[mirror_ubuntu-bionic-kernel.git] / scripts / recordmcount.h

/*
 * recordmcount.h
 *
 * This code was taken out of recordmcount.c written by
 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
 *
 * The original code had the same algorithms for both 32bit
 * and 64bit ELF files, but the code was duplicated to support
 * the difference in structures that were used. This
 * file creates a macro of everything that is different between
 * the 64 and 32 bit code, such that by including this header
 * twice we can create both sets of functions by including this
 * header once with RECORD_MCOUNT_64 undefined, and again with
 * it defined.
 *
 * This conversion to macros was done by:
 * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
 *
 * Licensed under the GNU General Public License, version 2 (GPLv2).
 */
#undef append_func
#undef is_fake_mcount
#undef fn_is_fake_mcount
#undef MIPS_is_fake_mcount
#undef sift_rel_mcount
#undef nop_mcount
#undef find_secsym_ndx
#undef __has_rel_mcount
#undef has_rel_mcount
#undef tot_relsize
#undef get_mcountsym
#undef do_func
#undef Elf_Addr
#undef Elf_Ehdr
#undef Elf_Shdr
#undef Elf_Rel
#undef Elf_Rela
#undef Elf_Sym
#undef ELF_R_SYM
#undef Elf_r_sym
#undef ELF_R_INFO
#undef Elf_r_info
#undef ELF_ST_BIND
#undef fn_ELF_R_SYM
#undef fn_ELF_R_INFO
#undef uint_t
#undef _w
#undef _align
#undef _size

#ifdef RECORD_MCOUNT_64
# define append_func		append64
# define sift_rel_mcount	sift64_rel_mcount
# define nop_mcount		nop_mcount_64
# define find_secsym_ndx	find64_secsym_ndx
# define __has_rel_mcount	__has64_rel_mcount
# define has_rel_mcount		has64_rel_mcount
# define tot_relsize		tot64_relsize
# define do_func		do64
# define get_mcountsym		get_mcountsym_64
# define is_fake_mcount		is_fake_mcount64
# define fn_is_fake_mcount	fn_is_fake_mcount64
# define MIPS_is_fake_mcount	MIPS64_is_fake_mcount
# define Elf_Addr		Elf64_Addr
# define Elf_Ehdr		Elf64_Ehdr
# define Elf_Shdr		Elf64_Shdr
# define Elf_Rel		Elf64_Rel
# define Elf_Rela		Elf64_Rela
# define Elf_Sym		Elf64_Sym
# define ELF_R_SYM		ELF64_R_SYM
# define Elf_r_sym		Elf64_r_sym
# define ELF_R_INFO		ELF64_R_INFO
# define Elf_r_info		Elf64_r_info
# define ELF_ST_BIND		ELF64_ST_BIND
# define fn_ELF_R_SYM		fn_ELF64_R_SYM
# define fn_ELF_R_INFO		fn_ELF64_R_INFO
# define uint_t			uint64_t
# define _w			w8
# define _align			7u
# define _size			8
#else
# define append_func		append32
# define sift_rel_mcount	sift32_rel_mcount
# define nop_mcount		nop_mcount_32
# define find_secsym_ndx	find32_secsym_ndx
# define __has_rel_mcount	__has32_rel_mcount
# define has_rel_mcount		has32_rel_mcount
# define tot_relsize		tot32_relsize
# define do_func		do32
# define get_mcountsym		get_mcountsym_32
# define is_fake_mcount		is_fake_mcount32
# define fn_is_fake_mcount	fn_is_fake_mcount32
# define MIPS_is_fake_mcount	MIPS32_is_fake_mcount
# define Elf_Addr		Elf32_Addr
# define Elf_Ehdr		Elf32_Ehdr
# define Elf_Shdr		Elf32_Shdr
# define Elf_Rel		Elf32_Rel
# define Elf_Rela		Elf32_Rela
# define Elf_Sym		Elf32_Sym
# define ELF_R_SYM		ELF32_R_SYM
# define Elf_r_sym		Elf32_r_sym
# define ELF_R_INFO		ELF32_R_INFO
# define Elf_r_info		Elf32_r_info
# define ELF_ST_BIND		ELF32_ST_BIND
# define fn_ELF_R_SYM		fn_ELF32_R_SYM
# define fn_ELF_R_INFO		fn_ELF32_R_INFO
# define uint_t			uint32_t
# define _w			w
# define _align			3u
# define _size			4
#endif

/* Functions and pointers that do_file() may override for specific e_machine. */
static int fn_is_fake_mcount(Elf_Rel const *rp)
{
	return 0;
}
static int (*is_fake_mcount)(Elf_Rel const *rp) = fn_is_fake_mcount;

static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
{
	return ELF_R_SYM(_w(rp->r_info));
}
static uint_t (*Elf_r_sym)(Elf_Rel const *rp) = fn_ELF_R_SYM;

static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
{
	rp->r_info = _w(ELF_R_INFO(sym, type));
}
static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;

/*
 * MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
 * _mcount symbol is needed for dynamic function tracer, with it, to disable
 * tracing(ftrace_make_nop), the instruction in the position is replaced with
 * the "b label" instruction, to enable tracing(ftrace_make_call), replace the
 * instruction back. So, here, we set the 2nd one as fake and filter it.
 *
 * c:	3c030000	lui	v1,0x0		<-->	b	label
 *		c: R_MIPS_HI16	_mcount
 *		c: R_MIPS_NONE	*ABS*
 *		c: R_MIPS_NONE	*ABS*
 * 10:	64630000	daddiu	v1,v1,0
 *		10: R_MIPS_LO16	_mcount
 *		10: R_MIPS_NONE	*ABS*
 *		10: R_MIPS_NONE	*ABS*
 * 14:	03e0082d	move	at,ra
 * 18:	0060f809	jalr	v1
 * label:
 */
#define MIPS_FAKEMCOUNT_OFFSET	4

static int MIPS_is_fake_mcount(Elf_Rel const *rp)
{
	static Elf_Addr old_r_offset;
	Elf_Addr current_r_offset = _w(rp->r_offset);
	int is_fake;

	is_fake = old_r_offset &&
		(current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
	old_r_offset = current_r_offset;

	return is_fake;
}

/* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
static void 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)
{
	/* Begin constructing output file */
	Elf_Shdr mcsec;
	char const *mc_name = (sizeof(Elf_Rela) == rel_entsize)
		? ".rela__mcount_loc"
		:  ".rel__mcount_loc";
	unsigned const old_shnum = w2(ehdr->e_shnum);
	uint_t const old_shoff = _w(ehdr->e_shoff);
	uint_t const old_shstr_sh_size   = _w(shstr->sh_size);
	uint_t const old_shstr_sh_offset = _w(shstr->sh_offset);
	uint_t t = 1 + strlen(mc_name) + _w(shstr->sh_size);
	uint_t new_e_shoff;

	shstr->sh_size = _w(t);
	shstr->sh_offset = _w(sb.st_size);
	t += sb.st_size;
	t += (_align & -t);  /* word-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) Elf_Shdr table, word-byte aligned */
	ulseek(fd_map, t, SEEK_SET);
	t += sizeof(Elf_Shdr) * old_shnum;
	uwrite(fd_map, old_shoff + (void *)ehdr,
	       sizeof(Elf_Shdr) * old_shnum);

	/* new sections __mcount_loc and .rel__mcount_loc */
	t += 2*sizeof(mcsec);
	mcsec.sh_name = w((sizeof(Elf_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(_size);
	mcsec.sh_entsize = _w(_size);
	uwrite(fd_map, &mcsec, sizeof(mcsec));

	mcsec.sh_name = w(old_shstr_sh_size);
	mcsec.sh_type = (sizeof(Elf_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(_size);
	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));
}

static unsigned get_mcountsym(Elf_Sym const *const sym0,
			      Elf_Rel const *relp,
			      char const *const str0)
{
	unsigned mcountsym = 0;

	Elf_Sym const *const symp =
		&sym0[Elf_r_sym(relp)];
	char const *symname = &str0[w(symp->st_name)];
	char const *mcount = gpfx == '_' ? "_mcount" : "mcount";

	if (symname[0] == '.')
		++symname;  /* ppc64 hack */
	if (strcmp(mcount, symname) == 0 ||
	    (altmcount && strcmp(altmcount, symname) == 0))
		mcountsym = Elf_r_sym(relp);

	return mcountsym;
}

/*
 * 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 uint_t *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)
{
	uint_t *const mloc0 = mlocp;
	Elf_Rel *mrelp = *mrelpp;
	Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
		+ (void *)ehdr);
	unsigned const symsec_sh_link = w(relhdr->sh_link);
	Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
	Elf_Sym const *const sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
		+ (void *)ehdr);

	Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
	char const *const str0 = (char const *)(_w(strsec->sh_offset)
		+ (void *)ehdr);

	Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
		+ (void *)ehdr);
	unsigned rel_entsize = _w(relhdr->sh_entsize);
	unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
	Elf_Rel const *relp = rel0;

	unsigned mcountsym = 0;
	unsigned t;

	for (t = nrel; t; --t) {
		if (!mcountsym)
			mcountsym = get_mcountsym(sym0, relp, str0);

		if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
			uint_t const addend = _w(_w(relp->r_offset) - recval);

			mrelp->r_offset = _w(offbase
				+ ((void *)mlocp - (void *)mloc0));
			Elf_r_info(mrelp, recsym, reltype);
			if (rel_entsize == sizeof(Elf_Rela)) {
				((Elf_Rela *)mrelp)->r_addend = addend;
				*mlocp++ = 0;
			} else
				*mlocp++ = addend;

			mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp);
		}
		relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
	}
	*mrelpp = mrelp;
	return mlocp;
}

/*
 * Read the relocation table again, but this time its called on sections
 * that are not going to be traced. The mcount calls here will be converted
 * into nops.
 */
static void nop_mcount(Elf_Shdr const *const relhdr,
		       Elf_Ehdr const *const ehdr,
		       const char *const txtname)
{
	Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
		+ (void *)ehdr);
	unsigned const symsec_sh_link = w(relhdr->sh_link);
	Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
	Elf_Sym const *const sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
		+ (void *)ehdr);

	Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
	char const *const str0 = (char const *)(_w(strsec->sh_offset)
		+ (void *)ehdr);

	Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
		+ (void *)ehdr);
	unsigned rel_entsize = _w(relhdr->sh_entsize);
	unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
	Elf_Rel const *relp = rel0;

	Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];

	unsigned mcountsym = 0;
	unsigned t;
	int once = 0;

	for (t = nrel; t; --t) {
		int ret = -1;

		if (!mcountsym)
			mcountsym = get_mcountsym(sym0, relp, str0);

		if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
			if (make_nop)
				ret = make_nop((void *)ehdr, shdr->sh_offset + relp->r_offset);
			if (warn_on_notrace_sect && !once) {
				printf("Section %s has mcount callers being ignored\n",
				       txtname);
				once = 1;
				/* just warn? */
				if (!make_nop)
					return;
			}
		}

		/*
		 * If we successfully removed the mcount, mark the relocation
		 * as a nop (don't do anything with it).
		 */
		if (!ret) {
			Elf_Rel rel;
			rel = *(Elf_Rel *)relp;
			Elf_r_info(&rel, Elf_r_sym(relp), rel_type_nop);
			ulseek(fd_map, (void *)relp - (void *)ehdr, SEEK_SET);
			uwrite(fd_map, &rel, sizeof(rel));
		}
		relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
	}
}


/*
 * 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 find_secsym_ndx(unsigned const txtndx,
				char const *const txtname,
				uint_t *const recvalp,
				Elf_Shdr const *const symhdr,
				Elf_Ehdr const *const ehdr)
{
	Elf_Sym const *const sym0 = (Elf_Sym const *)(_w(symhdr->sh_offset)
		+ (void *)ehdr);
	unsigned const nsym = _w(symhdr->sh_size) / _w(symhdr->sh_entsize);
	Elf_Sym const *symp;
	unsigned t;

	for (symp = sym0, t = nsym; t; --t, ++symp) {
		unsigned int const st_bind = ELF_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();
}


/* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
static char const *
__has_rel_mcount(Elf_Shdr const *const relhdr,  /* is SHT_REL or SHT_RELA */
		 Elf_Shdr const *const shdr0,
		 char const *const shstrtab,
		 char const *const fname)
{
	/* .sh_info depends on .sh_type == SHT_REL[,A] */
	Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
	char const *const txtname = &shstrtab[w(txthdr->sh_name)];

	if (strcmp("__mcount_loc", txtname) == 0) {
		fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
			fname);
		succeed_file();
	}
	if (w(txthdr->sh_type) != SHT_PROGBITS ||
	    !(w(txthdr->sh_flags) & SHF_EXECINSTR))
		return NULL;
	return txtname;
}

static char const *has_rel_mcount(Elf_Shdr const *const relhdr,
				  Elf_Shdr const *const shdr0,
				  char const *const shstrtab,
				  char const *const fname)
{
	if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
		return NULL;
	return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
}


static unsigned tot_relsize(Elf_Shdr const *const shdr0,
			    unsigned nhdr,
			    const char *const shstrtab,
			    const char *const fname)
{
	unsigned totrelsz = 0;
	Elf_Shdr const *shdrp = shdr0;
	char const *txtname;

	for (; nhdr; --nhdr, ++shdrp) {
		txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
		if (txtname && is_mcounted_section_name(txtname))
			totrelsz += _w(shdrp->sh_size);
	}
	return totrelsz;
}


/* Overall supervision for Elf32 ET_REL file. */
static void
do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
{
	Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
		+ (void *)ehdr);
	unsigned const nhdr = w2(ehdr->e_shnum);
	Elf_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];
	char const *const shstrtab = (char const *)(_w(shstr->sh_offset)
		+ (void *)ehdr);

	Elf_Shdr const *relhdr;
	unsigned k;

	/* Upper bound on space: assume all relevant relocs are for mcount. */
	unsigned const totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
	Elf_Rel *const mrel0 = umalloc(totrelsz);
	Elf_Rel *      mrelp = mrel0;

	/* 2*sizeof(address) <= sizeof(Elf_Rel) */
	uint_t *const mloc0 = umalloc(totrelsz>>1);
	uint_t *      mlocp = mloc0;

	unsigned rel_entsize = 0;
	unsigned symsec_sh_link = 0;

	for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
		char const *const txtname = has_rel_mcount(relhdr, shdr0,
			shstrtab, fname);
		if (txtname && is_mcounted_section_name(txtname)) {
			uint_t recval = 0;
			unsigned const recsym = find_secsym_ndx(
				w(relhdr->sh_info), txtname, &recval,
				&shdr0[symsec_sh_link = w(relhdr->sh_link)],
				ehdr);

			rel_entsize = _w(relhdr->sh_entsize);
			mlocp = sift_rel_mcount(mlocp,
				(void *)mlocp - (void *)mloc0, &mrelp,
				relhdr, ehdr, recsym, recval, reltype);
		} else if (txtname && (warn_on_notrace_sect || make_nop)) {
			/*
			 * This section is ignored by ftrace, but still
			 * has mcount calls. Convert them to nops now.
			 */
			nop_mcount(relhdr, ehdr, txtname);
		}
	}
	if (mloc0 != mlocp) {
		append_func(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
			    rel_entsize, symsec_sh_link);
	}
	free(mrel0);
	free(mloc0);
}
Commit	Line	Data
c28d5077 SR	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
412910cd WZ	22	#undef is_fake_mcount
	23	#undef fn_is_fake_mcount
	24	#undef MIPS_is_fake_mcount
c28d5077	25	#undef sift_rel_mcount
ffd618fa	26	#undef nop_mcount
c28d5077 SR	27	#undef find_secsym_ndx
	28	#undef __has_rel_mcount
	29	#undef has_rel_mcount
	30	#undef tot_relsize
37762cb9	31	#undef get_mcountsym
c28d5077	32	#undef do_func
412910cd	33	#undef Elf_Addr
c28d5077 SR	34	#undef Elf_Ehdr
	35	#undef Elf_Shdr
	36	#undef Elf_Rel
	37	#undef Elf_Rela
	38	#undef Elf_Sym
	39	#undef ELF_R_SYM
a2d49358	40	#undef Elf_r_sym
c28d5077	41	#undef ELF_R_INFO
a2d49358	42	#undef Elf_r_info
c28d5077	43	#undef ELF_ST_BIND
a2d49358 JR	44	#undef fn_ELF_R_SYM
a2d49358 JR	45	#undef fn_ELF_R_INFO
c28d5077 SR	46	#undef uint_t
	47	#undef _w
	48	#undef _align
	49	#undef _size
	50
	51	#ifdef RECORD_MCOUNT_64
	52	# define append_func append64
	53	# define sift_rel_mcount sift64_rel_mcount
ffd618fa	54	# define nop_mcount nop_mcount_64
c28d5077 SR	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
	59	# define do_func do64
37762cb9	60	# define get_mcountsym get_mcountsym_64
412910cd WZ	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
c28d5077 SR	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
a2d49358	71	# define Elf_r_sym Elf64_r_sym
c28d5077	72	# define ELF_R_INFO ELF64_R_INFO
a2d49358	73	# define Elf_r_info Elf64_r_info
c28d5077	74	# define ELF_ST_BIND ELF64_ST_BIND
a2d49358 JR	75	# define fn_ELF_R_SYM fn_ELF64_R_SYM
a2d49358 JR	76	# define fn_ELF_R_INFO fn_ELF64_R_INFO
c28d5077 SR	77	# define uint_t uint64_t
	78	# define _w w8
	79	# define _align 7u
	80	# define _size 8
	81	#else
	82	# define append_func append32
	83	# define sift_rel_mcount sift32_rel_mcount
ffd618fa	84	# define nop_mcount nop_mcount_32
c28d5077 SR	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
	89	# define do_func do32
37762cb9	90	# define get_mcountsym get_mcountsym_32
412910cd WZ	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
c28d5077 SR	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
a2d49358	101	# define Elf_r_sym Elf32_r_sym
c28d5077	102	# define ELF_R_INFO ELF32_R_INFO
a2d49358	103	# define Elf_r_info Elf32_r_info
c28d5077	104	# define ELF_ST_BIND ELF32_ST_BIND
a2d49358 JR	105	# define fn_ELF_R_SYM fn_ELF32_R_SYM
a2d49358 JR	106	# define fn_ELF_R_INFO fn_ELF32_R_INFO
c28d5077 SR	107	# define uint_t uint32_t
	108	# define _w w
	109	# define _align 3u
	110	# define _size 4
	111	#endif
	112
412910cd WZ	113	/* Functions and pointers that do_file() may override for specific e_machine. */
	114	static int fn_is_fake_mcount(Elf_Rel const *rp)
	115	{
	116	return 0;
	117	}
	118	static int (is_fake_mcount)(Elf_Rel const rp) = fn_is_fake_mcount;
	119
a2d49358 JR	120	static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
	121	{
	122	return ELF_R_SYM(_w(rp->r_info));
	123	}
	124	static uint_t (Elf_r_sym)(Elf_Rel const rp) = fn_ELF_R_SYM;
	125
	126	static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
	127	{
e63233f7	128	rp->r_info = _w(ELF_R_INFO(sym, type));
a2d49358 JR	129	}
	130	static void (Elf_r_info)(Elf_Rel const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
	131
412910cd WZ	132	/*
	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.
	138	*
	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
	149	* label:
	150	*/
	151	#define MIPS_FAKEMCOUNT_OFFSET 4
	152
	153	static int MIPS_is_fake_mcount(Elf_Rel const *rp)
	154	{
	155	static Elf_Addr old_r_offset;
	156	Elf_Addr current_r_offset = _w(rp->r_offset);
	157	int is_fake;
	158
	159	is_fake = old_r_offset &&
	160	(current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
	161	old_r_offset = current_r_offset;
	162
	163	return is_fake;
	164	}
a2d49358	165
c28d5077 SR	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)
	175	{
	176	/* Begin constructing output file */
	177	Elf_Shdr mcsec;
	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);
	186	uint_t new_e_shoff;
	187
	188	shstr->sh_size = _w(t);
	189	shstr->sh_offset = _w(sb.st_size);
	190	t += sb.st_size;
	191	t += (_align & -t); /* word-byte align */
	192	new_e_shoff = t;
	193
	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));
	198
	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);
	204
	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);
	211	mcsec.sh_addr = 0;
	212	mcsec.sh_offset = _w(t);
	213	mcsec.sh_size = _w((void )mlocp - (void )mloc0);
	214	mcsec.sh_link = 0;
	215	mcsec.sh_info = 0;
	216	mcsec.sh_addralign = _w(_size);
	217	mcsec.sh_entsize = _w(_size);
	218	uwrite(fd_map, &mcsec, sizeof(mcsec));
	219
	220	mcsec.sh_name = w(old_shstr_sh_size);
	221	mcsec.sh_type = (sizeof(Elf_Rela) == rel_entsize)
	222	? w(SHT_RELA)
	223	: w(SHT_REL);
	224	mcsec.sh_flags = 0;
	225	mcsec.sh_addr = 0;
	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));
233
234	uwrite(fd_map, mloc0, (void )mlocp - (void )mloc0);
235	uwrite(fd_map, mrel0, (void )mrelp - (void )mrel0);
236
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));
241	}
242
37762cb9 SR	243	static unsigned get_mcountsym(Elf_Sym const *const sym0,
	244	Elf_Rel const *relp,
	245	char const *const str0)
	246	{
	247	unsigned mcountsym = 0;
	248
	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";
	253
	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);
	259
	260	return mcountsym;
	261	}
	262
c28d5077 SR	263	/*
	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.
	267	*/
	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,
	274	uint_t const recval,
	275	unsigned const reltype)
	276	{
	277	uint_t *const mloc0 = mlocp;
	278	Elf_Rel mrelp = mrelpp;
	279	Elf_Shdr const shdr0 = (Elf_Shdr )(_w(ehdr->e_shoff)
	280	+ (void *)ehdr);
	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)
	284	+ (void *)ehdr);
	285
	286	Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
	287	char const const str0 = (char const )(_w(strsec->sh_offset)
	288	+ (void *)ehdr);
	289
	290	Elf_Rel const const rel0 = (Elf_Rel const )(_w(relhdr->sh_offset)
	291	+ (void *)ehdr);
	292	unsigned rel_entsize = _w(relhdr->sh_entsize);
	293	unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
	294	Elf_Rel const *relp = rel0;
	295
	296	unsigned mcountsym = 0;
	297	unsigned t;
	298
	299	for (t = nrel; t; --t) {
37762cb9 SR	300	if (!mcountsym)
37762cb9 SR	301	mcountsym = get_mcountsym(sym0, relp, str0);
c28d5077	302
412910cd	303	if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
c28d5077 SR	304	uint_t const addend = _w(_w(relp->r_offset) - recval);
	305
	306	mrelp->r_offset = _w(offbase
	307	+ ((void )mlocp - (void )mloc0));
a2d49358	308	Elf_r_info(mrelp, recsym, reltype);
dd5477ff	309	if (rel_entsize == sizeof(Elf_Rela)) {
c28d5077 SR	310	((Elf_Rela *)mrelp)->r_addend = addend;
	311	*mlocp++ = 0;
	312	} else
	313	*mlocp++ = addend;
	314
	315	mrelp = (Elf_Rel )(rel_entsize + (void )mrelp);
	316	}
	317	relp = (Elf_Rel const )(rel_entsize + (void )relp);
	318	}
	319	*mrelpp = mrelp;
	320	return mlocp;
	321	}
	322
ffd618fa SR	323	/*
	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
	326	* into nops.
	327	*/
	328	static void nop_mcount(Elf_Shdr const *const relhdr,
dfad3d59 SR	329	Elf_Ehdr const *const ehdr,
dfad3d59 SR	330	const char *const txtname)
ffd618fa SR	331	{
	332	Elf_Shdr const shdr0 = (Elf_Shdr )(_w(ehdr->e_shoff)
	333	+ (void *)ehdr);
	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)
	337	+ (void *)ehdr);
	338
	339	Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
	340	char const const str0 = (char const )(_w(strsec->sh_offset)
	341	+ (void *)ehdr);
	342
	343	Elf_Rel const const rel0 = (Elf_Rel const )(_w(relhdr->sh_offset)
	344	+ (void *)ehdr);
	345	unsigned rel_entsize = _w(relhdr->sh_entsize);
	346	unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
	347	Elf_Rel const *relp = rel0;
	348
	349	Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];
	350
	351	unsigned mcountsym = 0;
	352	unsigned t;
dfad3d59	353	int once = 0;
ffd618fa SR	354
	355	for (t = nrel; t; --t) {
	356	int ret = -1;
	357
37762cb9 SR	358	if (!mcountsym)
37762cb9 SR	359	mcountsym = get_mcountsym(sym0, relp, str0);
ffd618fa	360
dfad3d59 SR	361	if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
	362	if (make_nop)
	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",
	366	txtname);
	367	once = 1;
	368	/* just warn? */
	369	if (!make_nop)
	370	return;
	371	}
	372	}
ffd618fa SR	373
	374	/*
	375	* If we successfully removed the mcount, mark the relocation
	376	* as a nop (don't do anything with it).
	377	*/
	378	if (!ret) {
	379	Elf_Rel rel;
	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));
	384	}
	385	relp = (Elf_Rel const )(rel_entsize + (void )relp);
	386	}
	387	}
	388
c28d5077 SR	389
	390	/*
	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
	399	*/
	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)
	405	{
	406	Elf_Sym const const sym0 = (Elf_Sym const )(_w(symhdr->sh_offset)
	407	+ (void *)ehdr);
	408	unsigned const nsym = _w(symhdr->sh_size) / _w(symhdr->sh_entsize);
	409	Elf_Sym const *symp;
	410	unsigned t;
	411
	412	for (symp = sym0, t = nsym; t; --t, ++symp) {
	413	unsigned int const st_bind = ELF_ST_BIND(symp->st_info);
	414
	415	if (txtndx == w2(symp->st_shndx)
	416	/* avoid STB_WEAK */
	417	&& (STB_LOCAL == st_bind \|\| STB_GLOBAL == st_bind)) {
	418	*recvalp = _w(symp->st_value);
	419	return symp - sym0;
	420	}
	421	}
	422	fprintf(stderr, "Cannot find symbol for section %d: %s.\n",
	423	txtndx, txtname);
	424	fail_file();
	425	}
	426
	427
	428	/* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
	429	static char const *
	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)
	434	{
	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)];
	438
dd5477ff	439	if (strcmp("__mcount_loc", txtname) == 0) {
c28d5077 SR	440	fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
	441	fname);
	442	succeed_file();
	443	}
dd5477ff	444	if (w(txthdr->sh_type) != SHT_PROGBITS \|\|
ffd618fa	445	!(w(txthdr->sh_flags) & SHF_EXECINSTR))
c28d5077 SR	446	return NULL;
	447	return txtname;
	448	}
	449
	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)
	454	{
dd5477ff	455	if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
c28d5077 SR	456	return NULL;
	457	return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
	458	}
	459
	460
	461	static unsigned tot_relsize(Elf_Shdr const *const shdr0,
	462	unsigned nhdr,
	463	const char *const shstrtab,
	464	const char *const fname)
	465	{
	466	unsigned totrelsz = 0;
	467	Elf_Shdr const *shdrp = shdr0;
ffd618fa	468	char const *txtname;
c28d5077 SR	469
c28d5077 SR	470	for (; nhdr; --nhdr, ++shdrp) {
ffd618fa SR	471	txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
ffd618fa SR	472	if (txtname && is_mcounted_section_name(txtname))
c28d5077 SR	473	totrelsz += _w(shdrp->sh_size);
	474	}
	475	return totrelsz;
	476	}
	477
	478
	479	/* Overall supervision for Elf32 ET_REL file. */
	480	static void
	481	do_func(Elf_Ehdr const ehdr, char const const fname, unsigned const reltype)
	482	{
	483	Elf_Shdr const shdr0 = (Elf_Shdr )(_w(ehdr->e_shoff)
	484	+ (void *)ehdr);
	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)
	488	+ (void *)ehdr);
	489
	490	Elf_Shdr const *relhdr;
	491	unsigned k;
	492
	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;
	497
	498	/* 2sizeof(address) <= sizeof(Elf_Rel) /
	499	uint_t *const mloc0 = umalloc(totrelsz>>1);
	500	uint_t * mlocp = mloc0;
	501
	502	unsigned rel_entsize = 0;
	503	unsigned symsec_sh_link = 0;
	504
	505	for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
	506	char const *const txtname = has_rel_mcount(relhdr, shdr0,
	507	shstrtab, fname);
ffd618fa	508	if (txtname && is_mcounted_section_name(txtname)) {
c28d5077 SR	509	uint_t recval = 0;
	510	unsigned const recsym = find_secsym_ndx(
	511	w(relhdr->sh_info), txtname, &recval,
	512	&shdr0[symsec_sh_link = w(relhdr->sh_link)],
	513	ehdr);
	514
	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);
dfad3d59	519	} else if (txtname && (warn_on_notrace_sect \|\| make_nop)) {
ffd618fa SR	520	/*
	521	* This section is ignored by ftrace, but still
	522	* has mcount calls. Convert them to nops now.
	523	*/
dfad3d59	524	nop_mcount(relhdr, ehdr, txtname);
c28d5077 SR	525	}
	526	}
	527	if (mloc0 != mlocp) {
	528	append_func(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
	529	rel_entsize, symsec_sh_link);
	530	}
	531	free(mrel0);
	532	free(mloc0);
	533	}