mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-06 02:24:14 +08:00
f296388682
Do the mcount offset adjustment in the recordmcount.pl/recordmcount.[ch] at compile time and not in ftrace_call_adjust at run time. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
472 lines
12 KiB
C
472 lines
12 KiB
C
/*
|
|
* 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>
|
|
|
|
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 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 */
|
|
|
|
/* 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);
|
|
else
|
|
free(ehdr_curr);
|
|
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);
|
|
}
|
|
|
|
/* ulseek, uread, ...: Check return value for errors. */
|
|
|
|
static off_t
|
|
ulseek(int const fd, off_t const offset, int const whence)
|
|
{
|
|
off_t const w = lseek(fd, offset, whence);
|
|
if (w == (off_t)-1) {
|
|
perror("lseek");
|
|
fail_file();
|
|
}
|
|
return w;
|
|
}
|
|
|
|
static size_t
|
|
uread(int const fd, void *const buf, size_t const count)
|
|
{
|
|
size_t const n = read(fd, buf, count);
|
|
if (n != count) {
|
|
perror("read");
|
|
fail_file();
|
|
}
|
|
return n;
|
|
}
|
|
|
|
static size_t
|
|
uwrite(int const fd, void const *const buf, size_t const count)
|
|
{
|
|
size_t const n = write(fd, buf, count);
|
|
if (n != count) {
|
|
perror("write");
|
|
fail_file();
|
|
}
|
|
return n;
|
|
}
|
|
|
|
static void *
|
|
umalloc(size_t size)
|
|
{
|
|
void *const addr = malloc(size);
|
|
if (addr == 0) {
|
|
fprintf(stderr, "malloc failed: %zu bytes\n", size);
|
|
fail_file();
|
|
}
|
|
return addr;
|
|
}
|
|
|
|
static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
|
|
static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
|
|
static unsigned char *ideal_nop;
|
|
|
|
static char rel_type_nop;
|
|
|
|
static int (*make_nop)(void *map, size_t const offset);
|
|
|
|
static int make_nop_x86(void *map, size_t const offset)
|
|
{
|
|
uint32_t *ptr;
|
|
unsigned char *op;
|
|
|
|
/* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */
|
|
ptr = map + offset;
|
|
if (*ptr != 0)
|
|
return -1;
|
|
|
|
op = map + offset - 1;
|
|
if (*op != 0xe8)
|
|
return -1;
|
|
|
|
/* convert to nop */
|
|
ulseek(fd_map, offset - 1, SEEK_SET);
|
|
uwrite(fd_map, ideal_nop, 5);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* 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; new info will be appended to the file.
|
|
* Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
|
|
* do not propagate to the file until an explicit overwrite at the last.
|
|
* This preserves most aspects of consistency (all except .st_size)
|
|
* for simultaneous readers of the file while we are appending to it.
|
|
* However, multiple writers still are bad. We choose not to use
|
|
* locking because it is expensive and the use case of kernel build
|
|
* makes multiple writers unlikely.
|
|
*/
|
|
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_PRIVATE,
|
|
fd_map, 0);
|
|
mmap_failed = 0;
|
|
if (addr == MAP_FAILED) {
|
|
mmap_failed = 1;
|
|
addr = umalloc(sb.st_size);
|
|
uread(fd_map, addr, sb.st_size);
|
|
}
|
|
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);
|
|
|
|
/* Names of the sections that could contain calls to mcount. */
|
|
static int
|
|
is_mcounted_section_name(char const *const txtname)
|
|
{
|
|
return strcmp(".text", txtname) == 0 ||
|
|
strcmp(".ref.text", txtname) == 0 ||
|
|
strcmp(".sched.text", txtname) == 0 ||
|
|
strcmp(".spinlock.text", txtname) == 0 ||
|
|
strcmp(".irqentry.text", txtname) == 0 ||
|
|
strcmp(".kprobes.text", txtname) == 0 ||
|
|
strcmp(".text.unlikely", txtname) == 0;
|
|
}
|
|
|
|
/* 32 bit and 64 bit are very similar */
|
|
#include "recordmcount.h"
|
|
#define RECORD_MCOUNT_64
|
|
#include "recordmcount.h"
|
|
|
|
/* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
|
|
* http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
|
|
* We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
|
|
* to imply the order of the members; the spec does not say so.
|
|
* typedef unsigned char Elf64_Byte;
|
|
* fails on MIPS64 because their <elf.h> already has it!
|
|
*/
|
|
|
|
typedef uint8_t myElf64_Byte; /* Type for a 8-bit quantity. */
|
|
|
|
union mips_r_info {
|
|
Elf64_Xword r_info;
|
|
struct {
|
|
Elf64_Word r_sym; /* Symbol index. */
|
|
myElf64_Byte r_ssym; /* Special symbol. */
|
|
myElf64_Byte r_type3; /* Third relocation. */
|
|
myElf64_Byte r_type2; /* Second relocation. */
|
|
myElf64_Byte r_type; /* First relocation. */
|
|
} r_mips;
|
|
};
|
|
|
|
static uint64_t MIPS64_r_sym(Elf64_Rel const *rp)
|
|
{
|
|
return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);
|
|
}
|
|
|
|
static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
|
|
{
|
|
rp->r_info = ((union mips_r_info){
|
|
.r_mips = { .r_sym = w(sym), .r_type = type }
|
|
}).r_info;
|
|
}
|
|
|
|
static void
|
|
do_file(char const *const fname)
|
|
{
|
|
Elf32_Ehdr *const ehdr = mmap_file(fname);
|
|
unsigned int reltype = 0;
|
|
|
|
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_REL
|
|
|| ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
|
|
fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
|
|
fail_file();
|
|
}
|
|
|
|
gpfx = 0;
|
|
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:
|
|
reltype = R_386_32;
|
|
make_nop = make_nop_x86;
|
|
ideal_nop = ideal_nop5_x86_32;
|
|
mcount_adjust_32 = -1;
|
|
break;
|
|
case EM_ARM: reltype = R_ARM_ABS32;
|
|
altmcount = "__gnu_mcount_nc";
|
|
break;
|
|
case EM_IA_64: reltype = R_IA64_IMM64; gpfx = '_'; break;
|
|
case EM_MIPS: /* reltype: e_class */ gpfx = '_'; break;
|
|
case EM_PPC: reltype = R_PPC_ADDR32; gpfx = '_'; break;
|
|
case EM_PPC64: reltype = R_PPC64_ADDR64; gpfx = '_'; break;
|
|
case EM_S390: /* reltype: e_class */ gpfx = '_'; break;
|
|
case EM_SH: reltype = R_SH_DIR32; break;
|
|
case EM_SPARCV9: reltype = R_SPARC_64; gpfx = '_'; break;
|
|
case EM_X86_64:
|
|
make_nop = make_nop_x86;
|
|
ideal_nop = ideal_nop5_x86_64;
|
|
reltype = R_X86_64_64;
|
|
mcount_adjust_64 = -1;
|
|
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_REL file: %s\n", fname);
|
|
fail_file();
|
|
}
|
|
if (w2(ehdr->e_machine) == EM_S390) {
|
|
reltype = R_390_32;
|
|
mcount_adjust_32 = -4;
|
|
}
|
|
if (w2(ehdr->e_machine) == EM_MIPS) {
|
|
reltype = R_MIPS_32;
|
|
is_fake_mcount32 = MIPS32_is_fake_mcount;
|
|
}
|
|
do32(ehdr, fname, reltype);
|
|
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_REL file: %s\n", fname);
|
|
fail_file();
|
|
}
|
|
if (w2(ghdr->e_machine) == EM_S390) {
|
|
reltype = R_390_64;
|
|
mcount_adjust_64 = -8;
|
|
}
|
|
if (w2(ghdr->e_machine) == EM_MIPS) {
|
|
reltype = R_MIPS_64;
|
|
Elf64_r_sym = MIPS64_r_sym;
|
|
Elf64_r_info = MIPS64_r_info;
|
|
is_fake_mcount64 = MIPS64_is_fake_mcount;
|
|
}
|
|
do64(ghdr, fname, reltype);
|
|
break;
|
|
}
|
|
} /* end switch */
|
|
|
|
cleanup();
|
|
}
|
|
|
|
int
|
|
main(int argc, char *argv[])
|
|
{
|
|
const char ftrace[] = "/ftrace.o";
|
|
int ftrace_size = sizeof(ftrace) - 1;
|
|
int n_error = 0; /* gcc-4.3.0 false positive complaint */
|
|
int c;
|
|
int i;
|
|
|
|
while ((c = getopt(argc, argv, "w")) >= 0) {
|
|
switch (c) {
|
|
case 'w':
|
|
warn_on_notrace_sect = 1;
|
|
break;
|
|
default:
|
|
fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
if ((argc - optind) < 1) {
|
|
fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
|
|
return 0;
|
|
}
|
|
|
|
/* Process each file in turn, allowing deep failure. */
|
|
for (i = optind; i < argc; i++) {
|
|
char *file = argv[i];
|
|
int const sjval = setjmp(jmpenv);
|
|
int len;
|
|
|
|
/*
|
|
* The file kernel/trace/ftrace.o references the mcount
|
|
* function but does not call it. Since ftrace.o should
|
|
* not be traced anyway, we just skip it.
|
|
*/
|
|
len = strlen(file);
|
|
if (len >= ftrace_size &&
|
|
strcmp(file + (len - ftrace_size), ftrace) == 0)
|
|
continue;
|
|
|
|
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;
|
|
}
|
|
|
|
|