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Message-ID: <ZxfLEqlbGLnK15sf@J2N7QTR9R3>
Date: Tue, 22 Oct 2024 16:56:02 +0100
From: Mark Rutland <mark.rutland@....com>
To: Anshuman Khandual <anshuman.khandual@....com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
Jonathan Corbet <corbet@....net>, Marc Zyngier <maz@...nel.org>,
Oliver Upton <oliver.upton@...ux.dev>,
James Morse <james.morse@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>, Mark Brown <broonie@...nel.org>,
kvmarm@...ts.linux.dev
Subject: Re: [PATCH 1/3] arm64/cpufeature: Add field details for
ID_AA64DFR1_EL1 register
On Tue, Oct 01, 2024 at 10:06:00AM +0530, Anshuman Khandual wrote:
> This adds required field details for ID_AA64DFR1_EL1, and also drops dummy
> ftr_raz[] array which is now redundant. These register fields will be used
> to enable increased breakpoint and watchpoint registers via FEAT_Debugv8p9
> later.
>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> cc: Mark Brown <broonie@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Marc Zyngier <maz@...nel.org>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
> arch/arm64/kernel/cpufeature.c | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 718728a85430..bd4d85f5dd92 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -530,6 +530,21 @@ static const struct arm64_ftr_bits ftr_id_aa64dfr0[] = {
> ARM64_FTR_END,
> };
>
> +static const struct arm64_ftr_bits ftr_id_aa64dfr1[] = {
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_ABL_CMPs_SHIFT, 8, 0),
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_DPFZS_SHIFT, 4, 0),
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_EBEP_SHIFT, 4, 0),
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_ITE_SHIFT, 4, 0),
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_ABLE_SHIFT, 4, 0),
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_PMICNTR_SHIFT, 4, 0),
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_SPMU_SHIFT, 4, 0),
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_CTX_CMPs_SHIFT, 8, 0),
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_WRPs_SHIFT, 8, 0),
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_BRPs_SHIFT, 8, 0),
> + ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR1_EL1_SYSPMUID_SHIFT, 8, 0),
> + ARM64_FTR_END,
> +};
> +
Is there some general principle that has been applied here? e.g. is this
STRICT unless we know of variation in practice?
e.g. it seems a bit odd that ABLE cannot vary while the number of
breakpoints can...
I suspect we will see systems with mismatched EBEP too, but maybe I'm
wrong.
Mark.
> static const struct arm64_ftr_bits ftr_mvfr0[] = {
> ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, MVFR0_EL1_FPRound_SHIFT, 4, 0),
> ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, MVFR0_EL1_FPShVec_SHIFT, 4, 0),
> @@ -708,10 +723,6 @@ static const struct arm64_ftr_bits ftr_single32[] = {
> ARM64_FTR_END,
> };
>
> -static const struct arm64_ftr_bits ftr_raz[] = {
> - ARM64_FTR_END,
> -};
> -
> #define __ARM64_FTR_REG_OVERRIDE(id_str, id, table, ovr) { \
> .sys_id = id, \
> .reg = &(struct arm64_ftr_reg){ \
> @@ -784,7 +795,7 @@ static const struct __ftr_reg_entry {
>
> /* Op1 = 0, CRn = 0, CRm = 5 */
> ARM64_FTR_REG(SYS_ID_AA64DFR0_EL1, ftr_id_aa64dfr0),
> - ARM64_FTR_REG(SYS_ID_AA64DFR1_EL1, ftr_raz),
> + ARM64_FTR_REG(SYS_ID_AA64DFR1_EL1, ftr_id_aa64dfr1),
>
> /* Op1 = 0, CRn = 0, CRm = 6 */
> ARM64_FTR_REG(SYS_ID_AA64ISAR0_EL1, ftr_id_aa64isar0),
> --
> 2.25.1
>
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