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arm: mm: introduce special ptes for LPAE 

We need a mechanism to tag ptes as being special, this indicates that no
attempt should be made to access the underlying struct page * associated
with the pte.  This is used by the fast_gup when operating on ptes as it
has no means to access VMAs (that also contain this information)
locklessly.

The L_PTE_SPECIAL bit is already allocated for LPAE, this patch modifies
pte_special and pte_mkspecial to make use of it, and defines
__HAVE_ARCH_PTE_SPECIAL.

This patch also excludes special ptes from the icache/dcache sync logic.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Steve Capper 2014-10-09 15:29:16 -07:00 committed by Linus Torvalds
parent 2667f50e8b
commit bd951303be
3 changed files with 11 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/arm/include/asm/pgtable-2level.h
View File

@ -182,6 +182,8 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
#define pmd_addr_end(addr,end) (end)
#define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,pte,ext)
#define pte_special(pte) (0)
static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
/*
* We don't have huge page support for short descriptors, for the moment

7
arch/arm/include/asm/pgtable-3level.h
View File

@ -213,6 +213,13 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
#define pmd_isclear(pmd, val) (!(pmd_val(pmd) & (val)))
#define pmd_young(pmd) (pmd_isset((pmd), PMD_SECT_AF))
#define pte_special(pte) (pte_isset((pte), L_PTE_SPECIAL))
static inline pte_t pte_mkspecial(pte_t pte)
{
pte_val(pte) |= L_PTE_SPECIAL;
return pte;
}
#define __HAVE_ARCH_PTE_SPECIAL
#define __HAVE_ARCH_PMD_WRITE
#define pmd_write(pmd) (pmd_isclear((pmd), L_PMD_SECT_RDONLY))

6
arch/arm/include/asm/pgtable.h
View File

@ -226,7 +226,6 @@ static inline pte_t *pmd_page_vaddr(pmd_t pmd)
#define pte_dirty(pte) (pte_isset((pte), L_PTE_DIRTY))
#define pte_young(pte) (pte_isset((pte), L_PTE_YOUNG))
#define pte_exec(pte) (pte_isclear((pte), L_PTE_XN))
#define pte_special(pte) (0)
#define pte_valid_user(pte) \
(pte_valid(pte) && pte_isset((pte), L_PTE_USER) && pte_young(pte))
@ -245,7 +244,8 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
unsigned long ext = 0;
if (addr < TASK_SIZE && pte_valid_user(pteval)) {
__sync_icache_dcache(pteval);
if (!pte_special(pteval))
__sync_icache_dcache(pteval);
ext |= PTE_EXT_NG;
}
@ -264,8 +264,6 @@ PTE_BIT_FUNC(mkyoung, |= L_PTE_YOUNG);
PTE_BIT_FUNC(mkexec, &= ~L_PTE_XN);
PTE_BIT_FUNC(mknexec, |= L_PTE_XN);
static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER |