4 * This code was taken out of recordmcount.c written by
5 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
7 * The original code had the same algorithms for both 32bit
8 * and 64bit ELF files, but the code was duplicated to support
9 * the difference in structures that were used. This
10 * file creates a macro of everything that is different between
11 * the 64 and 32 bit code, such that by including this header
12 * twice we can create both sets of functions by including this
13 * header once with RECORD_MCOUNT_64 undefined, and again with
16 * This conversion to macros was done by:
17 * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
19 * Licensed under the GNU General Public License, version 2 (GPLv2).
23 #undef fn_is_fake_mcount
24 #undef MIPS_is_fake_mcount
25 #undef sift_rel_mcount
27 #undef find_secsym_ndx
28 #undef __has_rel_mcount
51 #ifdef RECORD_MCOUNT_64
52 # define append_func append64
53 # define sift_rel_mcount sift64_rel_mcount
54 # define nop_mcount nop_mcount_64
55 # define find_secsym_ndx find64_secsym_ndx
56 # define __has_rel_mcount __has64_rel_mcount
57 # define has_rel_mcount has64_rel_mcount
58 # define tot_relsize tot64_relsize
60 # define get_mcountsym get_mcountsym_64
61 # define is_fake_mcount is_fake_mcount64
62 # define fn_is_fake_mcount fn_is_fake_mcount64
63 # define MIPS_is_fake_mcount MIPS64_is_fake_mcount
64 # define Elf_Addr Elf64_Addr
65 # define Elf_Ehdr Elf64_Ehdr
66 # define Elf_Shdr Elf64_Shdr
67 # define Elf_Rel Elf64_Rel
68 # define Elf_Rela Elf64_Rela
69 # define Elf_Sym Elf64_Sym
70 # define ELF_R_SYM ELF64_R_SYM
71 # define Elf_r_sym Elf64_r_sym
72 # define ELF_R_INFO ELF64_R_INFO
73 # define Elf_r_info Elf64_r_info
74 # define ELF_ST_BIND ELF64_ST_BIND
75 # define fn_ELF_R_SYM fn_ELF64_R_SYM
76 # define fn_ELF_R_INFO fn_ELF64_R_INFO
77 # define uint_t uint64_t
82 # define append_func append32
83 # define sift_rel_mcount sift32_rel_mcount
84 # define nop_mcount nop_mcount_32
85 # define find_secsym_ndx find32_secsym_ndx
86 # define __has_rel_mcount __has32_rel_mcount
87 # define has_rel_mcount has32_rel_mcount
88 # define tot_relsize tot32_relsize
90 # define get_mcountsym get_mcountsym_32
91 # define is_fake_mcount is_fake_mcount32
92 # define fn_is_fake_mcount fn_is_fake_mcount32
93 # define MIPS_is_fake_mcount MIPS32_is_fake_mcount
94 # define Elf_Addr Elf32_Addr
95 # define Elf_Ehdr Elf32_Ehdr
96 # define Elf_Shdr Elf32_Shdr
97 # define Elf_Rel Elf32_Rel
98 # define Elf_Rela Elf32_Rela
99 # define Elf_Sym Elf32_Sym
100 # define ELF_R_SYM ELF32_R_SYM
101 # define Elf_r_sym Elf32_r_sym
102 # define ELF_R_INFO ELF32_R_INFO
103 # define Elf_r_info Elf32_r_info
104 # define ELF_ST_BIND ELF32_ST_BIND
105 # define fn_ELF_R_SYM fn_ELF32_R_SYM
106 # define fn_ELF_R_INFO fn_ELF32_R_INFO
107 # define uint_t uint32_t
113 /* Functions and pointers that do_file() may override for specific e_machine. */
114 static int fn_is_fake_mcount(Elf_Rel
const *rp
)
118 static int (*is_fake_mcount
)(Elf_Rel
const *rp
) = fn_is_fake_mcount
;
120 static uint_t
fn_ELF_R_SYM(Elf_Rel
const *rp
)
122 return ELF_R_SYM(_w(rp
->r_info
));
124 static uint_t (*Elf_r_sym
)(Elf_Rel
const *rp
) = fn_ELF_R_SYM
;
126 static void fn_ELF_R_INFO(Elf_Rel
*const rp
, unsigned sym
, unsigned type
)
128 rp
->r_info
= _w(ELF_R_INFO(sym
, type
));
130 static void (*Elf_r_info
)(Elf_Rel
*const rp
, unsigned sym
, unsigned type
) = fn_ELF_R_INFO
;
133 * MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
134 * _mcount symbol is needed for dynamic function tracer, with it, to disable
135 * tracing(ftrace_make_nop), the instruction in the position is replaced with
136 * the "b label" instruction, to enable tracing(ftrace_make_call), replace the
137 * instruction back. So, here, we set the 2nd one as fake and filter it.
139 * c: 3c030000 lui v1,0x0 <--> b label
140 * c: R_MIPS_HI16 _mcount
141 * c: R_MIPS_NONE *ABS*
142 * c: R_MIPS_NONE *ABS*
143 * 10: 64630000 daddiu v1,v1,0
144 * 10: R_MIPS_LO16 _mcount
145 * 10: R_MIPS_NONE *ABS*
146 * 10: R_MIPS_NONE *ABS*
147 * 14: 03e0082d move at,ra
148 * 18: 0060f809 jalr v1
151 #define MIPS_FAKEMCOUNT_OFFSET 4
153 static int MIPS_is_fake_mcount(Elf_Rel
const *rp
)
155 static Elf_Addr old_r_offset
;
156 Elf_Addr current_r_offset
= _w(rp
->r_offset
);
159 is_fake
= old_r_offset
&&
160 (current_r_offset
- old_r_offset
== MIPS_FAKEMCOUNT_OFFSET
);
161 old_r_offset
= current_r_offset
;
166 /* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
167 static void append_func(Elf_Ehdr
*const ehdr
,
168 Elf_Shdr
*const shstr
,
169 uint_t
const *const mloc0
,
170 uint_t
const *const mlocp
,
171 Elf_Rel
const *const mrel0
,
172 Elf_Rel
const *const mrelp
,
173 unsigned int const rel_entsize
,
174 unsigned int const symsec_sh_link
)
176 /* Begin constructing output file */
178 char const *mc_name
= (sizeof(Elf_Rela
) == rel_entsize
)
179 ? ".rela__mcount_loc"
180 : ".rel__mcount_loc";
181 unsigned const old_shnum
= w2(ehdr
->e_shnum
);
182 uint_t
const old_shoff
= _w(ehdr
->e_shoff
);
183 uint_t
const old_shstr_sh_size
= _w(shstr
->sh_size
);
184 uint_t
const old_shstr_sh_offset
= _w(shstr
->sh_offset
);
185 uint_t t
= 1 + strlen(mc_name
) + _w(shstr
->sh_size
);
188 shstr
->sh_size
= _w(t
);
189 shstr
->sh_offset
= _w(sb
.st_size
);
191 t
+= (_align
& -t
); /* word-byte align */
194 /* body for new shstrtab */
195 ulseek(fd_map
, sb
.st_size
, SEEK_SET
);
196 uwrite(fd_map
, old_shstr_sh_offset
+ (void *)ehdr
, old_shstr_sh_size
);
197 uwrite(fd_map
, mc_name
, 1 + strlen(mc_name
));
199 /* old(modified) Elf_Shdr table, word-byte aligned */
200 ulseek(fd_map
, t
, SEEK_SET
);
201 t
+= sizeof(Elf_Shdr
) * old_shnum
;
202 uwrite(fd_map
, old_shoff
+ (void *)ehdr
,
203 sizeof(Elf_Shdr
) * old_shnum
);
205 /* new sections __mcount_loc and .rel__mcount_loc */
206 t
+= 2*sizeof(mcsec
);
207 mcsec
.sh_name
= w((sizeof(Elf_Rela
) == rel_entsize
) + strlen(".rel")
208 + old_shstr_sh_size
);
209 mcsec
.sh_type
= w(SHT_PROGBITS
);
210 mcsec
.sh_flags
= _w(SHF_ALLOC
);
212 mcsec
.sh_offset
= _w(t
);
213 mcsec
.sh_size
= _w((void *)mlocp
- (void *)mloc0
);
216 mcsec
.sh_addralign
= _w(_size
);
217 mcsec
.sh_entsize
= _w(_size
);
218 uwrite(fd_map
, &mcsec
, sizeof(mcsec
));
220 mcsec
.sh_name
= w(old_shstr_sh_size
);
221 mcsec
.sh_type
= (sizeof(Elf_Rela
) == rel_entsize
)
226 mcsec
.sh_offset
= _w((void *)mlocp
- (void *)mloc0
+ t
);
227 mcsec
.sh_size
= _w((void *)mrelp
- (void *)mrel0
);
228 mcsec
.sh_link
= w(symsec_sh_link
);
229 mcsec
.sh_info
= w(old_shnum
);
230 mcsec
.sh_addralign
= _w(_size
);
231 mcsec
.sh_entsize
= _w(rel_entsize
);
232 uwrite(fd_map
, &mcsec
, sizeof(mcsec
));
234 uwrite(fd_map
, mloc0
, (void *)mlocp
- (void *)mloc0
);
235 uwrite(fd_map
, mrel0
, (void *)mrelp
- (void *)mrel0
);
237 ehdr
->e_shoff
= _w(new_e_shoff
);
238 ehdr
->e_shnum
= w2(2 + w2(ehdr
->e_shnum
)); /* {.rel,}__mcount_loc */
239 ulseek(fd_map
, 0, SEEK_SET
);
240 uwrite(fd_map
, ehdr
, sizeof(*ehdr
));
243 static unsigned get_mcountsym(Elf_Sym
const *const sym0
,
245 char const *const str0
)
247 unsigned mcountsym
= 0;
249 Elf_Sym
const *const symp
=
250 &sym0
[Elf_r_sym(relp
)];
251 char const *symname
= &str0
[w(symp
->st_name
)];
252 char const *mcount
= gpfx
== '_' ? "_mcount" : "mcount";
254 if (symname
[0] == '.')
255 ++symname
; /* ppc64 hack */
256 if (strcmp(mcount
, symname
) == 0 ||
257 (altmcount
&& strcmp(altmcount
, symname
) == 0))
258 mcountsym
= Elf_r_sym(relp
);
264 * Look at the relocations in order to find the calls to mcount.
265 * Accumulate the section offsets that are found, and their relocation info,
266 * onto the end of the existing arrays.
268 static uint_t
*sift_rel_mcount(uint_t
*mlocp
,
269 unsigned const offbase
,
270 Elf_Rel
**const mrelpp
,
271 Elf_Shdr
const *const relhdr
,
272 Elf_Ehdr
const *const ehdr
,
273 unsigned const recsym
,
275 unsigned const reltype
)
277 uint_t
*const mloc0
= mlocp
;
278 Elf_Rel
*mrelp
= *mrelpp
;
279 Elf_Shdr
*const shdr0
= (Elf_Shdr
*)(_w(ehdr
->e_shoff
)
281 unsigned const symsec_sh_link
= w(relhdr
->sh_link
);
282 Elf_Shdr
const *const symsec
= &shdr0
[symsec_sh_link
];
283 Elf_Sym
const *const sym0
= (Elf_Sym
const *)(_w(symsec
->sh_offset
)
286 Elf_Shdr
const *const strsec
= &shdr0
[w(symsec
->sh_link
)];
287 char const *const str0
= (char const *)(_w(strsec
->sh_offset
)
290 Elf_Rel
const *const rel0
= (Elf_Rel
const *)(_w(relhdr
->sh_offset
)
292 unsigned rel_entsize
= _w(relhdr
->sh_entsize
);
293 unsigned const nrel
= _w(relhdr
->sh_size
) / rel_entsize
;
294 Elf_Rel
const *relp
= rel0
;
296 unsigned mcountsym
= 0;
299 for (t
= nrel
; t
; --t
) {
301 mcountsym
= get_mcountsym(sym0
, relp
, str0
);
303 if (mcountsym
== Elf_r_sym(relp
) && !is_fake_mcount(relp
)) {
304 uint_t
const addend
= _w(_w(relp
->r_offset
) - recval
);
306 mrelp
->r_offset
= _w(offbase
307 + ((void *)mlocp
- (void *)mloc0
));
308 Elf_r_info(mrelp
, recsym
, reltype
);
309 if (rel_entsize
== sizeof(Elf_Rela
)) {
310 ((Elf_Rela
*)mrelp
)->r_addend
= addend
;
315 mrelp
= (Elf_Rel
*)(rel_entsize
+ (void *)mrelp
);
317 relp
= (Elf_Rel
const *)(rel_entsize
+ (void *)relp
);
324 * Read the relocation table again, but this time its called on sections
325 * that are not going to be traced. The mcount calls here will be converted
328 static void nop_mcount(Elf_Shdr
const *const relhdr
,
329 Elf_Ehdr
const *const ehdr
,
330 const char *const txtname
)
332 Elf_Shdr
*const shdr0
= (Elf_Shdr
*)(_w(ehdr
->e_shoff
)
334 unsigned const symsec_sh_link
= w(relhdr
->sh_link
);
335 Elf_Shdr
const *const symsec
= &shdr0
[symsec_sh_link
];
336 Elf_Sym
const *const sym0
= (Elf_Sym
const *)(_w(symsec
->sh_offset
)
339 Elf_Shdr
const *const strsec
= &shdr0
[w(symsec
->sh_link
)];
340 char const *const str0
= (char const *)(_w(strsec
->sh_offset
)
343 Elf_Rel
const *const rel0
= (Elf_Rel
const *)(_w(relhdr
->sh_offset
)
345 unsigned rel_entsize
= _w(relhdr
->sh_entsize
);
346 unsigned const nrel
= _w(relhdr
->sh_size
) / rel_entsize
;
347 Elf_Rel
const *relp
= rel0
;
349 Elf_Shdr
const *const shdr
= &shdr0
[w(relhdr
->sh_info
)];
351 unsigned mcountsym
= 0;
355 for (t
= nrel
; t
; --t
) {
359 mcountsym
= get_mcountsym(sym0
, relp
, str0
);
361 if (mcountsym
== Elf_r_sym(relp
) && !is_fake_mcount(relp
)) {
363 ret
= make_nop((void *)ehdr
, shdr
->sh_offset
+ relp
->r_offset
);
364 if (warn_on_notrace_sect
&& !once
) {
365 printf("Section %s has mcount callers being ignored\n",
375 * If we successfully removed the mcount, mark the relocation
376 * as a nop (don't do anything with it).
380 rel
= *(Elf_Rel
*)relp
;
381 Elf_r_info(&rel
, Elf_r_sym(relp
), rel_type_nop
);
382 ulseek(fd_map
, (void *)relp
- (void *)ehdr
, SEEK_SET
);
383 uwrite(fd_map
, &rel
, sizeof(rel
));
385 relp
= (Elf_Rel
const *)(rel_entsize
+ (void *)relp
);
391 * Find a symbol in the given section, to be used as the base for relocating
392 * the table of offsets of calls to mcount. A local or global symbol suffices,
393 * but avoid a Weak symbol because it may be overridden; the change in value
394 * would invalidate the relocations of the offsets of the calls to mcount.
395 * Often the found symbol will be the unnamed local symbol generated by
396 * GNU 'as' for the start of each section. For example:
397 * Num: Value Size Type Bind Vis Ndx Name
398 * 2: 00000000 0 SECTION LOCAL DEFAULT 1
400 static unsigned find_secsym_ndx(unsigned const txtndx
,
401 char const *const txtname
,
402 uint_t
*const recvalp
,
403 Elf_Shdr
const *const symhdr
,
404 Elf_Ehdr
const *const ehdr
)
406 Elf_Sym
const *const sym0
= (Elf_Sym
const *)(_w(symhdr
->sh_offset
)
408 unsigned const nsym
= _w(symhdr
->sh_size
) / _w(symhdr
->sh_entsize
);
412 for (symp
= sym0
, t
= nsym
; t
; --t
, ++symp
) {
413 unsigned int const st_bind
= ELF_ST_BIND(symp
->st_info
);
415 if (txtndx
== w2(symp
->st_shndx
)
417 && (STB_LOCAL
== st_bind
|| STB_GLOBAL
== st_bind
)) {
418 *recvalp
= _w(symp
->st_value
);
422 fprintf(stderr
, "Cannot find symbol for section %d: %s.\n",
428 /* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
430 __has_rel_mcount(Elf_Shdr
const *const relhdr
, /* is SHT_REL or SHT_RELA */
431 Elf_Shdr
const *const shdr0
,
432 char const *const shstrtab
,
433 char const *const fname
)
435 /* .sh_info depends on .sh_type == SHT_REL[,A] */
436 Elf_Shdr
const *const txthdr
= &shdr0
[w(relhdr
->sh_info
)];
437 char const *const txtname
= &shstrtab
[w(txthdr
->sh_name
)];
439 if (strcmp("__mcount_loc", txtname
) == 0) {
440 fprintf(stderr
, "warning: __mcount_loc already exists: %s\n",
444 if (w(txthdr
->sh_type
) != SHT_PROGBITS
||
445 !(w(txthdr
->sh_flags
) & SHF_EXECINSTR
))
450 static char const *has_rel_mcount(Elf_Shdr
const *const relhdr
,
451 Elf_Shdr
const *const shdr0
,
452 char const *const shstrtab
,
453 char const *const fname
)
455 if (w(relhdr
->sh_type
) != SHT_REL
&& w(relhdr
->sh_type
) != SHT_RELA
)
457 return __has_rel_mcount(relhdr
, shdr0
, shstrtab
, fname
);
461 static unsigned tot_relsize(Elf_Shdr
const *const shdr0
,
463 const char *const shstrtab
,
464 const char *const fname
)
466 unsigned totrelsz
= 0;
467 Elf_Shdr
const *shdrp
= shdr0
;
470 for (; nhdr
; --nhdr
, ++shdrp
) {
471 txtname
= has_rel_mcount(shdrp
, shdr0
, shstrtab
, fname
);
472 if (txtname
&& is_mcounted_section_name(txtname
))
473 totrelsz
+= _w(shdrp
->sh_size
);
479 /* Overall supervision for Elf32 ET_REL file. */
481 do_func(Elf_Ehdr
*const ehdr
, char const *const fname
, unsigned const reltype
)
483 Elf_Shdr
*const shdr0
= (Elf_Shdr
*)(_w(ehdr
->e_shoff
)
485 unsigned const nhdr
= w2(ehdr
->e_shnum
);
486 Elf_Shdr
*const shstr
= &shdr0
[w2(ehdr
->e_shstrndx
)];
487 char const *const shstrtab
= (char const *)(_w(shstr
->sh_offset
)
490 Elf_Shdr
const *relhdr
;
493 /* Upper bound on space: assume all relevant relocs are for mcount. */
494 unsigned const totrelsz
= tot_relsize(shdr0
, nhdr
, shstrtab
, fname
);
495 Elf_Rel
*const mrel0
= umalloc(totrelsz
);
496 Elf_Rel
* mrelp
= mrel0
;
498 /* 2*sizeof(address) <= sizeof(Elf_Rel) */
499 uint_t
*const mloc0
= umalloc(totrelsz
>>1);
500 uint_t
* mlocp
= mloc0
;
502 unsigned rel_entsize
= 0;
503 unsigned symsec_sh_link
= 0;
505 for (relhdr
= shdr0
, k
= nhdr
; k
; --k
, ++relhdr
) {
506 char const *const txtname
= has_rel_mcount(relhdr
, shdr0
,
508 if (txtname
&& is_mcounted_section_name(txtname
)) {
510 unsigned const recsym
= find_secsym_ndx(
511 w(relhdr
->sh_info
), txtname
, &recval
,
512 &shdr0
[symsec_sh_link
= w(relhdr
->sh_link
)],
515 rel_entsize
= _w(relhdr
->sh_entsize
);
516 mlocp
= sift_rel_mcount(mlocp
,
517 (void *)mlocp
- (void *)mloc0
, &mrelp
,
518 relhdr
, ehdr
, recsym
, recval
, reltype
);
519 } else if (txtname
&& (warn_on_notrace_sect
|| make_nop
)) {
521 * This section is ignored by ftrace, but still
522 * has mcount calls. Convert them to nops now.
524 nop_mcount(relhdr
, ehdr
, txtname
);
527 if (mloc0
!= mlocp
) {
528 append_func(ehdr
, shstr
, mloc0
, mlocp
, mrel0
, mrelp
,
529 rel_entsize
, symsec_sh_link
);