ARM: 6380/1: Introduce __sync_icache_dcache() for VIPT caches

On SMP systems, there is a small chance of a PTE becoming visible to a
different CPU before the current cache maintenance operations in
update_mmu_cache(). To avoid this, cache maintenance must be handled in
set_pte_at() (similar to IA-64 and PowerPC).

This patch provides a unified VIPT cache handling mechanism and
implements the __sync_icache_dcache() function for ARMv6 onwards
architectures. It is called from set_pte_at() and replaces the
update_mmu_cache(). The latter is still used on VIVT hardware where a
vm_area_struct is required.

Tested-by: Rabin Vincent <rabin.vincent@stericsson.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Catalin Marinas 2010-09-13 15:58:06 +01:00 committed by Russell King
parent c01778001a
commit 6012191aa9
4 changed files with 64 additions and 6 deletions

View file

@ -278,9 +278,24 @@ extern struct page *empty_zero_page;
#define set_pte_ext(ptep,pte,ext) cpu_set_pte_ext(ptep,pte,ext)
#define set_pte_at(mm,addr,ptep,pteval) do { \
set_pte_ext(ptep, pteval, (addr) >= TASK_SIZE ? 0 : PTE_EXT_NG); \
} while (0)
#if __LINUX_ARM_ARCH__ < 6
static inline void __sync_icache_dcache(pte_t pteval)
{
}
#else
extern void __sync_icache_dcache(pte_t pteval);
#endif
static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pteval)
{
if (addr >= TASK_SIZE)
set_pte_ext(ptep, pteval, 0);
else {
__sync_icache_dcache(pteval);
set_pte_ext(ptep, pteval, PTE_EXT_NG);
}
}
/*
* The following only work if pte_present() is true.
@ -290,8 +305,13 @@ extern struct page *empty_zero_page;
#define pte_write(pte) (pte_val(pte) & L_PTE_WRITE)
#define pte_dirty(pte) (pte_val(pte) & L_PTE_DIRTY)
#define pte_young(pte) (pte_val(pte) & L_PTE_YOUNG)
#define pte_exec(pte) (pte_val(pte) & L_PTE_EXEC)
#define pte_special(pte) (0)
#define pte_present_user(pte) \
((pte_val(pte) & (L_PTE_PRESENT | L_PTE_USER)) == \
(L_PTE_PRESENT | L_PTE_USER))
#define PTE_BIT_FUNC(fn,op) \
static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }

View file

@ -562,10 +562,18 @@ extern void flush_tlb_kernel_range(unsigned long start, unsigned long end);
/*
* If PG_dcache_clean is not set for the page, we need to ensure that any
* cache entries for the kernels virtual memory range are written
* back to the page.
* back to the page. On ARMv6 and later, the cache coherency is handled via
* the set_pte_at() function.
*/
#if __LINUX_ARM_ARCH__ < 6
extern void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
pte_t *ptep);
#else
static inline void update_mmu_cache(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep)
{
}
#endif
#endif

View file

@ -28,6 +28,7 @@
static unsigned long shared_pte_mask = L_PTE_MT_BUFFERABLE;
#if __LINUX_ARM_ARCH__ < 6
/*
* We take the easy way out of this problem - we make the
* PTE uncacheable. However, we leave the write buffer on.
@ -168,10 +169,8 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
return;
mapping = page_mapping(page);
#ifndef CONFIG_SMP
if (!test_and_set_bit(PG_dcache_clean, &page->flags))
__flush_dcache_page(mapping, page);
#endif
if (mapping) {
if (cache_is_vivt())
make_coherent(mapping, vma, addr, ptep, pfn);
@ -179,6 +178,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
__flush_icache_all();
}
}
#endif /* __LINUX_ARM_ARCH__ < 6 */
/*
* Check whether the write buffer has physical address aliasing

View file

@ -215,6 +215,36 @@ static void __flush_dcache_aliases(struct address_space *mapping, struct page *p
flush_dcache_mmap_unlock(mapping);
}
#if __LINUX_ARM_ARCH__ >= 6
void __sync_icache_dcache(pte_t pteval)
{
unsigned long pfn;
struct page *page;
struct address_space *mapping;
if (!pte_present_user(pteval))
return;
if (cache_is_vipt_nonaliasing() && !pte_exec(pteval))
/* only flush non-aliasing VIPT caches for exec mappings */
return;
pfn = pte_pfn(pteval);
if (!pfn_valid(pfn))
return;
page = pfn_to_page(pfn);
if (cache_is_vipt_aliasing())
mapping = page_mapping(page);
else
mapping = NULL;
if (!test_and_set_bit(PG_dcache_clean, &page->flags))
__flush_dcache_page(mapping, page);
/* pte_exec() already checked above for non-aliasing VIPT cache */
if (cache_is_vipt_nonaliasing() || pte_exec(pteval))
__flush_icache_all();
}
#endif
/*
* Ensure cache coherency between kernel mapping and userspace mapping
* of this page.