ARM: vexpress/MCPM: fix cache disable sequence when CONFIG_FRAME_POINTER=y

If CONFIG_FRAME_POINTER=y we get the following error:

arch/arm/mach-vexpress/tc2_pm.c: In function 'tc2_pm_down':
arch/arm/mach-vexpress/tc2_pm.c:200:1: error: fp cannot be used in asm here

Let's fix that by explicitly preserving r11 on the stack and removing it
from the clobber list.

Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

1 files changed, 12 insertions, 4 deletions

diff --git a/arch/arm/mach-vexpress/dcscb.c b/arch/arm/mach-vexpress/dcscb.c
index 85fffa702f5b..3a6384c6c435 100644
--- a/arch/arm/mach-vexpress/dcscb.c
+++ b/arch/arm/mach-vexpress/dcscb.c
@@ -144,8 +144,13 @@ static void dcscb_power_down(void)
                  * Let's do it in the safest possible way i.e. with
                  * no memory access within the following sequence
                  * including to the stack.
+                 *
+                 * Note: fp is preserved to the stack explicitly prior doing
+                 * this since adding it to the clobber list is incompatible
+                 * with having CONFIG_FRAME_POINTER=y.
                  */
                 asm volatile(
+                "str    fp, [sp, #-4]! \n\t"
                 "mrc    p15, 0, r0, c1, c0, 0   @ get CR \n\t"
                 "bic    r0, r0, #"__stringify(CR_C)" \n\t"
                 "mcr    p15, 0, r0, c1, c0, 0   @ set CR \n\t"
@@ -156,9 +161,10 @@ static void dcscb_power_down(void)
                 "bic    r0, r0, #(1 << 6)       @ disable local coherency \n\t"
                 "mcr    p15, 0, r0, c1, c0, 1   @ set AUXCR \n\t"
                 "isb    \n\t"
-                "dsb    "
+                "dsb    \n\t"
+                "ldr    fp, [sp], #4"
                 : : : "r0","r1","r2","r3","r4","r5","r6","r7",
-                      "r9","r10","r11","lr","memory");
+                      "r9","r10","lr","memory");
 
                 /*
                  * This is a harmless no-op.  On platforms with a real
@@ -182,6 +188,7 @@ static void dcscb_power_down(void)
                  * Let's do it in the safest possible way as above.
                  */
                 asm volatile(
+                "str    fp, [sp, #-4]! \n\t"
                 "mrc    p15, 0, r0, c1, c0, 0   @ get CR \n\t"
                 "bic    r0, r0, #"__stringify(CR_C)" \n\t"
                 "mcr    p15, 0, r0, c1, c0, 0   @ set CR \n\t"
@@ -192,9 +199,10 @@ static void dcscb_power_down(void)
                 "bic    r0, r0, #(1 << 6)       @ disable local coherency \n\t"
                 "mcr    p15, 0, r0, c1, c0, 1   @ set AUXCR \n\t"
                 "isb    \n\t"
-                "dsb    "
+                "dsb    \n\t"
+                "ldr    fp, [sp], #4"
                 : : : "r0","r1","r2","r3","r4","r5","r6","r7",
-                      "r9","r10","r11","lr","memory");
+                      "r9","r10","lr","memory");
         }
 
         __mcpm_cpu_down(cpu, cluster);