perf: Drop the skip argument from perf_arch_fetch_regs_caller

Drop this argument now that we always want to rewind only to the
state of the first caller.
It means frame pointers are not necessary anymore to reliably get
the source of an event. But this also means we need this helper
to be a macro now, as an inline function is not an option since
we need to know when to provide a default implentation.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: David Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 12 insertions, 26 deletions

diff --git a/arch/powerpc/include/asm/perf_event.h b/arch/powerpc/include/asm/perf_event.h
index e6d4ce69b126..5c16b891d501 100644
--- a/arch/powerpc/include/asm/perf_event.h
+++ b/arch/powerpc/include/asm/perf_event.h
@@ -21,3 +21,15 @@
 #ifdef CONFIG_FSL_EMB_PERF_EVENT
 #include <asm/perf_event_fsl_emb.h>
 #endif
+
+#ifdef CONFIG_PERF_EVENTS
+#include <asm/ptrace.h>
+#include <asm/reg.h>
+
+#define perf_arch_fetch_caller_regs(regs, __ip)                 \
+        do {                                                    \
+                (regs)->nip = __ip;                             \
+                (regs)->gpr[1] = *(unsigned long *)__get_SP();  \
+                asm volatile("mfmsr %0" : "=r" ((regs)->msr));  \
+        } while (0)
+#endif
diff --git a/arch/powerpc/kernel/misc.S b/arch/powerpc/kernel/misc.S
index 22e507c8a556..2d29752cbe16 100644
--- a/arch/powerpc/kernel/misc.S
+++ b/arch/powerpc/kernel/misc.S
@@ -127,29 +127,3 @@ _GLOBAL(__setup_cpu_power7)
 _GLOBAL(__restore_cpu_power7)
         /* place holder */
         blr
-
-/*
- * Get a minimal set of registers for our caller's nth caller.
- * r3 = regs pointer, r5 = n.
- *
- * We only get R1 (stack pointer), NIP (next instruction pointer)
- * and LR (link register).  These are all we can get in the
- * general case without doing complicated stack unwinding, but
- * fortunately they are enough to do a stack backtrace, which
- * is all we need them for.
- */
-_GLOBAL(perf_arch_fetch_caller_regs)
-        mr      r6,r1
-        cmpwi   r5,0
-        mflr    r4
-        ble     2f
-        mtctr   r5
-1:      PPC_LL  r6,0(r6)
-        bdnz    1b
-        PPC_LL  r4,PPC_LR_STKOFF(r6)
-2:      PPC_LL  r7,0(r6)
-        PPC_LL  r7,PPC_LR_STKOFF(r7)
-        PPC_STL r6,GPR1-STACK_FRAME_OVERHEAD(r3)
-        PPC_STL r4,_NIP-STACK_FRAME_OVERHEAD(r3)
-        PPC_STL r7,_LINK-STACK_FRAME_OVERHEAD(r3)
-        blr