From mboxrd@z Thu Jan 1 00:00:00 1970 From: andre.przywara@arm.com (Andre Przywara) Date: Wed, 01 Apr 2015 10:27:32 +0100 Subject: [PATCH] arm64: fix midr range for Cortex-A57 erratum 832075 In-Reply-To: <20150401092229.GC1552@arm.com> References: <1427833848-12188-1-git-send-email-byan@nvidia.com> <20150401092229.GC1552@arm.com> Message-ID: <551BBA04.3030402@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 01/04/15 10:22, Will Deacon wrote: > On Tue, Mar 31, 2015 at 10:17:21PM +0100, Paul Walmsley wrote: >> On Tue, 31 Mar 2015, Bo Yan wrote: >> >>> Register MIDR_EL1 is masked to get variant and revision fields, then >>> compared against midr_range_min and midr_range_max when checking >>> whether CPU is affected by any particular erratum. However, variant >>> and revision fields in MIDR_EL1 are separated by 16 bits, so the min >>> and max of midr range should be constructed accordingly, otherwise >>> the patch will not be applied when variant field is non-0. Ah yes, good catch, thank you! >>> >>> Signed-off-by: Bo Yan >>> --- >>> arch/arm64/kernel/cpu_errata.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c >>> index fa62637e63a8..7838f1578019 100644 >>> --- a/arch/arm64/kernel/cpu_errata.c >>> +++ b/arch/arm64/kernel/cpu_errata.c >>> @@ -88,7 +88,7 @@ struct arm64_cpu_capabilities arm64_errata[] = { >>> /* Cortex-A57 r0p0 - r1p2 */ >>> .desc = "ARM erratum 832075", >>> .capability = ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE, >>> - MIDR_RANGE(MIDR_CORTEX_A57, 0x00, 0x12), >>> + MIDR_RANGE(MIDR_CORTEX_A57, 0x00, 0x100002), >>> }, >>> #endif >>> { >>> -- >>> 2.1.4 >> >> Reviewed-by: Paul Walmsley >> >> Reviewed against DDI0488G section 4.3.1 "Main ID Register, EL1". Looks >> like a cut-and-paste error from the A53 workarounds. > > Thanks guys, I agree that this is a bug. I'll apply this, but using an > explicit shift to set the variant (tweaked version below). > > Will > > --->8 > > diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c > index a66f4fa4d541..c998345a052f 100644 > --- a/arch/arm64/kernel/cpu_errata.c > +++ b/arch/arm64/kernel/cpu_errata.c > @@ -70,7 +70,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = { > /* Cortex-A57 r0p0 - r1p2 */ > .desc = "ARM erratum 832075", > .capability = ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE, > - MIDR_RANGE(MIDR_CORTEX_A57, 0x00, 0x12), > + MIDR_RANGE(MIDR_CORTEX_A57, 0x00, (1 << MIDR_VARIANT_SHIFT) | 2, > }, > #endif > { > I like this version more: Acked-by: Andre Przywara Cheers, Andre.