[PATCH v3 1/2] ARM: shmobile: Move shmobile_smp_{mpidr, fn, arg}[] from .text to .bss

[Geert Uytterhoeven]

If CONFIG_DEBUG_RODATA=y, the kernel crashes during system suspend:

    Freezing user space processes ... (elapsed 0.004 seconds) done.
    Freezing remaining freezable tasks ... (elapsed 0.002 seconds)
    done.
    PM: suspend of devices complete after 111.948 msecs
    PM: late suspend of devices complete after 1.086 msecs
    PM: noirq suspend of devices complete after 11.576 msecs
    Disabling non-boot CPUs ...
    Kernel panic - not syncing: Attempted to kill the idle task!
    1014ec ---[ end Kernel panic - not syncing: Attempted to kill the idle task!
    CPU0: stopping

This happens because the .text section is marked read-only, while the
arrays shmobile_smp_mpidr[], shmobile_smp_fn[], and shmobile_smp_arg[]
are being written to.

Fix this by moving these arrays from the .text to the .bss section.
This requires accessing them through PC-relative offsets.

Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
Reviewed-by: Kees Cook <keescook at chromium.org>
Reviewed-by: Nicolas Pitre <nico at linaro.org>
---
v3:
  - Use .bss instead of .data, as requested by Nicolas Pitre
    <nicolas.pitre at linaro.org>,
  - Add Reviewed-by,

v2:
  - Add Reviewed-by,
  - Store offsets instead of pointers, as suggested by Nicolas Pitre
    <nicolas.pitre at linaro.org>.
---
 arch/arm/mach-shmobile/headsmp.S | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mach-shmobile/headsmp.S b/arch/arm/mach-shmobile/headsmp.S
index 330c1fc63197df89..94d86ed164144cdf 100644
--- a/arch/arm/mach-shmobile/headsmp.S
+++ b/arch/arm/mach-shmobile/headsmp.S
@@ -50,9 +50,11 @@ ENTRY(shmobile_smp_boot)
 	mrc	p15, 0, r1, c0, c0, 5		@ r1 = MPIDR
 	and	r0, r1, r0			@ r0 = cpu_logical_map() value
 	mov	r1, #0				@ r1 = CPU index
-	adr	r5, 1f				@ array of per-cpu mpidr values
-	adr	r6, 2f				@ array of per-cpu functions
-	adr	r7, 3f				@ array of per-cpu arguments
+	adr	r2, 1f
+	ldmia	r2, {r5, r6, r7}
+	add	r5, r5, r2			@ array of per-cpu mpidr values
+	add	r6, r6, r2			@ array of per-cpu functions
+	add	r7, r7, r2			@ array of per-cpu arguments
 
 shmobile_smp_boot_find_mpidr:
 	ldr	r8, [r5, r1, lsl #2]
@@ -80,12 +82,18 @@ ENTRY(shmobile_smp_sleep)
 	b	shmobile_smp_boot
 ENDPROC(shmobile_smp_sleep)
 
+	.align	2
+1:	.long	shmobile_smp_mpidr - .
+	.long	shmobile_smp_fn - 1b
+	.long	shmobile_smp_arg - 1b
+
+	.bss
 	.globl	shmobile_smp_mpidr
 shmobile_smp_mpidr:
-1:	.space	NR_CPUS * 4
+	.space	NR_CPUS * 4
 	.globl	shmobile_smp_fn
 shmobile_smp_fn:
-2:	.space	NR_CPUS * 4
+	.space	NR_CPUS * 4
 	.globl	shmobile_smp_arg
 shmobile_smp_arg:
-3:	.space	NR_CPUS * 4
+	.space	NR_CPUS * 4
-- 
1.9.1