linux-kernel - [PATCH 50/52] arm: Invalidate icache on prefetch abort outside of user mapping on Cortex-A15

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Date:   Mon, 26 Feb 2018 16:20:24 +0800
From:   Alex Shi <alex.shi@...aro.org>
To:     Marc Zyngier <marc.zyngier@....com>,
        Will Deacon <will.deacon@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        stable@...r.kernel.org, Russell King <linux@...linux.org.uk>,
        linux-arm-kernel@...ts.infradead.org (moderated list:ARM PORT),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 50/52] arm: Invalidate icache on prefetch abort outside of user mapping on Cortex-A15

From: Marc Zyngier <marc.zyngier@....com>

** Not yet queued for inclusion in mainline **

In order to prevent aliasing attacks on the branch predictor,
invalidate the icache on Cortex-A15, which has the side effect
of invalidating the BTB. This requires ACTLR[0] to be set to 1
(secure operation).

Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Alex Shi <alex.shi@...aro.org>
---
 arch/arm/include/asm/cp15.h | 1 +
 arch/arm/mm/fault.c         | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/arch/arm/include/asm/cp15.h b/arch/arm/include/asm/cp15.h
index 0672ddc..b74b174 100644
--- a/arch/arm/include/asm/cp15.h
+++ b/arch/arm/include/asm/cp15.h
@@ -65,6 +65,7 @@
 #define write_sysreg(v, ...)		__write_sysreg(v, __VA_ARGS__)
 
 #define BPIALL				__ACCESS_CP15(c7, 0, c5, 6)
+#define ICIALLU				__ACCESS_CP15(c7, 0, c5, 0)
 
 extern unsigned long cr_alignment;	/* defined in entry-armv.S */
 
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 17fd0c7..a9c924b 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -409,6 +409,10 @@ do_pabt_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 		case ARM_CPU_PART_CORTEX_A17:
 			write_sysreg(0, BPIALL);
 			break;
+
+		case ARM_CPU_PART_CORTEX_A15:
+			write_sysreg(0, ICIALLU);
+			break;
 		}
 	}
 #endif
-- 
2.7.4