On Thu, 28 Jan 2016, Geert Uytterhoeven wrote:
> When CONFIG_ARM_KERNMEM_PERMS=y and 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 .data section.
> This requires accessing them through a pointer after virtual to physical
> translation.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> ---
> arch/arm/mach-shmobile/headsmp.S | 22 ++++++++++++++++------
> 1 file changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/mach-shmobile/headsmp.S b/arch/arm/mach-shmobile/headsmp.S
> index 330c1fc63197df89..f924273ceaf476b4 100644
> --- a/arch/arm/mach-shmobile/headsmp.S
> +++ b/arch/arm/mach-shmobile/headsmp.S
> @@ -50,9 +50,12 @@ 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, {r4, r5, r6, r7}
> + sub r2, r2, r4 @ virt->phys offset
> + 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
You could do something slightly more efficient like this:
adr r2, 1f
ldmia r2, {r5, r6, r7}
add r5, r5, r2
add r6, r6, r2
add r7, r7, r2
[...]
1: .long shmobile_smp_mpidr - .
.long shmobile_smp_fn - 1b
.long shmobile_smp_arg - 1b
Nicolas
