author: Linus Torvalds <torvalds@linux-foundation.org> 2021-09-09 13:25:49 -0700
committer: Linus Torvalds <torvalds@linux-foundation.org> 2021-09-09 13:25:49 -0700
commit: 35776f10513c0d523c5dd2f1b415f642497779e2
parent: 43175623dd0dffccacbf014e368ee77f77c73898
Commit Summary:
Diffstat:
1 file changed, 20 insertions, 6 deletions
diff --git a/mm/maccess.c b/mm/maccess.c
index 3bd70405f2d8..d3f1a1f0b1c1 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -24,13 +24,21 @@ bool __weak copy_from_kernel_nofault_allowed(const void *unsafe_src,
long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
{
+ unsigned long align = 0;
+
+ if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
+ align = (unsigned long)dst | (unsigned long)src;
+
if (!copy_from_kernel_nofault_allowed(src, size))
return -ERANGE;
pagefault_disable();
- copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
- copy_from_kernel_nofault_loop(dst, src, size, u32, Efault);
- copy_from_kernel_nofault_loop(dst, src, size, u16, Efault);
+ if (!(align & 7))
+ copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
+ if (!(align & 3))
+ copy_from_kernel_nofault_loop(dst, src, size, u32, Efault);
+ if (!(align & 1))
+ copy_from_kernel_nofault_loop(dst, src, size, u16, Efault);
copy_from_kernel_nofault_loop(dst, src, size, u8, Efault);
pagefault_enable();
return 0;
@@ -50,10 +58,18 @@ EXPORT_SYMBOL_GPL(copy_from_kernel_nofault);
long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
{
+ unsigned long align = 0;
+
+ if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
+ align = (unsigned long)dst | (unsigned long)src;
+
pagefault_disable();
- copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);
- copy_to_kernel_nofault_loop(dst, src, size, u32, Efault);
- copy_to_kernel_nofault_loop(dst, src, size, u16, Efault);
+ if (!(align & 7))
+ copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);
+ if (!(align & 3))
+ copy_to_kernel_nofault_loop(dst, src, size, u32, Efault);
+ if (!(align & 1))
+ copy_to_kernel_nofault_loop(dst, src, size, u16, Efault);
copy_to_kernel_nofault_loop(dst, src, size, u8, Efault);
pagefault_enable();
return 0;