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>

diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
index 81aca077fbb60d1f4e46e2d61bfd3e8ee8e6c238..3dc26f95d46e8a1ea439dba8ae144bae0dc9444d 100644 (file)
--- 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",