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Message-ID: <20180207104320.GM5862@e103592.cambridge.arm.com>
Date: Wed, 7 Feb 2018 10:43:21 +0000
From: Dave Martin <Dave.Martin@....com>
To: Suzuki K Poulose <suzuki.poulose@....com>
Cc: linux-arm-kernel@...ts.infradead.org, mark.rutland@....com,
catalin.marinas@....com, will.deacon@....com,
linux-kernel@...r.kernel.org, Dave Martin <dave.martin@....com>
Subject: Re: [PATCH 2/2] arm64: Expose Arm v8.4 features
On Thu, Feb 01, 2018 at 10:38:38AM +0000, Suzuki K Poulose wrote:
> Expose the new features introduced by Arm v8.4 extensions to
> Arm v8-A profile.
>
> These include :
>
> 1) Data indpendent timing of instructions. (DIT, exposed as HWCAP_DIT)
> 2) Unaligned atomic instructions and Single-copy atomicity of loads
> and stores. (AT, expose as HWCAP_USCAT)
> 3) LDAPR and STLR instructions with immediate offsets (extension to
> LRCPC, exposed as HWCAP_ILRCPC)
> 4) Flag manipulation instructions (TS, exposed as HWCAP_FLAGM).
>
> While at it get rid of the RES0 entries in the cpu-feature-registers.txt
> documentation.
Should we write somewhere than fields that are not described here are
implicitly RES0, or would that be too strong a statement?
Cheers
---Dave
> Cc: Dave Martin <dave.martin@....com>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will.deacon@....com>
> Cc: Mark Rutland <mark.rutland@....com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
> Documentation/arm64/cpu-feature-registers.txt | 18 ++++++++++--------
> Documentation/arm64/elf_hwcaps.txt | 16 ++++++++++++++++
> arch/arm64/include/asm/sysreg.h | 3 +++
> arch/arm64/include/uapi/asm/hwcap.h | 4 ++++
> arch/arm64/kernel/cpufeature.c | 7 +++++++
> arch/arm64/kernel/cpuinfo.c | 4 ++++
> 6 files changed, 44 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/arm64/cpu-feature-registers.txt b/Documentation/arm64/cpu-feature-registers.txt
> index a70090b28b07..7964f03846b1 100644
> --- a/Documentation/arm64/cpu-feature-registers.txt
> +++ b/Documentation/arm64/cpu-feature-registers.txt
> @@ -110,7 +110,7 @@ infrastructure:
> x--------------------------------------------------x
> | Name | bits | visible |
> |--------------------------------------------------|
> - | RES0 | [63-52] | n |
> + | TS | [55-52] | y |
> |--------------------------------------------------|
> | FHM | [51-48] | y |
> |--------------------------------------------------|
> @@ -124,8 +124,6 @@ infrastructure:
> |--------------------------------------------------|
> | RDM | [31-28] | y |
> |--------------------------------------------------|
> - | RES0 | [27-24] | n |
> - |--------------------------------------------------|
> | ATOMICS | [23-20] | y |
> |--------------------------------------------------|
> | CRC32 | [19-16] | y |
> @@ -135,8 +133,6 @@ infrastructure:
> | SHA1 | [11-8] | y |
> |--------------------------------------------------|
> | AES | [7-4] | y |
> - |--------------------------------------------------|
> - | RES0 | [3-0] | n |
> x--------------------------------------------------x
>
>
> @@ -144,12 +140,10 @@ infrastructure:
> x--------------------------------------------------x
> | Name | bits | visible |
> |--------------------------------------------------|
> - | RES0 | [63-36] | n |
> + | DIT | [51-48] | y |
> |--------------------------------------------------|
> | SVE | [35-32] | y |
> |--------------------------------------------------|
> - | RES0 | [31-28] | n |
> - |--------------------------------------------------|
> | GIC | [27-24] | n |
> |--------------------------------------------------|
> | AdvSIMD | [23-20] | y |
> @@ -199,6 +193,14 @@ infrastructure:
> | DPB | [3-0] | y |
> x--------------------------------------------------x
>
> + 5) ID_AA64MMFR2_EL1 - Memory model feature register 2
> +
> + x--------------------------------------------------x
> + | Name | bits | visible |
> + |--------------------------------------------------|
> + | AT | [35-32] | y |
> + x--------------------------------------------------x
> +
> Appendix I: Example
> ---------------------------
>
> diff --git a/Documentation/arm64/elf_hwcaps.txt b/Documentation/arm64/elf_hwcaps.txt
> index 57324ee55ecc..d6aff2c5e9e2 100644
> --- a/Documentation/arm64/elf_hwcaps.txt
> +++ b/Documentation/arm64/elf_hwcaps.txt
> @@ -162,3 +162,19 @@ HWCAP_SVE
> HWCAP_ASIMDFHM
>
> Functionality implied by ID_AA64ISAR0_EL1.FHM == 0b0001.
> +
> +HWCAP_DIT
> +
> + Functionality implied by ID_AA64PFR0_EL1.DIT == 0b0001.
> +
> +HWCAP_USCAT
> +
> + Functionality implied by ID_AA64MMFR2_EL1.AT == 0b0001.
> +
> +HWCAP_ILRCPC
> +
> + Functionality implied by ID_AA64ISR1_EL1.LRCPC == 0b0002.
> +
> +HWCAP_FLAGM
> +
> + Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0001.
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index 0e1960c59197..e7b9f154e476 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -490,6 +490,7 @@
> #define SCTLR_EL1_BUILD_BUG_ON_MISSING_BITS BUILD_BUG_ON((SCTLR_EL1_SET ^ SCTLR_EL1_CLEAR) != ~0)
>
> /* id_aa64isar0 */
> +#define ID_AA64ISAR0_TS_SHIFT 52
> #define ID_AA64ISAR0_FHM_SHIFT 48
> #define ID_AA64ISAR0_DP_SHIFT 44
> #define ID_AA64ISAR0_SM4_SHIFT 40
> @@ -511,6 +512,7 @@
> /* id_aa64pfr0 */
> #define ID_AA64PFR0_CSV3_SHIFT 60
> #define ID_AA64PFR0_CSV2_SHIFT 56
> +#define ID_AA64PFR0_DIT_SHIFT 48
> #define ID_AA64PFR0_SVE_SHIFT 32
> #define ID_AA64PFR0_RAS_SHIFT 28
> #define ID_AA64PFR0_GIC_SHIFT 24
> @@ -568,6 +570,7 @@
> #define ID_AA64MMFR1_VMIDBITS_16 2
>
> /* id_aa64mmfr2 */
> +#define ID_AA64MMFR2_AT_SHIFT 32
> #define ID_AA64MMFR2_LVA_SHIFT 16
> #define ID_AA64MMFR2_IESB_SHIFT 12
> #define ID_AA64MMFR2_LSM_SHIFT 8
> diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h
> index f018c3deea3b..17c65c8f33cb 100644
> --- a/arch/arm64/include/uapi/asm/hwcap.h
> +++ b/arch/arm64/include/uapi/asm/hwcap.h
> @@ -44,5 +44,9 @@
> #define HWCAP_SHA512 (1 << 21)
> #define HWCAP_SVE (1 << 22)
> #define HWCAP_ASIMDFHM (1 << 23)
> +#define HWCAP_DIT (1 << 24)
> +#define HWCAP_USCAT (1 << 25)
> +#define HWCAP_ILRCPC (1 << 26)
> +#define HWCAP_FLAGM (1 << 27)
>
> #endif /* _UAPI__ASM_HWCAP_H */
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 1c39a635a71c..796e83dde9fc 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -123,6 +123,7 @@ cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused)
> * sync with the documentation of the CPU feature register ABI.
> */
> static const struct arm64_ftr_bits ftr_id_aa64isar0[] = {
> + ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_TS_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_FHM_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_DP_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SM4_SHIFT, 4, 0),
> @@ -148,6 +149,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar1[] = {
> static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
> ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV3_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV2_SHIFT, 4, 0),
> + ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_DIT_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SVE_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_RAS_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_GIC_SHIFT, 4, 0),
> @@ -192,6 +194,7 @@ static const struct arm64_ftr_bits ftr_id_aa64mmfr1[] = {
> };
>
> static const struct arm64_ftr_bits ftr_id_aa64mmfr2[] = {
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_AT_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_LVA_SHIFT, 4, 0),
> /* While IESB is good to have, it is not fatal if we miss this on some CPUs */
> ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_IESB_SHIFT, 4, 0),
> @@ -1083,14 +1086,18 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
> HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SM4_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_SM4),
> HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_DP_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_ASIMDDP),
> HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_FHM_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_ASIMDFHM),
> + HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_TS_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_FLAGM),
> HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, HWCAP_FP),
> HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, HWCAP_FPHP),
> HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, HWCAP_ASIMD),
> HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, HWCAP_ASIMDHP),
> + HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_DIT_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, HWCAP_DIT),
> HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_DPB_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_DCPOP),
> HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_JSCVT_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_JSCVT),
> HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_FCMA_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_FCMA),
> HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_LRCPC_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_LRCPC),
> + HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_LRCPC_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, HWCAP_ILRCPC),
> + HWCAP_CAP(SYS_ID_AA64MMFR2_EL1, ID_AA64MMFR2_AT_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_USCAT),
> #ifdef CONFIG_ARM64_SVE
> HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_SVE_SHIFT, FTR_UNSIGNED, ID_AA64PFR0_SVE, CAP_HWCAP, HWCAP_SVE),
> #endif
> diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
> index 7f94623df8a5..e9ab7b3ed317 100644
> --- a/arch/arm64/kernel/cpuinfo.c
> +++ b/arch/arm64/kernel/cpuinfo.c
> @@ -77,6 +77,10 @@ static const char *const hwcap_str[] = {
> "sha512",
> "sve",
> "asimdfhm",
> + "dit",
> + "uscat",
> + "ilrcpc",
> + "flagm",
> NULL
> };
>
> --
> 2.14.3
>
>
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> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
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