linux-kernel - Re: [PATCH 6/6] kexec jump: fix for ftrace

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Date:	Thu, 7 Aug 2008 11:24:05 +0200
From:	Pavel Machek <pavel@...e.cz>
To:	Huang Ying <ying.huang@...el.com>
Cc:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	nigel@...el.suspend2.net, "Rafael J. Wysocki" <rjw@...k.pl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Vivek Goyal <vgoyal@...hat.com>, mingo@...e.hu,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Kexec Mailing List <kexec@...ts.infradead.org>
Subject: Re: [PATCH 6/6] kexec jump: fix for ftrace

> Restore ftrace after jumping back from kexeced kernel.
> 
> Signed-off-by: Huang Ying <ying.huang@...el.com>
> 
> ---
>  arch/x86/kernel/machine_kexec_32.c |   19 +++++++++++++++++++
>  kernel/kexec.c                     |    2 --
>  2 files changed, 19 insertions(+), 2 deletions(-)
> 
> @@ -124,7 +126,15 @@ void machine_kexec(struct kimage *image)
>  				       unsigned int has_pae,
>  				       unsigned int preserve_context);
>  
> +#ifdef CONFIG_KEXEC_JUMP
> +	if (kexec_image->preserve_context)
> +		save_processor_state();
> +#endif
> +
> +#ifdef CONFIG_FTRACE
> +	save_ftrace_enabled = ftrace_enabled;
>  	tracer_disable();
> +#endif
>  
>  	/* Interrupts aren't acceptable while we reboot */
>  	raw_local_irq_disable();

The patch does way more than its changelog says...
									Pavel


> @@ -182,6 +192,15 @@ void machine_kexec(struct kimage *image)
>  					   (unsigned long)page_list,
>  					   image->start, cpu_has_pae,
>  					   image->preserve_context);
> +
> +#ifdef CONFIG_KEXEC_JUMP
> +	if (kexec_image->preserve_context)
> +		restore_processor_state();
> +#endif
> +
> +#ifdef CONFIG_FTRACE
> +	ftrace_enabled = save_ftrace_enabled;
> +#endif
>  }
>  
>  void arch_crash_save_vmcoreinfo(void)
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -1469,7 +1469,6 @@ int kernel_kexec(void)
>  		error = device_power_down(PMSG_FREEZE);
>  		if (error)
>  			goto Enable_irqs;
> -		save_processor_state();
>  	} else
>  #endif
>  	{
> @@ -1482,7 +1481,6 @@ int kernel_kexec(void)
>  
>  #ifdef CONFIG_KEXEC_JUMP
>  	if (kexec_image->preserve_context) {
> -		restore_processor_state();
>  		device_power_up(PMSG_RESTORE);
>   Enable_irqs:
>  		local_irq_enable();
> 

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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