ARM: perf: fix link error when CONFIG_HW_PERF_EVENTS is not selected

Commit e50c541 (ARM: perf: add guest vs host discrimination) broken the link as perf_instruction_pointer and perf_misc_flags are not defined when CONFIG_HW_PERF_EVENTS is not selected.

As it make little sense to try and profile a guest without any HW event, just fallback to the original code when this config option is not selected.

Reported-by Russell King <[email protected]>

Cc Will Deacon <[email protected]>

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm/include/asm/perf_event.h | 2 ++
 1 file changed, 2 insertions(+)

arch/arm/include/asm/perf_event.h +0 -0

index 00416ed..7558775 100644
@@ -21,9 +21,11 @@
 #define C(_x)				PERF_COUNT_HW_CACHE_##_x

Quoted 21 lines · Marc Zyngier

Commit e50c541 (ARM: perf: add guest vs host discrimination) broken the link as perf_instruction_pointer and perf_misc_flags are not defined when CONFIG_HW_PERF_EVENTS is not selected.

As it make little sense to try and profile a guest without any HW event, just fallback to the original code when this config option is not selected.

Reported-by Russell King <[email protected]>

Cc Will Deacon <[email protected]>

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm/include/asm/perf_event.h | 2 ++
 1 file changed, 2 insertions(+)

arch/arm/include/asm/perf_event.h +0 -0

index 00416ed..7558775 100644
@@ -21,9 +21,11 @@
 #define C(_x)				PERF_COUNT_HW_CACHE_##_x

arch/arm/include/asm/perf_event.h line 31

Quoted 10 lines

arch/arm/include/asm/perf_event.h +2 -0

 #define CACHE_OP_UNSUPPORTED		0xFFFF
 
+#ifdef CONFIG_HW_PERF_EVENTS
 struct pt_regs;
 extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
 extern unsigned long perf_misc_flags(struct pt_regs *regs);
 #define perf_misc_flags(regs)	perf_misc_flags(regs)
+#endif
 
 #endif /* __ARM_PERF_EVENT_H__ */

Acked-by Will Deacon <[email protected]>

Thanks Marc for the fix and Russell for reporting the issue.

Please can you stick this in the patch system as I don't have any other perf patches pending for 3.8?