[MIPS] lockdep: fix TRACE_IRQFLAGS_SUPPORT

In handle_sys and its variants, we must reload some registers which
might be clobbered by trace_hardirqs_on().
Also we must make sure trace_hardirqs_on() called in kernel level (not
exception level).

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/scall32-o32.S

@@ -28,18 +28,7 @@
 NESTED(handle_sys, PT_SIZE, sp)
 	.set	noat
 	SAVE_SOME
-#ifdef CONFIG_TRACE_IRQFLAGS
-	TRACE_IRQS_ON
-#ifdef CONFIG_64BIT
-	LONG_L	$8, PT_R8(sp)
-	LONG_L	$9, PT_R9(sp)
-#endif
-	LONG_L	$7, PT_R7(sp)
-	LONG_L	$6, PT_R6(sp)
-	LONG_L	$5, PT_R5(sp)
-	LONG_L	$4, PT_R4(sp)
-	LONG_L	$2, PT_R2(sp)
-#endif
+	TRACE_IRQS_ON_RELOAD
 	STI
 	.set	at
 

arch/mips/kernel/scall64-64.S

@@ -34,7 +34,7 @@ NESTED(handle_sys64, PT_SIZE, sp)
 	 */
 	.set	noat
 	SAVE_SOME
-	TRACE_IRQS_ON
+	TRACE_IRQS_ON_RELOAD
 	STI
 	.set	at
 #endif

arch/mips/kernel/scall64-n32.S

@@ -33,7 +33,7 @@ NESTED(handle_sysn32, PT_SIZE, sp)
 #ifndef CONFIG_MIPS32_O32
 	.set	noat
 	SAVE_SOME
-	TRACE_IRQS_ON
+	TRACE_IRQS_ON_RELOAD
 	STI
 	.set	at
 #endif

arch/mips/kernel/scall64-o32.S

@@ -28,7 +28,7 @@
 NESTED(handle_sys, PT_SIZE, sp)
 	.set	noat
 	SAVE_SOME
-	TRACE_IRQS_ON
+	TRACE_IRQS_ON_RELOAD
 	STI
 	.set	at
 	ld	t1, PT_EPC(sp)		# skip syscall on return

include/asm-mips/irqflags.h

@@ -213,12 +213,37 @@ static inline int raw_irqs_disabled_flags(unsigned long flags)
  * Do the CPU's IRQ-state tracing from assembly code.
  */
 #ifdef CONFIG_TRACE_IRQFLAGS
+/* Reload some registers clobbered by trace_hardirqs_on */
+#ifdef CONFIG_64BIT
+# define TRACE_IRQS_RELOAD_REGS						\
+	LONG_L	$11, PT_R11(sp);					\
+	LONG_L	$10, PT_R10(sp);					\
+	LONG_L	$9, PT_R9(sp);						\
+	LONG_L	$8, PT_R8(sp);						\
+	LONG_L	$7, PT_R7(sp);						\
+	LONG_L	$6, PT_R6(sp);						\
+	LONG_L	$5, PT_R5(sp);						\
+	LONG_L	$4, PT_R4(sp);						\
+	LONG_L	$2, PT_R2(sp)
+#else
+# define TRACE_IRQS_RELOAD_REGS						\
+	LONG_L	$7, PT_R7(sp);						\
+	LONG_L	$6, PT_R6(sp);						\
+	LONG_L	$5, PT_R5(sp);						\
+	LONG_L	$4, PT_R4(sp);						\
+	LONG_L	$2, PT_R2(sp)
+#endif
 # define TRACE_IRQS_ON							\
+	CLI;	/* make sure trace_hardirqs_on() is called in kernel level */ \
 	jal	trace_hardirqs_on
+# define TRACE_IRQS_ON_RELOAD						\
+	TRACE_IRQS_ON;							\
+	TRACE_IRQS_RELOAD_REGS
 # define TRACE_IRQS_OFF							\
 	jal	trace_hardirqs_off
 #else
 # define TRACE_IRQS_ON
+# define TRACE_IRQS_ON_RELOAD
 # define TRACE_IRQS_OFF
 #endif