[tip:x86/urgent] x86/unwind: Disable unwinder warnings on 32-bit

[tip-bot for Josh Poimboeuf <tipbot@zytor.com>]

Commit-ID:  d4a2d031dd42f9594107d317e2a9a0c6d73ad46b
Gitweb:     https://git.kernel.org/tip/d4a2d031dd42f9594107d317e2a9a0c6d73ad46b
Author:     Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Mon, 9 Oct 2017 20:20:05 -0500
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 10 Oct 2017 12:49:49 +0200

x86/unwind: Disable unwinder warnings on 32-bit

x86-32 doesn't have stack validation, so in most cases it doesn't make
sense to warn about bad frame pointers.

Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: LKP <lkp@01.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a69658760800bf281e6353248c23e0fa0acf5230.1507597785.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/unwind_frame.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
index 81aca07..3dc26f9 100644
--- a/arch/x86/kernel/unwind_frame.c
+++ b/arch/x86/kernel/unwind_frame.c
@@ -355,6 +355,13 @@ bad_address:
 	    state->regs->sp < (unsigned long)task_pt_regs(state->task))
 		goto the_end;
 
+	/*
+	 * There are some known frame pointer issues on 32-bit.  Disable
+	 * unwinder warnings on 32-bit until it gets objtool support.
+	 */
+	if (IS_ENABLED(CONFIG_X86_32))
+		goto the_end;
+
 	if (state->regs) {
 		printk_deferred_once(KERN_WARNING
 			"WARNING: kernel stack regs at %p in %s:%d has bad 'bp' value %p\n",