From: Josh Poimboeuf jpoimboe@redhat.com
[ Upstream commit db6c6a0df840e3f52c84cc302cc1a08ba11a4416 ]
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
e6da9567959e ("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 torvalds@linux-foundation.org Signed-off-by: Josh Poimboeuf jpoimboe@redhat.com Signed-off-by: Borislav Petkov bp@suse.de Acked-by: Linus Torvalds torvalds@linux-foundation.org Link: https://lkml.kernel.org/r/5b1e2536cdbaa5246b60d7791b76130a74082c62.159975146... Signed-off-by: Sasha Levin sashal@kernel.org --- tools/objtool/check.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 247fbb5f6a389..2c8e2dae17016 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -502,7 +502,7 @@ static int add_jump_destinations(struct objtool_file *file) insn->type != INSN_JUMP_UNCONDITIONAL) continue;
- if (insn->ignore || insn->offset == FAKE_JUMP_OFFSET) + if (insn->offset == FAKE_JUMP_OFFSET) continue;
rela = find_rela_by_dest_range(insn->sec, insn->offset,