core: attempt to detect deadlock on spin locks

Attempts to detect and report deadlock on spin locks..

Reviewed-by: Igor Opaniuk <igor.opaniuk@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

core/arch/arm/include/kernel/spinlock.h

@@ -57,13 +57,47 @@ void __cpu_spin_unlock(unsigned int *lock);
 /* returns 0 on locking success, non zero on failure */
 unsigned int __cpu_spin_trylock(unsigned int *lock);
 
-static inline void cpu_spin_lock(unsigned int *lock)
+static inline void cpu_spin_lock_no_dldetect(unsigned int *lock)
 {
 	assert(thread_foreign_intr_disabled());
 	__cpu_spin_lock(lock);
 	spinlock_count_incr();
 }
 
+#ifdef CFG_TEE_CORE_DEBUG
+#define cpu_spin_lock(lock) \
+	cpu_spin_lock_dldetect(__func__, __LINE__, lock)
+
+static inline void cpu_spin_lock_dldetect(const char *func, const int line,
+					  unsigned int *lock)
+{
+	unsigned int retries = 0;
+	unsigned int reminder = 0;
+
+	assert(thread_foreign_intr_disabled());
+
+	while (__cpu_spin_trylock(lock)) {
+		retries++;
+		if (!retries) {
+			/* wrapped, time to report */
+			trace_printf(func, line, TRACE_ERROR, true,
+				     "possible spinlock deadlock reminder %u",
+				      reminder);
+			if (reminder < UINT_MAX)
+				reminder++;
+		}
+	}
+
+	spinlock_count_incr();
+}
+#else
+static inline void cpu_spin_lock(unsigned int *lock)
+{
+	cpu_spin_lock_no_dldetect(lock);
+}
+#endif
+
+
 static inline bool cpu_spin_trylock(unsigned int *lock)
 {
 	unsigned int rc;
@@ -82,14 +116,35 @@ static inline void cpu_spin_unlock(unsigned int *lock)
 	spinlock_count_decr();
 }
 
-static inline uint32_t cpu_spin_lock_xsave(unsigned int *lock)
+static inline uint32_t cpu_spin_lock_xsave_no_dldetect(unsigned int *lock)
 {
 	uint32_t exceptions = thread_mask_exceptions(THREAD_EXCP_ALL);
 
 	cpu_spin_lock(lock);
 	return exceptions;
 }
 
+
+#ifdef CFG_TEE_CORE_DEBUG
+#define cpu_spin_lock_xsave(lock) \
+	cpu_spin_lock_xsave_dldetect(__func__, __LINE__, lock)
+
+static inline uint32_t cpu_spin_lock_xsave_dldetect(const char *func,
+						    const int line,
+						    unsigned int *lock)
+{
+	uint32_t exceptions = thread_mask_exceptions(THREAD_EXCP_ALL);
+
+	cpu_spin_lock_dldetect(func, line, lock);
+	return exceptions;
+}
+#else
+static inline uint32_t cpu_spin_lock_xsave(unsigned int *lock)
+{
+	return cpu_spin_lock_xsave_no_dldetect(lock);
+}
+#endif
+
 static inline void cpu_spin_unlock_xrestore(unsigned int *lock,
 					    uint32_t exceptions)
 {

core/arch/arm/kernel/trace_ext.c

@@ -44,7 +44,7 @@ void trace_ext_puts(const char *str)
 
 	if (mmu_enabled && !cpu_spin_trylock(&puts_lock)) {
 		was_contended = true;
-		cpu_spin_lock(&puts_lock);
+		cpu_spin_lock_no_dldetect(&puts_lock);
 	}
 
 	console_flush();