linux-kernel - [PATCH 4.4 045/131] ARM: 8494/1: mm: Enable PXN when running non-LPAE kernel on LPAE processor

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Message-Id: <20190401170056.076456035@linuxfoundation.org>
Date:   Mon,  1 Apr 2019 19:01:55 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jungseung Lee <js07.lee@...sung.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Ben Hutchings <ben@...adent.org.uk>,
        Russell King <rmk+kernel@....linux.org.uk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 045/131] ARM: 8494/1: mm: Enable PXN when running non-LPAE kernel on LPAE processor

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit ad84f56bf6d620fe6ed4d57ce6ec9945684d7f35 ]

The VMSA field of MMFR0 (bottom 4 bits) is incremented for each
added feature.  PXN is supported if the value is >= 4 and LPAE
is supported if it is >= 5.

In case a kernel with CONFIG_ARM_LPAE disabled is used on a
processor that supports LPAE, we can still use PXN in short
descriptors.  So check for >= 4 not == 4.

Signed-off-by: Jungseung Lee <js07.lee@...sung.com>
Acked-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Russell King <rmk+kernel@....linux.org.uk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm/mm/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index e47cffd25c6c..aead23f15213 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -572,7 +572,7 @@ static void __init build_mem_type_table(void)
 	 * in the Short-descriptor translation table format descriptors.
 	 */
 	if (cpu_arch == CPU_ARCH_ARMv7 &&
-		(read_cpuid_ext(CPUID_EXT_MMFR0) & 0xF) == 4) {
+		(read_cpuid_ext(CPUID_EXT_MMFR0) & 0xF) >= 4) {
 		user_pmd_table |= PMD_PXNTABLE;
 	}
 #endif
-- 
2.19.1