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Groups > linux.kernel > #1550040

[RFC PATCH 02/10] arm64: cpufeature: Don't enforce system-wide SPE capability

From Will Deacon <will.deacon@arm.com>
Newsgroups linux.kernel
Subject [RFC PATCH 02/10] arm64: cpufeature: Don't enforce system-wide SPE capability
Date 2017-01-03 19:20 +0100
Message-ID <sVBQJ-1Kc-13@gated-at.bofh.it> (permalink)
References <sVBQJ-1Kc-7@gated-at.bofh.it>
Organization linux.* mail to news gateway

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The statistical profiling extension (SPE) is an optional feature of
ARMv8.1 and is unlikely to be supported by all of the CPUs in a
heterogeneous system.

This patch updates the cpufeature checks so that such systems are not
tainted as unsupported.

Reviewed-by: Suzuki Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm64/include/asm/sysreg.h | 1 +
 arch/arm64/kernel/cpufeature.c  | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 98ae03f8eedd..e156e7793a65 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -190,6 +190,7 @@
 #define ID_AA64MMFR2_CNP_SHIFT		0
 
 /* id_aa64dfr0 */
+#define ID_AA64DFR0_PMSVER_SHIFT	32
 #define ID_AA64DFR0_CTX_CMPS_SHIFT	28
 #define ID_AA64DFR0_WRPS_SHIFT		20
 #define ID_AA64DFR0_BRPS_SHIFT		12
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 47d0226620e8..c18eb78d3a00 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -180,7 +180,8 @@ static const struct arm64_ftr_bits ftr_id_mmfr0[] = {
 };
 
 static const struct arm64_ftr_bits ftr_id_aa64dfr0[] = {
-	ARM64_FTR_BITS(FTR_STRICT, FTR_EXACT, 32, 32, 0),
+	ARM64_FTR_BITS(FTR_STRICT, FTR_EXACT, 36, 28, 0),
+	ARM64_FTR_BITS(FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64DFR0_PMSVER_SHIFT, 4, 0),
 	ARM64_FTR_BITS(FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_CTX_CMPS_SHIFT, 4, 0),
 	ARM64_FTR_BITS(FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_WRPS_SHIFT, 4, 0),
 	ARM64_FTR_BITS(FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_BRPS_SHIFT, 4, 0),
-- 
2.1.4

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Thread

[RFC PATCH 00/10] Add support for the ARMv8.2 Statistical Profiling Extension Will Deacon <will.deacon@arm.com> - 2017-01-03 19:20 +0100
  [RFC PATCH 02/10] arm64: cpufeature: Don't enforce system-wide SPE capability Will Deacon <will.deacon@arm.com> - 2017-01-03 19:20 +0100
    Re: [RFC PATCH 02/10] arm64: cpufeature: Don't enforce system-wide  SPE capability Mark Rutland <mark.rutland@arm.com> - 2017-01-04 12:10 +0100
  [RFC PATCH 05/10] genirq: export irq_get_percpu_devid_partition to modules Will Deacon <will.deacon@arm.com> - 2017-01-03 19:20 +0100
  [RFC PATCH 01/10] arm64: cpufeature: allow for version discrepancy in PMU implementations Will Deacon <will.deacon@arm.com> - 2017-01-03 19:20 +0100
    Re: [RFC PATCH 01/10] arm64: cpufeature: allow for version  discrepancy in PMU implementations Mark Rutland <mark.rutland@arm.com> - 2017-01-04 11:30 +0100
  [RFC PATCH 04/10] arm64: head.S: Enable EL1 (host) access to SPE when entered at EL2 Will Deacon <will.deacon@arm.com> - 2017-01-03 19:20 +0100
  [RFC PATCH 09/10] drivers/perf: Add support for ARMv8.2 Statistical Profiling Extension Will Deacon <will.deacon@arm.com> - 2017-01-03 19:20 +0100
    Re: [RFC PATCH 09/10] drivers/perf: Add support for ARMv8.2  Statistical Profiling Extension Peter Zijlstra <peterz@infradead.org> - 2017-01-04 11:40 +0100
      Re: [RFC PATCH 09/10] drivers/perf: Add support for ARMv8.2  Statistical Profiling Extension Will Deacon <will.deacon@arm.com> - 2017-01-04 20:20 +0100
        Re: [RFC PATCH 09/10] drivers/perf: Add support for ARMv8.2  Statistical Profiling Extension Peter Zijlstra <peterz@infradead.org> - 2017-01-05 12:40 +0100
    Re: [RFC PATCH 09/10] drivers/perf: Add support for ARMv8.2  Statistical Profiling Extension Kim Phillips <kim.phillips@arm.com> - 2017-01-10 23:10 +0100
      Re: [RFC PATCH 09/10] drivers/perf: Add support for ARMv8.2  Statistical Profiling Extension Will Deacon <will.deacon@arm.com> - 2017-01-11 13:40 +0100
        Re: [RFC PATCH 09/10] drivers/perf: Add support for ARMv8.2  Statistical Profiling Extension Kim Phillips <kim.phillips@arm.com> - 2017-01-11 22:10 +0100
          Re: [RFC PATCH 09/10] drivers/perf: Add support for ARMv8.2  Statistical Profiling Extension Will Deacon <will.deacon@arm.com> - 2017-01-13 14:40 +0100
      Re: [RFC PATCH 09/10] drivers/perf: Add support for ARMv8.2  Statistical Profiling Extension Marc Zyngier <marc.zyngier@arm.com> - 2017-01-12 12:40 +0100
  [RFC PATCH 07/10] perf: Directly pass PERF_AUX_* flags to perf_aux_output_end Will Deacon <will.deacon@arm.com> - 2017-01-03 19:20 +0100
  [RFC PATCH 03/10] arm64: KVM: Save/restore the host SPE state when entering/leaving a VM Will Deacon <will.deacon@arm.com> - 2017-01-03 19:20 +0100
  [RFC PATCH 10/10] dt-bindings: Document devicetree binding for ARM SPE Will Deacon <will.deacon@arm.com> - 2017-01-03 19:20 +0100
  [RFC PATCH 08/10] perf/core: Add PERF_AUX_FLAG_COLLISION to report colliding samples Will Deacon <will.deacon@arm.com> - 2017-01-03 19:20 +0100

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