linux-kernel - [PATCH 1/8] arm64: Set the safe value for L1 icache policy

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Message-Id: <1467977839-27543-2-git-send-email-suzuki.poulose@arm.com>
Date:	Fri,  8 Jul 2016 12:37:10 +0100
From:	Suzuki K Poulose <suzuki.poulose@....com>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org, catalin.marinas@....com,
	mark.rutland@....com, will.deacon@....com,
	Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH 1/8] arm64: Set the safe value for L1 icache policy

Right now we use 0 as the safe value for CTR_EL0:L1Ip, which is
not defined at the moment. The safer value for the L1Ip should be
the weakest of the policies, which happens to be AIVIVT. While at it,
fix the comment about safe_val.

Cc: Mark Rutland <mark.rutland@....com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will.deacon@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 arch/arm64/include/asm/cpufeature.h | 2 +-
 arch/arm64/kernel/cpufeature.c      | 5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 49dd1bd..2926c7d 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -62,7 +62,7 @@ struct arm64_ftr_bits {
 	enum ftr_type	type;
 	u8		shift;
 	u8		width;
-	s64		safe_val; /* safe value for discrete features */
+	s64		safe_val; /* safe value for FTR_EXACT features */
 };
 
 /*
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 916d27a..3566b6d 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -147,9 +147,10 @@ static struct arm64_ftr_bits ftr_ctr[] = {
 	ARM64_FTR_BITS(FTR_STRICT, FTR_LOWER_SAFE, 16, 4, 1),	/* DminLine */
 	/*
 	 * Linux can handle differing I-cache policies. Userspace JITs will
-	 * make use of *minLine
+	 * make use of *minLine.
+	 * If we have differing I-cache policies, report it as the weakest - AIVIVT.
 	 */
-	ARM64_FTR_BITS(FTR_NONSTRICT, FTR_EXACT, 14, 2, 0),	/* L1Ip */
+	ARM64_FTR_BITS(FTR_NONSTRICT, FTR_EXACT, 14, 2, ICACHE_POLICY_AIVIVT),	/* L1Ip */
 	ARM64_FTR_BITS(FTR_STRICT, FTR_EXACT, 4, 10, 0),	/* RAZ */
 	ARM64_FTR_BITS(FTR_STRICT, FTR_LOWER_SAFE, 0, 4, 0),	/* IminLine */
 	ARM64_FTR_END,
-- 
2.7.4