[tip: x86/entry] compiler_attributes.h: Support no_sanitize_undefined check with GCC 4

[tip-bot2 for Marco Elver]

The following commit has been merged into the x86/entry branch of tip:

Commit-ID:     33aea07f30c261eff7ba229f19fd1b161e0fb851
Gitweb:        https://git.kernel.org/tip/33aea07f30c261eff7ba229f19fd1b161e0fb851
Author:        Marco Elver <elver@xxxxxxxxxx>
AuthorDate:    Tue, 16 Jun 2020 01:15:29 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Tue, 16 Jun 2020 15:35:02 +02:00

compiler_attributes.h: Support no_sanitize_undefined check with GCC 4

UBSAN is supported since GCC 4.9, which unfortunately did not yet have
__has_attribute(). To work around, the __GCC4_has_attribute workaround
requires defining which compiler version supports the given attribute.

In the case of no_sanitize_undefined, it is the first version that
supports UBSAN, which is GCC 4.9.

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Miguel Ojeda <miguel.ojeda.sandonis@xxxxxxxxx>
Link: https://lkml.kernel.org/r/20200615231529.GA119644@xxxxxxxxxx
---
 include/linux/compiler_attributes.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
index cdf0165..c8f03d2 100644
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -40,6 +40,7 @@
 # define __GCC4_has_attribute___noclone__             1
 # define __GCC4_has_attribute___nonstring__           0
 # define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8)
+# define __GCC4_has_attribute___no_sanitize_undefined__ (__GNUC_MINOR__ >= 9)
 # define __GCC4_has_attribute___fallthrough__         0
 #endif