[PATCH 0/4] Patches for -next
Catalin Marinas
catalin.marinas at arm.com
Thu May 27 07:04:24 EDT 2010
On Wed, 2010-05-26 at 19:28 +0100, Russell King - ARM Linux wrote:
> On Wed, May 26, 2010 at 02:06:35PM +0100, Catalin Marinas wrote:
> > +#ifdef CONFIG_SMP
> > +void __sync_icache_dcache(pte_t pteval)
> > +{
> > + struct page *page = pte_page(pteval);
> > + struct address_space *mapping = page_mapping(page);
>
> Err. no. You're assuming that the physical page associated with the
> PTE always has a struct page. What if it's a device mapping? What
> if it's a mapping for some memory which isn't being handled by the
> kernel?
>
> You want this to be:
>
> unsigned long pfn = pte_pfn(pteval);
>
> if (pfn_valid(pfn)) {
> struct page *page = pfn_to_page(pfn);
> struct address_space *mapping = page_mapping(page);
BTW, if we only target non-aliasing VIPT hardware, is there a need for
"mapping" above? See below for an updated patch. I got some ideas from
IA-64 to do additional checks on pteval before deciding to flush the
cache. With this change, the D-cache won't be flushed at all for a page
cache page which is not mapped as executable (update_mmu_cache is a
no-op). It shouldn't matter since we don't have aliases.
ARM: Synchronise the I and D caches via set_pte_at() on SMP systems
From: Catalin Marinas <catalin.marinas at arm.com>
On SMP systems, there is a small chance of a PTE becoming visible to a
different CPU before the cache maintenance operations in
update_mmu_cache(). This patch follows the IA-64 and PowerPC approach of
synchronising the I and D caches via the set_pte_at() function. In this
case, there is no need for update_mmu_cache() to be implemented since
lazy cache flushing is already handled by the time this function is
called.
Signed-off-by: Catalin Marinas <catalin.marinas at arm.com>
---
arch/arm/include/asm/pgtable.h | 25 ++++++++++++++++++++++---
arch/arm/include/asm/tlbflush.h | 10 +++++++++-
arch/arm/mm/fault-armv.c | 2 ++
arch/arm/mm/flush.c | 15 +++++++++++++++
4 files changed, 48 insertions(+), 4 deletions(-)
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index ab68cf1..a3752f5 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -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)
+#ifndef CONFIG_SMP
+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.
@@ -292,6 +307,10 @@ extern struct page *empty_zero_page;
#define pte_young(pte) (pte_val(pte) & L_PTE_YOUNG)
#define pte_special(pte) (0)
+#define pte_present_exec_user(pte) \
+ ((pte_val(pte) & (L_PTE_PRESENT | L_PTE_EXEC | L_PTE_USER)) == \
+ (L_PTE_PRESENT | L_PTE_EXEC | L_PTE_USER))
+
#define PTE_BIT_FUNC(fn,op) \
static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }
diff --git a/arch/arm/include/asm/tlbflush.h b/arch/arm/include/asm/tlbflush.h
index 40a7092..6aabedd 100644
--- a/arch/arm/include/asm/tlbflush.h
+++ b/arch/arm/include/asm/tlbflush.h
@@ -554,10 +554,18 @@ 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 SMP systems, the cache coherency is handled in the
+ * set_pte_at() function.
*/
+#ifndef CONFIG_SMP
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
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index 91a691f..030f1da 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -28,6 +28,7 @@
static unsigned long shared_pte_mask = L_PTE_MT_BUFFERABLE;
+#ifndef CONFIG_SMP
/*
* We take the easy way out of this problem - we make the
* PTE uncacheable. However, we leave the write buffer on.
@@ -177,6 +178,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
__flush_icache_all();
}
}
+#endif /* !CONFIG_SMP */
/*
* Check whether the write buffer has physical address aliasing
diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
index 6f55e36..2d08a5e 100644
--- a/arch/arm/mm/flush.c
+++ b/arch/arm/mm/flush.c
@@ -212,6 +212,21 @@ static void __flush_dcache_aliases(struct address_space *mapping, struct page *p
flush_dcache_mmap_unlock(mapping);
}
+#ifdef CONFIG_SMP
+void __sync_icache_dcache(pte_t pteval)
+{
+ unsigned long pfn = pte_pfn(pteval);
+
+ if (pfn_valid(pfn) && pte_present_exec_user(pteval)) {
+ struct page *page = pfn_to_page(pfn);
+
+ if (!test_and_set_bit(PG_dcache_clean, &page->flags))
+ __flush_dcache_page(NULL, page);
+ __flush_icache_all();
+ }
+}
+#endif
+
/*
* Ensure cache coherency between kernel mapping and userspace mapping
* of this page.
--
Catalin
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