Messages in this thread Patch in this message | | | From | Matt Helsley <> | Subject | [RFC][PATCH v4 05/32] objtool: recordmcount: Convert do_func() relhdrs | Date | Tue, 2 Jun 2020 12:49:58 -0700 |
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Use objtool's ELF data structures to visit the relocation sections in the top-level ELF file walking function, do_func(). This means we can pass pointers to the relocation header structures into nested functions and avoid the indexing patterns for them.
These conversions don't use libelf/objtool to modify the ELF file -- it only changes the way we walk the ELF sections and do lookups to find the relocations.
Signed-off-by: Matt Helsley <mhelsley@vmware.com> --- tools/objtool/recordmcount.h | 62 +++++++++++++++++++----------------- 1 file changed, 32 insertions(+), 30 deletions(-)
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h index 1a848b8104c8..3c4807dca3d0 100644 --- a/tools/objtool/recordmcount.h +++ b/tools/objtool/recordmcount.h @@ -285,7 +285,7 @@ static unsigned get_mcountsym(Elf_Sym const *const sym0, return mcountsym; } -static void get_sym_str_and_relp(Elf_Shdr const *const relhdr, +static void get_sym_str_and_relp(GElf_Shdr const *const relhdr, Elf_Ehdr const *const ehdr, Elf_Sym const **sym0, char const **str0, @@ -293,10 +293,10 @@ static void get_sym_str_and_relp(Elf_Shdr const *const relhdr, { Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff) + (void *)ehdr); - unsigned const symsec_sh_link = w(relhdr->sh_link); + unsigned const symsec_sh_link = 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) + Elf_Rel const *const rel0 = (Elf_Rel const *)(relhdr->sh_offset + (void *)ehdr); *sym0 = (Elf_Sym const *)(_w(symsec->sh_offset) @@ -316,9 +316,9 @@ static void get_sym_str_and_relp(Elf_Shdr const *const relhdr, static uint_t *sift_rel_mcount(uint_t *mlocp, unsigned const offbase, Elf_Rel **const mrelpp, - Elf_Shdr const *const relhdr, + GElf_Shdr const *const relhdr, Elf_Ehdr const *const ehdr, - unsigned const recsym, + unsigned const recsym_index, uint_t const recval, unsigned const reltype) { @@ -327,8 +327,8 @@ static uint_t *sift_rel_mcount(uint_t *mlocp, 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 int rel_entsize = relhdr->sh_entsize; + unsigned const nrel = relhdr->sh_size / rel_entsize; unsigned mcountsym = 0; unsigned t; @@ -344,7 +344,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp, _w(_w(relp->r_offset) - recval + mcount_adjust); mrelp->r_offset = _w(offbase + ((void *)mlocp - (void *)mloc0)); - Elf_r_info(mrelp, recsym, reltype); + Elf_r_info(mrelp, recsym_index, reltype); if (rel_entsize == sizeof(Elf_Rela)) { ((Elf_Rela *)mrelp)->r_addend = addend; *mlocp++ = 0; @@ -364,7 +364,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp, * that are not going to be traced. The mcount calls here will be converted * into nops. */ -static int nop_mcount(Elf_Shdr const *const relhdr, +static int nop_mcount(GElf_Shdr const *const relhdr, Elf_Ehdr const *const ehdr, const char *const txtname) { @@ -373,9 +373,9 @@ static int nop_mcount(Elf_Shdr const *const relhdr, 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; + Elf_Shdr const *const shdr = &shdr0[relhdr->sh_info]; + unsigned int rel_entsize = relhdr->sh_entsize; + unsigned const nrel = relhdr->sh_size / rel_entsize; unsigned mcountsym = 0; unsigned t; int once = 0; @@ -464,13 +464,13 @@ static int find_secsym_ndx(unsigned const txtndx, } /* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */ -static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */ +static char const * __has_rel_mcount(GElf_Shdr const *const relhdr, /* reltype */ 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)]; + Elf_Shdr const *const txthdr = &shdr0[relhdr->sh_info]; char const *const txtname = &shstrtab[w(txthdr->sh_name)]; if (w(txthdr->sh_type) != SHT_PROGBITS || @@ -479,30 +479,29 @@ static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */ return txtname; } -static char const *has_rel_mcount(Elf_Shdr const *const relhdr, +static char const *has_rel_mcount(GElf_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) + if (relhdr->sh_type != SHT_REL && 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) { + struct section *sec; unsigned totrelsz = 0; - Elf_Shdr const *shdrp = shdr0; char const *txtname; - for (; nhdr; --nhdr, ++shdrp) { - txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname); + list_for_each_entry(sec, &lf->sections, list) { + txtname = has_rel_mcount(&sec->sh, shdr0, shstrtab, fname); if (txtname && is_mcounted_section_name(txtname)) - totrelsz += _w(shdrp->sh_size); + totrelsz += sec->sh.sh_size; } return totrelsz; } @@ -514,13 +513,11 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname, { 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; + GElf_Shdr const *relhdr; /* Upper bound on space: assume all relevant relocs are for mcount. */ unsigned totrelsz; @@ -534,12 +531,14 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned rel_entsize = 0; unsigned symsec_sh_link = 0; + struct section *sec; + int result = 0; if (find_section_by_name(lf, "__mcount_loc") != NULL) return 0; - totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname); + totrelsz = tot_relsize(shdr0, shstrtab, fname); if (totrelsz == 0) return 0; mrel0 = umalloc(totrelsz); @@ -555,22 +554,25 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname, return -1; } - for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) { - char const *const txtname = has_rel_mcount(relhdr, shdr0, + list_for_each_entry(sec, &lf->sections, list) { + char const *txtname; + + relhdr = &sec->sh; + txtname = has_rel_mcount(relhdr, shdr0, shstrtab, fname); if (txtname && is_mcounted_section_name(txtname)) { unsigned int recsym; uint_t recval = 0; - symsec_sh_link = w(relhdr->sh_link); - result = find_secsym_ndx(w(relhdr->sh_info), txtname, + symsec_sh_link = relhdr->sh_link; + result = find_secsym_ndx(relhdr->sh_info, txtname, &recval, &recsym, &shdr0[symsec_sh_link], ehdr); if (result) goto out; - rel_entsize = _w(relhdr->sh_entsize); + rel_entsize = relhdr->sh_entsize; mlocp = sift_rel_mcount(mlocp, (void *)mlocp - (void *)mloc0, &mrelp, relhdr, ehdr, recsym, recval, reltype); -- 2.20.1
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