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From: AKASHI Takahiro <takahiro.akashi@linaro.org>
To: James Morse <james.morse@arm.com>
Cc: catalin.marinas@arm.com, will.deacon@arm.com,
	dhowells@redhat.com, vgoyal@redhat.com,
	herbert@gondor.apana.org.au, davem@davemloft.net,
	dyoung@redhat.com, bhe@redhat.com, arnd@arndb.de,
	ard.biesheuvel@linaro.org, bhsharma@redhat.com,
	kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v9 07/11] arm64: kexec_file: add crash dump support
Date: Fri, 18 May 2018 18:50:59 +0900	[thread overview]
Message-ID: <20180518095057.GN2737@linaro.org> (raw)
In-Reply-To: <512cde7d-d84b-3623-cb09-a2d78acc11dc@arm.com>

On Wed, May 16, 2018 at 11:06:02AM +0100, James Morse wrote:
> Hi Akashi,
> 
> On 15/05/18 18:11, James Morse wrote:
> > On 25/04/18 07:26, AKASHI Takahiro wrote:
> >> Enabling crash dump (kdump) includes
> >> * prepare contents of ELF header of a core dump file, /proc/vmcore,
> >>   using crash_prepare_elf64_headers(), and
> >> * add two device tree properties, "linux,usable-memory-range" and
> >>   "linux,elfcorehdr", which represent repsectively a memory range
> >>   to be used by crash dump kernel and the header's location
> 
> >> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
> >> index 37c0a9dc2e47..ec674f4d267c 100644
> >> --- a/arch/arm64/kernel/machine_kexec_file.c
> >> +++ b/arch/arm64/kernel/machine_kexec_file.c
> 
> >> +static struct crash_mem *get_crash_memory_ranges(void)
> >> +{
> >> +	unsigned int nr_ranges;
> >> +	struct crash_mem *cmem;
> >> +
> >> +	nr_ranges = 1; /* for exclusion of crashkernel region */
> >> +	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ranges_callback);
> >> +
> >> +	cmem = vmalloc(sizeof(struct crash_mem) +
> >> +			sizeof(struct crash_mem_range) * nr_ranges);
> >> +	if (!cmem)
> >> +		return NULL;
> >> +
> >> +	cmem->max_nr_ranges = nr_ranges;
> >> +	cmem->nr_ranges = 0;
> >> +	walk_system_ram_res(0, -1, cmem, add_mem_range_callback);
> >> +
> >> +	/* Exclude crashkernel region */
> >> +	if (crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end)) {
> >> +		vfree(cmem);
> >> +		return NULL;
> >> +	}
> >> +
> >> +	return cmem;
> >> +}
> > 
> > Could this function be included in prepare_elf_headers() so that the alloc() and
> > free() occur together.
> > 
> > 
> >> +static int prepare_elf_headers(void **addr, unsigned long *sz)
> >> +{
> >> +	struct crash_mem *cmem;
> >> +	int ret = 0;
> >> +
> >> +	cmem = get_crash_memory_ranges();
> >> +	if (!cmem)
> >> +		return -ENOMEM;
> >> +
> >> +	ret =  crash_prepare_elf64_headers(cmem, true, addr, sz);
> >> +
> >> +	vfree(cmem);
> > 
> >> +	return ret;
> >> +}
> > 
> > All this is moving memory-range information from core-code's
> > walk_system_ram_res() into core-code's struct crash_mem, and excluding
> > crashk_res, which again is accessible to the core code.
> > 
> > It looks like this is duplicated in arch/x86 and arch/arm64 because arm64
> > doesn't have a second 'crashk_low_res' region, and always wants elf64, instead
> > of when IS_ENABLED(CONFIG_X86_64).
> 
> Thinking about it some more: don't we want to walk memblock here, not
> walk_system_ram_res()? What we want is a list of not-nomap regions that the
> kernel may have been using, to form part of vmcore.
> walk_system_ram_res() is becoming a murkier list of maybe-nomap, maybe-reserved.
> 
> I think we should walk the same list here as we do in patch 4.

For consistency, yes.
I missed that.

-Takahiro AKASHI

> 
> 
> Thanks,
> 
> James

  reply	other threads:[~2018-05-18  9:51 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-25  6:26 [PATCH v9 00/11] arm64: kexec: add kexec_file_load() support AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 01/11] asm-generic: add kexec_file_load system call to unistd.h AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 02/11] kexec_file: make kexec_image_post_load_cleanup_default() global AKASHI Takahiro
2018-04-28  9:45   ` Dave Young
2018-05-01 17:46   ` James Morse
2018-05-07  4:40     ` AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 03/11] arm64: kexec_file: invoke the kernel without purgatory AKASHI Takahiro
2018-05-01 17:46   ` James Morse
2018-05-07  5:22     ` AKASHI Takahiro
2018-05-11 17:03       ` James Morse
2018-05-15  4:45         ` AKASHI Takahiro
2018-05-15 16:15           ` James Morse
2018-05-18  6:22             ` AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 04/11] arm64: kexec_file: allocate memory walking through memblock list AKASHI Takahiro
2018-05-01 17:46   ` James Morse
2018-05-07  5:59     ` AKASHI Takahiro
2018-05-15  4:35       ` AKASHI Takahiro
2018-05-15 16:17         ` James Morse
2018-05-17  2:10       ` Baoquan He
2018-05-17  2:15         ` Baoquan He
2018-05-17 18:04           ` James Morse
2018-05-18  1:37             ` Baoquan He
2018-05-18  5:07               ` AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 05/11] arm64: kexec_file: load initrd and device-tree AKASHI Takahiro
2018-05-15 16:20   ` James Morse
2018-05-18  7:11     ` AKASHI Takahiro
2018-05-18  7:42       ` AKASHI Takahiro
2018-05-18 15:59         ` James Morse
2018-04-25  6:26 ` [PATCH v9 06/11] arm64: kexec_file: allow for loading Image-format kernel AKASHI Takahiro
2018-05-01 17:46   ` James Morse
2018-05-07  7:21     ` AKASHI Takahiro
2018-05-11 17:07       ` James Morse
2018-05-15  5:13         ` AKASHI Takahiro
2018-05-15 17:14           ` James Morse
2018-05-21  9:32             ` AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 07/11] arm64: kexec_file: add crash dump support AKASHI Takahiro
2018-05-15 17:11   ` James Morse
2018-05-16  8:34     ` James Morse
2018-05-18  9:58       ` AKASHI Takahiro
2018-05-16 10:06     ` James Morse
2018-05-18  9:50       ` AKASHI Takahiro [this message]
2018-05-18 10:39     ` AKASHI Takahiro
2018-05-18 16:00       ` James Morse
2018-05-21  9:46         ` AKASHI Takahiro
2018-05-15 17:12   ` James Morse
2018-05-18 15:35     ` Rob Herring
2018-05-21 10:14       ` AKASHI Takahiro
2018-05-24 14:25         ` Rob Herring
2018-04-25  6:26 ` [PATCH v9 08/11] arm64: enable KEXEC_FILE config AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 09/11] include: pe.h: remove message[] from mz header definition AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 10/11] arm64: kexec_file: add kernel signature verification support AKASHI Takahiro
2018-04-25  6:26 ` [PATCH v9 11/11] arm64: kexec_file: add kaslr support AKASHI Takahiro

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