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>

diff --git a/arch/microblaze/lib/uaccess_old.S b/arch/microblaze/lib/uaccess_old.S
index f037266cdaf3e358676c0428e83393c16dd410cb..f085995ee8482da474be869148b581543cbf786f 100644 (file)
--- 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