RE: [v2][PATCH 4/7] book3e/kexec/kdump: introduce a kexec kernel flag

Bhushan Bharat-R65777
2013-07-02T05:37:42Z

> -----Original Message-----
> From: Linuxppc-dev [mailto:linuxppc-dev-
> bounces+bharat.bhushan=freescale.com@lists.ozlabs.org] On Behalf Of Tiejun Chen
> Sent: Thursday, June 20, 2013 1:23 PM
> To: benh@kernel.crashing.org
> Cc: linuxppc-dev@lists.ozlabs.org; linux-kernel@vger.kernel.org
> Subject: [v2][PATCH 4/7] book3e/kexec/kdump: introduce a kexec kernel flag
>
> 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.chen@windriver.com>
> ---
> arch/powerpc/include/asm/smp.h | 3 +++
> arch/powerpc/kernel/head_64.S | 12 ++++++++++++
> arch/powerpc/kernel/misc_64.S | 6 ++++++
> arch/powerpc/platforms/85xx/smp.c | 14 ++++++++++++++
> 4 files changed, 35 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
> index ffbaabe..fbc3d9b 100644
> --- a/arch/powerpc/include/asm/smp.h
> +++ b/arch/powerpc/include/asm/smp.h
> @@ -200,6 +200,9 @@ extern void generic_secondary_thread_init(void);
> extern unsigned long __secondary_hold_spinloop;
> extern unsigned long __secondary_hold_acknowledge;
> extern char __secondary_hold;
> +#if defined(CONFIG_KEXEC) || defined(CONFIG_CRASH_DUMP)
> +extern unsigned long __run_at_kexec;
> +#endif
>
> extern void __early_start(void);
> #endif /* __ASSEMBLY__ */
> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
> index 3e19ba2..ffa4b18 100644
> --- a/arch/powerpc/kernel/head_64.S
> +++ b/arch/powerpc/kernel/head_64.S
> @@ -89,6 +89,12 @@ __secondary_hold_spinloop:
> __secondary_hold_acknowledge:
> .llong 0x0
>
> +#if defined(CONFIG_KEXEC) || defined(CONFIG_CRASH_DUMP)
> + .globl __run_at_kexec
> +__run_at_kexec:
> + .llong 0x0 /* Flag for the secondary kernel from kexec. */
> +#endif
> +
> #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 +423,12 @@ _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 6a17599..b308373 100644
> --- a/arch/powerpc/platforms/85xx/smp.c
> +++ b/arch/powerpc/platforms/85xx/smp.c
> @@ -150,6 +150,9 @@ static int __cpuinit smp_85xx_kick_cpu(int nr)
> int hw_cpu = get_hard_smp_processor_id(nr);
> int ioremappable;
> int ret = 0;
> +#if defined(CONFIG_KEXEC) || defined(CONFIG_CRASH_DUMP)
> + unsigned long *ptr;
> +#endif

What about if we can remove the ifdef around *ptr ...

>
> WARN_ON(nr < 0 || nr >= NR_CPUS);
> WARN_ON(hw_cpu < 0 || hw_cpu >= NR_CPUS);
> @@ -238,11 +241,22 @@ out:
> #else
> smp_generic_kick_cpu(nr);
>
> +#if defined(CONFIG_KEXEC) || defined(CONFIG_CRASH_DUMP)
> + ptr = (unsigned long *)((unsigned long)&__run_at_kexec);

... #endif here ...

> + /* 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) {
> +#endif

... remove #endif ...

> 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);
> +#if defined(CONFIG_KEXEC) || defined(CONFIG_CRASH_DUMP)
> + }
> +#endif

--- remove above 3 lines

-Bharat

> #endif
>
> local_irq_restore(flags);
> --
> 1.7.9.5
>
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