Complete irq tracing support for ARM

Before this patch enabling and disabling irqs in assembler code and by
the hardware wasn't tracked completly.

I had to transpose two instructions in arch/arm/lib/bitops.h because
restore_irqs doesn't preserve the flags with CONFIG_TRACE_IRQFLAGS=y

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

3 files changed, 49 insertions, 12 deletions

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 15f8a092b700..44912cd5da13 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -74,23 +74,56 @@
  * Enable and disable interrupts
  */
 #if __LINUX_ARM_ARCH__ >= 6
-        .macro  disable_irq
+        .macro  disable_irq_notrace
         cpsid   i
         .endm
 
-        .macro  enable_irq
+        .macro  enable_irq_notrace
         cpsie   i
         .endm
 #else
-        .macro  disable_irq
+        .macro  disable_irq_notrace
         msr     cpsr_c, #PSR_I_BIT | SVC_MODE
         .endm
 
-        .macro  enable_irq
+        .macro  enable_irq_notrace
         msr     cpsr_c, #SVC_MODE
         .endm
 #endif
 
+        .macro asm_trace_hardirqs_off
+#if defined(CONFIG_TRACE_IRQFLAGS)
+        stmdb   sp!, {r0-r3, ip, lr}
+        bl      trace_hardirqs_off
+        ldmia   sp!, {r0-r3, ip, lr}
+#endif
+        .endm
+
+        .macro asm_trace_hardirqs_on_cond, cond
+#if defined(CONFIG_TRACE_IRQFLAGS)
+        /*
+         * actually the registers should be pushed and pop'd conditionally, but
+         * after bl the flags are certainly clobbered
+         */
+        stmdb   sp!, {r0-r3, ip, lr}
+        bl\cond trace_hardirqs_on
+        ldmia   sp!, {r0-r3, ip, lr}
+#endif
+        .endm
+
+        .macro asm_trace_hardirqs_on
+        asm_trace_hardirqs_on_cond al
+        .endm
+
+        .macro disable_irq
+        disable_irq_notrace
+        asm_trace_hardirqs_off
+        .endm
+
+        .macro enable_irq
+        asm_trace_hardirqs_on
+        enable_irq_notrace
+        .endm
 /*
  * Save the current IRQ state and disable IRQs.  Note that this macro
  * assumes FIQs are enabled, and that the processor is in SVC mode.
@@ -104,10 +137,16 @@
  * Restore interrupt state previously stored in a register.  We don't
  * guarantee that this will preserve the flags.
  */
-        .macro  restore_irqs, oldcpsr
+        .macro  restore_irqs_notrace, oldcpsr
         msr     cpsr_c, \oldcpsr
         .endm
 
+        .macro restore_irqs, oldcpsr
+        tst     \oldcpsr, #PSR_I_BIT
+        asm_trace_hardirqs_on_cond eq
+        restore_irqs_notrace \oldcpsr
+        .endm
+
 #define USER(x...)                              \
 9999:   x;                                      \
         .section __ex_table,"a";                \
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index fc8af43c5000..792abd0dfae1 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -151,6 +151,8 @@ ENDPROC(__und_invalid)
         @  r4 - orig_r0 (see pt_regs definition in ptrace.h)
         @
         stmia   r5, {r0 - r4}
+
+        asm_trace_hardirqs_off
         .endm
 
         .align  5
@@ -206,9 +208,6 @@ ENDPROC(__dabt_svc)
 __irq_svc:
         svc_entry
 
-#ifdef CONFIG_TRACE_IRQFLAGS
-        bl      trace_hardirqs_off
-#endif
 #ifdef CONFIG_PREEMPT
         get_thread_info tsk
         ldr     r8, [tsk, #TI_PREEMPT]          @ get preempt count
@@ -383,6 +382,8 @@ ENDPROC(__pabt_svc)
         @ Clear FP to mark the first stack frame
         @
         zero_fp
+
+        asm_trace_hardirqs_off
         .endm
 
         .macro  kuser_cmpxchg_check
@@ -437,9 +438,6 @@ __irq_usr:
         usr_entry
         kuser_cmpxchg_check
 
-#ifdef CONFIG_TRACE_IRQFLAGS
-        bl      trace_hardirqs_off
-#endif
         get_thread_info tsk
 #ifdef CONFIG_PREEMPT
         ldr     r8, [tsk, #TI_PREEMPT]          @ get preempt count
diff --git a/arch/arm/lib/bitops.h b/arch/arm/lib/bitops.h
index c7f2627385e7..d42252918bfb 100644
--- a/arch/arm/lib/bitops.h
+++ b/arch/arm/lib/bitops.h
@@ -60,8 +60,8 @@
         tst     r2, r0, lsl r3
         \instr  r2, r2, r0, lsl r3
         \store  r2, [r1]
-        restore_irqs ip
         moveq   r0, #0
+        restore_irqs ip
         mov     pc, lr
         .endm
 #endif