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: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm/include/asm/perf_event.h b/arch/arm/include/asm/perf_event.h
index 625cd621a436db1d24d1d9ee53dffe0fe0ff70d8..00416edeceadaf1f8b68583a7c6d2e979fb2b1d3 100644 (file)
--- a/arch/arm/include/asm/perf_event.h
+++ b/arch/arm/include/asm/perf_event.h
@@ -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__ */

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 93971b1a4f0bb0d38eebd573f8618e994273b079..27413aa41ea742809fff0e9cd508aa5916bdd3d0 100644 (file)
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -572,6 +572,10 @@ 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;
 
@@ -599,9 +603,41 @@ 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;
+}