Subject: [PATCH v5 2/2] arm64: Work around Falkor erratum 1009

From: [email-masked] (Christopher Covington)
Date: Mon, 30 Jan 2017 18:08:17 -0500

During a TLB invalidate sequence targeting the inner shareable domain,
Falkor may prematurely complete the DSB before all loads and stores using
the old translation are observed. Instruction fetches are not subject to
the conditions of this erratum. If the original code sequence includes
multiple TLB invalidate instructions followed by a single DSB, onle one of
the TLB instructions needs to be repeated to work around this erratum.
While the erratum only applies to cases in which the TLBI specifies the
inner-shareable domain (*IS form of TLBI) and the DSB is ISH form or
stronger (OSH, SYS), this changes applies the workaround overabundantly--
to local TLBI, DSB NSH sequences as well--for simplicity.

Based on work by Shanker Donthineni <[email-masked]>

Signed-off-by: Christopher Covington <[email-masked]>
---
Based on https://git.kernel.org/cgit/linux/kernel/git/arm64/linux.git/log/?h=for-next/core
---
 Documentation/arm64/silicon-errata.txt |  1 +
 arch/arm64/Kconfig                     | 10 ++++++++++
 arch/arm64/include/asm/cpucaps.h       |  3 ++-
 arch/arm64/include/asm/tlbflush.h      | 18 +++++++++++++++---
 arch/arm64/kernel/cpu_errata.c         |  9 +++++++++
 5 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 06a516af5103..50da8391e9dd 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -64,3 +64,4 @@ stable kernels.
 |                |                 |                 |                         |
 | Freescale/NXP  | LS2080A/LS1043A | A-008585        | FSL_ERRATUM_A008585     |
 | Qualcomm Tech. | Falkor v1       | E1003           | QCOM_FALKOR_ERRATUM_1003|
+| Qualcomm Tech. | Falkor v1       | E1009           | QCOM_FALKOR_ERRATUM_1009|
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 33a8b16ba864..b5284a79bada 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -491,6 +491,16 @@ config QCOM_FALKOR_ERRATUM_1003
 
 	  If unsure, say Y.
 
+config QCOM_FALKOR_ERRATUM_1009
+	bool "Falkor E1009: Prematurely complete a DSB after a TLBI"
+	default y
+	help
+	  On Falkor v1, the CPU may prematurely complete a DSB following a
+	  TLBI xxIS invalidate maintenance operation. Repeat the TLBI operation
+	  one more time to fix the issue.
+
+	  If unsure, say Y.
+
 endmenu

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 5aaf7eede432..55bcd02e4a3f 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -36,7 +36,8 @@
 #define ARM64_MISMATCHED_CACHE_LINE_SIZE	15
 #define ARM64_HAS_NO_FPSIMD			16
 #define ARM64_WORKAROUND_QCOM_FALKOR_E1003	17
+#define ARM64_WORKAROUND_REPEAT_TLBI		18
 
-#define ARM64_NCAPS				18
+#define ARM64_NCAPS				19
 
 #endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index deab52374119..fc434f421c7b 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -36,9 +36,21 @@
  * not. The macros handles invoking the asm with or without the
  * register argument as appropriate.
  */
-#define __TLBI_0(op, arg)		asm ("tlbi " #op)
-#define __TLBI_1(op, arg)		asm ("tlbi " #op ", %0" : : "r" (arg))
-#define __TLBI_N(op, arg, n, ...)	__TLBI_##n(op, arg)
+#define __TLBI_0(op, arg) asm volatile ("tlbi " #op "\n"		       \
+			    ALTERNATIVE("nop\n		nop",		       \
+					"dsb ish\n	tlbi " #op,	       \
+					ARM64_WORKAROUND_REPEAT_TLBI,	       \
+					CONFIG_QCOM_FALKOR_ERRATUM_1009)       \
+			    : : )
+
+#define __TLBI_1(op, arg) asm volatile ("tlbi " #op ", %0\n"		       \
+			    ALTERNATIVE("nop\n		nop",		       \
+					"dsb ish\n	tlbi " #op ", %0",     \
+					ARM64_WORKAROUND_REPEAT_TLBI,	       \
+					CONFIG_QCOM_FALKOR_ERRATUM_1009)       \
+			    : : "r" (arg))
+
+#define __TLBI_N(op, arg, n, ...) __TLBI_##n(op, arg)
 
 #define __tlbi(op, ...)		__TLBI_N(op, ##__VA_ARGS__, 1, 0)
 
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 502a79f211b0..f6cc67e7626e 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -142,6 +142,15 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 			   MIDR_CPU_VAR_REV(0, 0)),
 	},
 #endif
+#ifdef CONFIG_QCOM_FALKOR_ERRATUM_1009
+	{
+		.desc = "Qualcomm Technologies Falkor erratum 1009",
+		.capability = ARM64_WORKAROUND_REPEAT_TLBI,
+		MIDR_RANGE(MIDR_QCOM_FALKOR_V1,
+			   MIDR_CPU_VAR_REV(0, 0),
+			   MIDR_CPU_VAR_REV(0, 0)),
+	},
+#endif
 	{
 	}
 };
-- 
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Forum, a Linux Foundation Collaborative Project.