microblaze: Fix stack usage in PAGE_SIZE copy_tofrom_user

If access to user space failed we need to reconstruct
stack pointer and restore all register.

This patch fixed problem introduces by:
"microblaze: Add loop unrolling for PAGE in copy_tofrom_user"
(sha1: ebe211254bfa6295f4ab0b33c7c881bdfabbab60)

Signed-off-by: Michal Simek <monstr@monstr.eu>

1 files changed, 62 insertions, 36 deletions

diff --git a/arch/microblaze/lib/uaccess_old.S b/arch/microblaze/lib/uaccess_old.S
index f037266cdaf3..f085995ee848 100644
--- a/arch/microblaze/lib/uaccess_old.S
+++ b/arch/microblaze/lib/uaccess_old.S
@@ -122,22 +122,22 @@ __strnlen_user:
 15:     swi     r24, r5, 0x0018 + offset;       \
 16:     swi     r25, r5, 0x001C + offset;       \
         .section __ex_table,"a";                \
-        .word   1b, 0f;                         \
-        .word   2b, 0f;                         \
-        .word   3b, 0f;                         \
-        .word   4b, 0f;                         \
-        .word   5b, 0f;                         \
-        .word   6b, 0f;                         \
-        .word   7b, 0f;                         \
-        .word   8b, 0f;                         \
-        .word   9b, 0f;                         \
-        .word   10b, 0f;                        \
-        .word   11b, 0f;                        \
-        .word   12b, 0f;                        \
-        .word   13b, 0f;                        \
-        .word   14b, 0f;                        \
-        .word   15b, 0f;                        \
-        .word   16b, 0f;                        \
+        .word   1b, 33f;                        \
+        .word   2b, 33f;                        \
+        .word   3b, 33f;                        \
+        .word   4b, 33f;                        \
+        .word   5b, 33f;                        \
+        .word   6b, 33f;                        \
+        .word   7b, 33f;                        \
+        .word   8b, 33f;                        \
+        .word   9b, 33f;                        \
+        .word   10b, 33f;                       \
+        .word   11b, 33f;                       \
+        .word   12b, 33f;                       \
+        .word   13b, 33f;                       \
+        .word   14b, 33f;                       \
+        .word   15b, 33f;                       \
+        .word   16b, 33f;                       \
         .text
 
 #define COPY_80(offset) \
@@ -190,14 +190,17 @@ w2:	sw	r4, r5, r3
 
 .align 4 /* Alignment is important to keep icache happy */
 page:   /* Create room on stack and save registers for storign values */
-        addik   r1, r1, -32
-        swi     r19, r1, 4
-        swi     r20, r1, 8
-        swi     r21, r1, 12
-        swi     r22, r1, 16
-        swi     r23, r1, 20
-        swi     r24, r1, 24
-        swi     r25, r1, 28
+        addik   r1, r1, -40
+        swi     r5, r1, 0
+        swi     r6, r1, 4
+        swi     r7, r1, 8
+        swi     r19, r1, 12
+        swi     r20, r1, 16
+        swi     r21, r1, 20
+        swi     r22, r1, 24
+        swi     r23, r1, 28
+        swi     r24, r1, 32
+        swi     r25, r1, 36
 loop:   /* r4, r19, r20, r21, r22, r23, r24, r25 are used for storing values */
         /* Loop unrolling to get performance boost */
         COPY_80(0x000);
@@ -205,21 +208,44 @@ loop:	/* r4, r19, r20, r21, r22, r23, r24, r25 are used for storing values */
         COPY_80(0x100);
         COPY_80(0x180);
         /* copy loop */
-        addik   r6, r6, 0x200
-        addik   r7, r7, -0x200
-        bneid   r7, loop
-        addik   r5, r5, 0x200
+        addik   r6, r6, 0x200
+        addik   r7, r7, -0x200
+        bneid   r7, loop
+        addik   r5, r5, 0x200
+
         /* Restore register content */
-        lwi     r19, r1, 4
-        lwi     r20, r1, 8
-        lwi     r21, r1, 12
-        lwi     r22, r1, 16
-        lwi     r23, r1, 20
-        lwi     r24, r1, 24
-        lwi     r25, r1, 28
-        addik   r1, r1, 32
+        lwi     r5, r1, 0
+        lwi     r6, r1, 4
+        lwi     r7, r1, 8
+        lwi     r19, r1, 12
+        lwi     r20, r1, 16
+        lwi     r21, r1, 20
+        lwi     r22, r1, 24
+        lwi     r23, r1, 28
+        lwi     r24, r1, 32
+        lwi     r25, r1, 36
+        addik   r1, r1, 40
         /* return back */
+        addik   r3, r0, 0
+        rtsd    r15, 8
+        nop
+
+/* Fault case - return temp count */
+33:
         addik   r3, r7, 0
+        /* Restore register content */
+        lwi     r5, r1, 0
+        lwi     r6, r1, 4
+        lwi     r7, r1, 8
+        lwi     r19, r1, 12
+        lwi     r20, r1, 16
+        lwi     r21, r1, 20
+        lwi     r22, r1, 24
+        lwi     r23, r1, 28
+        lwi     r24, r1, 32
+        lwi     r25, r1, 36
+        addik   r1, r1, 40
+        /* return back */
         rtsd    r15, 8
         nop