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jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds

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.

Peter Zijlstra committed 4 years ago

Commit 656d0541 parent a6a5eb21 file · +2 −2Browse files

Unified · Split

include/linux/jump_label.h+2−2
@@ -256,9 +256,9 @@ extern void static_key_disable_cpuslocked(struct static_key *key); · 255 unmodified lines
256256 #include <linux/atomic.h>
257257 #include <linux/bug.h>
258258
259−static inline int static_key_count(struct static_key *key)
259+static __always_inline int static_key_count(struct static_key *key)
260260 {
261− return atomic_read(&key->enabled);
261+ return arch_atomic_read(&key->enabled);
262262 }
263263
264264 static __always_inline void jump_label_init(void)