powerpc/40x: Reorder a few instructions in critical exception prolog

In order to ease preparation for CONFIG_VMAP_STACK, reorder
a few instruction, especially save r1 into stack frame earlier.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c895ecf958c86d1736bdd2ff6f36626b55f35fd2.1615552866.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index 067ae13..5b337bf 100644 (file)
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -119,6 +119,9 @@ _ENTRY(saved_ksp_limit)
        lwz     r11,TASK_STACK-THREAD(r11) /* this thread's kernel stack */
 1:     addi    r11,r11,THREAD_SIZE-INT_FRAME_SIZE /* Alloc an excpt frm  */
        tophys(r11,r11)
+       stw     r1,GPR1(r11)
+       stw     r1,0(r11)
+       tovirt(r1,r11)
        stw     r10,_CCR(r11)           /* save various registers          */
        stw     r12,GPR12(r11)
        stw     r9,GPR9(r11)
@@ -129,14 +132,11 @@ _ENTRY(saved_ksp_limit)
        stw     r10,GPR10(r11)
        stw     r12,GPR11(r11)
        mfspr   r12,SPRN_DEAR           /* save DEAR and ESR in the frame  */
-       stw     r12,_DEAR(r11)          /* since they may have had stuff   */
        mfspr   r9,SPRN_ESR             /* in them at the point where the  */
+       stw     r12,_DEAR(r11)          /* since they may have had stuff   */
        stw     r9,_ESR(r11)            /* exception was taken             */
        mfspr   r12,SPRN_SRR2
-       stw     r1,GPR1(r11)
        mfspr   r9,SPRN_SRR3
-       stw     r1,0(r11)
-       tovirt(r1,r11)
        rlwinm  r9,r9,0,14,12           /* clear MSR_WE (necessary?)       */
        stw     r0,GPR0(r11)
        lis     r10, STACK_FRAME_REGS_MARKER@ha /* exception frame marker */