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git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - scripts/recordmcount.c
2 * recordmcount.c: construct a table of the locations of calls to 'mcount'
3 * so that ftrace can find them quickly.
4 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
5 * Licensed under the GNU General Public License, version 2 (GPLv2).
7 * Restructured to fit Linux format, as well as other updates:
8 * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
12 * Strategy: alter the .o file in-place.
14 * Append a new STRTAB that has the new section names, followed by a new array
15 * ElfXX_Shdr[] that has the new section headers, followed by the section
16 * contents for __mcount_loc and its relocations. The old shstrtab strings,
17 * and the old ElfXX_Shdr[] array, remain as "garbage" (commonly, a couple
18 * kilobytes.) Subsequent processing by /bin/ld (or the kernel module loader)
19 * will ignore the garbage regions, because they are not designated by the
20 * new .e_shoff nor the new ElfXX_Shdr[]. [In order to remove the garbage,
21 * then use "ld -r" to create a new file that omits the garbage.]
24 #include <sys/types.h>
37 * glibc synced up and added the metag number but didn't add the relocations.
38 * Work around this in a crude manner for now.
43 #ifndef R_METAG_ADDR32
44 #define R_METAG_ADDR32 2
47 #define R_METAG_NONE 3
51 #define EM_AARCH64 183
52 #define R_AARCH64_NONE 0
53 #define R_AARCH64_ABS64 257
57 #define R_ARM_THM_CALL 10
60 static int fd_map
; /* File descriptor for file being modified. */
61 static int mmap_failed
; /* Boolean flag. */
62 static char gpfx
; /* prefix for global symbol name (sometimes '_') */
63 static struct stat sb
; /* Remember .st_size, etc. */
64 static jmp_buf jmpenv
; /* setjmp/longjmp per-file error escape */
65 static const char *altmcount
; /* alternate mcount symbol name */
66 static int warn_on_notrace_sect
; /* warn when section has mcount not being recorded */
67 static void *file_map
; /* pointer of the mapped file */
68 static void *file_end
; /* pointer to the end of the mapped file */
69 static int file_updated
; /* flag to state file was changed */
70 static void *file_ptr
; /* current file pointer location */
71 static void *file_append
; /* added to the end of the file */
72 static size_t file_append_size
; /* how much is added to end of file */
74 /* setjmp() return values */
76 SJ_SETJMP
= 0, /* hardwired first return */
81 /* Per-file resource cleanup when multiple files. */
86 munmap(file_map
, sb
.st_size
);
96 static void __attribute__((noreturn
))
100 longjmp(jmpenv
, SJ_FAIL
);
103 static void __attribute__((noreturn
))
107 longjmp(jmpenv
, SJ_SUCCEED
);
110 /* ulseek, uread, ...: Check return value for errors. */
113 ulseek(int const fd
, off_t
const offset
, int const whence
)
117 file_ptr
= file_map
+ offset
;
123 file_ptr
= file_map
+ (sb
.st_size
- offset
);
126 if (file_ptr
< file_map
) {
127 fprintf(stderr
, "lseek: seek before file\n");
130 return file_ptr
- file_map
;
134 uread(int const fd
, void *const buf
, size_t const count
)
136 size_t const n
= read(fd
, buf
, count
);
145 uwrite(int const fd
, void const *const buf
, size_t const count
)
152 if (file_ptr
+ count
>= file_end
) {
153 off_t aoffset
= (file_ptr
+ count
) - file_end
;
155 if (aoffset
> file_append_size
) {
156 file_append
= realloc(file_append
, aoffset
);
157 file_append_size
= aoffset
;
163 if (file_ptr
< file_end
) {
164 cnt
= file_end
- file_ptr
;
167 idx
= aoffset
- count
;
172 memcpy(file_ptr
, buf
, cnt
);
175 memcpy(file_append
+ idx
, buf
+ cnt
, count
- cnt
);
184 void *const addr
= malloc(size
);
186 fprintf(stderr
, "malloc failed: %zu bytes\n", size
);
192 static unsigned char ideal_nop5_x86_64
[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
193 static unsigned char ideal_nop5_x86_32
[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
194 static unsigned char *ideal_nop
;
196 static char rel_type_nop
;
198 static int (*make_nop
)(void *map
, size_t const offset
);
200 static int make_nop_x86(void *map
, size_t const offset
)
205 /* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */
210 op
= map
+ offset
- 1;
215 ulseek(fd_map
, offset
- 1, SEEK_SET
);
216 uwrite(fd_map
, ideal_nop
, 5);
220 static unsigned char ideal_nop4_arm_le
[4] = { 0x00, 0x00, 0xa0, 0xe1 }; /* mov r0, r0 */
221 static unsigned char ideal_nop4_arm_be
[4] = { 0xe1, 0xa0, 0x00, 0x00 }; /* mov r0, r0 */
222 static unsigned char *ideal_nop4_arm
;
224 static unsigned char bl_mcount_arm_le
[4] = { 0xfe, 0xff, 0xff, 0xeb }; /* bl */
225 static unsigned char bl_mcount_arm_be
[4] = { 0xeb, 0xff, 0xff, 0xfe }; /* bl */
226 static unsigned char *bl_mcount_arm
;
228 static unsigned char push_arm_le
[4] = { 0x04, 0xe0, 0x2d, 0xe5 }; /* push {lr} */
229 static unsigned char push_arm_be
[4] = { 0xe5, 0x2d, 0xe0, 0x04 }; /* push {lr} */
230 static unsigned char *push_arm
;
232 static unsigned char ideal_nop2_thumb_le
[2] = { 0x00, 0xbf }; /* nop */
233 static unsigned char ideal_nop2_thumb_be
[2] = { 0xbf, 0x00 }; /* nop */
234 static unsigned char *ideal_nop2_thumb
;
236 static unsigned char push_bl_mcount_thumb_le
[6] = { 0x00, 0xb5, 0xff, 0xf7, 0xfe, 0xff }; /* push {lr}, bl */
237 static unsigned char push_bl_mcount_thumb_be
[6] = { 0xb5, 0x00, 0xf7, 0xff, 0xff, 0xfe }; /* push {lr}, bl */
238 static unsigned char *push_bl_mcount_thumb
;
240 static int make_nop_arm(void *map
, size_t const offset
)
248 if (memcmp(ptr
, bl_mcount_arm
, 4) == 0) {
249 if (memcmp(ptr
- 4, push_arm
, 4) == 0) {
253 ideal_nop
= ideal_nop4_arm
;
255 } else if (memcmp(ptr
- 2, push_bl_mcount_thumb
, 6) == 0) {
259 ideal_nop
= ideal_nop2_thumb
;
264 ulseek(fd_map
, off
, SEEK_SET
);
267 uwrite(fd_map
, ideal_nop
, nop_size
);
273 static unsigned char ideal_nop4_arm64
[4] = {0x1f, 0x20, 0x03, 0xd5};
274 static int make_nop_arm64(void *map
, size_t const offset
)
279 /* bl <_mcount> is 0x94000000 before relocation */
280 if (*ptr
!= 0x94000000)
284 ulseek(fd_map
, offset
, SEEK_SET
);
285 uwrite(fd_map
, ideal_nop
, 4);
290 * Get the whole file as a programming convenience in order to avoid
291 * malloc+lseek+read+free of many pieces. If successful, then mmap
292 * avoids copying unused pieces; else just read the whole file.
293 * Open for both read and write; new info will be appended to the file.
294 * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
295 * do not propagate to the file until an explicit overwrite at the last.
296 * This preserves most aspects of consistency (all except .st_size)
297 * for simultaneous readers of the file while we are appending to it.
298 * However, multiple writers still are bad. We choose not to use
299 * locking because it is expensive and the use case of kernel build
300 * makes multiple writers unlikely.
302 static void *mmap_file(char const *fname
)
304 fd_map
= open(fname
, O_RDONLY
);
305 if (fd_map
< 0 || fstat(fd_map
, &sb
) < 0) {
309 if (!S_ISREG(sb
.st_mode
)) {
310 fprintf(stderr
, "not a regular file: %s\n", fname
);
313 file_map
= mmap(0, sb
.st_size
, PROT_READ
|PROT_WRITE
, MAP_PRIVATE
,
316 if (file_map
== MAP_FAILED
) {
318 file_map
= umalloc(sb
.st_size
);
319 uread(fd_map
, file_map
, sb
.st_size
);
323 file_end
= file_map
+ sb
.st_size
;
328 static void write_file(const char *fname
)
330 char tmp_file
[strlen(fname
) + 4];
336 sprintf(tmp_file
, "%s.rc", fname
);
339 * After reading the entire file into memory, delete it
340 * and write it back, to prevent weird side effects of modifying
341 * an object file in place.
343 fd_map
= open(tmp_file
, O_WRONLY
| O_TRUNC
| O_CREAT
, sb
.st_mode
);
348 n
= write(fd_map
, file_map
, sb
.st_size
);
349 if (n
!= sb
.st_size
) {
353 if (file_append_size
) {
354 n
= write(fd_map
, file_append
, file_append_size
);
355 if (n
!= file_append_size
) {
361 if (rename(tmp_file
, fname
) < 0) {
367 /* w8rev, w8nat, ...: Handle endianness. */
369 static uint64_t w8rev(uint64_t const x
)
371 return ((0xff & (x
>> (0 * 8))) << (7 * 8))
372 | ((0xff & (x
>> (1 * 8))) << (6 * 8))
373 | ((0xff & (x
>> (2 * 8))) << (5 * 8))
374 | ((0xff & (x
>> (3 * 8))) << (4 * 8))
375 | ((0xff & (x
>> (4 * 8))) << (3 * 8))
376 | ((0xff & (x
>> (5 * 8))) << (2 * 8))
377 | ((0xff & (x
>> (6 * 8))) << (1 * 8))
378 | ((0xff & (x
>> (7 * 8))) << (0 * 8));
381 static uint32_t w4rev(uint32_t const x
)
383 return ((0xff & (x
>> (0 * 8))) << (3 * 8))
384 | ((0xff & (x
>> (1 * 8))) << (2 * 8))
385 | ((0xff & (x
>> (2 * 8))) << (1 * 8))
386 | ((0xff & (x
>> (3 * 8))) << (0 * 8));
389 static uint32_t w2rev(uint16_t const x
)
391 return ((0xff & (x
>> (0 * 8))) << (1 * 8))
392 | ((0xff & (x
>> (1 * 8))) << (0 * 8));
395 static uint64_t w8nat(uint64_t const x
)
400 static uint32_t w4nat(uint32_t const x
)
405 static uint32_t w2nat(uint16_t const x
)
410 static uint64_t (*w8
)(uint64_t);
411 static uint32_t (*w
)(uint32_t);
412 static uint32_t (*w2
)(uint16_t);
414 /* Names of the sections that could contain calls to mcount. */
416 is_mcounted_section_name(char const *const txtname
)
418 return strcmp(".text", txtname
) == 0 ||
419 strcmp(".init.text", txtname
) == 0 ||
420 strcmp(".ref.text", txtname
) == 0 ||
421 strcmp(".sched.text", txtname
) == 0 ||
422 strcmp(".spinlock.text", txtname
) == 0 ||
423 strcmp(".irqentry.text", txtname
) == 0 ||
424 strcmp(".softirqentry.text", txtname
) == 0 ||
425 strcmp(".kprobes.text", txtname
) == 0 ||
426 strcmp(".cpuidle.text", txtname
) == 0 ||
427 strcmp(".text.unlikely", txtname
) == 0;
430 /* 32 bit and 64 bit are very similar */
431 #include "recordmcount.h"
432 #define RECORD_MCOUNT_64
433 #include "recordmcount.h"
435 static int arm_is_fake_mcount(Elf32_Rel
const *rp
)
437 switch (ELF32_R_TYPE(w(rp
->r_info
))) {
447 /* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
448 * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
449 * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
450 * to imply the order of the members; the spec does not say so.
451 * typedef unsigned char Elf64_Byte;
452 * fails on MIPS64 because their <elf.h> already has it!
455 typedef uint8_t myElf64_Byte
; /* Type for a 8-bit quantity. */
460 Elf64_Word r_sym
; /* Symbol index. */
461 myElf64_Byte r_ssym
; /* Special symbol. */
462 myElf64_Byte r_type3
; /* Third relocation. */
463 myElf64_Byte r_type2
; /* Second relocation. */
464 myElf64_Byte r_type
; /* First relocation. */
468 static uint64_t MIPS64_r_sym(Elf64_Rel
const *rp
)
470 return w(((union mips_r_info
){ .r_info
= rp
->r_info
}).r_mips
.r_sym
);
473 static void MIPS64_r_info(Elf64_Rel
*const rp
, unsigned sym
, unsigned type
)
475 rp
->r_info
= ((union mips_r_info
){
476 .r_mips
= { .r_sym
= w(sym
), .r_type
= type
}
481 do_file(char const *const fname
)
483 Elf32_Ehdr
*const ehdr
= mmap_file(fname
);
484 unsigned int reltype
= 0;
489 switch (ehdr
->e_ident
[EI_DATA
]) {
490 static unsigned int const endian
= 1;
492 fprintf(stderr
, "unrecognized ELF data encoding %d: %s\n",
493 ehdr
->e_ident
[EI_DATA
], fname
);
497 if (*(unsigned char const *)&endian
!= 1) {
498 /* main() is big endian, file.o is little endian. */
503 ideal_nop4_arm
= ideal_nop4_arm_le
;
504 bl_mcount_arm
= bl_mcount_arm_le
;
505 push_arm
= push_arm_le
;
506 ideal_nop2_thumb
= ideal_nop2_thumb_le
;
507 push_bl_mcount_thumb
= push_bl_mcount_thumb_le
;
510 if (*(unsigned char const *)&endian
!= 0) {
511 /* main() is little endian, file.o is big endian. */
516 ideal_nop4_arm
= ideal_nop4_arm_be
;
517 bl_mcount_arm
= bl_mcount_arm_be
;
518 push_arm
= push_arm_be
;
519 ideal_nop2_thumb
= ideal_nop2_thumb_be
;
520 push_bl_mcount_thumb
= push_bl_mcount_thumb_be
;
523 if (memcmp(ELFMAG
, ehdr
->e_ident
, SELFMAG
) != 0
524 || w2(ehdr
->e_type
) != ET_REL
525 || ehdr
->e_ident
[EI_VERSION
] != EV_CURRENT
) {
526 fprintf(stderr
, "unrecognized ET_REL file %s\n", fname
);
531 switch (w2(ehdr
->e_machine
)) {
533 fprintf(stderr
, "unrecognized e_machine %d %s\n",
534 w2(ehdr
->e_machine
), fname
);
539 rel_type_nop
= R_386_NONE
;
540 make_nop
= make_nop_x86
;
541 ideal_nop
= ideal_nop5_x86_32
;
542 mcount_adjust_32
= -1;
544 case EM_ARM
: reltype
= R_ARM_ABS32
;
545 altmcount
= "__gnu_mcount_nc";
546 make_nop
= make_nop_arm
;
547 rel_type_nop
= R_ARM_NONE
;
548 is_fake_mcount32
= arm_is_fake_mcount
;
551 reltype
= R_AARCH64_ABS64
;
552 make_nop
= make_nop_arm64
;
553 rel_type_nop
= R_AARCH64_NONE
;
554 ideal_nop
= ideal_nop4_arm64
;
557 case EM_IA_64
: reltype
= R_IA64_IMM64
; gpfx
= '_'; break;
558 case EM_METAG
: reltype
= R_METAG_ADDR32
;
559 altmcount
= "_mcount_wrapper";
560 rel_type_nop
= R_METAG_NONE
;
561 /* We happen to have the same requirement as MIPS */
562 is_fake_mcount32
= MIPS32_is_fake_mcount
;
564 case EM_MIPS
: /* reltype: e_class */ gpfx
= '_'; break;
565 case EM_PPC
: reltype
= R_PPC_ADDR32
; gpfx
= '_'; break;
566 case EM_PPC64
: reltype
= R_PPC64_ADDR64
; gpfx
= '_'; break;
567 case EM_S390
: /* reltype: e_class */ gpfx
= '_'; break;
568 case EM_SH
: reltype
= R_SH_DIR32
; break;
569 case EM_SPARCV9
: reltype
= R_SPARC_64
; gpfx
= '_'; break;
571 make_nop
= make_nop_x86
;
572 ideal_nop
= ideal_nop5_x86_64
;
573 reltype
= R_X86_64_64
;
574 rel_type_nop
= R_X86_64_NONE
;
575 mcount_adjust_64
= -1;
579 switch (ehdr
->e_ident
[EI_CLASS
]) {
581 fprintf(stderr
, "unrecognized ELF class %d %s\n",
582 ehdr
->e_ident
[EI_CLASS
], fname
);
586 if (w2(ehdr
->e_ehsize
) != sizeof(Elf32_Ehdr
)
587 || w2(ehdr
->e_shentsize
) != sizeof(Elf32_Shdr
)) {
589 "unrecognized ET_REL file: %s\n", fname
);
592 if (w2(ehdr
->e_machine
) == EM_MIPS
) {
594 is_fake_mcount32
= MIPS32_is_fake_mcount
;
596 do32(ehdr
, fname
, reltype
);
599 Elf64_Ehdr
*const ghdr
= (Elf64_Ehdr
*)ehdr
;
600 if (w2(ghdr
->e_ehsize
) != sizeof(Elf64_Ehdr
)
601 || w2(ghdr
->e_shentsize
) != sizeof(Elf64_Shdr
)) {
603 "unrecognized ET_REL file: %s\n", fname
);
606 if (w2(ghdr
->e_machine
) == EM_S390
) {
608 mcount_adjust_64
= -14;
610 if (w2(ghdr
->e_machine
) == EM_MIPS
) {
612 Elf64_r_sym
= MIPS64_r_sym
;
613 Elf64_r_info
= MIPS64_r_info
;
614 is_fake_mcount64
= MIPS64_is_fake_mcount
;
616 do64(ghdr
, fname
, reltype
);
626 main(int argc
, char *argv
[])
628 const char ftrace
[] = "/ftrace.o";
629 int ftrace_size
= sizeof(ftrace
) - 1;
630 int n_error
= 0; /* gcc-4.3.0 false positive complaint */
634 while ((c
= getopt(argc
, argv
, "w")) >= 0) {
637 warn_on_notrace_sect
= 1;
640 fprintf(stderr
, "usage: recordmcount [-w] file.o...\n");
645 if ((argc
- optind
) < 1) {
646 fprintf(stderr
, "usage: recordmcount [-w] file.o...\n");
650 /* Process each file in turn, allowing deep failure. */
651 for (i
= optind
; i
< argc
; i
++) {
652 char *file
= argv
[i
];
653 int const sjval
= setjmp(jmpenv
);
657 * The file kernel/trace/ftrace.o references the mcount
658 * function but does not call it. Since ftrace.o should
659 * not be traced anyway, we just skip it.
662 if (len
>= ftrace_size
&&
663 strcmp(file
+ (len
- ftrace_size
), ftrace
) == 0)
668 fprintf(stderr
, "internal error: %s\n", file
);
671 case SJ_SETJMP
: /* normal sequence */
672 /* Avoid problems if early cleanup() */
680 case SJ_FAIL
: /* error in do_file or below */
681 fprintf(stderr
, "%s: failed\n", file
);
684 case SJ_SUCCEED
: /* premature success */