ARM: 7668/1: fix memset-related crashes caused by recent GCC (4.7.2) optimizations

[pandora-kernel.git] / arch / arm / lib / memset.S

diff --git a/arch/arm/lib/memset.S b/arch/arm/lib/memset.S
index 761eefa..d912e73 100644 (file)
--- a/arch/arm/lib/memset.S
+++ b/arch/arm/lib/memset.S
@@ -19,20 +19,24 @@
 1:     subs    r2, r2, #4              @ 1 do we have enough
        blt     5f                      @ 1 bytes to align with?
        cmp     r3, #2                  @ 1
-       strltb  r1, [r0], #1            @ 1
-       strleb  r1, [r0], #1            @ 1
-       strb    r1, [r0], #1            @ 1
+       strltb  r1, [ip], #1            @ 1
+       strleb  r1, [ip], #1            @ 1
+       strb    r1, [ip], #1            @ 1
        add     r2, r2, r3              @ 1 (r2 = r2 - (4 - r3))
 /*
  * The pointer is now aligned and the length is adjusted.  Try doing the
- * memzero again.
+ * memset again.
  */
 
 ENTRY(memset)
-       ands    r3, r0, #3              @ 1 unaligned?
+/*
+ * Preserve the contents of r0 for the return value.
+ */
+       mov     ip, r0
+       ands    r3, ip, #3              @ 1 unaligned?
        bne     1b                      @ 1
 /*
- * we know that the pointer in r0 is aligned to a word boundary.
+ * we know that the pointer in ip is aligned to a word boundary.
  */
        orr     r1, r1, r1, lsl #8
        orr     r1, r1, r1, lsl #16
@@ -43,29 +47,28 @@ ENTRY(memset)
 #if ! CALGN(1)+0
 
 /*
- * We need an extra register for this loop - save the return address and
- * use the LR
+ * We need 2 extra registers for this loop - use r8 and the LR
  */
-       str     lr, [sp, #-4]!
-       mov     ip, r1
+       stmfd   sp!, {r8, lr}
+       mov     r8, r1
        mov     lr, r1
 
 2:     subs    r2, r2, #64
-       stmgeia r0!, {r1, r3, ip, lr}   @ 64 bytes at a time.
-       stmgeia r0!, {r1, r3, ip, lr}
-       stmgeia r0!, {r1, r3, ip, lr}
-       stmgeia r0!, {r1, r3, ip, lr}
+       stmgeia ip!, {r1, r3, r8, lr}   @ 64 bytes at a time.
+       stmgeia ip!, {r1, r3, r8, lr}
+       stmgeia ip!, {r1, r3, r8, lr}
+       stmgeia ip!, {r1, r3, r8, lr}
        bgt     2b
-       ldmeqfd sp!, {pc}               @ Now <64 bytes to go.
+       ldmeqfd sp!, {r8, pc}           @ Now <64 bytes to go.
 /*
  * No need to correct the count; we're only testing bits from now on
  */
        tst     r2, #32
-       stmneia r0!, {r1, r3, ip, lr}
-       stmneia r0!, {r1, r3, ip, lr}
+       stmneia ip!, {r1, r3, r8, lr}
+       stmneia ip!, {r1, r3, r8, lr}
        tst     r2, #16
-       stmneia r0!, {r1, r3, ip, lr}
-       ldr     lr, [sp], #4
+       stmneia ip!, {r1, r3, r8, lr}
+       ldmfd   sp!, {r8, lr}
 
 #else
 
@@ -74,54 +77,54 @@ ENTRY(memset)
  * whole cache lines at once.
  */
 
-       stmfd   sp!, {r4-r7, lr}
+       stmfd   sp!, {r4-r8, lr}
        mov     r4, r1
        mov     r5, r1
        mov     r6, r1
        mov     r7, r1
-       mov     ip, r1
+       mov     r8, r1
        mov     lr, r1
 
        cmp     r2, #96
-       tstgt   r0, #31
+       tstgt   ip, #31
        ble     3f
 
-       and     ip, r0, #31
-       rsb     ip, ip, #32
-       sub     r2, r2, ip
-       movs    ip, ip, lsl #(32 - 4)
-       stmcsia r0!, {r4, r5, r6, r7}
-       stmmiia r0!, {r4, r5}
-       tst     ip, #(1 << 30)
-       mov     ip, r1
-       strne   r1, [r0], #4
+       and     r8, ip, #31
+       rsb     r8, r8, #32
+       sub     r2, r2, r8
+       movs    r8, r8, lsl #(32 - 4)
+       stmcsia ip!, {r4, r5, r6, r7}
+       stmmiia ip!, {r4, r5}
+       tst     r8, #(1 << 30)
+       mov     r8, r1
+       strne   r1, [ip], #4
 
 3:     subs    r2, r2, #64
-       stmgeia r0!, {r1, r3-r7, ip, lr}
-       stmgeia r0!, {r1, r3-r7, ip, lr}
+       stmgeia ip!, {r1, r3-r8, lr}
+       stmgeia ip!, {r1, r3-r8, lr}
        bgt     3b
-       ldmeqfd sp!, {r4-r7, pc}
+       ldmeqfd sp!, {r4-r8, pc}
 
        tst     r2, #32
-       stmneia r0!, {r1, r3-r7, ip, lr}
+       stmneia ip!, {r1, r3-r8, lr}
        tst     r2, #16
-       stmneia r0!, {r4-r7}
-       ldmfd   sp!, {r4-r7, lr}
+       stmneia ip!, {r4-r7}
+       ldmfd   sp!, {r4-r8, lr}
 
 #endif
 
 4:     tst     r2, #8
-       stmneia r0!, {r1, r3}
+       stmneia ip!, {r1, r3}
        tst     r2, #4
-       strne   r1, [r0], #4
+       strne   r1, [ip], #4
 /*
  * When we get here, we've got less than 4 bytes to zero.  We
  * may have an unaligned pointer as well.
  */
 5:     tst     r2, #2
-       strneb  r1, [r0], #1
-       strneb  r1, [r0], #1
+       strneb  r1, [ip], #1
+       strneb  r1, [ip], #1
        tst     r2, #1
-       strneb  r1, [r0], #1
+       strneb  r1, [ip], #1
        mov     pc, lr
 ENDPROC(memset)