[PATCH] x86_64: Bug in new out of line put_user()

The new out of line put_user() assembly on x86_64 changes %rcx without
telling GCC about it causing things like:

http://bugme.osdl.org/show_bug.cgi?id=4515 

See to it that %rcx is not changed (made it consistent with get_user()).

Signed-off-by: Alexander Nyberg <alexn@telia.com>
Signed-off-by: ak@suse.de
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 20 insertions, 11 deletions

diff --git a/arch/x86_64/lib/getuser.S b/arch/x86_64/lib/getuser.S
index f94ea8a44051..f80bafee8669 100644
--- a/arch/x86_64/lib/getuser.S
+++ b/arch/x86_64/lib/getuser.S
@@ -78,9 +78,9 @@ __get_user_4:
 __get_user_8:
         GET_THREAD_INFO(%r8)
         addq $7,%rcx
-        jc bad_get_user
+        jc 40f
         cmpq threadinfo_addr_limit(%r8),%rcx
-        jae     bad_get_user
+        jae     40f
         subq    $7,%rcx
 4:      movq (%rcx),%rdx
         xorl %eax,%eax
diff --git a/arch/x86_64/lib/putuser.S b/arch/x86_64/lib/putuser.S
index 0dee1fdcb162..d9d3e5ec9ad1 100644
--- a/arch/x86_64/lib/putuser.S
+++ b/arch/x86_64/lib/putuser.S
@@ -46,36 +46,45 @@ __put_user_1:
 __put_user_2:
         GET_THREAD_INFO(%r8)
         addq $1,%rcx
-        jc bad_put_user
+        jc 20f
         cmpq threadinfo_addr_limit(%r8),%rcx
-        jae      bad_put_user
-2:      movw %dx,-1(%rcx)
+        jae 20f
+2:      decq %rcx
+        movw %dx,(%rcx)
         xorl %eax,%eax
         ret
+20:     decq %rcx
+        jmp bad_put_user
 
         .p2align 4
 .globl __put_user_4
 __put_user_4:
         GET_THREAD_INFO(%r8)
         addq $3,%rcx
-        jc bad_put_user
+        jc 30f
         cmpq threadinfo_addr_limit(%r8),%rcx
-        jae bad_put_user
-3:      movl %edx,-3(%rcx)
+        jae 30f
+3:      subq $3,%rcx
+        movl %edx,(%rcx)
         xorl %eax,%eax
         ret
+30:     subq $3,%rcx
+        jmp bad_put_user
 
         .p2align 4
 .globl __put_user_8
 __put_user_8:
         GET_THREAD_INFO(%r8)
         addq $7,%rcx
-        jc bad_put_user
+        jc 40f
         cmpq threadinfo_addr_limit(%r8),%rcx
-        jae     bad_put_user
-4:      movq %rdx,-7(%rcx)
+        jae 40f
+4:      subq $7,%rcx
+        movq %rdx,(%rcx)
         xorl %eax,%eax
         ret
+40:     subq $7,%rcx
+        jmp bad_put_user
 
 bad_put_user:
         movq $(-EFAULT),%rax