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Date: Mon, 10 Dec 2012 19:40:06 +0530 From: Santosh Shilimkar <santosh.shilimkar@...com> To: "'Russell King'" <linux@....linux.org.uk>, "'Catalin Marinas'" <Catalin.Marinas@....com> CC: Boojin Kim <boojin.kim@...sung.com>, <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>, "'Will Deacon'" <will.deacon@....com>, "'Kukjin Kim'" <kgene.kim@...sung.com> Subject: Re: [PATCH 1/3] ARM: MM: Add the workaround of Errata 774769 On Monday 10 December 2012 05:28 AM, Boojin Kim wrote: > This patch adds the workaround of Errata 774769 that configures write streaming > on versions of A15 affected by this erratum such that no streaming-write ever > allocates into the L2 cache. > > Signed-off-by: Boojin Kim <boojin.kim@...sung.com> > --- > arch/arm/Kconfig | 11 +++++++++++ > arch/arm/mach-exynos/Kconfig | 1 + > arch/arm/mm/proc-v7.S | 16 ++++++++++++++-- > 3 files changed, 26 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 9759fec..11a57e2 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -1417,6 +1417,17 @@ config ARM_ERRATA_775420 > to deadlock. This workaround puts DSB before executing ISB if > an abort may occur on cache maintenance. > > +config ARM_ERRATA_774769 > + bool "ARM errata: data corruption may occur with store streaming in a system" > + depends on CPU_V7 > + help > + This option enables the workaround for the erratum 774769 affecting > + Cortex-A15 (r0p4). > + External memory may be corrupted on erratum 774769. > + The workaround is to configure write streaming on versions of A15 > + affected by this erratum such that no streaming-write ever allocates > + into the L2 cache. > + > endmenu > > source "arch/arm/common/Kconfig" > diff --git a/arch/arm/mach-exynos/Kconfig b/arch/arm/mach-exynos/Kconfig > index da55107..e1168fb 100644 > --- a/arch/arm/mach-exynos/Kconfig > +++ b/arch/arm/mach-exynos/Kconfig > @@ -22,6 +22,7 @@ config ARCH_EXYNOS4 > config ARCH_EXYNOS5 > bool "SAMSUNG EXYNOS5" > select HAVE_SMP > + select ARM_ERRATA_774769 > help > Samsung EXYNOS5 (Cortex-A15) SoC based systems > > diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S > index 846d279..06cbdfa 100644 > --- a/arch/arm/mm/proc-v7.S > +++ b/arch/arm/mm/proc-v7.S > @@ -208,7 +208,7 @@ __v7_setup: > orreq r10, r10, #(1 << 22) @ set the Write Allocate disable bit > mcreq p15, 1, r10, c9, c0, 2 @ write the L2 cache aux ctrl register > #endif > - b 3f > + b 4f > > /* Cortex-A9 Errata */ > 2: ldr r10, =0x00000c09 @ Cortex-A9 primary part number > @@ -243,8 +243,20 @@ __v7_setup: > mcrlt p15, 0, r10, c15, c0, 1 @ write diagnostic register > 1: > #endif > + b 4f > > -3: mov r10, #0 > + /* Cortex-A15 Errata */ > +3: ldr r10, =0x00000c0f @ Cortex-A15 primary part number > + teq r0, r10 > + bne 4f > +#ifdef CONFIG_ARM_ERRATA_774769 > + teq r6, #0x4 @ present in r0p4 > + mrceq p15, 0, r10, c1, c0, 1 @ read aux control register > + orreq r10, r10, #1 << 25 @ set bit #25 > + mcreq p15, 0, r10, c1, c0, 1 @ write aux control register This will fault on kernels booted in non-secure mode. The comment is applicable for other two patches in series as well. Russell/Catalin, Whats the stand on such erratas ? I saw on one of thread one of you suggesting to stop patching kernel where secure/non-secure kernel will need different errata WA. Regards Santosh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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