From d5ab2bc36c6b0ce2f3409f934ff9cdf6d6768fa2 Mon Sep 17 00:00:00 2001 From: Tiezhu Yang Date: Mon, 11 Mar 2024 22:23:47 +0800 Subject: objtool: Check local label in add_dead_ends() When update the latest upstream gcc and binutils, it generates more objtool warnings on LoongArch, like this: init/main.o: warning: objtool: unexpected relocation symbol type in .rela.discard.unreachable We can see that the reloc sym name is local label instead of section in relocation section '.rela.discard.unreachable', in this case, the reloc sym type is STT_NOTYPE instead of STT_SECTION. As suggested by Peter Zijlstra, we add a "local_label" member in struct symbol, then set it as true if symbol type is STT_NOTYPE and symbol name starts with ".L" string in classify_symbols(). Let's check reloc->sym->local_label to not return -1 in add_dead_ends(), and also use reloc->sym->offset instead of reloc addend which is 0 to find the corresponding instruction. At the same time, let's replace the variable "addend" with "offset" to reflect the reality. Here are some detailed info: [fedora@linux 6.8.test]$ gcc --version gcc (GCC) 14.0.1 20240129 (experimental) [fedora@linux 6.8.test]$ as --version GNU assembler (GNU Binutils) 2.42.50.20240129 [fedora@linux 6.8.test]$ readelf -r init/main.o | grep -A 2 "rela.discard.unreachable" Relocation section '.rela.discard.unreachable' at offset 0x6028 contains 1 entry: Offset Info Type Sym. Value Sym. Name + Addend 000000000000 00d900000063 R_LARCH_32_PCREL 00000000000002c4 .L500^B1 + 0 Signed-off-by: Tiezhu Yang Signed-off-by: Huacai Chen --- tools/objtool/check.c | 40 +++++++++++++++++++++---------------- tools/objtool/include/objtool/elf.h | 1 + 2 files changed, 24 insertions(+), 17 deletions(-) (limited to 'tools/objtool') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 548ec3cd7c00..d0e82c729dd9 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -20,6 +20,7 @@ #include #include #include +#include struct alternative { struct alternative *next; @@ -584,7 +585,7 @@ static int add_dead_ends(struct objtool_file *file) struct section *rsec; struct reloc *reloc; struct instruction *insn; - s64 addend; + unsigned long offset; /* * Check for manually annotated dead ends. @@ -594,27 +595,28 @@ static int add_dead_ends(struct objtool_file *file) goto reachable; for_each_reloc(rsec, reloc) { - - if (reloc->sym->type != STT_SECTION) { + if (reloc->sym->type == STT_SECTION) { + offset = reloc_addend(reloc); + } else if (reloc->sym->local_label) { + offset = reloc->sym->offset; + } else { WARN("unexpected relocation symbol type in %s", rsec->name); return -1; } - addend = reloc_addend(reloc); - - insn = find_insn(file, reloc->sym->sec, addend); + insn = find_insn(file, reloc->sym->sec, offset); if (insn) insn = prev_insn_same_sec(file, insn); - else if (addend == reloc->sym->sec->sh.sh_size) { + else if (offset == reloc->sym->sec->sh.sh_size) { insn = find_last_insn(file, reloc->sym->sec); if (!insn) { WARN("can't find unreachable insn at %s+0x%" PRIx64, - reloc->sym->sec->name, addend); + reloc->sym->sec->name, offset); return -1; } } else { WARN("can't find unreachable insn at %s+0x%" PRIx64, - reloc->sym->sec->name, addend); + reloc->sym->sec->name, offset); return -1; } @@ -633,27 +635,28 @@ reachable: return 0; for_each_reloc(rsec, reloc) { - - if (reloc->sym->type != STT_SECTION) { + if (reloc->sym->type == STT_SECTION) { + offset = reloc_addend(reloc); + } else if (reloc->sym->local_label) { + offset = reloc->sym->offset; + } else { WARN("unexpected relocation symbol type in %s", rsec->name); return -1; } - addend = reloc_addend(reloc); - - insn = find_insn(file, reloc->sym->sec, addend); + insn = find_insn(file, reloc->sym->sec, offset); if (insn) insn = prev_insn_same_sec(file, insn); - else if (addend == reloc->sym->sec->sh.sh_size) { + else if (offset == reloc->sym->sec->sh.sh_size) { insn = find_last_insn(file, reloc->sym->sec); if (!insn) { WARN("can't find reachable insn at %s+0x%" PRIx64, - reloc->sym->sec->name, addend); + reloc->sym->sec->name, offset); return -1; } } else { WARN("can't find reachable insn at %s+0x%" PRIx64, - reloc->sym->sec->name, addend); + reloc->sym->sec->name, offset); return -1; } @@ -2522,6 +2525,9 @@ static int classify_symbols(struct objtool_file *file) struct symbol *func; for_each_sym(file, func) { + if (func->type == STT_NOTYPE && strstarts(func->name, ".L")) + func->local_label = true; + if (func->bind != STB_GLOBAL) continue; diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index 9f71e988eca4..2b8a69de4db8 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -67,6 +67,7 @@ struct symbol { u8 profiling_func : 1; u8 warned : 1; u8 embedded_insn : 1; + u8 local_label : 1; struct list_head pv_target; struct reloc *relocs; }; -- cgit v1.2.3