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[3/4] powerpc/perf: Use the address from SIAR register to set cpumode flags

Message ID 1602154329-2092-4-git-send-email-atrajeev@linux.vnet.ibm.com (mailing list archive)
State Superseded
Headers show
Series powerpc/perf: Power PMU fixes for power10 DD1 | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (d1def5df359f3f1882cc29d8baa5cd2a4861a6c6)
snowpatch_ozlabs/checkpatch success total: 0 errors, 0 warnings, 0 checks, 24 lines checked
snowpatch_ozlabs/needsstable success Patch has no Fixes tags

Commit Message

Athira Rajeev Oct. 8, 2020, 10:52 a.m. UTC
While setting the processor mode for any sample, `perf_get_misc_flags`
expects the privilege level to differentiate the userspace and kernel
address. On power10 DD1, there is an issue that causes [MSR_HV MSR_PR] bits
of Sampled Instruction Event Register (SIER) not to be set for marked
events. Hence add a check to use the address in Sampled Instruction Address
Register (SIAR) to identify the privilege level.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
---
 arch/powerpc/perf/core-book3s.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
diff mbox series

Patch

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index d766090..c018004 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -250,11 +250,25 @@  static inline u32 perf_flags_from_msr(struct pt_regs *regs)
 static inline u32 perf_get_misc_flags(struct pt_regs *regs)
 {
 	bool use_siar = regs_use_siar(regs);
+	unsigned long mmcra = regs->dsisr;
+	int marked = mmcra & MMCRA_SAMPLE_ENABLE;
 
 	if (!use_siar)
 		return perf_flags_from_msr(regs);
 
 	/*
+	 * Check the address in SIAR to identify the
+	 * privilege levels since the SIER[MSR_HV, MSR_PR]
+	 * bits are not set for marked events in power10
+	 * DD1.
+	 */
+	if (marked && (ppmu->flags & PPMU_P10_DD1)) {
+		if (is_kernel_addr(mfspr(SPRN_SIAR)))
+			return PERF_RECORD_MISC_KERNEL;
+		return PERF_RECORD_MISC_USER;
+	}
+
+	/*
 	 * If we don't have flags in MMCRA, rather than using
 	 * the MSR, we intuit the flags from the address in
 	 * SIAR which should give slightly more reliable