From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org, jpoimboe@redhat.com
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
elver@google.com, jbaron@akamai.com, rostedt@goodmis.org,
ardb@kernel.org, kernel test robot <lkp@intel.com>
Subject: [PATCH 3/3] jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds
Date: Mon, 02 May 2022 13:07:44 +0200 [thread overview]
Message-ID: <20220502111216.350926848@infradead.org> (raw)
In-Reply-To: 20220502110741.951055904@infradead.org
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
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
include/linux/jump_label.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -256,9 +256,9 @@ extern void static_key_disable_cpuslocke
#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 READ_ONCE_NOCHECK(&key->enabled.count);
}
static __always_inline void jump_label_init(void)
next prev parent reply other threads:[~2022-05-02 11:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-02 11:07 [PATCH 0/3] x86: Address various objtool complaints Peter Zijlstra
2022-05-02 11:07 ` [PATCH 1/3] objtool: Mark __ubsan_handle_builtin_unreachable() as noreturn Peter Zijlstra
2022-05-02 11:07 ` [PATCH 2/3] x86/cpu: Elide KCSAN for cpu_has() and friends Peter Zijlstra
2022-05-02 11:54 ` Marco Elver
2022-05-02 18:47 ` Josh Poimboeuf
2022-05-03 14:20 ` Mark Rutland
2022-05-30 10:38 ` [tip: objtool/urgent] " tip-bot2 for Peter Zijlstra
2022-05-02 11:07 ` Peter Zijlstra [this message]
2022-05-02 11:23 ` [PATCH 3/3] jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds Marco Elver
2022-05-02 13:01 ` Peter Zijlstra
2022-05-02 13:09 ` [PATCH v2 " Peter Zijlstra
2022-05-02 13:25 ` Marco Elver
2022-05-02 14:54 ` Peter Zijlstra
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