powerpc/perf: Add support for SIER

On power8 we have a new SIER (Sampled Instruction Event Register), which
captures information about instructions when we have random sampling
enabled.

Add support for loading the SIER into pt_regs, overloading regs->dar.
Also set the new NO_SIPR flag in regs->result if we don't have SIPR.

Update regs_sihv/sipr() to look for SIPR/SIHV in SIER.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 5735ebb..5c6fbe2 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -671,6 +671,11 @@
 #define SPRN_PMC8	794
 #define SPRN_SIAR	780
 #define SPRN_SDAR	781
+#define SPRN_SIER	784
+#define   SIER_SIPR		0x2000000	/* Sampled MSR_PR */
+#define   SIER_SIHV		0x1000000	/* Sampled MSR_HV */
+#define   SIER_SIAR_VALID	0x0400000	/* SIAR contents valid */
+#define   SIER_SDAR_VALID	0x0200000	/* SDAR contents valid */
 
 #define SPRN_PA6T_MMCR0 795
 #define   PA6T_MMCR0_EN0	0x0000000000000001UL