locking/local_lock: Support Clang's context analysis

Add support for Clang's context analysis for local_lock_t and
local_trylock_t.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-20-elver@google.com

1 files changed, 57 insertions, 14 deletions

diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h
index 1a1ea1232add..e8c4803d8db4 100644
--- a/include/linux/local_lock_internal.h
+++ b/include/linux/local_lock_internal.h
@@ -10,21 +10,23 @@
 
 #ifndef CONFIG_PREEMPT_RT
 
-typedef struct {
+context_lock_struct(local_lock) {
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	struct lockdep_map	dep_map;
 	struct task_struct	*owner;
 #endif
-} local_lock_t;
+};
+typedef struct local_lock local_lock_t;
 
 /* local_trylock() and local_trylock_irqsave() only work with local_trylock_t */
-typedef struct {
+context_lock_struct(local_trylock) {
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	struct lockdep_map	dep_map;
 	struct task_struct	*owner;
 #endif
 	u8		acquired;
-} local_trylock_t;
+};
+typedef struct local_trylock local_trylock_t;
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 # define LOCAL_LOCK_DEBUG_INIT(lockname)		\
@@ -84,9 +86,14 @@ do {								\
 			      0, LD_WAIT_CONFIG, LD_WAIT_INV,	\
 			      LD_LOCK_PERCPU);			\
 	local_lock_debug_init(lock);				\
+	__assume_ctx_lock(lock);				\
 } while (0)
 
-#define __local_trylock_init(lock) __local_lock_init((local_lock_t *)lock)
+#define __local_trylock_init(lock)				\
+do {								\
+	__local_lock_init((local_lock_t *)lock);		\
+	__assume_ctx_lock(lock);				\
+} while (0)
 
 #define __spinlock_nested_bh_init(lock)				\
 do {								\
@@ -97,6 +104,7 @@ do {								\
 			      0, LD_WAIT_CONFIG, LD_WAIT_INV,	\
 			      LD_LOCK_NORMAL);			\
 	local_lock_debug_init(lock);				\
+	__assume_ctx_lock(lock);				\
 } while (0)
 
 #define __local_lock_acquire(lock)					\
@@ -119,22 +127,25 @@ do {								\
 	do {							\
 		preempt_disable();				\
 		__local_lock_acquire(lock);			\
+		__acquire(lock);				\
 	} while (0)
 
 #define __local_lock_irq(lock)					\
 	do {							\
 		local_irq_disable();				\
 		__local_lock_acquire(lock);			\
+		__acquire(lock);				\
 	} while (0)
 
 #define __local_lock_irqsave(lock, flags)			\
 	do {							\
 		local_irq_save(flags);				\
 		__local_lock_acquire(lock);			\
+		__acquire(lock);				\
 	} while (0)
 
 #define __local_trylock(lock)					\
-	({							\
+	__try_acquire_ctx_lock(lock, ({				\
 		local_trylock_t *__tl;				\
 								\
 		preempt_disable();				\
@@ -148,10 +159,10 @@ do {								\
 				(local_lock_t *)__tl);		\
 		}						\
 		!!__tl;						\
-	})
+	}))
 
 #define __local_trylock_irqsave(lock, flags)			\
-	({							\
+	__try_acquire_ctx_lock(lock, ({				\
 		local_trylock_t *__tl;				\
 								\
 		local_irq_save(flags);				\
@@ -165,7 +176,7 @@ do {								\
 				(local_lock_t *)__tl);		\
 		}						\
 		!!__tl;						\
-	})
+	}))
 
 /* preemption or migration must be disabled before calling __local_lock_is_locked */
 #define __local_lock_is_locked(lock) READ_ONCE(this_cpu_ptr(lock)->acquired)
@@ -188,18 +199,21 @@ do {								\
 
 #define __local_unlock(lock)					\
 	do {							\
+		__release(lock);				\
 		__local_lock_release(lock);			\
 		preempt_enable();				\
 	} while (0)
 
 #define __local_unlock_irq(lock)				\
 	do {							\
+		__release(lock);				\
 		__local_lock_release(lock);			\
 		local_irq_enable();				\
 	} while (0)
 
 #define __local_unlock_irqrestore(lock, flags)			\
 	do {							\
+		__release(lock);				\
 		__local_lock_release(lock);			\
 		local_irq_restore(flags);			\
 	} while (0)
@@ -208,13 +222,19 @@ do {								\
 	do {							\
 		lockdep_assert_in_softirq();			\
 		local_lock_acquire((lock));			\
+		__acquire(lock);				\
 	} while (0)
 
 #define __local_unlock_nested_bh(lock)				\
-	local_lock_release((lock))
+	do {							\
+		__release(lock);				\
+		local_lock_release((lock));			\
+	} while (0)
 
 #else /* !CONFIG_PREEMPT_RT */
 
+#include <linux/spinlock.h>
+
 /*
  * On PREEMPT_RT local_lock maps to a per CPU spinlock, which protects the
  * critical section while staying preemptible.
@@ -269,7 +289,7 @@ do {								\
 } while (0)
 
 #define __local_trylock(lock)					\
-	({							\
+	__try_acquire_ctx_lock(lock, context_unsafe(({		\
 		int __locked;					\
 								\
 		if (in_nmi() | in_hardirq()) {			\
@@ -281,17 +301,40 @@ do {								\
 				migrate_enable();		\
 		}						\
 		__locked;					\
-	})
+	})))
 
 #define __local_trylock_irqsave(lock, flags)			\
-	({							\
+	__try_acquire_ctx_lock(lock, ({				\
 		typecheck(unsigned long, flags);		\
 		flags = 0;					\
 		__local_trylock(lock);				\
-	})
+	}))
 
 /* migration must be disabled before calling __local_lock_is_locked */
 #define __local_lock_is_locked(__lock)					\
 	(rt_mutex_owner(&this_cpu_ptr(__lock)->lock) == current)
 
 #endif /* CONFIG_PREEMPT_RT */
+
+#if defined(WARN_CONTEXT_ANALYSIS)
+/*
+ * Because the compiler only knows about the base per-CPU variable, use this
+ * helper function to make the compiler think we lock/unlock the @base variable,
+ * and hide the fact we actually pass the per-CPU instance to lock/unlock
+ * functions.
+ */
+static __always_inline local_lock_t *__this_cpu_local_lock(local_lock_t __percpu *base)
+	__returns_ctx_lock(base) __attribute__((overloadable))
+{
+	return this_cpu_ptr(base);
+}
+#ifndef CONFIG_PREEMPT_RT
+static __always_inline local_trylock_t *__this_cpu_local_lock(local_trylock_t __percpu *base)
+	__returns_ctx_lock(base) __attribute__((overloadable))
+{
+	return this_cpu_ptr(base);
+}
+#endif /* CONFIG_PREEMPT_RT */
+#else  /* WARN_CONTEXT_ANALYSIS */
+#define __this_cpu_local_lock(base) this_cpu_ptr(base)
+#endif /* WARN_CONTEXT_ANALYSIS */