Commit c28d5077 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
Browse files

ftrace: Remove duplicate code for 64 and 32 bit in recordmcount.c 



The elf reader for recordmcount.c had duplicate functions for both
32 bit and 64 bit elf handling. This was due to the need of using
the 32 and 64 bit elf structures.

This patch consolidates the two by using macros to define the 32
and 64 bit names in a recordmcount.h file, and then by just defining
a RECORD_MCOUNT_64 macro and including recordmcount.h twice we
create the funtions for both the 32 bit version as well as the
64 bit version using one code source.

Cc: John Reiser <jreiser@bitwagon.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 72441cb1

scripts/recordmcount.c

+4 −544
Original line number Diff line number Diff line
@@ -212,550 +212,10 @@ is_mcounted_section_name(char const *const txtname) 
		0 == strcmp(".text.unlikely", txtname);

}



/* Append the new shstrtab, Elf32_Shdr[], __mcount_loc and its relocations. */

static void append32(Elf32_Ehdr *const ehdr,

		     Elf32_Shdr *const shstr,

		     uint32_t const *const mloc0,

		     uint32_t const *const mlocp,

		     Elf32_Rel const *const mrel0,

		     Elf32_Rel const *const mrelp,

		     unsigned int const rel_entsize,

		     unsigned int const symsec_sh_link)

{

	/* Begin constructing output file */

	Elf32_Shdr mcsec;

	char const *mc_name = (sizeof(Elf32_Rela) == rel_entsize)

		? ".rela__mcount_loc"

		:  ".rel__mcount_loc";

	unsigned const old_shnum = w2(ehdr->e_shnum);

	uint32_t const old_shoff = w(ehdr->e_shoff);

	uint32_t const old_shstr_sh_size   = w(shstr->sh_size);

	uint32_t const old_shstr_sh_offset = w(shstr->sh_offset);

	uint32_t t = 1 + strlen(mc_name) + w(shstr->sh_size);

	uint32_t new_e_shoff;



	shstr->sh_size = w(t);

	shstr->sh_offset = w(sb.st_size);

	t += sb.st_size;

	t += (3u & -t);  /* 4-byte align */

	new_e_shoff = t;



	/* body for new shstrtab */

	ulseek(fd_map, sb.st_size, SEEK_SET);

	uwrite(fd_map, old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size);

	uwrite(fd_map, mc_name, 1 + strlen(mc_name));



	/* old(modified) Elf32_Shdr table, 4-byte aligned */

	ulseek(fd_map, t, SEEK_SET);

	t += sizeof(Elf32_Shdr) * old_shnum;

	uwrite(fd_map, old_shoff + (void *)ehdr,

	       sizeof(Elf32_Shdr) * old_shnum);



	/* new sections __mcount_loc and .rel__mcount_loc */

	t += 2*sizeof(mcsec);

	mcsec.sh_name = w((sizeof(Elf32_Rela) == rel_entsize) + strlen(".rel")

		+ old_shstr_sh_size);

	mcsec.sh_type = w(SHT_PROGBITS);

	mcsec.sh_flags = w(SHF_ALLOC);

	mcsec.sh_addr = 0;

	mcsec.sh_offset = w(t);

	mcsec.sh_size = w((void *)mlocp - (void *)mloc0);

	mcsec.sh_link = 0;

	mcsec.sh_info = 0;

	mcsec.sh_addralign = w(4);

	mcsec.sh_entsize = w(4);

	uwrite(fd_map, &mcsec, sizeof(mcsec));



	mcsec.sh_name = w(old_shstr_sh_size);

	mcsec.sh_type = (sizeof(Elf32_Rela) == rel_entsize)

		? w(SHT_RELA)

		: w(SHT_REL);

	mcsec.sh_flags = 0;

	mcsec.sh_addr = 0;

	mcsec.sh_offset = w((void *)mlocp - (void *)mloc0 + t);

	mcsec.sh_size   = w((void *)mrelp - (void *)mrel0);

	mcsec.sh_link = w(symsec_sh_link);

	mcsec.sh_info = w(old_shnum);

	mcsec.sh_addralign = w(4);

	mcsec.sh_entsize = w(rel_entsize);

	uwrite(fd_map, &mcsec, sizeof(mcsec));



	uwrite(fd_map, mloc0, (void *)mlocp - (void *)mloc0);

	uwrite(fd_map, mrel0, (void *)mrelp - (void *)mrel0);



	ehdr->e_shoff = w(new_e_shoff);

	ehdr->e_shnum = w2(2 + w2(ehdr->e_shnum));  /* {.rel,}__mcount_loc */

	ulseek(fd_map, 0, SEEK_SET);

	uwrite(fd_map, ehdr, sizeof(*ehdr));

}



/*

 * append64 and append32 (and other analogous pairs) could be templated

 * using C++, but the complexity is high.  (For an example, look at p_elf.h

 * in the source for UPX, http://upx.sourceforge.net)  So: remember to make

 * the corresponding change in the routine for the other size.

 */

static void append64(Elf64_Ehdr *const ehdr,

		     Elf64_Shdr *const shstr,

		     uint64_t const *const mloc0,

		     uint64_t const *const mlocp,

		     Elf64_Rel const *const mrel0,

		     Elf64_Rel const *const mrelp,

		     unsigned int const rel_entsize,

		     unsigned int const symsec_sh_link)

{

	/* Begin constructing output file */

	Elf64_Shdr mcsec;

	char const *mc_name = (sizeof(Elf64_Rela) == rel_entsize)

		? ".rela__mcount_loc"

		:  ".rel__mcount_loc";

	unsigned const old_shnum = w2(ehdr->e_shnum);

	uint64_t const old_shoff = w8(ehdr->e_shoff);

	uint64_t const old_shstr_sh_size   = w8(shstr->sh_size);

	uint64_t const old_shstr_sh_offset = w8(shstr->sh_offset);

	uint64_t t = 1 + strlen(mc_name) + w8(shstr->sh_size);

	uint64_t new_e_shoff;



	shstr->sh_size = w8(t);

	shstr->sh_offset = w8(sb.st_size);

	t += sb.st_size;

	t += (7u & -t);  /* 8-byte align */

	new_e_shoff = t;



	/* body for new shstrtab */

	ulseek(fd_map, sb.st_size, SEEK_SET);

	uwrite(fd_map, old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size);

	uwrite(fd_map, mc_name, 1 + strlen(mc_name));



	/* old(modified) Elf64_Shdr table, 8-byte aligned */

	ulseek(fd_map, t, SEEK_SET);

	t += sizeof(Elf64_Shdr) * old_shnum;

	uwrite(fd_map, old_shoff + (void *)ehdr,

		sizeof(Elf64_Shdr) * old_shnum);



	/* new sections __mcount_loc and .rel__mcount_loc */

	t += 2*sizeof(mcsec);

	mcsec.sh_name = w((sizeof(Elf64_Rela) == rel_entsize) + strlen(".rel")

		+ old_shstr_sh_size);

	mcsec.sh_type = w(SHT_PROGBITS);

	mcsec.sh_flags = w8(SHF_ALLOC);

	mcsec.sh_addr = 0;

	mcsec.sh_offset = w8(t);

	mcsec.sh_size = w8((void *)mlocp - (void *)mloc0);

	mcsec.sh_link = 0;

	mcsec.sh_info = 0;

	mcsec.sh_addralign = w8(8);

	mcsec.sh_entsize = w8(8);

	uwrite(fd_map, &mcsec, sizeof(mcsec));



	mcsec.sh_name = w(old_shstr_sh_size);

	mcsec.sh_type = (sizeof(Elf64_Rela) == rel_entsize)

		? w(SHT_RELA)

		: w(SHT_REL);

	mcsec.sh_flags = 0;

	mcsec.sh_addr = 0;

	mcsec.sh_offset = w8((void *)mlocp - (void *)mloc0 + t);

	mcsec.sh_size   = w8((void *)mrelp - (void *)mrel0);

	mcsec.sh_link = w(symsec_sh_link);

	mcsec.sh_info = w(old_shnum);

	mcsec.sh_addralign = w8(8);

	mcsec.sh_entsize = w8(rel_entsize);

	uwrite(fd_map, &mcsec, sizeof(mcsec));



	uwrite(fd_map, mloc0, (void *)mlocp - (void *)mloc0);

	uwrite(fd_map, mrel0, (void *)mrelp - (void *)mrel0);



	ehdr->e_shoff = w8(new_e_shoff);

	ehdr->e_shnum = w2(2 + w2(ehdr->e_shnum));  /* {.rel,}__mcount_loc */

	ulseek(fd_map, 0, SEEK_SET);

	uwrite(fd_map, ehdr, sizeof(*ehdr));

}



/*

 * Look at the relocations in order to find the calls to mcount.

 * Accumulate the section offsets that are found, and their relocation info,

 * onto the end of the existing arrays.

 */

static uint32_t *sift32_rel_mcount(uint32_t *mlocp,

				   unsigned const offbase,

				   Elf32_Rel **const mrelpp,

				   Elf32_Shdr const *const relhdr,

				   Elf32_Ehdr const *const ehdr,

				   unsigned const recsym,

				   uint32_t const recval,

				   unsigned const reltype)

{

	uint32_t *const mloc0 = mlocp;

	Elf32_Rel *mrelp = *mrelpp;

	Elf32_Shdr *const shdr0 = (Elf32_Shdr *)(w(ehdr->e_shoff)

		+ (void *)ehdr);

	unsigned const symsec_sh_link = w(relhdr->sh_link);

	Elf32_Shdr const *const symsec = &shdr0[symsec_sh_link];

	Elf32_Sym const *const sym0 = (Elf32_Sym const *)(w(symsec->sh_offset)

		+ (void *)ehdr);



	Elf32_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];

	char const *const str0 = (char const *)(w(strsec->sh_offset)

		+ (void *)ehdr);



	Elf32_Rel const *const rel0 = (Elf32_Rel const *)(w(relhdr->sh_offset)

		+ (void *)ehdr);

	unsigned rel_entsize = w(relhdr->sh_entsize);

	unsigned const nrel = w(relhdr->sh_size) / rel_entsize;

	Elf32_Rel const *relp = rel0;



	unsigned mcountsym = 0;

	unsigned t;



	for (t = nrel; t; --t) {

		if (!mcountsym) {

			Elf32_Sym const *const symp =

				&sym0[ELF32_R_SYM(w(relp->r_info))];



			if (0 == strcmp((('_' == gpfx) ? "_mcount" : "mcount"),

					&str0[w(symp->st_name)]))

				mcountsym = ELF32_R_SYM(w(relp->r_info));

		}

		if (mcountsym == ELF32_R_SYM(w(relp->r_info))) {

			uint32_t const addend = w(w(relp->r_offset) - recval);

			mrelp->r_offset = w(offbase

				+ ((void *)mlocp - (void *)mloc0));

			mrelp->r_info = w(ELF32_R_INFO(recsym, reltype));

			if (sizeof(Elf32_Rela) == rel_entsize) {

				((Elf32_Rela *)mrelp)->r_addend = addend;

				*mlocp++ = 0;

			} else

				*mlocp++ = addend;



			mrelp = (Elf32_Rel *)(rel_entsize + (void *)mrelp);

		}

		relp = (Elf32_Rel const *)(rel_entsize + (void *)relp);

	}

	*mrelpp = mrelp;

	return mlocp;

}



static uint64_t *sift64_rel_mcount(uint64_t *mlocp,

				   unsigned const offbase,

				   Elf64_Rel **const mrelpp,

				   Elf64_Shdr const *const relhdr,

				   Elf64_Ehdr const *const ehdr,

				   unsigned const recsym,

				   uint64_t const recval,

				   unsigned const reltype)

{

	uint64_t *const mloc0 = mlocp;

	Elf64_Rel *mrelp = *mrelpp;

	Elf64_Shdr *const shdr0 = (Elf64_Shdr *)(w8(ehdr->e_shoff)

		+ (void *)ehdr);

	unsigned const symsec_sh_link = w(relhdr->sh_link);

	Elf64_Shdr const *const symsec = &shdr0[symsec_sh_link];

	Elf64_Sym const *const sym0 = (Elf64_Sym const *)(w8(symsec->sh_offset)

		+ (void *)ehdr);



	Elf64_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];

	char const *const str0 = (char const *)(w8(strsec->sh_offset)

		+ (void *)ehdr);



	Elf64_Rel const *const rel0 = (Elf64_Rel const *)(w8(relhdr->sh_offset)

		+ (void *)ehdr);

	unsigned rel_entsize = w8(relhdr->sh_entsize);

	unsigned const nrel = w8(relhdr->sh_size) / rel_entsize;

	Elf64_Rel const *relp = rel0;



	unsigned mcountsym = 0;

	unsigned t;



	for (t = nrel; 0 != t; --t) {

		if (!mcountsym) {

			Elf64_Sym const *const symp =

				&sym0[ELF64_R_SYM(w8(relp->r_info))];

			char const *symname = &str0[w(symp->st_name)];



			if ('.' == symname[0])

				++symname;  /* ppc64 hack */

			if (0 == strcmp((('_' == gpfx) ? "_mcount" : "mcount"),

					symname))

				mcountsym = ELF64_R_SYM(w8(relp->r_info));

		}



		if (mcountsym == ELF64_R_SYM(w8(relp->r_info))) {

			uint64_t const addend = w8(w8(relp->r_offset) - recval);



			mrelp->r_offset = w8(offbase

				+ ((void *)mlocp - (void *)mloc0));

			mrelp->r_info = w8(ELF64_R_INFO(recsym, reltype));

			if (sizeof(Elf64_Rela) == rel_entsize) {

				((Elf64_Rela *)mrelp)->r_addend = addend;

				*mlocp++ = 0;

			} else

				*mlocp++ = addend;



			mrelp = (Elf64_Rel *)(rel_entsize + (void *)mrelp);

		}

		relp = (Elf64_Rel const *)(rel_entsize + (void *)relp);

	}

	*mrelpp = mrelp;



	return mlocp;

}



/*

 * Find a symbol in the given section, to be used as the base for relocating

 * the table of offsets of calls to mcount.  A local or global symbol suffices,

 * but avoid a Weak symbol because it may be overridden; the change in value

 * would invalidate the relocations of the offsets of the calls to mcount.

 * Often the found symbol will be the unnamed local symbol generated by

 * GNU 'as' for the start of each section.  For example:

 *    Num:    Value  Size Type    Bind   Vis      Ndx Name

 *      2: 00000000     0 SECTION LOCAL  DEFAULT    1

 */

static unsigned find32_secsym_ndx(unsigned const txtndx,

				  char const *const txtname,

				  uint32_t *const recvalp,

				  Elf32_Shdr const *const symhdr,

				  Elf32_Ehdr const *const ehdr)

{

	Elf32_Sym const *const sym0 = (Elf32_Sym const *)(w(symhdr->sh_offset)

		+ (void *)ehdr);

	unsigned const nsym = w(symhdr->sh_size) / w(symhdr->sh_entsize);

	Elf32_Sym const *symp;

	unsigned t;



	for (symp = sym0, t = nsym; t; --t, ++symp) {

		unsigned int const st_bind = ELF32_ST_BIND(symp->st_info);



		if (txtndx == w2(symp->st_shndx)

			/* avoid STB_WEAK */

		    && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {

			*recvalp = w(symp->st_value);

			return symp - sym0;

		}

	}

	fprintf(stderr, "Cannot find symbol for section %d: %s.\n",

		txtndx, txtname);

	fail_file();

}



static unsigned find64_secsym_ndx(unsigned const txtndx,

				  char const *const txtname,

				  uint64_t *const recvalp,

				  Elf64_Shdr const *const symhdr,

				  Elf64_Ehdr const *const ehdr)

{

	Elf64_Sym const *const sym0 = (Elf64_Sym const *)(w8(symhdr->sh_offset)

		+ (void *)ehdr);

	unsigned const nsym = w8(symhdr->sh_size) / w8(symhdr->sh_entsize);

	Elf64_Sym const *symp;

	unsigned t;



	for (symp = sym0, t = nsym; t; --t, ++symp) {

		unsigned int const st_bind = ELF64_ST_BIND(symp->st_info);



		if (txtndx == w2(symp->st_shndx)

			/* avoid STB_WEAK */

		    && (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {

			*recvalp = w8(symp->st_value);

			return symp - sym0;

		}

	}

	fprintf(stderr, "Cannot find symbol for section %d: %s.\n",

		txtndx, txtname);

	fail_file();

}



/*

 * Evade ISO C restriction: no declaration after statement in

 * has32_rel_mcount.

 */

static char const *

__has32_rel_mcount(Elf32_Shdr const *const relhdr,  /* is SHT_REL or SHT_RELA */

		   Elf32_Shdr const *const shdr0,

		   char const *const shstrtab,

		   char const *const fname)

{

	/* .sh_info depends on .sh_type == SHT_REL[,A] */

	Elf32_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];

	char const *const txtname = &shstrtab[w(txthdr->sh_name)];



	if (0 == strcmp("__mcount_loc", txtname)) {

		fprintf(stderr, "warning: __mcount_loc already exists: %s\n",

			fname);

		succeed_file();

	}

	if (SHT_PROGBITS != w(txthdr->sh_type) ||

	    !is_mcounted_section_name(txtname))

		return NULL;

	return txtname;

}



static char const *has32_rel_mcount(Elf32_Shdr const *const relhdr,

				    Elf32_Shdr const *const shdr0,

				    char const *const shstrtab,

				    char const *const fname)

{

	if (SHT_REL  != w(relhdr->sh_type) && SHT_RELA != w(relhdr->sh_type))

		return NULL;

	return __has32_rel_mcount(relhdr, shdr0, shstrtab, fname);

}



static char const *__has64_rel_mcount(Elf64_Shdr const *const relhdr,

				      Elf64_Shdr const *const shdr0,

				      char const *const shstrtab,

				      char const *const fname)

{

	/* .sh_info depends on .sh_type == SHT_REL[,A] */

	Elf64_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];

	char const *const txtname = &shstrtab[w(txthdr->sh_name)];



	if (0 == strcmp("__mcount_loc", txtname)) {

		fprintf(stderr, "warning: __mcount_loc already exists: %s\n",

			fname);

		succeed_file();

	}

	if (SHT_PROGBITS != w(txthdr->sh_type) ||

	    !is_mcounted_section_name(txtname))

		return NULL;

	return txtname;

}



static char const *has64_rel_mcount(Elf64_Shdr const *const relhdr,

				    Elf64_Shdr const *const shdr0,

				    char const *const shstrtab,

				    char const *const fname)

{

	if (SHT_REL  != w(relhdr->sh_type) && SHT_RELA != w(relhdr->sh_type))

		return NULL;

	return __has64_rel_mcount(relhdr, shdr0, shstrtab, fname);

}



static unsigned tot32_relsize(Elf32_Shdr const *const shdr0,

			      unsigned nhdr,

			      const char *const shstrtab,

			      const char *const fname)

{

	unsigned totrelsz = 0;

	Elf32_Shdr const *shdrp = shdr0;

	for (; 0 != nhdr; --nhdr, ++shdrp) {

		if (has32_rel_mcount(shdrp, shdr0, shstrtab, fname))

			totrelsz += w(shdrp->sh_size);

	}

	return totrelsz;

}



static unsigned tot64_relsize(Elf64_Shdr const *const shdr0,

			      unsigned nhdr,

			      const char *const shstrtab,

			      const char *const fname)

{

	unsigned totrelsz = 0;

	Elf64_Shdr const *shdrp = shdr0;



	for (; nhdr; --nhdr, ++shdrp) {

		if (has64_rel_mcount(shdrp, shdr0, shstrtab, fname))

			totrelsz += w8(shdrp->sh_size);

	}

	return totrelsz;

}



/* Overall supervision for Elf32 ET_REL file. */

static void

do32(Elf32_Ehdr *const ehdr, char const *const fname, unsigned const reltype)

{

	Elf32_Shdr *const shdr0 = (Elf32_Shdr *)(w(ehdr->e_shoff)

		+ (void *)ehdr);

	unsigned const nhdr = w2(ehdr->e_shnum);

	Elf32_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];

	char const *const shstrtab = (char const *)(w(shstr->sh_offset)

		+ (void *)ehdr);



	Elf32_Shdr const *relhdr;

	unsigned k;



	/* Upper bound on space: assume all relevant relocs are for mcount. */

	unsigned const totrelsz = tot32_relsize(shdr0, nhdr, shstrtab, fname);

	Elf32_Rel *const mrel0 = umalloc(totrelsz);

	Elf32_Rel *      mrelp = mrel0;



	/* 2*sizeof(address) <= sizeof(Elf32_Rel) */

	uint32_t *const mloc0 = umalloc(totrelsz>>1);

	uint32_t *      mlocp = mloc0;



	unsigned rel_entsize = 0;

	unsigned symsec_sh_link = 0;



	for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {

		char const *const txtname = has32_rel_mcount(relhdr, shdr0,

			shstrtab, fname);

		if (txtname) {

			uint32_t recval = 0;

			unsigned const recsym = find32_secsym_ndx(

				w(relhdr->sh_info), txtname, &recval,

				&shdr0[symsec_sh_link = w(relhdr->sh_link)],

				ehdr);



			rel_entsize = w(relhdr->sh_entsize);

			mlocp = sift32_rel_mcount(mlocp,

				(void *)mlocp - (void *)mloc0, &mrelp,

				relhdr, ehdr, recsym, recval, reltype);

		}

	}

	if (mloc0 != mlocp) {

		append32(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,

			rel_entsize, symsec_sh_link);

	}

	free(mrel0);

	free(mloc0);

}



static void

do64(Elf64_Ehdr *const ehdr, char const *const fname, unsigned const reltype)

{

	Elf64_Shdr *const shdr0 = (Elf64_Shdr *)(w8(ehdr->e_shoff)

		+ (void *)ehdr);

	unsigned const nhdr = w2(ehdr->e_shnum);

	Elf64_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];

	char const *const shstrtab = (char const *)(w8(shstr->sh_offset)

		+ (void *)ehdr);



	Elf64_Shdr const *relhdr;

	unsigned k;



	/* Upper bound on space: assume all relevant relocs are for mcount. */

	unsigned const totrelsz = tot64_relsize(shdr0, nhdr, shstrtab, fname);

	Elf64_Rel *const mrel0 = umalloc(totrelsz);

	Elf64_Rel *      mrelp = mrel0;



	/* 2*sizeof(address) <= sizeof(Elf64_Rel) */

	uint64_t *const mloc0 = umalloc(totrelsz>>1);

	uint64_t *      mlocp = mloc0;



	unsigned rel_entsize = 0;

	unsigned symsec_sh_link = 0;



	for ((relhdr = shdr0), k = nhdr; k; --k, ++relhdr) {

		char const *const txtname = has64_rel_mcount(relhdr, shdr0,

			shstrtab, fname);

		if (txtname) {

			uint64_t recval = 0;

			unsigned const recsym = find64_secsym_ndx(

				w(relhdr->sh_info), txtname, &recval,

				&shdr0[symsec_sh_link = w(relhdr->sh_link)],

				ehdr);



			rel_entsize = w8(relhdr->sh_entsize);

			mlocp = sift64_rel_mcount(mlocp,

				(void *)mlocp - (void *)mloc0, &mrelp,

				relhdr, ehdr, recsym, recval, reltype);

		}

	}

	if (mloc0 != mlocp) {

		append64(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,

			rel_entsize, symsec_sh_link);

	}

	free(mrel0);

	free(mloc0);

}

/* 32 bit and 64 bit are very similar */

#include "recordmcount.h"

#define RECORD_MCOUNT_64

#include "recordmcount.h"



static void

do_file(char const *const fname)

scripts/recordmcount.h

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