[PATCH] x86_64: correct copy_user_generic return value when exception happens

Fix a bug that arch/x86_64/lib/copy_user:copy_user_generic will return a
wrong value when exception happens.

In the case the address is not 8-byte aligned (i.e.  go into
Lbad_alignment), if exception happens in Ls11, %rdx will be wrong number of
copied bytes, then copy_user_generic returns wrong value.  It also fixed a
bug of zeroing wrong number of bytes of destination at this situation.  (In
Lzero_rest)

Signed-off-by: Yanmin Zhang <yanmin.zhang@intel.com>
Signed-off-by: Nanhai Zou <nanhai.zou@intel.com>
Signed-off-by: Gordon Jin <gordon.jin@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/x86_64/lib/copy_user.S b/arch/x86_64/lib/copy_user.S
index 6859a780964c59eb12d186cb1118294e973b44ad..bd556c8042488a470f7b428e339061738b7fd8c5 100644 (file)
--- a/arch/x86_64/lib/copy_user.S
+++ b/arch/x86_64/lib/copy_user.S
@@ -73,7 +73,7 @@ bad_to_user:
  * rdx count
  *
  * Output:             
- * eax uncopied bytes or 0 if successfull. 
+ * eax uncopied bytes or 0 if successful.
  */
        .globl copy_user_generic        
        .p2align 4
@@ -179,9 +179,9 @@ copy_user_generic:
        movl $8,%r9d
        subl %ecx,%r9d
        movl %r9d,%ecx
-       subq %r9,%rdx
-       jz   .Lsmall_align
-       js   .Lsmall_align
+       cmpq %r9,%rdx
+       jz   .Lhandle_7
+       js   .Lhandle_7
 .Lalign_1:             
 .Ls11: movb (%rsi),%bl
 .Ld11: movb %bl,(%rdi)
@@ -189,10 +189,8 @@ copy_user_generic:
        incq %rdi
        decl %ecx
        jnz .Lalign_1
+       subq %r9,%rdx
        jmp .Lafter_bad_alignment
-.Lsmall_align:
-       addq %r9,%rdx
-       jmp .Lhandle_7
 #endif
        
        /* table sorted by exception address */ 
@@ -219,8 +217,8 @@ copy_user_generic:
        .quad .Ls10,.Le_byte
        .quad .Ld10,.Le_byte
 #ifdef FIX_ALIGNMENT   
-       .quad .Ls11,.Le_byte
-       .quad .Ld11,.Le_byte
+       .quad .Ls11,.Lzero_rest
+       .quad .Ld11,.Lzero_rest
 #endif
        .quad .Le5,.Le_zero
        .previous