linux-imx

/*

 * recordmcount.c: construct a table of the locations of calls to 'mcount'

 * so that ftrace can find them quickly.

 * 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 .o file in-place.

 *

 * Append a new STRTAB that has the new section names, followed by a new array

 * ElfXX_Shdr[] that has the new section headers, followed by the section

 * contents for __mcount_loc and its relocations.  The old shstrtab strings,

 * and the old ElfXX_Shdr[] array, remain as "garbage" (commonly, a couple

 * kilobytes.)  Subsequent processing by /bin/ld (or the kernel module loader)

 * will ignore the garbage regions, because they are not designated by the

 * new .e_shoff nor the new ElfXX_Shdr[].  [In order to remove the garbage,

 * then use "ld -r" to create a new file that omits the garbage.]

 */

​

#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>

​

#ifndef EM_AARCH64

#define EM_AARCH64  183

#define R_AARCH64_NONE      0

#define R_AARCH64_ABS64 257

#endif

​

static int fd_map;  /* File descriptor for file being modified. */

static int mmap_failed; /* Boolean flag. */

static char gpfx;   /* prefix for global symbol name (sometimes '_') */

static struct stat sb;  /* Remember .st_size, etc. */

static jmp_buf jmpenv;  /* setjmp/longjmp per-file error escape */

static const char *altmcount;   /* alternate mcount symbol name */

static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */

static void *file_map;  /* pointer of the mapped file */

static void *file_end;  /* pointer to the end of the mapped file */

static int file_updated; /* flag to state file was changed */

static void *file_ptr;  /* current file pointer location */

static void *file_append; /* added to the end of the file */

static size_t file_append_size; /* how much is added to end of file */

​

/* setjmp() return values */

enum {

    SJ_SETJMP = 0,  /* hardwired first return */

    SJ_FAIL,

    SJ_SUCCEED

};

​

/* Per-file resource cleanup when multiple files. */