From ee97638b5737cc0dba2f12a3bdcda761656b7c01 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Fri, 11 Aug 2017 12:24:15 -0500 Subject: [PATCH] objtool: Fix objtool fallthrough detection with function padding When GCC adds NOP padding between functions, those NOPs aren't associated with a function symbol, which breaks objtool's detection of a function falling through to another function. Instead it shows confusing errors like: drivers/mtd/chips/cfi_util.o: warning: objtool: cfi_qry_mode_on()+0x8b: return with modified stack frame drivers/mtd/chips/cfi_util.o: warning: objtool: cfi_qry_mode_on()+0x0: stack state mismatch: cfa1=-4-32 cfa2=7+8 drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: fixup_use_fwh_lock()+0x8: unknown stack-related register move drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: fixup_use_fwh_lock()+0x0: stack state mismatch: cfa1=6+16 cfa2=7+8 drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: do_otp_write()+0xa: unsupported stack pointer realignment drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: do_otp_write()+0x0: stack state mismatch: cfa1=-4-40 cfa2=7+8 Reported-by: kbuild test robot Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/43e7aae9a7a7710cd6df597fa9dc501da4ba0602.1502472193.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- tools/objtool/check.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 17375925e7aa..3dffeb944523 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1536,15 +1536,15 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, while (1) { next_insn = next_insn_same_sec(file, insn); - if (file->c_file && insn->func) { - if (func && func != insn->func) { - WARN("%s() falls through to next function %s()", - func->name, insn->func->name); - return 1; - } + + if (file->c_file && func && insn->func && func != insn->func) { + WARN("%s() falls through to next function %s()", + func->name, insn->func->name); + return 1; } - func = insn->func; + if (insn->func) + func = insn->func; if (func && insn->ignore) { WARN_FUNC("BUG: why am I validating an ignored function?", -- GitLab