[PATCH AUTOSEL 5.17 48/60] jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds

Sasha Levin
2022-06-07T19:18:09Z

From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit 656d054e0a15ec327bd82801ccd58201e59f6896 ]

When building x86_64 with JUMP_LABEL=n it's possible for
instrumentation to sneak into noinstr:

vmlinux.o: warning: objtool: exit_to_user_mode+0x14: call to static_key_count.constprop.0() leaves .noinstr.text section
vmlinux.o: warning: objtool: syscall_exit_to_user_mode+0x2d: call to static_key_count.constprop.0() leaves .noinstr.text section
vmlinux.o: warning: objtool: irqentry_exit_to_user_mode+0x1b: call to static_key_count.constprop.0() leaves .noinstr.text section

Switch to arch_ prefixed atomic to avoid the explicit instrumentation.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/jump_label.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 48b9b2a82767..019e55c13248 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -261,9 +261,9 @@ extern void static_key_disable_cpuslocked(struct static_key *key);
#include <linux/atomic.h>
#include <linux/bug.h>

-static inline int static_key_count(struct static_key *key)
+static __always_inline int static_key_count(struct static_key *key)
{
- return atomic_read(&key->enabled);
+ return arch_atomic_read(&key->enabled);
}

static __always_inline void jump_label_init(void)
--
2.35.1