diff mbox

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

Message ID 1483467027-14547-3-git-send-email-will.deacon@arm.com
State Accepted
Commit f31deaadff0d81a4963b5d816c1ae4a67296aa0c
Headers show

Commit Message

Will Deacon Jan. 3, 2017, 6:10 p.m. UTC
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(-)

-- 
2.1.4

Comments

Mark Rutland Jan. 4, 2017, 10:53 a.m. UTC | #1
On Tue, Jan 03, 2017 at 06:10:19PM +0000, Will Deacon wrote:
> 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>


I couldn't find this in the ARMV8.1 supplement, but it is in the SPE
spec. FWIW:

Acked-by: Mark Rutland <mark.rutland@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),


As a heads-up, this line will disappear with Suzuki's cpufeature updates
series, so you may spot a clash later on.

Thanks,
Mark.

> +	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

>
diff mbox

Patch

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),