[RFC PATCH 7/9] ARM64: mm: HugeTLB support.
From: Will Deacon <hidden>
Date: 2013-05-01 11:42:44
Also in:
linux-arch, linux-mm
Hi Steve, On Tue, Apr 30, 2013 at 05:30:46PM +0100, Steve Capper wrote:
Add huge page support to ARM64, different huge page sizes are
supported depending on the size of normal pages:
PAGE_SIZE is 4K:
2MB - (pmds) these can be allocated at any time.
1024MB - (puds) usually allocated on bootup with the command line
with something like: hugepagesz=1G hugepages=6
PAGE_SIZE is 64K:
512MB - (pmds), usually allocated on bootup via command line.[...]
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h index 75fd13d..c3cac68 100644 --- a/arch/arm64/include/asm/pgtable-hwdef.h +++ b/arch/arm64/include/asm/pgtable-hwdef.h@@ -53,6 +53,7 @@ #define PTE_TYPE_MASK (_AT(pteval_t, 3) << 0) #define PTE_TYPE_FAULT (_AT(pteval_t, 0) << 0) #define PTE_TYPE_PAGE (_AT(pteval_t, 3) << 0) +#define PTE_TYPE_HUGEPAGE (_AT(pmdval_t, 1) << 0)
This breaks PROT_NONE mappings, where you get: pte = pte_mkhuge(pte_modify(pte, newprot)); The pte_modify will clear the valid bit and set the prot_none bit (in order to create a present, faulting entry) but then your pte_mkhuge will come in and clobber that with a valid block entry. Will