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From: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
To: barebox@lists.infradead.org
Cc: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
Subject: [PATCH 2/2] ARM: MMU: fixed calculation of number of PTEs
Date: Thu, 17 Sep 2015 12:45:11 +0200	[thread overview]
Message-ID: <1442486711-6841-2-git-send-email-enrico.scholz@sigma-chemnitz.de> (raw)
In-Reply-To: <lya8smdz5d.fsf@ensc-virt.intern.sigma-chemnitz.de>

barebox uses 4KiB pages so that number of PTEs is 'size >> 12', not
'size >> 10'.

Thie 'size >> 10' limit is not an immediate problem because it allocates
too much PTEs only which are not used.  But it can overflow an integer
multiplication ('i * PAGE_SIZE') which causes undefined behaviour with
gcc5.

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
---
 arch/arm/cpu/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/cpu/mmu.c b/arch/arm/cpu/mmu.c
index 8ceb450..014bba2 100644
--- a/arch/arm/cpu/mmu.c
+++ b/arch/arm/cpu/mmu.c
@@ -213,7 +213,7 @@ static int arm_mmu_remap_sdram(struct memory_bank *bank)
 	unsigned long phys = (unsigned long)bank->start;
 	unsigned long ttb_start = phys >> 20;
 	unsigned long ttb_end = (phys >> 20) + (bank->size >> 20);
-	unsigned long num_ptes = bank->size >> 10;
+	unsigned long num_ptes = bank->size >> 12;
 	int i, pte;
 	u32 *ptes;
 
-- 
2.4.3


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      parent reply	other threads:[~2015-09-17 10:46 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-16 17:58 ARM: gcc5 causes undefined behaviour in mmu_init() Enrico Scholz
2015-09-17 10:45 ` [PATCH 1/2] ARM: MMU: fixed dma_flush_range() call Enrico Scholz
2015-09-21  6:11   ` Sascha Hauer
2015-09-17 10:45 ` Enrico Scholz [this message]

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