jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds

Peter Zijlstra · Peter Zijlstra · commit 656d054e0a15 · 2022-05-27T12:34:44.000+02:00
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 &lt;lkp@intel.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
@@ -256,9 +256,9 @@ 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)

Original file line number	Diff line number	Diff line change
`@@ -256,9 +256,9 @@ extern void static_key_disable_cpuslocked(struct static_key *key);`
`256`	`256`	`#include <linux/atomic.h>`
`257`	`257`	`#include <linux/bug.h>`
`258`	`258`
`259`		`-static inline int static_key_count(struct static_key *key)`
	`259`	`+static __always_inline int static_key_count(struct static_key *key)`
`260`	`260`	`{`
`261`		`- return atomic_read(&key->enabled);`
	`261`	`+ return arch_atomic_read(&key->enabled);`
`262`	`262`	`}`
`263`	`263`
`264`	`264`	`static __always_inline void jump_label_init(void)`