/*
   * 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 mcount_adjust

  #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 get_sym_str_and_relp

  #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 ELF_ST_TYPE

  #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 get_sym_str_and_relp	get_sym_str_and_relp_64

  # 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 mcount_adjust		mcount_adjust_64

  # 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 ELF_ST_TYPE		ELF64_ST_TYPE

  # 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 get_sym_str_and_relp	get_sym_str_and_relp_32

  # 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 mcount_adjust		mcount_adjust_32

  # 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 ELF_ST_TYPE		ELF32_ST_TYPE

  # 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;

  static int mcount_adjust = 0;

  /*
   * 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;
  }

  static void 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)
  {
  	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_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
  	Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
  		+ (void *)ehdr);
  
  	*sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
  				  + (void *)ehdr);
  
  	*str0 = (char const *)(_w(strsec->sh_offset)
  			       + (void *)ehdr);
  
  	*relp = rel0;
  }

  /*
   * 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_Sym const *sym0;
  	char const *str0;
  	Elf_Rel const *relp;

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

  	unsigned mcountsym = 0;
  	unsigned t;

  	get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);

  	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 + mcount_adjust);

  			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);

  	Elf_Sym const *sym0;
  	char const *str0;
  	Elf_Rel const *relp;
  	Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];

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

  	unsigned mcountsym = 0;
  	unsigned t;

  	int once = 0;

  	get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);

  	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
  ",
  				       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)) {

  			/* function symbols on ARM have quirks, avoid them */
  			if (w2(ehdr->e_machine) == EM_ARM
  			    && ELF_ST_TYPE(symp->st_info) == STT_FUNC)
  				continue;

  			*recvalp = _w(symp->st_value);
  			return symp - sym0;
  		}
  	}
  	fprintf(stderr, "Cannot find symbol for section %d: %s.
  ",
  		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
  ",
  			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);
  }