1 /*
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
22 #undef is_fake_mcount
23 #undef fn_is_fake_mcount
24 #undef MIPS_is_fake_mcount
25 #undef mcount_adjust
26 #undef sift_rel_mcount
27 #undef nop_mcount
28 #undef find_secsym_ndx
29 #undef __has_rel_mcount
30 #undef has_rel_mcount
31 #undef tot_relsize
32 #undef get_mcountsym
33 #undef get_sym_str_and_relp
34 #undef do_func
35 #undef Elf_Addr
36 #undef Elf_Ehdr
37 #undef Elf_Shdr
38 #undef Elf_Rel
39 #undef Elf_Rela
40 #undef Elf_Sym
41 #undef ELF_R_SYM
42 #undef Elf_r_sym
43 #undef ELF_R_INFO
44 #undef Elf_r_info
45 #undef ELF_ST_BIND
46 #undef ELF_ST_TYPE
47 #undef fn_ELF_R_SYM
48 #undef fn_ELF_R_INFO
49 #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
57 # define nop_mcount		nop_mcount_64
58 # 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
62 # define get_sym_str_and_relp	get_sym_str_and_relp_64
63 # define do_func		do64
64 # define get_mcountsym		get_mcountsym_64
65 # 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
68 # define mcount_adjust		mcount_adjust_64
69 # define Elf_Addr		Elf64_Addr
70 # 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
76 # define Elf_r_sym		Elf64_r_sym
77 # define ELF_R_INFO		ELF64_R_INFO
78 # define Elf_r_info		Elf64_r_info
79 # define ELF_ST_BIND		ELF64_ST_BIND
80 # define ELF_ST_TYPE		ELF64_ST_TYPE
81 # define fn_ELF_R_SYM		fn_ELF64_R_SYM
82 # define fn_ELF_R_INFO		fn_ELF64_R_INFO
83 # 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
90 # define nop_mcount		nop_mcount_32
91 # 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
95 # define get_sym_str_and_relp	get_sym_str_and_relp_32
96 # define do_func		do32
97 # define get_mcountsym		get_mcountsym_32
98 # 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
101 # define mcount_adjust		mcount_adjust_32
102 # define Elf_Addr		Elf32_Addr
103 # 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
109 # define Elf_r_sym		Elf32_r_sym
110 # define ELF_R_INFO		ELF32_R_INFO
111 # define Elf_r_info		Elf32_r_info
112 # define ELF_ST_BIND		ELF32_ST_BIND
113 # define ELF_ST_TYPE		ELF32_ST_TYPE
114 # define fn_ELF_R_SYM		fn_ELF32_R_SYM
115 # define fn_ELF_R_INFO		fn_ELF32_R_INFO
116 # define uint_t			uint32_t
117 # define _w			w
118 # define _align			3u
119 # define _size			4
120 #endif
121 
122 /* Functions and pointers that do_file() may override for specific e_machine. */
fn_is_fake_mcount(Elf_Rel const * rp)123 static int fn_is_fake_mcount(Elf_Rel const *rp)
124 {
125 	return 0;
126 }
127 static int (*is_fake_mcount)(Elf_Rel const *rp) = fn_is_fake_mcount;
128 
fn_ELF_R_SYM(Elf_Rel const * rp)129 static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
130 {
131 	return ELF_R_SYM(_w(rp->r_info));
132 }
133 static uint_t (*Elf_r_sym)(Elf_Rel const *rp) = fn_ELF_R_SYM;
134 
fn_ELF_R_INFO(Elf_Rel * const rp,unsigned sym,unsigned type)135 static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
136 {
137 	rp->r_info = _w(ELF_R_INFO(sym, type));
138 }
139 static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
140 
141 static int mcount_adjust = 0;
142 
143 /*
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 
MIPS_is_fake_mcount(Elf_Rel const * rp)164 static int MIPS_is_fake_mcount(Elf_Rel const *rp)
165 {
166 	static Elf_Addr old_r_offset = ~(Elf_Addr)0;
167 	Elf_Addr current_r_offset = _w(rp->r_offset);
168 	int is_fake;
169 
170 	is_fake = (old_r_offset != ~(Elf_Addr)0) &&
171 		(current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
172 	old_r_offset = current_r_offset;
173 
174 	return is_fake;
175 }
176 
177 /* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
append_func(Elf_Ehdr * const ehdr,Elf_Shdr * const shstr,uint_t const * const mloc0,uint_t const * const mlocp,Elf_Rel const * const mrel0,Elf_Rel const * const mrelp,unsigned int const rel_entsize,unsigned int const symsec_sh_link)178 static 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 
get_mcountsym(Elf_Sym const * const sym0,Elf_Rel const * relp,char const * const str0)254 static 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";
264 	char const *fentry = "__fentry__";
265 
266 	if (symname[0] == '.')
267 		++symname;  /* ppc64 hack */
268 	if (strcmp(mcount, symname) == 0 ||
269 	    (altmcount && strcmp(altmcount, symname) == 0) ||
270 	    (strcmp(fentry, symname) == 0))
271 		mcountsym = Elf_r_sym(relp);
272 
273 	return mcountsym;
274 }
275 
get_sym_str_and_relp(Elf_Shdr const * const relhdr,Elf_Ehdr const * const ehdr,Elf_Sym const ** sym0,char const ** str0,Elf_Rel const ** relp)276 static 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 
299 /*
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  */
sift_rel_mcount(uint_t * mlocp,unsigned const offbase,Elf_Rel ** const mrelpp,Elf_Shdr const * const relhdr,Elf_Ehdr const * const ehdr,unsigned const recsym,uint_t const recval,unsigned const reltype)304 static 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;
315 	Elf_Sym const *sym0;
316 	char const *str0;
317 	Elf_Rel const *relp;
318 	unsigned rel_entsize = _w(relhdr->sh_entsize);
319 	unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
320 	unsigned mcountsym = 0;
321 	unsigned t;
322 
323 	get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
324 
325 	for (t = nrel; t; --t) {
326 		if (!mcountsym)
327 			mcountsym = get_mcountsym(sym0, relp, str0);
328 
329 		if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
330 			uint_t const addend =
331 				_w(_w(relp->r_offset) - recval + mcount_adjust);
332 			mrelp->r_offset = _w(offbase
333 				+ ((void *)mlocp - (void *)mloc0));
334 			Elf_r_info(mrelp, recsym, reltype);
335 			if (rel_entsize == sizeof(Elf_Rela)) {
336 				((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 
349 /*
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  */
nop_mcount(Elf_Shdr const * const relhdr,Elf_Ehdr const * const ehdr,const char * const txtname)354 static void nop_mcount(Elf_Shdr const *const relhdr,
355 		       Elf_Ehdr const *const ehdr,
356 		       const char *const txtname)
357 {
358 	Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
359 		+ (void *)ehdr);
360 	Elf_Sym const *sym0;
361 	char const *str0;
362 	Elf_Rel const *relp;
363 	Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];
364 	unsigned rel_entsize = _w(relhdr->sh_entsize);
365 	unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
366 	unsigned mcountsym = 0;
367 	unsigned t;
368 	int once = 0;
369 
370 	get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
371 
372 	for (t = nrel; t; --t) {
373 		int ret = -1;
374 
375 		if (!mcountsym)
376 			mcountsym = get_mcountsym(sym0, relp, str0);
377 
378 		if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
379 			if (make_nop)
380 				ret = make_nop((void *)ehdr, _w(shdr->sh_offset) + _w(relp->r_offset));
381 			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 		}
390 
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 
406 
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  */
find_secsym_ndx(unsigned const txtndx,char const * const txtname,uint_t * const recvalp,Elf_Shdr const * const symhdr,Elf_Ehdr const * const ehdr)417 static 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)) {
435 			/* 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 
440 			*recvalp = _w(symp->st_value);
441 			return symp - sym0;
442 		}
443 	}
444 	fprintf(stderr, "Cannot find symbol for section %u: %s.\n",
445 		txtndx, txtname);
446 	fail_file();
447 }
448 
449 
450 /* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
451 static char const *
__has_rel_mcount(Elf_Shdr const * const relhdr,Elf_Shdr const * const shdr0,char const * const shstrtab,char const * const fname)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 
461 	if (strcmp("__mcount_loc", txtname) == 0) {
462 		fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
463 			fname);
464 		succeed_file();
465 	}
466 	if (w(txthdr->sh_type) != SHT_PROGBITS ||
467 	    !(_w(txthdr->sh_flags) & SHF_EXECINSTR))
468 		return NULL;
469 	return txtname;
470 }
471 
has_rel_mcount(Elf_Shdr const * const relhdr,Elf_Shdr const * const shdr0,char const * const shstrtab,char const * const fname)472 static 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 {
477 	if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
478 		return NULL;
479 	return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
480 }
481 
482 
tot_relsize(Elf_Shdr const * const shdr0,unsigned nhdr,const char * const shstrtab,const char * const fname)483 static 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;
490 	char const *txtname;
491 
492 	for (; nhdr; --nhdr, ++shdrp) {
493 		txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
494 		if (txtname && is_mcounted_section_name(txtname))
495 			totrelsz += _w(shdrp->sh_size);
496 	}
497 	return totrelsz;
498 }
499 
500 
501 /* Overall supervision for Elf32 ET_REL file. */
502 static void
do_func(Elf_Ehdr * const ehdr,char const * const fname,unsigned const reltype)503 do_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);
530 		if (txtname && is_mcounted_section_name(txtname)) {
531 			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);
541 		} else if (txtname && (warn_on_notrace_sect || make_nop)) {
542 			/*
543 			 * This section is ignored by ftrace, but still
544 			 * has mcount calls. Convert them to nops now.
545 			 */
546 			nop_mcount(relhdr, ehdr, txtname);
547 		}
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 }
556