[PATCH] ppc64: fix oprofile sample bit handling
Oprofile was hardwiring the MMCRA sample bit to 1 but on newer cpus
(eg POWER5) we want to vary it based on the group being sampled.
Add a temporary workaround until people update their oprofile userspace.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/oprofile/op_model_power4.c b/arch/powerpc/oprofile/op_model_power4.c
index 8864493..c4ee547 100644
--- a/arch/powerpc/oprofile/op_model_power4.c
+++ b/arch/powerpc/oprofile/op_model_power4.c
@@ -17,6 +17,7 @@
#include <asm/systemcfg.h>
#include <asm/rtas.h>
#include <asm/oprofile_impl.h>
+#include <asm/reg.h>
#define dbg(args...)
@@ -81,6 +82,26 @@
extern void ppc64_enable_pmcs(void);
+/*
+ * Older CPUs require the MMCRA sample bit to be always set, but newer
+ * CPUs only want it set for some groups. Eventually we will remove all
+ * knowledge of this bit in the kernel, oprofile userspace should be
+ * setting it when required.
+ *
+ * In order to keep current installations working we force the bit for
+ * those older CPUs. Once everyone has updated their oprofile userspace we
+ * can remove this hack.
+ */
+static inline int mmcra_must_set_sample(void)
+{
+ if (__is_processor(PV_POWER4) || __is_processor(PV_POWER4p) ||
+ __is_processor(PV_970) || __is_processor(PV_970FX) ||
+ __is_processor(PV_970MP))
+ return 1;
+
+ return 0;
+}
+
static void power4_cpu_setup(void *unused)
{
unsigned int mmcr0 = mmcr0_val;
@@ -98,7 +119,8 @@
mtspr(SPRN_MMCR1, mmcr1_val);
- mmcra |= MMCRA_SAMPLE_ENABLE;
+ if (mmcra_must_set_sample())
+ mmcra |= MMCRA_SAMPLE_ENABLE;
mtspr(SPRN_MMCRA, mmcra);
dbg("setup on cpu %d, mmcr0 %lx\n", smp_processor_id(),