Re: [PATCH 4/5] arm: Add kexec_image_info - Russell King

From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: "Łukasz Stelmach" <l.stelmach@samsung.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Enrico Weigelt <info@metux.net>,
	Kees Cook <keescook@chromium.org>, Ingo Molnar <mingo@kernel.org>,
	Ben Dooks <ben-linux@fluff.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	AKASHI Takahiro <takahiro.akashi@linaro.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH 4/5] arm: Add kexec_image_info
Date: Mon, 1 Jun 2020 15:56:14 +0100	[thread overview]
Message-ID: <20200601145614.GK1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <20200601142754.26139-5-l.stelmach@samsung.com>

On Mon, Jun 01, 2020 at 04:27:53PM +0200, Łukasz Stelmach wrote:
> Add kexec_image_info to print detailed information about a kexec image.

Isn't this already visible through kexec debugging?  Why do we need
to duplicate the same output in the kernel?  Do we think that the
kexec interfaces are that fragile that they don't work?

> 
> Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
> ---
>  arch/arm/kernel/machine_kexec.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
> index 76300f3813e8..c10a2dfd53d1 100644
> --- a/arch/arm/kernel/machine_kexec.c
> +++ b/arch/arm/kernel/machine_kexec.c
> @@ -31,6 +31,32 @@ extern unsigned long kexec_boot_atags;
>  
>  static atomic_t waiting_for_crash_ipi;
>  
> +/**
> + * kexec_image_info - For debugging output.
> + */
> +#define kexec_image_info(_i) _kexec_image_info(__func__, __LINE__, _i)
> +static void _kexec_image_info(const char *func, int line,
> +	const struct kimage *kimage)
> +{
> +	unsigned long i;
> +
> +	pr_debug("%s:%d:\n", func, line);
> +	pr_debug("  kexec kimage info:\n");
> +	pr_debug("    type:        %d\n", kimage->type);
> +	pr_debug("    start:       %lx\n", kimage->start);
> +	pr_debug("    head:        %lx\n", kimage->head);
> +	pr_debug("    nr_segments: %lu\n", kimage->nr_segments);
> +
> +	for (i = 0; i < kimage->nr_segments; i++) {
> +		pr_debug("      segment[%lu]: %08lx - %08lx, 0x%x bytes, %lu pages\n",
> +			i,
> +			kimage->segment[i].mem,
> +			kimage->segment[i].mem + kimage->segment[i].memsz,
> +			kimage->segment[i].memsz,
> +			kimage->segment[i].memsz /  PAGE_SIZE);
> +	}
> +}
> +
>  /*
>   * Provide a dummy crash_notes definition while crash dump arrives to arm.
>   * This prevents breakage of crash_notes attribute in kernel/ksysfs.c.
> @@ -42,6 +68,8 @@ int machine_kexec_prepare(struct kimage *image)
>  	__be32 header;
>  	int i, err;
>  
> +	kexec_image_info(image);
> +
>  	image->arch.kernel_r2 = image->start - KEXEC_ARM_ZIMAGE_OFFSET
>  				     + KEXEC_ARM_ATAGS_OFFSET;
>  
> -- 
> 2.26.2
> 
> 

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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