linux-kernel - [PATCH] ARM: LPAE: initialize cachepolicy correctly

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Message-Id: <20160904053331.7264-1-stefan@agner.ch>
Date:   Sat,  3 Sep 2016 22:33:31 -0700
From:   Stefan Agner <stefan@...er.ch>
To:     linux@...linux.org.uk
Cc:     ard.biesheuvel@...aro.org, matt@...eblueprint.co.uk,
        kirill.shutemov@...ux.intel.com, l.stach@...gutronix.de,
        arnd@...db.de, nicolas.pitre@...aro.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Stefan Agner <stefan@...er.ch>
Subject: [PATCH] ARM: LPAE: initialize cachepolicy correctly

The cachepolicy variable gets initialized using a masked pmd
So far, the pmd has been masked with flags valid for the 2-page
table format. In the LPAE case, this lead to a wrong assumption
of what the initial cachepolicy has been used. Later a check
forces the cache policy to writealloc and prints the following
warning:
Forcing write-allocate cache policy for SMP

This patch uses PMD_SECT_WBWA to mask all cache setting flags.
The define represents the complete mask of the cache relevant
flags for both page table formats.

Signed-off-by: Stefan Agner <stefan@...er.ch>
---
 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 724d6be..241e5e2 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -137,7 +137,7 @@ void __init init_default_cache_policy(unsigned long pmd)

 	initial_pmd_value = pmd;

-	pmd &= PMD_SECT_TEX(1) | PMD_SECT_BUFFERABLE | PMD_SECT_CACHEABLE;
+	pmd &= PMD_SECT_WBWA;

 	for (i = 0; i < ARRAY_SIZE(cache_policies); i++)
 		if (cache_policies[i].pmd == pmd) {
-- 
2.9.0