From: Josh Poimboeuf Date: Thu, 10 Sep 2020 15:24:57 +0000 (-0500) Subject: objtool: Fix noreturn detection for ignored functions X-Git-Tag: baikal/aarch64/sdk6.1~8368^2 X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=1c62809ca7d8c7fa3a2683ce9f3ab95b734d0aac;p=kernel.git objtool: Fix noreturn detection for ignored functions When a function is annotated with STACK_FRAME_NON_STANDARD, objtool doesn't validate its code paths. It also skips sibling call detection within the function. But sibling call detection is actually needed for the case where the ignored function doesn't have any return instructions. Otherwise objtool naively marks the function as implicit static noreturn, which affects the reachability of its callers, resulting in "unreachable instruction" warnings. Fix it by just enabling sibling call detection for ignored functions. The 'insn->ignore' check in add_jump_destinations() is no longer needed after 6ede9303b57b ("objtool: Don't use ignore flag for fake jumps"). Fixes the following warning: arch/x86/kvm/vmx/vmx.o: warning: objtool: vmx_handle_exit_irqoff()+0x142: unreachable instruction which triggers on an allmodconfig with CONFIG_GCOV_KERNEL unset. Reported-by: Linus Torvalds Signed-off-by: Josh Poimboeuf Signed-off-by: Borislav Petkov Acked-by: Linus Torvalds Link: https://lkml.kernel.org/r/5b1e2536cdbaa5246b60d7791b76130a74082c62.1599751464.git.jpoimboe@redhat.com --- diff --git a/tools/objtool/check.c b/tools/objtool/check.c index e034a8f24f466..90a66891441ab 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -619,7 +619,7 @@ static int add_jump_destinations(struct objtool_file *file) if (!is_static_jump(insn)) continue; - if (insn->ignore || insn->offset == FAKE_JUMP_OFFSET) + if (insn->offset == FAKE_JUMP_OFFSET) continue; reloc = find_reloc_by_dest_range(file->elf, insn->sec,