diff options
Diffstat (limited to 'arch/x86/lib')
| -rw-r--r-- | arch/x86/lib/Makefile | 2 | ||||
| -rw-r--r-- | arch/x86/lib/usercopy.c | 43 |
2 files changed, 44 insertions, 1 deletions
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index 5d46ddcb69c5..b00f6785da74 100644 --- a/arch/x86/lib/Makefile +++ b/arch/x86/lib/Makefile @@ -18,7 +18,7 @@ obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o lib-y := delay.o lib-y += thunk_$(BITS).o -lib-y += usercopy_$(BITS).o getuser.o putuser.o +lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o lib-y += memcpy_$(BITS).o lib-$(CONFIG_SMP) += rwlock.o lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c new file mode 100644 index 000000000000..97be9cb54483 --- /dev/null +++ b/arch/x86/lib/usercopy.c @@ -0,0 +1,43 @@ +/* + * User address space access functions. + * + * For licencing details see kernel-base/COPYING + */ + +#include <linux/highmem.h> +#include <linux/module.h> + +/* + * best effort, GUP based copy_from_user() that is NMI-safe + */ +unsigned long +copy_from_user_nmi(void *to, const void __user *from, unsigned long n) +{ + unsigned long offset, addr = (unsigned long)from; + unsigned long size, len = 0; + struct page *page; + void *map; + int ret; + + do { + ret = __get_user_pages_fast(addr, 1, 0, &page); + if (!ret) + break; + + offset = addr & (PAGE_SIZE - 1); + size = min(PAGE_SIZE - offset, n - len); + + map = kmap_atomic(page); + memcpy(to, map+offset, size); + kunmap_atomic(map); + put_page(page); + + len += size; + to += size; + addr += size; + + } while (len < n); + + return len; +} +EXPORT_SYMBOL_GPL(copy_from_user_nmi); |