rela
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# define Elf_Sym Elf64_Sym
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# define ELF_R_SYM ELF64_R_SYM
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# define Elf_r_sym Elf64_r_sym
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# define ELF_R_INFO ELF64_R_INFO
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# define Elf_r_info Elf64_r_info
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# define ELF_ST_BIND ELF64_ST_BIND
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# define ELF_ST_TYPE ELF64_ST_TYPE
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# define fn_ELF_R_SYM fn_ELF64_R_SYM
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# define fn_ELF_R_INFO fn_ELF64_R_INFO
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# define uint_t uint64_t
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# define _w w8
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#else
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# define extable_ent_size 8
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# define compare_extable compare_extable_32
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# define do_func do32
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# define Elf_Addr Elf32_Addr
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# define Elf_Ehdr Elf32_Ehdr
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# define Elf_Shdr Elf32_Shdr
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# define Elf_Rel Elf32_Rel
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# define Elf_Rela Elf32_Rela
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# define Elf_Sym Elf32_Sym
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# define ELF_R_SYM ELF32_R_SYM
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# define Elf_r_sym Elf32_r_sym
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# define ELF_R_INFO ELF32_R_INFO
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# define Elf_r_info Elf32_r_info
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# define ELF_ST_BIND ELF32_ST_BIND
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# define ELF_ST_TYPE ELF32_ST_TYPE
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# define fn_ELF_R_SYM fn_ELF32_R_SYM
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# define fn_ELF_R_INFO fn_ELF32_R_INFO
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# define uint_t uint32_t
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# define _w w
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#endif
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static int compare_extable(const void *a, const void *b)
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{
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const uint_t *aa = a;
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const uint_t *bb = b;
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if (_w(*aa) < _w(*bb))
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return -1;
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if (_w(*aa) > _w(*bb))
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return 1;
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return 0;
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}
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static void
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do_func(Elf_Ehdr *const ehdr, char const *const fname)
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{
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Elf_Shdr *shdr;
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Elf_Shdr *shstrtab_sec;
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Elf_Shdr *strtab_sec = NULL;
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Elf_Shdr *symtab_sec = NULL;
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Elf_Shdr *extab_sec = NULL;
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Elf_Sym *sym;
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Elf_Sym *sort_needed_sym;
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Elf_Shdr *sort_needed_sec;
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uint32_t *sort_done_location;
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const char *secstrtab;
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const char *strtab;
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int i;
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int idx;
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shdr = (Elf_Shdr *)((void *)ehdr + _w(ehdr->e_shoff));
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shstrtab_sec = shdr + w2(ehdr->e_shstrndx);
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secstrtab = (const char *)ehdr + _w(shstrtab_sec->sh_offset);
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for (i = 0; i < w2(ehdr->e_shnum); i++) {
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idx = w(shdr[i].sh_name);
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if (strcmp(secstrtab + idx, "__ex_table") == 0)
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extab_sec = shdr + i;
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if (strcmp(secstrtab + idx, ".symtab") == 0)
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symtab_sec = shdr + i;
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if (strcmp(secstrtab + idx, ".strtab") == 0)
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strtab_sec = shdr + i;
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}
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if (strtab_sec == NULL) {
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fprintf(stderr, "no .strtab in file: %s\n", fname);
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fail_file();
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}
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if (symtab_sec == NULL) {
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fprintf(stderr, "no .symtab in file: %s\n", fname);
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fail_file();
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}
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if (extab_sec == NULL) {
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fprintf(stderr, "no __ex_table in file: %s\n", fname);
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fail_file();
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}
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strtab = (const char *)ehdr + _w(strtab_sec->sh_offset);
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/* Sort the table in place */
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qsort((void *)ehdr + _w(extab_sec->sh_offset),
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(_w(extab_sec->sh_size) / extable_ent_size),
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extable_ent_size, compare_extable);
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/* find main_extable_sort_needed */
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sort_needed_sym = NULL;
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for (i = 0; i < _w(symtab_sec->sh_size) / sizeof(Elf_Sym); i++) {
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sym = (void *)ehdr + _w(symtab_sec->sh_offset);
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sym += i;
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if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
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continue;
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idx = w(sym->st_name);
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if (strcmp(strtab + idx, "main_extable_sort_needed") == 0) {
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sort_needed_sym = sym;
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break;
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}
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}
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if (sort_needed_sym == NULL) {
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fprintf(stderr,
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"no main_extable_sort_needed symbol in file: %s\n",
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fname);
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fail_file();
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}
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sort_needed_sec = &shdr[w2(sort_needed_sym->st_shndx)];
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sort_done_location = (void *)ehdr +
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_w(sort_needed_sec->sh_offset) +
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_w(sort_needed_sym->st_value) -
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_w(sort_needed_sec->sh_addr);
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printf("sort done marker at %lx\n",
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(unsigned long) (_w(sort_needed_sec->sh_offset) +
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_w(sort_needed_sym->st_value) -
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_w(sort_needed_sec->sh_addr)));
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/* We sorted it, clear the flag. */
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*sort_done_location = 0;
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}
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