[POWERPC] Oprofile enhanced instruction sampling support

Oprofile enhanced instruction sampling support.

When performing instruction sampling, the mmcra[SLOT] field can be used to
more accurately identify the address of the sampled instruction.

Tested on power4, js20, power5 and power5+.

Signed-off-by: Will Schmidt <will_schmidt@vnet.ibm.com>
cc: Maynard Johnson <maynardj@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/powerpc/oprofile/op_model_power4.c b/arch/powerpc/oprofile/op_model_power4.c
index fe597a154d4f..a7c206b665af 100644
--- a/arch/powerpc/oprofile/op_model_power4.c
+++ b/arch/powerpc/oprofile/op_model_power4.c
@@ -1,5 +1,7 @@
 /*
  * Copyright (C) 2004 Anton Blanchard <anton@au.ibm.com>, IBM
+ * Added mmcra[slot] support:
+ * Copyright (C) 2006-2007 Will Schmidt <willschm@us.ibm.com>, IBM
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -181,11 +183,17 @@ static void __attribute_used__ kernel_unknown_bucket(void)
  * On GQ and newer the MMCRA stores the HV and PR bits at the time
  * the SIAR was sampled. We use that to work out if the SIAR was sampled in
  * the hypervisor, our exception vectors or RTAS.
+ * If the MMCRA_SAMPLE_ENABLE bit is set, we can use the MMCRA[slot] bits
+ * to more accurately identify the address of the sampled instruction. The
+ * mmcra[slot] bits represent the slot number of a sampled instruction
+ * within an instruction group.  The slot will contain a value between 1
+ * and 5 if MMCRA_SAMPLE_ENABLE is set, otherwise 0.
  */
 static unsigned long get_pc(struct pt_regs *regs)
 {
         unsigned long pc = mfspr(SPRN_SIAR);
         unsigned long mmcra;
+        unsigned long slot;
 
         /* Cant do much about it */
         if (!cur_cpu_spec->oprofile_mmcra_sihv)
@@ -193,6 +201,12 @@ static unsigned long get_pc(struct pt_regs *regs)
 
         mmcra = mfspr(SPRN_MMCRA);
 
+        if (mmcra & MMCRA_SAMPLE_ENABLE) {
+                slot = ((mmcra & MMCRA_SLOT) >> MMCRA_SLOT_SHIFT);
+                if (slot > 1)
+                        pc += 4 * (slot - 1);
+        }
+
         /* Were we in the hypervisor? */
         if (firmware_has_feature(FW_FEATURE_LPAR) &&
             (mmcra & cur_cpu_spec->oprofile_mmcra_sihv))