Commit e50c5418 authored by Marc Zyngier's avatar Marc Zyngier Committed by Will Deacon
Browse files

ARM: perf: add guest vs host discrimination 



Add minimal guest support to perf, so it can distinguish whether
the PMU interrupt was in the host or the guest, as well as collecting
some very basic information (guest PC, user vs kernel mode).

This is not feature complete though, as it doesn't support backtracing
in the guest.

Based on the x86 implementation, tested with KVM/ARM.

Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 3d70f8c6

arch/arm/include/asm/perf_event.h

+5 −0
Original line number Diff line number Diff line
@@ -21,4 +21,9 @@ 
#define C(_x)				PERF_COUNT_HW_CACHE_##_x

#define CACHE_OP_UNSUPPORTED		0xFFFF



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 /* __ARM_PERF_EVENT_H__ */

arch/arm/kernel/perf_event.c

+36 −0
Original line number Diff line number Diff line
@@ -576,6 +576,10 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) 
{

	struct frame_tail __user *tail;



	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {

		/* We don't support guest os callchain now */

		return;

	}



	tail = (struct frame_tail __user *)regs->ARM_fp - 1;
@@ -603,9 +607,41 @@ perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs) 
{

	struct stackframe fr;



	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {

		/* We don't support guest os callchain now */

		return;

	}



	fr.fp = regs->ARM_fp;

	fr.sp = regs->ARM_sp;

	fr.lr = regs->ARM_lr;

	fr.pc = regs->ARM_pc;

	walk_stackframe(&fr, callchain_trace, entry);

}



unsigned long perf_instruction_pointer(struct pt_regs *regs)

{

	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())

		return perf_guest_cbs->get_guest_ip();



	return instruction_pointer(regs);

}



unsigned long perf_misc_flags(struct pt_regs *regs)

{

	int misc = 0;



	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {

		if (perf_guest_cbs->is_user_mode())

			misc |= PERF_RECORD_MISC_GUEST_USER;

		else

			misc |= PERF_RECORD_MISC_GUEST_KERNEL;

	} else {

		if (user_mode(regs))

			misc |= PERF_RECORD_MISC_USER;

		else

			misc |= PERF_RECORD_MISC_KERNEL;

	}



	return misc;

}

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