Messages in this thread Patch in this message | | | Date | Thu, 10 Jun 2021 21:33:44 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 01/13] objtool: Rewrite hashtable sizing |
| |
On Thu, Jun 10, 2021 at 11:50:36AM -0700, Sami Tolvanen wrote: > On Thu, Jun 10, 2021 at 11:14 AM Nathan Chancellor <nathan@kernel.org> wrote: > > Adding Sami because I am not sure why this patch would have much of an impact > > in relation to LTO. https://git.kernel.org/tip/25cf0d8aa2a3 is the patch in > > question. > > It's because LLVM enables -ffunction-sections with LTO, so using .text > section size to estimate the reloc hash table size isn't going to be > accurate, as confirmed by objtool output with --stats: > > OBJTOOL vmlinux.o > nr_sections: 141481 > section_bits: 17 > nr_symbols: 215262 > symbol_bits: 17 > max_reloc: 24850 > tot_reloc: 590890 > reloc_bits: 10
Bah. Would something like the *completely* untested below help with that?
--- diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 25f6d293bc86..8676c7598728 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -288,6 +288,9 @@ static int read_sections(struct elf *elf) } sec->len = sec->sh.sh_size; + if (sec->sh.sh_flags & SHF_EXECINSTR) + elf->text_size += sec->len; + list_add_tail(&sec->list, &elf->sections); elf_hash_add(section, &sec->hash, sec->idx); elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name)); @@ -581,13 +584,7 @@ static int read_relocs(struct elf *elf) unsigned int symndx; unsigned long nr_reloc, max_reloc = 0, tot_reloc = 0; - sec = find_section_by_name(elf, ".text"); - if (!sec) { - WARN("no .text"); - return -1; - } - - if (!elf_alloc_hash(reloc, sec->len / 16)) + if (!elf_alloc_hash(reloc, elf->text_size / 16)) return -1; list_for_each_entry(sec, &elf->sections, list) { diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index 90082751f851..e34395047530 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -83,6 +83,7 @@ struct elf { int fd; bool changed; char *name; + unsigned int text_size; struct list_head sections; int symbol_bits;
| |