On Tue, 2013-07-09 at 16:03 +0800, Tiejun Chen wrote:
> We need to introduce a flag to indicate we're already running
> a kexec kernel then we can go proper path. For example, We
> shouldn't access spin_table from the bootloader to up any secondary
> cpu for kexec kernel, and kexec kernel already know how to jump to
> generic_secondary_smp_init.
>
> Signed-off-by: Tiejun Chen <tiejun.c...@windriver.com>
> ---
> arch/powerpc/include/asm/smp.h | 1 +
> arch/powerpc/kernel/head_64.S | 10 ++++++++++
> arch/powerpc/kernel/misc_64.S | 6 ++++++
> arch/powerpc/platforms/85xx/smp.c | 20 +++++++++++++++-----
> 4 files changed, 32 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
> index ffbaabe..59165a3 100644
> --- a/arch/powerpc/include/asm/smp.h
> +++ b/arch/powerpc/include/asm/smp.h
> @@ -200,6 +200,7 @@ extern void generic_secondary_thread_init(void);
> extern unsigned long __secondary_hold_spinloop;
> extern unsigned long __secondary_hold_acknowledge;
> extern char __secondary_hold;
> +extern unsigned long __run_at_kexec;
>
> extern void __early_start(void);
> #endif /* __ASSEMBLY__ */
> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
> index 7dc56be..0b46c9d 100644
> --- a/arch/powerpc/kernel/head_64.S
> +++ b/arch/powerpc/kernel/head_64.S
> @@ -89,6 +89,10 @@ __secondary_hold_spinloop:
> __secondary_hold_acknowledge:
> .llong 0x0
>
> + .globl __run_at_kexec
> +__run_at_kexec:
> + .llong 0x0 /* Flag for the secondary kernel from kexec. */
> +
No leading underscores please -- and why does this need to be 64-bit?
> #ifdef CONFIG_RELOCATABLE
> /* This flag is set to 1 by a loader if the kernel should run
> * at the loaded address instead of the linked address. This
> @@ -417,6 +421,12 @@ _STATIC(__after_prom_start)
> #if defined(CONFIG_PPC_BOOK3E)
> tovirt(r26,r26) /* on booke, we already run at
> PAGE_OFFSET */
> #endif
> +#if defined(CONFIG_KEXEC) || defined(CONFIG_CRASH_DUMP)
> + /* If relocated we need to restore this flag on that relocated address.
> */
> + ld r7,__run_at_kexec-_stext(r26)
> + std r7,__run_at_kexec-_stext(r26)
> +#endif
> +
> lwz r7,__run_at_load-_stext(r26)
> #if defined(CONFIG_PPC_BOOK3E)
> tophys(r26,r26) /* Restore for the remains. */
> diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
> index 20cbb98..c89aead 100644
> --- a/arch/powerpc/kernel/misc_64.S
> +++ b/arch/powerpc/kernel/misc_64.S
> @@ -619,6 +619,12 @@ _GLOBAL(kexec_sequence)
> bl .copy_and_flush /* (dest, src, copy limit, start offset) */
> 1: /* assume normal blr return */
>
> + /* notify we're going into kexec kernel for SMP. */
> + LOAD_REG_ADDR(r3,__run_at_kexec)
> + li r4,1
> + std r4,0(r3)
> + sync
> +
> /* release other cpus to the new kernel secondary start at 0x60 */
> mflr r5
> li r6,1
> diff --git a/arch/powerpc/platforms/85xx/smp.c
> b/arch/powerpc/platforms/85xx/smp.c
> index 5ced4f5..14d461b 100644
> --- a/arch/powerpc/platforms/85xx/smp.c
> +++ b/arch/powerpc/platforms/85xx/smp.c
> @@ -150,6 +150,9 @@ static int smp_85xx_kick_cpu(int nr)
> int hw_cpu = get_hard_smp_processor_id(nr);
> int ioremappable;
> int ret = 0;
> +#ifdef CONFIG_PPC64
> + unsigned long *ptr = NULL;
> +#endif
Looks like an unnecessary initialization.
>
> WARN_ON(nr < 0 || nr >= NR_CPUS);
> WARN_ON(hw_cpu < 0 || hw_cpu >= NR_CPUS);
> @@ -238,11 +241,18 @@ out:
> #else
> smp_generic_kick_cpu(nr);
>
> - flush_spin_table(spin_table);
> - out_be32(&spin_table->pir, hw_cpu);
> - out_be64((u64 *)(&spin_table->addr_h),
> - __pa((u64)*((unsigned long long *)generic_secondary_smp_init)));
> - flush_spin_table(spin_table);
> + ptr = (unsigned long *)((unsigned long)&__run_at_kexec);
> + /* We shouldn't access spin_table from the bootloader to up any
> + * secondary cpu for kexec kernel, and kexec kernel already
> + * know how to jump to generic_secondary_smp_init.
> + */
> + if (!*ptr) {
> + flush_spin_table(spin_table);
> + out_be32(&spin_table->pir, hw_cpu);
> + out_be64((u64 *)(&spin_table->addr_h),
> + __pa((u64)*((unsigned long long
> *)generic_secondary_smp_init)));
> + flush_spin_table(spin_table);
> + }
> #endif
Please use a more descriptive name than "ptr".
How is all that different than just:
if (!__run_at_kexec) {
...
}
-Scott
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