On Thu, 2010-07-08 at 17:55 +1000, Matt Evans wrote:
> With dynamic PACAs, the kexecing CPU's PACA won't lie within the kernel
> static data and there is a chance that something may stomp it when preparing
> to kexec. This patch switches this final CPU to a static PACA just before
> we pull the switch.
>
> Signed-off-by: Matt Evans <m...@ozlabs.org>
> ---
> v2: Changes from Milton's review:
> - Use setup_paca() and move from setup_64.c,
> - SLB cache inval. not required,
> - Adjust 'paca' (oops..), and
> - Poison data_offset/per_cpu_offset
>
> arch/powerpc/include/asm/paca.h | 2 +-
> arch/powerpc/kernel/machine_kexec_64.c | 20 ++++++++++++++++++++
> arch/powerpc/kernel/paca.c | 10 ++++++++++
> arch/powerpc/kernel/setup_64.c | 10 ----------
> 4 files changed, 31 insertions(+), 11 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
> index 8ce7963..1ff6662 100644
> --- a/arch/powerpc/include/asm/paca.h
> +++ b/arch/powerpc/include/asm/paca.h
> @@ -146,7 +146,7 @@ struct paca_struct {
> extern struct paca_struct *paca;
> extern __initdata struct paca_struct boot_paca;
> extern void initialise_paca(struct paca_struct *new_paca, int cpu);
> -
> +extern void setup_paca(struct paca_struct *new_paca);
> extern void allocate_pacas(void);
> extern void free_unused_pacas(void);
>
> diff --git a/arch/powerpc/kernel/machine_kexec_64.c
> b/arch/powerpc/kernel/machine_kexec_64.c
> index 26f9900..c4d0123 100644
> --- a/arch/powerpc/kernel/machine_kexec_64.c
> +++ b/arch/powerpc/kernel/machine_kexec_64.c
> @@ -273,6 +273,12 @@ static void kexec_prepare_cpus(void)
> static union thread_union kexec_stack __init_task_data =
> { };
>
> +/*
> + * For similar reasons to the stack above, the kexecing CPU needs to be on a
> + * static PACA; we switch to kexec_paca.
> + */
> +struct paca_struct kexec_paca;
> +Hopelessly late probably but .. we could use boot_paca which already exists and is static. cheers
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