linux-kernel - [PATCH v2] ARM: errata: Workaround errata A12 857271 / A17 857272

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Date:   Tue, 23 Apr 2019 15:59:59 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Russell King <linux@...linux.org.uk>
Cc:     mark.rutland@....com, Salva.Climent@....com,
        marc.w.gonzalez@...e.fr, linux-rockchip@...ts.infradead.org,
        sonnyrao@...omium.org, will.deacon@....com, bbatacha@....com,
        mka@...omium.org, robin.murphy@....com, heiko@...ech.de,
        Douglas Anderson <dianders@...omium.org>,
        linux-arm-kernel@...ts.infradead.org,
        Arnd Bergmann <arnd@...db.de>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-kernel@...r.kernel.org, Paul Burton <paul.burton@...s.com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tony Lindgren <tony@...mide.com>
Subject: [PATCH v2] ARM: errata: Workaround errata A12 857271 / A17 857272

This adds support for working around errata A12 857271 / A17 857272.
These errata were causing hangs on rk3288-based Chromebooks and it was
confirmed that this workaround fixed the problems.  In the Chrome OS
3.14 kernel this was treated as two errata: ERRATA_FOOBAR [1] and
ERRATA_CR711784 [2].  Apparently the two errata got lumped together at
some point in time.

Let's actually get the workaround landed.

[1] https://crrev.com/c/342753
[2] https://crbug.com/711784

Signed-off-by: Douglas Anderson <dianders@...omium.org>
Signed-off-by: Sonny Rao <sonnyrao@...omium.org>
---

Changes in v2:
- Squashed bits 10 and 11 into one errata.

 arch/arm/Kconfig      | 18 ++++++++++++++++++
 arch/arm/mm/proc-v7.S | 10 ++++++++++
 2 files changed, 28 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index b509cd338219..59fdcd51d7ee 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1172,6 +1172,14 @@ config ARM_ERRATA_825619
 	  DMB NSHST or DMB ISHST instruction followed by a mix of Cacheable
 	  and Device/Strongly-Ordered loads and stores might cause deadlock
 
+config ARM_ERRATA_857271
+	bool "ARM errata: A12: CPU might deadlock under some very rare internal conditions"
+	depends on CPU_V7
+	help
+	  This option enables the workaround for the 857271 Cortex-A12
+	  (all revs) erratum. Under very rare timing conditions, the CPU might
+	  hang. The workaround is expected to have a < 1% performance impact.
+
 config ARM_ERRATA_852421
 	bool "ARM errata: A17: DMB ST might fail to create order between stores"
 	depends on CPU_V7
@@ -1193,6 +1201,16 @@ config ARM_ERRATA_852423
 	  config option from the A12 erratum due to the way errata are checked
 	  for and handled.
 
+config ARM_ERRATA_857272
+	bool "ARM errata: A17: CPU might deadlock under some very rare internal conditions"
+	depends on CPU_V7
+	help
+	  This option enables the workaround for the 857272 Cortex-A17 erratum.
+	  This erratum is not known to be fixed in any A17 revision.
+	  This is identical to Cortex-A12 erratum 857271.  It is a separate
+	  config option from the A12 erratum due to the way errata are checked
+	  for and handled.
+
 endmenu
 
 source "arch/arm/common/Kconfig"
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 339eb17c9808..2966086d8a45 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -391,6 +391,11 @@ __ca12_errata:
 	mrc	p15, 0, r10, c15, c0, 1		@ read diagnostic register
 	orr	r10, r10, #1 << 24		@ set bit #24
 	mcr	p15, 0, r10, c15, c0, 1		@ write diagnostic register
+#endif
+#ifdef CONFIG_ARM_ERRATA_857271
+	mrc	p15, 0, r10, c15, c0, 1		@ read diagnostic register
+	orr	r10, r10, #3 << 10		@ set bits #10 and #11
+	mcr	p15, 0, r10, c15, c0, 1		@ write diagnostic register
 #endif
 	b	__errata_finish
 
@@ -406,6 +411,11 @@ __ca17_errata:
 	mrcle	p15, 0, r10, c15, c0, 1		@ read diagnostic register
 	orrle	r10, r10, #1 << 12		@ set bit #12
 	mcrle	p15, 0, r10, c15, c0, 1		@ write diagnostic register
+#endif
+#ifdef CONFIG_ARM_ERRATA_857272
+	mrc	p15, 0, r10, c15, c0, 1		@ read diagnostic register
+	orr	r10, r10, #3 << 10		@ set bits #10 and #11
+	mcr	p15, 0, r10, c15, c0, 1		@ write diagnostic register
 #endif
 	b	__errata_finish
 
-- 
2.21.0.593.g511ec345e18-goog