diff options
author | Ingo Molnar <mingo@elte.hu> | 2009-09-07 08:19:51 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-09-07 08:19:51 +0200 |
commit | a1922ed661ab2c1637d0b10cde933bd9cd33d965 (patch) | |
tree | 0f1777542b385ebefd30b3586d830fd8ed6fda5b /arch/x86/mm/gup.c | |
parent | 75e33751ca8bbb72dd6f1a74d2810ddc8cbe4bdf (diff) | |
parent | d28daf923ac5e4a0d7cecebae56f3e339189366b (diff) |
Merge branch 'tracing/core' into tracing/hw-breakpoints
Conflicts:
arch/Kconfig
kernel/trace/trace.h
Merge reason: resolve the conflicts, plus adopt to the new
ring-buffer APIs.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/mm/gup.c')
-rw-r--r-- | arch/x86/mm/gup.c | 67 |
1 files changed, 64 insertions, 3 deletions
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index 6340cef6798..71da1bca13c 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c @@ -14,7 +14,7 @@ static inline pte_t gup_get_pte(pte_t *ptep) { #ifndef CONFIG_X86_PAE - return *ptep; + return ACCESS_ONCE(*ptep); #else /* * With get_user_pages_fast, we walk down the pagetables without taking @@ -219,6 +219,62 @@ static int gup_pud_range(pgd_t pgd, unsigned long addr, unsigned long end, return 1; } +/* + * Like get_user_pages_fast() except its IRQ-safe in that it won't fall + * back to the regular GUP. + */ +int __get_user_pages_fast(unsigned long start, int nr_pages, int write, + struct page **pages) +{ + struct mm_struct *mm = current->mm; + unsigned long addr, len, end; + unsigned long next; + unsigned long flags; + pgd_t *pgdp; + int nr = 0; + + start &= PAGE_MASK; + addr = start; + len = (unsigned long) nr_pages << PAGE_SHIFT; + end = start + len; + if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ, + (void __user *)start, len))) + return 0; + + /* + * XXX: batch / limit 'nr', to avoid large irq off latency + * needs some instrumenting to determine the common sizes used by + * important workloads (eg. DB2), and whether limiting the batch size + * will decrease performance. + * + * It seems like we're in the clear for the moment. Direct-IO is + * the main guy that batches up lots of get_user_pages, and even + * they are limited to 64-at-a-time which is not so many. + */ + /* + * This doesn't prevent pagetable teardown, but does prevent + * the pagetables and pages from being freed on x86. + * + * So long as we atomically load page table pointers versus teardown + * (which we do on x86, with the above PAE exception), we can follow the + * address down to the the page and take a ref on it. + */ + local_irq_save(flags); + pgdp = pgd_offset(mm, addr); + do { + pgd_t pgd = *pgdp; + + next = pgd_addr_end(addr, end); + if (pgd_none(pgd)) + break; + if (!gup_pud_range(pgd, addr, next, write, pages, &nr)) + break; + } while (pgdp++, addr = next, addr != end); + local_irq_restore(flags); + + return nr; +} + /** * get_user_pages_fast() - pin user pages in memory * @start: starting user address @@ -247,11 +303,16 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, start &= PAGE_MASK; addr = start; len = (unsigned long) nr_pages << PAGE_SHIFT; + end = start + len; - if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ, - (void __user *)start, len))) + if (end < start) goto slow_irqon; +#ifdef CONFIG_X86_64 + if (end >> __VIRTUAL_MASK_SHIFT) + goto slow_irqon; +#endif + /* * XXX: batch / limit 'nr', to avoid large irq off latency * needs some instrumenting to determine the common sizes used by |