x86/unwind/orc: Silence warnings caused by missing ORC data

The ORC unwinder attempts to fall back to frame pointers when ORC data
is missing for a given instruction.  It sets state->error, but then
tries to keep going as a best-effort type of thing.  That may result in
further warnings if the unwinder gets lost.

Until we have some way to register generated code with the unwinder,
missing ORC will be expected, and occasionally going off the rails will
also be expected.  So don't warn about it.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Ivan Babrou <ivan@cloudflare.com>
Link: https://lkml.kernel.org/r/06d02c4bbb220bd31668db579278b0352538efbb.1612534649.git.jpoimboe@redhat.com

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 1bcc14c870abd4fb9c0ec3cf04bfc966b3186391..a1202536fc57cc2b4af2b0bfde3f08fb6f9c034a 100644 (file)
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -13,7 +13,7 @@
 
 #define orc_warn_current(args...)                                      \
 ({                                                                     \
-       if (state->task == current)                                     \
+       if (state->task == current && !state->error)                    \
                orc_warn(args);                                         \
 })