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Date: Tue, 15 Mar 2022 10:43:46 -0000 From: "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de> To: linux-tip-commits@...r.kernel.org Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org, linux-kernel@...r.kernel.org Subject: [tip: x86/core] objtool: Rework ASM_REACHABLE The following commit has been merged into the x86/core branch of tip: Commit-ID: 0e5b613b4d4be3345dda349fb90dd73d2103302f Gitweb: https://git.kernel.org/tip/0e5b613b4d4be3345dda349fb90dd73d2103302f Author: Peter Zijlstra <peterz@...radead.org> AuthorDate: Tue, 08 Mar 2022 16:30:49 +01:00 Committer: Peter Zijlstra <peterz@...radead.org> CommitterDate: Tue, 15 Mar 2022 10:32:44 +01:00 objtool: Rework ASM_REACHABLE Currently ASM_REACHABLE only works for UD2 instructions; reorder things to also allow over-riding dead_end_function(). To that end: - Mark INSN_BUG instructions in decode_instructions(), this saves having to iterate all instructions yet again. - Have add_call_destinations() set insn->dead_end for dead_end_function() calls. - Move add_dead_ends() *after* add_call_destinations() such that ASM_REACHABLE can clear the ->dead_end mark. - have validate_branch() only check ->dead_end. Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org> Acked-by: Josh Poimboeuf <jpoimboe@...hat.com> Link: https://lore.kernel.org/r/20220308154319.410010807@infradead.org --- tools/objtool/check.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 0c857e7..894c9a7 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -395,6 +395,14 @@ static int decode_instructions(struct objtool_file *file) if (ret) goto err; + /* + * By default, "ud2" is a dead end unless otherwise + * annotated, because GCC 7 inserts it for certain + * divide-by-zero cases. + */ + if (insn->type == INSN_BUG) + insn->dead_end = true; + hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset)); list_add_tail(&insn->list, &file->insn_list); nr_insns++; @@ -524,14 +532,6 @@ static int add_dead_ends(struct objtool_file *file) struct instruction *insn; /* - * By default, "ud2" is a dead end unless otherwise annotated, because - * GCC 7 inserts it for certain divide-by-zero cases. - */ - for_each_insn(file, insn) - if (insn->type == INSN_BUG) - insn->dead_end = true; - - /* * Check for manually annotated dead ends. */ sec = find_section_by_name(file->elf, ".rela.discard.unreachable"); @@ -1114,6 +1114,9 @@ static void annotate_call_site(struct objtool_file *file, list_add_tail(&insn->call_node, &file->mcount_loc_list); return; } + + if (!sibling && dead_end_function(file, sym)) + insn->dead_end = true; } static void add_call_dest(struct objtool_file *file, struct instruction *insn, @@ -2089,10 +2092,6 @@ static int decode_sections(struct objtool_file *file) if (ret) return ret; - ret = add_dead_ends(file); - if (ret) - return ret; - add_ignores(file); add_uaccess_safe(file); @@ -2131,6 +2130,14 @@ static int decode_sections(struct objtool_file *file) if (ret) return ret; + /* + * Must be after add_call_destinations() such that it can override + * dead_end_function() marks. + */ + ret = add_dead_ends(file); + if (ret) + return ret; + ret = add_jump_table_alts(file); if (ret) return ret; @@ -3138,7 +3145,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, return 1; } - if (dead_end_function(file, insn->call_dest)) + if (insn->dead_end) return 0; break;
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