diff options
Diffstat (limited to 'scripts/recordmcount.h')
| -rw-r--r-- | scripts/recordmcount.h | 366 |
1 files changed, 366 insertions, 0 deletions
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h new file mode 100644 index 000000000000..7f39d0943d2d --- /dev/null +++ b/scripts/recordmcount.h @@ -0,0 +1,366 @@ +/* + * 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 sift_rel_mcount +#undef find_secsym_ndx +#undef __has_rel_mcount +#undef has_rel_mcount +#undef tot_relsize +#undef do_func +#undef Elf_Ehdr +#undef Elf_Shdr +#undef Elf_Rel +#undef Elf_Rela +#undef Elf_Sym +#undef ELF_R_SYM +#undef ELF_R_INFO +#undef ELF_ST_BIND +#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 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 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_INFO ELF64_R_INFO +# define ELF_ST_BIND ELF64_ST_BIND +# 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 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 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_INFO ELF32_R_INFO +# define ELF_ST_BIND ELF32_ST_BIND +# define uint_t uint32_t +# define _w w +# define _align 3u +# define _size 4 +#endif + +/* 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)); +} + + +/* + * 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) { + Elf_Sym const *const symp = + &sym0[ELF_R_SYM(_w(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 = ELF_R_SYM(_w(relp->r_info)); + } + + if (mcountsym == ELF_R_SYM(_w(relp->r_info))) { + uint_t const addend = _w(_w(relp->r_offset) - recval); + + mrelp->r_offset = _w(offbase + + ((void *)mlocp - (void *)mloc0)); + mrelp->r_info = _w(ELF_R_INFO(recsym, reltype)); + if (sizeof(Elf_Rela) == rel_entsize) { + ((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; +} + + +/* + * 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 (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 *has_rel_mcount(Elf_Shdr const *const relhdr, + Elf_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 __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; + + for (; nhdr; --nhdr, ++shdrp) { + if (has_rel_mcount(shdrp, shdr0, shstrtab, fname)) + 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) { + 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); + } + } + if (mloc0 != mlocp) { + append_func(ehdr, shstr, mloc0, mlocp, mrel0, mrelp, + rel_entsize, symsec_sh_link); + } + free(mrel0); + free(mloc0); +} |