linux-kernel - Re: [PATCH v3 02/17] ARM: add self test for runtime patch mechanism

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Message-ID: <alpine.LFD.2.02.1209211331320.6667@xanadu.home>
Date:	Fri, 21 Sep 2012 13:40:22 -0400 (EDT)
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	Cyril Chemparathy <cyril@...com>
cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	arnd@...db.de, catalin.marinas@....com, grant.likely@...retlab.ca,
	linux@....linux.org.uk, will.deacon@....com
Subject: Re: [PATCH v3 02/17] ARM: add self test for runtime patch
 mechanism

On Tue, 11 Sep 2012, Cyril Chemparathy wrote:

> This patch adds basic sanity tests to ensure that the instruction patching
> results in valid instruction encodings.  This is done by verifying the output
> of the patch process against a vector of assembler generated instructions at
> init time.
> 
> Signed-off-by: Cyril Chemparathy <cyril@...com>
> ---
>  arch/arm/Kconfig                |   12 +++++++
>  arch/arm/kernel/runtime-patch.c |   75 +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 87 insertions(+)
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 36de4ea..bfcd29d 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -207,6 +207,18 @@ config ARM_PATCH_PHYS_VIRT
>  	  this feature (eg, building a kernel for a single machine) and
>  	  you need to shrink the kernel to the minimal size.
>  
> +config ARM_RUNTIME_PATCH_TEST
> +	bool "Self test runtime patching mechanism" if ARM_RUNTIME_PATCH
> +	default y

Here you probably want this instead:

	bool "Self test runtime patching mechanism"
	default y
	depends on ARM_RUNTIME_PATCH

Otherwise ARM_RUNTIME_PATCH_TEST will be forced to y whenever 
ARM_RUNTIME_PATCH is unset.  That doesn't currently affect the build 
since the containing .c file is only compiled when ARM_RUNTIME_PATCH is 
set but that is still not strictly right.

[...]
> @@ -189,5 +261,8 @@ void __init runtime_patch_kernel(void)
>  	const void *start = &__runtime_patch_table_begin;
>  	const void *end   = &__runtime_patch_table_end;
>  
> +#ifdef CONFIG_ARM_RUNTIME_PATCH_TEST
> +	runtime_patch_test();
> +#endif
>  	BUG_ON(runtime_patch(start, end - start));

I think you shoulld have runtime_patch_test() return a possible error 
code and use BUG_ON() with it as well.

With those minor changes you can add...

Reviewed-by: Nicolas Pitre <nico@...aro.org>


Nicolas
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