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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, mark.rutland@arm.com,
	kernel test robot <lkp@intel.com>
Subject: [PATCH 5/7] jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds
Date: Thu, 26 May 2022 12:52:57 +0200	[thread overview]
Message-ID: <20220526105958.007232892@infradead.org> (raw)
In-Reply-To: 20220526105252.440440893@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

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>
---
 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 arch_atomic_read(&key->enabled);
 }
 
 static __always_inline void jump_label_init(void)



  parent reply	other threads:[~2022-05-26 11:05 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-26 10:52 [PATCH 0/7] x86: Address various objtool complaints Peter Zijlstra
2022-05-26 10:52 ` [PATCH 1/7] x86/entry: Anchor annotation Peter Zijlstra
2022-05-26 15:04   ` Josh Poimboeuf
2022-05-26 10:52 ` [PATCH 2/7] objtool: Extend UNWIND_HINT based ENDBR rules Peter Zijlstra
2022-05-26 15:05   ` Josh Poimboeuf
2022-05-28 14:09     ` Peter Zijlstra
2022-05-26 10:52 ` [PATCH 3/7] objtool: Mark __ubsan_handle_builtin_unreachable() as noreturn Peter Zijlstra
2022-05-30 13:17   ` Marco Elver
2022-05-26 10:52 ` [PATCH 4/7] x86/cpu: Elide KCSAN for cpu_has() and friends Peter Zijlstra
2022-05-30 13:14   ` Marco Elver
2022-05-26 10:52 ` Peter Zijlstra [this message]
2022-05-30 13:20   ` [PATCH 5/7] jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds Marco Elver
2022-05-26 10:52 ` [PATCH 6/7] x86: Always inline on_thread_stack() and current_top_of_stack() Peter Zijlstra
2022-05-30 10:38   ` [tip: objtool/urgent] " tip-bot2 for Peter Zijlstra
2022-05-30 13:21   ` [PATCH 6/7] " Marco Elver
2022-05-26 10:52 ` [PATCH 7/7] context_tracking: Always inline empty stubs Peter Zijlstra
2022-05-26 15:02   ` Josh Poimboeuf
2022-05-26 15:10     ` Mark Rutland
2022-05-26 15:16       ` Josh Poimboeuf
2022-05-26 15:26         ` Mark Rutland
2022-05-30 10:38   ` [tip: objtool/urgent] " tip-bot2 for Peter Zijlstra

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