arc: fix irq_lock/unlock ordering bug

benwrs · galak · commit d39e0a92c45d · 2016-12-02T18:07:57.000Z
Memory accesses could be reordered before an irq_lock() or after an irq_unlock() without the memory barriers. See commit 15bc537 for the ARM fix for a complete description of the issue and fix. Change-Id: I056afb0406cabe0e1ce2612904e727ccce5f6308 Signed-off-by: Benjamin Walsh <benjamin.walsh@windriver.com>
diff --git a/include/arch/arc/v2/irq.h b/include/arch/arc/v2/irq.h
@@ -81,7 +81,7 @@ static ALWAYS_INLINE unsigned int _arch_irq_lock(void)
 {
 	unsigned int key;
 
-	__asm__ volatile("clri %0" : "=r"(key));
+	__asm__ volatile("clri %0" : "=r"(key):: "memory");
 	return key;
 }
 
@@ -100,7 +100,7 @@ static ALWAYS_INLINE unsigned int _arch_irq_lock(void)
 
 static ALWAYS_INLINE void _arch_irq_unlock(unsigned int key)
 {
-	__asm__ volatile("seti %0" : : "ir"(key));
+	__asm__ volatile("seti %0" : : "ir"(key) : "memory");
 }
 
 #endif /* _ASMLANGUAGE */

Original file line number	Diff line number	Diff line change
`@@ -81,7 +81,7 @@ static ALWAYS_INLINE unsigned int _arch_irq_lock(void)`
`81`	`81`	`{`
`82`	`82`	`unsigned int key;`
`83`	`83`
`84`		`- __asm__ volatile("clri %0" : "=r"(key));`
	`84`	`+ __asm__ volatile("clri %0" : "=r"(key):: "memory");`
`85`	`85`	`return key;`
`86`	`86`	`}`
`87`	`87`
`@@ -100,7 +100,7 @@ static ALWAYS_INLINE unsigned int _arch_irq_lock(void)`
`100`	`100`
`101`	`101`	`static ALWAYS_INLINE void _arch_irq_unlock(unsigned int key)`
`102`	`102`	`{`
`103`		`- __asm__ volatile("seti %0" : : "ir"(key));`
	`103`	`+ __asm__ volatile("seti %0" : : "ir"(key) : "memory");`
`104`	`104`	`}`
`105`	`105`
`106`	`106`	`#endif /* _ASMLANGUAGE */`