From: Gregory CLEMENT <gregory.clement@bootlin.com>
To: Russell King <linux@armlinux.org.uk>, Arnd Bergmann <arnd@arndb.de>
Cc: Gregory CLEMENT <gregory.clement@bootlin.com>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 4/6] ARM: mm: Aligned pte allocation to one page
Date: Thu, 11 Jun 2020 15:49:12 +0200 [thread overview]
Message-ID: <20200611134914.765827-5-gregory.clement@bootlin.com> (raw)
In-Reply-To: <20200611134914.765827-1-gregory.clement@bootlin.com>
In pte_offset_kernel() the pte_index macro is used. This macro makes
the assumption that the address is aligned to a page size.
In arm_pte_allocation, the size allocated is the size needed for 512
entries. Actually this size was calculated to fit in a 4K page. When
using larger page, the size of the table allocated is no more
aligned which end to give a wrong physical address.
The solution is to round up the allocation to a page size instead of
the exact size of the tables (which is 4KB). It allows to comply with
the assumption of pte_index() but the drawback is a waste of memory
for the early allocation if page size is bigger than 4KB.
This is inspired from fa0ca2726ea9 ("DSMP 64K support") and
4ef803e12baf ("mmu: large-page: Added support for multiple kernel page
sizes") from
https://github.com/MarvellEmbeddedProcessors/linux-marvell.git
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
---
arch/arm/mm/mmu.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index ec8d0008bfa1..b7fdea7e0cbe 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -715,7 +715,9 @@ static pte_t * __init arm_pte_alloc(pmd_t *pmd, unsigned long addr,
void *(*alloc)(unsigned long sz))
{
if (pmd_none(*pmd)) {
- pte_t *pte = alloc(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE);
+ /* The PTE needs to be page to be page aligned */
+ pte_t *pte = alloc(round_up(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE,
+ PAGE_SIZE));
__pmd_populate(pmd, __pa(pte), prot);
}
BUG_ON(pmd_bad(*pmd));
--
2.26.2
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next prev parent reply other threads:[~2020-06-11 13:50 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-11 13:49 [PATCH v2 0/6] ARM: Add support for large kernel page (from 8K to 64K) Gregory CLEMENT
2020-06-11 13:49 ` [PATCH v2 1/6] ARM: Use PAGE_SIZE for ELF_EXEC_PAGESIZE Gregory CLEMENT
2020-06-12 8:22 ` Arnd Bergmann
2020-06-12 8:35 ` Russell King - ARM Linux admin
2020-06-12 8:46 ` Arnd Bergmann
2020-06-12 8:50 ` Russell King - ARM Linux admin
2020-06-12 11:50 ` Catalin Marinas
2020-06-12 12:06 ` Gregory CLEMENT
2020-06-12 8:52 ` Gregory CLEMENT
2020-06-11 13:49 ` [PATCH v2 2/6] ARM: pagetable: prepare hardware page table to use large page Gregory CLEMENT
2020-06-11 13:49 ` [PATCH v2 3/6] ARM: Make the number of fix bitmap depend on the page size Gregory CLEMENT
2020-06-11 13:49 ` Gregory CLEMENT [this message]
2020-06-12 8:37 ` [PATCH v2 4/6] ARM: mm: Aligned pte allocation to one page Arnd Bergmann
2020-06-12 10:25 ` Catalin Marinas
2020-06-12 11:56 ` Gregory CLEMENT
2020-06-11 13:49 ` [PATCH v2 5/6] ARM: Add large kernel page support Gregory CLEMENT
2020-06-11 13:49 ` [PATCH v2 6/6] ARM: Add 64K page support at MMU level Gregory CLEMENT
2020-06-11 16:21 ` [PATCH v2 0/6] ARM: Add support for large kernel page (from 8K to 64K) Russell King - ARM Linux admin
2020-06-12 9:15 ` Gregory CLEMENT
2020-06-12 9:23 ` Arnd Bergmann
2020-06-12 12:21 ` Catalin Marinas
2020-06-12 12:49 ` Arnd Bergmann
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