linux-kernel - [PATCH 7/8] membarrier: Remove arm (32) support for SYNC

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Message-Id: <2142129092ff9aa00e600c42a26c4015b7f5ceec.1623813516.git.luto@kernel.org>
Date:   Tue, 15 Jun 2021 20:21:12 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     x86@...nel.org
Cc:     Dave Hansen <dave.hansen@...el.com>,
        LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Russell King <linux@...linux.org.uk>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 7/8] membarrier: Remove arm (32) support for SYNC_CORE

On arm32, the only way to safely flush icache from usermode is to call
cacheflush(2).  This also handles any required pipeline flushes, so
membarrier's SYNC_CORE feature is useless on arm.  Remove it.

Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Russell King <linux@...linux.org.uk>
Cc: linux-arm-kernel@...ts.infradead.org
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 arch/arm/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 24804f11302d..89a885fba724 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -10,7 +10,6 @@ config ARM
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_KEEPINITRD
 	select ARCH_HAS_KCOV
-	select ARCH_HAS_MEMBARRIER_SYNC_CORE
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_PTE_SPECIAL if ARM_LPAE
 	select ARCH_HAS_PHYS_TO_DMA
-- 
2.31.1