blob: 2e7793735e145157d5e3cf849679ed70ed2924a7 [file] [log] [blame]
Steven Rostedtc28d5072010-10-13 19:06:14 -04001/*
2 * recordmcount.h
3 *
4 * This code was taken out of recordmcount.c written by
5 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
6 *
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
14 * it defined.
15 *
16 * This conversion to macros was done by:
17 * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
18 *
19 * Licensed under the GNU General Public License, version 2 (GPLv2).
20 */
21#undef append_func
Wu Zhangjin412910c2010-10-27 18:59:08 +080022#undef is_fake_mcount
23#undef fn_is_fake_mcount
24#undef MIPS_is_fake_mcount
Martin Schwidefsky07d8b592011-05-10 10:10:40 +020025#undef mcount_adjust
Steven Rostedtc28d5072010-10-13 19:06:14 -040026#undef sift_rel_mcount
Steven Rostedtffd618f2011-04-08 03:58:48 -040027#undef nop_mcount
Steven Rostedtc28d5072010-10-13 19:06:14 -040028#undef find_secsym_ndx
29#undef __has_rel_mcount
30#undef has_rel_mcount
31#undef tot_relsize
Steven Rostedt37762cb2011-04-20 20:47:34 -040032#undef get_mcountsym
Steven Rostedt41b402a2011-04-20 21:13:06 -040033#undef get_sym_str_and_relp
Steven Rostedtc28d5072010-10-13 19:06:14 -040034#undef do_func
Wu Zhangjin412910c2010-10-27 18:59:08 +080035#undef Elf_Addr
Steven Rostedtc28d5072010-10-13 19:06:14 -040036#undef Elf_Ehdr
37#undef Elf_Shdr
38#undef Elf_Rel
39#undef Elf_Rela
40#undef Elf_Sym
41#undef ELF_R_SYM
John Reisera2d493582010-10-27 18:59:07 +080042#undef Elf_r_sym
Steven Rostedtc28d5072010-10-13 19:06:14 -040043#undef ELF_R_INFO
John Reisera2d493582010-10-27 18:59:07 +080044#undef Elf_r_info
Steven Rostedtc28d5072010-10-13 19:06:14 -040045#undef ELF_ST_BIND
Rabin Vincent9905ce82011-05-11 22:53:51 +053046#undef ELF_ST_TYPE
John Reisera2d493582010-10-27 18:59:07 +080047#undef fn_ELF_R_SYM
48#undef fn_ELF_R_INFO
Steven Rostedtc28d5072010-10-13 19:06:14 -040049#undef uint_t
50#undef _w
51#undef _align
52#undef _size
53
54#ifdef RECORD_MCOUNT_64
55# define append_func append64
56# define sift_rel_mcount sift64_rel_mcount
Steven Rostedtffd618f2011-04-08 03:58:48 -040057# define nop_mcount nop_mcount_64
Steven Rostedtc28d5072010-10-13 19:06:14 -040058# define find_secsym_ndx find64_secsym_ndx
59# define __has_rel_mcount __has64_rel_mcount
60# define has_rel_mcount has64_rel_mcount
61# define tot_relsize tot64_relsize
Steven Rostedt41b402a2011-04-20 21:13:06 -040062# define get_sym_str_and_relp get_sym_str_and_relp_64
Steven Rostedtc28d5072010-10-13 19:06:14 -040063# define do_func do64
Steven Rostedt37762cb2011-04-20 20:47:34 -040064# define get_mcountsym get_mcountsym_64
Wu Zhangjin412910c2010-10-27 18:59:08 +080065# define is_fake_mcount is_fake_mcount64
66# define fn_is_fake_mcount fn_is_fake_mcount64
67# define MIPS_is_fake_mcount MIPS64_is_fake_mcount
Martin Schwidefsky07d8b592011-05-10 10:10:40 +020068# define mcount_adjust mcount_adjust_64
Wu Zhangjin412910c2010-10-27 18:59:08 +080069# define Elf_Addr Elf64_Addr
Steven Rostedtc28d5072010-10-13 19:06:14 -040070# define Elf_Ehdr Elf64_Ehdr
71# define Elf_Shdr Elf64_Shdr
72# define Elf_Rel Elf64_Rel
73# define Elf_Rela Elf64_Rela
74# define Elf_Sym Elf64_Sym
75# define ELF_R_SYM ELF64_R_SYM
John Reisera2d493582010-10-27 18:59:07 +080076# define Elf_r_sym Elf64_r_sym
Steven Rostedtc28d5072010-10-13 19:06:14 -040077# define ELF_R_INFO ELF64_R_INFO
John Reisera2d493582010-10-27 18:59:07 +080078# define Elf_r_info Elf64_r_info
Steven Rostedtc28d5072010-10-13 19:06:14 -040079# define ELF_ST_BIND ELF64_ST_BIND
Rabin Vincent9905ce82011-05-11 22:53:51 +053080# define ELF_ST_TYPE ELF64_ST_TYPE
John Reisera2d493582010-10-27 18:59:07 +080081# define fn_ELF_R_SYM fn_ELF64_R_SYM
82# define fn_ELF_R_INFO fn_ELF64_R_INFO
Steven Rostedtc28d5072010-10-13 19:06:14 -040083# define uint_t uint64_t
84# define _w w8
85# define _align 7u
86# define _size 8
87#else
88# define append_func append32
89# define sift_rel_mcount sift32_rel_mcount
Steven Rostedtffd618f2011-04-08 03:58:48 -040090# define nop_mcount nop_mcount_32
Steven Rostedtc28d5072010-10-13 19:06:14 -040091# define find_secsym_ndx find32_secsym_ndx
92# define __has_rel_mcount __has32_rel_mcount
93# define has_rel_mcount has32_rel_mcount
94# define tot_relsize tot32_relsize
Steven Rostedt41b402a2011-04-20 21:13:06 -040095# define get_sym_str_and_relp get_sym_str_and_relp_32
Steven Rostedtc28d5072010-10-13 19:06:14 -040096# define do_func do32
Steven Rostedt37762cb2011-04-20 20:47:34 -040097# define get_mcountsym get_mcountsym_32
Wu Zhangjin412910c2010-10-27 18:59:08 +080098# define is_fake_mcount is_fake_mcount32
99# define fn_is_fake_mcount fn_is_fake_mcount32
100# define MIPS_is_fake_mcount MIPS32_is_fake_mcount
Martin Schwidefsky07d8b592011-05-10 10:10:40 +0200101# define mcount_adjust mcount_adjust_32
Wu Zhangjin412910c2010-10-27 18:59:08 +0800102# define Elf_Addr Elf32_Addr
Steven Rostedtc28d5072010-10-13 19:06:14 -0400103# define Elf_Ehdr Elf32_Ehdr
104# define Elf_Shdr Elf32_Shdr
105# define Elf_Rel Elf32_Rel
106# define Elf_Rela Elf32_Rela
107# define Elf_Sym Elf32_Sym
108# define ELF_R_SYM ELF32_R_SYM
John Reisera2d493582010-10-27 18:59:07 +0800109# define Elf_r_sym Elf32_r_sym
Steven Rostedtc28d5072010-10-13 19:06:14 -0400110# define ELF_R_INFO ELF32_R_INFO
John Reisera2d493582010-10-27 18:59:07 +0800111# define Elf_r_info Elf32_r_info
Steven Rostedtc28d5072010-10-13 19:06:14 -0400112# define ELF_ST_BIND ELF32_ST_BIND
Rabin Vincent9905ce82011-05-11 22:53:51 +0530113# define ELF_ST_TYPE ELF32_ST_TYPE
John Reisera2d493582010-10-27 18:59:07 +0800114# define fn_ELF_R_SYM fn_ELF32_R_SYM
115# define fn_ELF_R_INFO fn_ELF32_R_INFO
Steven Rostedtc28d5072010-10-13 19:06:14 -0400116# define uint_t uint32_t
117# define _w w
118# define _align 3u
119# define _size 4
120#endif
121
Wu Zhangjin412910c2010-10-27 18:59:08 +0800122/* Functions and pointers that do_file() may override for specific e_machine. */
123static int fn_is_fake_mcount(Elf_Rel const *rp)
124{
125 return 0;
126}
127static int (*is_fake_mcount)(Elf_Rel const *rp) = fn_is_fake_mcount;
128
John Reisera2d493582010-10-27 18:59:07 +0800129static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
130{
131 return ELF_R_SYM(_w(rp->r_info));
132}
133static uint_t (*Elf_r_sym)(Elf_Rel const *rp) = fn_ELF_R_SYM;
134
135static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
136{
John Reisere63233f72010-11-22 19:41:44 -0800137 rp->r_info = _w(ELF_R_INFO(sym, type));
John Reisera2d493582010-10-27 18:59:07 +0800138}
139static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
140
Martin Schwidefsky07d8b592011-05-10 10:10:40 +0200141static int mcount_adjust = 0;
142
Wu Zhangjin412910c2010-10-27 18:59:08 +0800143/*
144 * MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
145 * _mcount symbol is needed for dynamic function tracer, with it, to disable
146 * tracing(ftrace_make_nop), the instruction in the position is replaced with
147 * the "b label" instruction, to enable tracing(ftrace_make_call), replace the
148 * instruction back. So, here, we set the 2nd one as fake and filter it.
149 *
150 * c: 3c030000 lui v1,0x0 <--> b label
151 * c: R_MIPS_HI16 _mcount
152 * c: R_MIPS_NONE *ABS*
153 * c: R_MIPS_NONE *ABS*
154 * 10: 64630000 daddiu v1,v1,0
155 * 10: R_MIPS_LO16 _mcount
156 * 10: R_MIPS_NONE *ABS*
157 * 10: R_MIPS_NONE *ABS*
158 * 14: 03e0082d move at,ra
159 * 18: 0060f809 jalr v1
160 * label:
161 */
162#define MIPS_FAKEMCOUNT_OFFSET 4
163
164static int MIPS_is_fake_mcount(Elf_Rel const *rp)
165{
Alex Smith91ad11d2014-06-17 10:39:53 +0100166 static Elf_Addr old_r_offset = ~(Elf_Addr)0;
Wu Zhangjin412910c2010-10-27 18:59:08 +0800167 Elf_Addr current_r_offset = _w(rp->r_offset);
168 int is_fake;
169
Alex Smith91ad11d2014-06-17 10:39:53 +0100170 is_fake = (old_r_offset != ~(Elf_Addr)0) &&
Wu Zhangjin412910c2010-10-27 18:59:08 +0800171 (current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
172 old_r_offset = current_r_offset;
173
174 return is_fake;
175}
John Reisera2d493582010-10-27 18:59:07 +0800176
Steven Rostedtc28d5072010-10-13 19:06:14 -0400177/* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
178static void append_func(Elf_Ehdr *const ehdr,
179 Elf_Shdr *const shstr,
180 uint_t const *const mloc0,
181 uint_t const *const mlocp,
182 Elf_Rel const *const mrel0,
183 Elf_Rel const *const mrelp,
184 unsigned int const rel_entsize,
185 unsigned int const symsec_sh_link)
186{
187 /* Begin constructing output file */
188 Elf_Shdr mcsec;
189 char const *mc_name = (sizeof(Elf_Rela) == rel_entsize)
190 ? ".rela__mcount_loc"
191 : ".rel__mcount_loc";
192 unsigned const old_shnum = w2(ehdr->e_shnum);
193 uint_t const old_shoff = _w(ehdr->e_shoff);
194 uint_t const old_shstr_sh_size = _w(shstr->sh_size);
195 uint_t const old_shstr_sh_offset = _w(shstr->sh_offset);
196 uint_t t = 1 + strlen(mc_name) + _w(shstr->sh_size);
197 uint_t new_e_shoff;
198
199 shstr->sh_size = _w(t);
200 shstr->sh_offset = _w(sb.st_size);
201 t += sb.st_size;
202 t += (_align & -t); /* word-byte align */
203 new_e_shoff = t;
204
205 /* body for new shstrtab */
206 ulseek(fd_map, sb.st_size, SEEK_SET);
207 uwrite(fd_map, old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size);
208 uwrite(fd_map, mc_name, 1 + strlen(mc_name));
209
210 /* old(modified) Elf_Shdr table, word-byte aligned */
211 ulseek(fd_map, t, SEEK_SET);
212 t += sizeof(Elf_Shdr) * old_shnum;
213 uwrite(fd_map, old_shoff + (void *)ehdr,
214 sizeof(Elf_Shdr) * old_shnum);
215
216 /* new sections __mcount_loc and .rel__mcount_loc */
217 t += 2*sizeof(mcsec);
218 mcsec.sh_name = w((sizeof(Elf_Rela) == rel_entsize) + strlen(".rel")
219 + old_shstr_sh_size);
220 mcsec.sh_type = w(SHT_PROGBITS);
221 mcsec.sh_flags = _w(SHF_ALLOC);
222 mcsec.sh_addr = 0;
223 mcsec.sh_offset = _w(t);
224 mcsec.sh_size = _w((void *)mlocp - (void *)mloc0);
225 mcsec.sh_link = 0;
226 mcsec.sh_info = 0;
227 mcsec.sh_addralign = _w(_size);
228 mcsec.sh_entsize = _w(_size);
229 uwrite(fd_map, &mcsec, sizeof(mcsec));
230
231 mcsec.sh_name = w(old_shstr_sh_size);
232 mcsec.sh_type = (sizeof(Elf_Rela) == rel_entsize)
233 ? w(SHT_RELA)
234 : w(SHT_REL);
235 mcsec.sh_flags = 0;
236 mcsec.sh_addr = 0;
237 mcsec.sh_offset = _w((void *)mlocp - (void *)mloc0 + t);
238 mcsec.sh_size = _w((void *)mrelp - (void *)mrel0);
239 mcsec.sh_link = w(symsec_sh_link);
240 mcsec.sh_info = w(old_shnum);
241 mcsec.sh_addralign = _w(_size);
242 mcsec.sh_entsize = _w(rel_entsize);
243 uwrite(fd_map, &mcsec, sizeof(mcsec));
244
245 uwrite(fd_map, mloc0, (void *)mlocp - (void *)mloc0);
246 uwrite(fd_map, mrel0, (void *)mrelp - (void *)mrel0);
247
248 ehdr->e_shoff = _w(new_e_shoff);
249 ehdr->e_shnum = w2(2 + w2(ehdr->e_shnum)); /* {.rel,}__mcount_loc */
250 ulseek(fd_map, 0, SEEK_SET);
251 uwrite(fd_map, ehdr, sizeof(*ehdr));
252}
253
Steven Rostedt37762cb2011-04-20 20:47:34 -0400254static unsigned get_mcountsym(Elf_Sym const *const sym0,
255 Elf_Rel const *relp,
256 char const *const str0)
257{
258 unsigned mcountsym = 0;
259
260 Elf_Sym const *const symp =
261 &sym0[Elf_r_sym(relp)];
262 char const *symname = &str0[w(symp->st_name)];
263 char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
Steven Rostedt48bb5dc2011-02-09 13:13:23 -0500264 char const *fentry = "__fentry__";
Steven Rostedt37762cb2011-04-20 20:47:34 -0400265
266 if (symname[0] == '.')
267 ++symname; /* ppc64 hack */
268 if (strcmp(mcount, symname) == 0 ||
Steven Rostedt48bb5dc2011-02-09 13:13:23 -0500269 (altmcount && strcmp(altmcount, symname) == 0) ||
270 (strcmp(fentry, symname) == 0))
Steven Rostedt37762cb2011-04-20 20:47:34 -0400271 mcountsym = Elf_r_sym(relp);
272
273 return mcountsym;
274}
275
Steven Rostedt41b402a2011-04-20 21:13:06 -0400276static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
277 Elf_Ehdr const *const ehdr,
278 Elf_Sym const **sym0,
279 char const **str0,
280 Elf_Rel const **relp)
281{
282 Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
283 + (void *)ehdr);
284 unsigned const symsec_sh_link = w(relhdr->sh_link);
285 Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
286 Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
287 Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
288 + (void *)ehdr);
289
290 *sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
291 + (void *)ehdr);
292
293 *str0 = (char const *)(_w(strsec->sh_offset)
294 + (void *)ehdr);
295
296 *relp = rel0;
297}
298
Steven Rostedtc28d5072010-10-13 19:06:14 -0400299/*
300 * Look at the relocations in order to find the calls to mcount.
301 * Accumulate the section offsets that are found, and their relocation info,
302 * onto the end of the existing arrays.
303 */
304static uint_t *sift_rel_mcount(uint_t *mlocp,
305 unsigned const offbase,
306 Elf_Rel **const mrelpp,
307 Elf_Shdr const *const relhdr,
308 Elf_Ehdr const *const ehdr,
309 unsigned const recsym,
310 uint_t const recval,
311 unsigned const reltype)
312{
313 uint_t *const mloc0 = mlocp;
314 Elf_Rel *mrelp = *mrelpp;
Steven Rostedt41b402a2011-04-20 21:13:06 -0400315 Elf_Sym const *sym0;
316 char const *str0;
317 Elf_Rel const *relp;
Steven Rostedtc28d5072010-10-13 19:06:14 -0400318 unsigned rel_entsize = _w(relhdr->sh_entsize);
319 unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
Steven Rostedtc28d5072010-10-13 19:06:14 -0400320 unsigned mcountsym = 0;
321 unsigned t;
322
Steven Rostedt41b402a2011-04-20 21:13:06 -0400323 get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
324
Steven Rostedtc28d5072010-10-13 19:06:14 -0400325 for (t = nrel; t; --t) {
Steven Rostedt37762cb2011-04-20 20:47:34 -0400326 if (!mcountsym)
327 mcountsym = get_mcountsym(sym0, relp, str0);
Steven Rostedtc28d5072010-10-13 19:06:14 -0400328
Wu Zhangjin412910c2010-10-27 18:59:08 +0800329 if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
Martin Schwidefsky07d8b592011-05-10 10:10:40 +0200330 uint_t const addend =
331 _w(_w(relp->r_offset) - recval + mcount_adjust);
Steven Rostedtc28d5072010-10-13 19:06:14 -0400332 mrelp->r_offset = _w(offbase
333 + ((void *)mlocp - (void *)mloc0));
John Reisera2d493582010-10-27 18:59:07 +0800334 Elf_r_info(mrelp, recsym, reltype);
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400335 if (rel_entsize == sizeof(Elf_Rela)) {
Steven Rostedtc28d5072010-10-13 19:06:14 -0400336 ((Elf_Rela *)mrelp)->r_addend = addend;
337 *mlocp++ = 0;
338 } else
339 *mlocp++ = addend;
340
341 mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp);
342 }
343 relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
344 }
345 *mrelpp = mrelp;
346 return mlocp;
347}
348
Steven Rostedtffd618f2011-04-08 03:58:48 -0400349/*
350 * Read the relocation table again, but this time its called on sections
351 * that are not going to be traced. The mcount calls here will be converted
352 * into nops.
353 */
354static void nop_mcount(Elf_Shdr const *const relhdr,
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400355 Elf_Ehdr const *const ehdr,
356 const char *const txtname)
Steven Rostedtffd618f2011-04-08 03:58:48 -0400357{
358 Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
359 + (void *)ehdr);
Steven Rostedt41b402a2011-04-20 21:13:06 -0400360 Elf_Sym const *sym0;
361 char const *str0;
362 Elf_Rel const *relp;
363 Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];
Steven Rostedtffd618f2011-04-08 03:58:48 -0400364 unsigned rel_entsize = _w(relhdr->sh_entsize);
365 unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
Steven Rostedtffd618f2011-04-08 03:58:48 -0400366 unsigned mcountsym = 0;
367 unsigned t;
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400368 int once = 0;
Steven Rostedtffd618f2011-04-08 03:58:48 -0400369
Steven Rostedt41b402a2011-04-20 21:13:06 -0400370 get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
371
Steven Rostedtffd618f2011-04-08 03:58:48 -0400372 for (t = nrel; t; --t) {
373 int ret = -1;
374
Steven Rostedt37762cb2011-04-20 20:47:34 -0400375 if (!mcountsym)
376 mcountsym = get_mcountsym(sym0, relp, str0);
Steven Rostedtffd618f2011-04-08 03:58:48 -0400377
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400378 if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
379 if (make_nop)
libinc84da8b2015-11-03 08:58:47 +0800380 ret = make_nop((void *)ehdr, _w(shdr->sh_offset) + _w(relp->r_offset));
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400381 if (warn_on_notrace_sect && !once) {
382 printf("Section %s has mcount callers being ignored\n",
383 txtname);
384 once = 1;
385 /* just warn? */
386 if (!make_nop)
387 return;
388 }
389 }
Steven Rostedtffd618f2011-04-08 03:58:48 -0400390
391 /*
392 * If we successfully removed the mcount, mark the relocation
393 * as a nop (don't do anything with it).
394 */
395 if (!ret) {
396 Elf_Rel rel;
397 rel = *(Elf_Rel *)relp;
398 Elf_r_info(&rel, Elf_r_sym(relp), rel_type_nop);
399 ulseek(fd_map, (void *)relp - (void *)ehdr, SEEK_SET);
400 uwrite(fd_map, &rel, sizeof(rel));
401 }
402 relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
403 }
404}
405
Steven Rostedtc28d5072010-10-13 19:06:14 -0400406
407/*
408 * Find a symbol in the given section, to be used as the base for relocating
409 * the table of offsets of calls to mcount. A local or global symbol suffices,
410 * but avoid a Weak symbol because it may be overridden; the change in value
411 * would invalidate the relocations of the offsets of the calls to mcount.
412 * Often the found symbol will be the unnamed local symbol generated by
413 * GNU 'as' for the start of each section. For example:
414 * Num: Value Size Type Bind Vis Ndx Name
415 * 2: 00000000 0 SECTION LOCAL DEFAULT 1
416 */
417static unsigned find_secsym_ndx(unsigned const txtndx,
418 char const *const txtname,
419 uint_t *const recvalp,
420 Elf_Shdr const *const symhdr,
421 Elf_Ehdr const *const ehdr)
422{
423 Elf_Sym const *const sym0 = (Elf_Sym const *)(_w(symhdr->sh_offset)
424 + (void *)ehdr);
425 unsigned const nsym = _w(symhdr->sh_size) / _w(symhdr->sh_entsize);
426 Elf_Sym const *symp;
427 unsigned t;
428
429 for (symp = sym0, t = nsym; t; --t, ++symp) {
430 unsigned int const st_bind = ELF_ST_BIND(symp->st_info);
431
432 if (txtndx == w2(symp->st_shndx)
433 /* avoid STB_WEAK */
434 && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {
Rabin Vincent9905ce82011-05-11 22:53:51 +0530435 /* function symbols on ARM have quirks, avoid them */
436 if (w2(ehdr->e_machine) == EM_ARM
437 && ELF_ST_TYPE(symp->st_info) == STT_FUNC)
438 continue;
439
Steven Rostedtc28d5072010-10-13 19:06:14 -0400440 *recvalp = _w(symp->st_value);
441 return symp - sym0;
442 }
443 }
nixiaomingac5db1f2018-05-24 11:16:12 +0800444 fprintf(stderr, "Cannot find symbol for section %u: %s.\n",
Steven Rostedtc28d5072010-10-13 19:06:14 -0400445 txtndx, txtname);
446 fail_file();
447}
448
449
450/* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
451static char const *
452__has_rel_mcount(Elf_Shdr const *const relhdr, /* is SHT_REL or SHT_RELA */
453 Elf_Shdr const *const shdr0,
454 char const *const shstrtab,
455 char const *const fname)
456{
457 /* .sh_info depends on .sh_type == SHT_REL[,A] */
458 Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
459 char const *const txtname = &shstrtab[w(txthdr->sh_name)];
460
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400461 if (strcmp("__mcount_loc", txtname) == 0) {
Steven Rostedtc28d5072010-10-13 19:06:14 -0400462 fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
463 fname);
464 succeed_file();
465 }
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400466 if (w(txthdr->sh_type) != SHT_PROGBITS ||
David Daney2e885052011-12-19 17:42:42 -0800467 !(_w(txthdr->sh_flags) & SHF_EXECINSTR))
Steven Rostedtc28d5072010-10-13 19:06:14 -0400468 return NULL;
469 return txtname;
470}
471
472static char const *has_rel_mcount(Elf_Shdr const *const relhdr,
473 Elf_Shdr const *const shdr0,
474 char const *const shstrtab,
475 char const *const fname)
476{
Steven Rostedtdd5477f2011-04-06 13:21:17 -0400477 if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
Steven Rostedtc28d5072010-10-13 19:06:14 -0400478 return NULL;
479 return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
480}
481
482
483static unsigned tot_relsize(Elf_Shdr const *const shdr0,
484 unsigned nhdr,
485 const char *const shstrtab,
486 const char *const fname)
487{
488 unsigned totrelsz = 0;
489 Elf_Shdr const *shdrp = shdr0;
Steven Rostedtffd618f2011-04-08 03:58:48 -0400490 char const *txtname;
Steven Rostedtc28d5072010-10-13 19:06:14 -0400491
492 for (; nhdr; --nhdr, ++shdrp) {
Steven Rostedtffd618f2011-04-08 03:58:48 -0400493 txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
494 if (txtname && is_mcounted_section_name(txtname))
Steven Rostedtc28d5072010-10-13 19:06:14 -0400495 totrelsz += _w(shdrp->sh_size);
496 }
497 return totrelsz;
498}
499
500
501/* Overall supervision for Elf32 ET_REL file. */
502static void
503do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
504{
505 Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
506 + (void *)ehdr);
507 unsigned const nhdr = w2(ehdr->e_shnum);
508 Elf_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];
509 char const *const shstrtab = (char const *)(_w(shstr->sh_offset)
510 + (void *)ehdr);
511
512 Elf_Shdr const *relhdr;
513 unsigned k;
514
515 /* Upper bound on space: assume all relevant relocs are for mcount. */
516 unsigned const totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
517 Elf_Rel *const mrel0 = umalloc(totrelsz);
518 Elf_Rel * mrelp = mrel0;
519
520 /* 2*sizeof(address) <= sizeof(Elf_Rel) */
521 uint_t *const mloc0 = umalloc(totrelsz>>1);
522 uint_t * mlocp = mloc0;
523
524 unsigned rel_entsize = 0;
525 unsigned symsec_sh_link = 0;
526
527 for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
528 char const *const txtname = has_rel_mcount(relhdr, shdr0,
529 shstrtab, fname);
Steven Rostedtffd618f2011-04-08 03:58:48 -0400530 if (txtname && is_mcounted_section_name(txtname)) {
Steven Rostedtc28d5072010-10-13 19:06:14 -0400531 uint_t recval = 0;
532 unsigned const recsym = find_secsym_ndx(
533 w(relhdr->sh_info), txtname, &recval,
534 &shdr0[symsec_sh_link = w(relhdr->sh_link)],
535 ehdr);
536
537 rel_entsize = _w(relhdr->sh_entsize);
538 mlocp = sift_rel_mcount(mlocp,
539 (void *)mlocp - (void *)mloc0, &mrelp,
540 relhdr, ehdr, recsym, recval, reltype);
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400541 } else if (txtname && (warn_on_notrace_sect || make_nop)) {
Steven Rostedtffd618f2011-04-08 03:58:48 -0400542 /*
543 * This section is ignored by ftrace, but still
544 * has mcount calls. Convert them to nops now.
545 */
Steven Rostedtdfad3d52011-04-12 18:53:25 -0400546 nop_mcount(relhdr, ehdr, txtname);
Steven Rostedtc28d5072010-10-13 19:06:14 -0400547 }
548 }
549 if (mloc0 != mlocp) {
550 append_func(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
551 rel_entsize, symsec_sh_link);
552 }
553 free(mrel0);
554 free(mloc0);
555}