From: james.morse@arm•com (James Morse)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] arm64: kdump: retain reserved memory regions
Date: Wed, 10 Jan 2018 11:26:55 +0000 [thread overview]
Message-ID: <5A55F87F.2080501@arm.com> (raw)
In-Reply-To: <20180110100943.6082-1-takahiro.akashi@linaro.org>
Hi Akashi,
On 10/01/18 10:09, AKASHI Takahiro wrote:
> This is a fix against the issue that crash dump kernel may hang up
> during booting, which can happen on any ACPI-based system with "ACPI
> Reclaim Memory."
>
> <kicking off kdump after panic>
> Bye!
> (snip...)
> ACPI: Core revision 20170728
> pud=000000002e7d0003, *pmd=000000002e7c0003, *pte=00e8000039710707
> Internal error: Oops: 96000021 [#1] SMP
> Modules linked in:
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.0-rc6 #1
> task: ffff000008d05180 task.stack: ffff000008cc0000
> PC is at acpi_ns_lookup+0x25c/0x3c0
> LR is at acpi_ds_load1_begin_op+0xa4/0x294
> (snip...)
> Process swapper/0 (pid: 0, stack limit = 0xffff000008cc0000)
> Call trace:
> (snip...)
> [<ffff0000084a6764>] acpi_ns_lookup+0x25c/0x3c0
> [<ffff00000849b4f8>] acpi_ds_load1_begin_op+0xa4/0x294
> [<ffff0000084ad4ac>] acpi_ps_build_named_op+0xc4/0x198
> [<ffff0000084ad6cc>] acpi_ps_create_op+0x14c/0x270
> [<ffff0000084acfa8>] acpi_ps_parse_loop+0x188/0x5c8
> [<ffff0000084ae048>] acpi_ps_parse_aml+0xb0/0x2b8
> [<ffff0000084a8e10>] acpi_ns_one_complete_parse+0x144/0x184
> [<ffff0000084a8e98>] acpi_ns_parse_table+0x48/0x68
> [<ffff0000084a82cc>] acpi_ns_load_table+0x4c/0xdc
> [<ffff0000084b32f8>] acpi_tb_load_namespace+0xe4/0x264
> [<ffff000008baf9b4>] acpi_load_tables+0x48/0xc0
> [<ffff000008badc20>] acpi_early_init+0x9c/0xd0
> [<ffff000008b70d50>] start_kernel+0x3b4/0x43c
> Code: b9008fb9 2a000318 36380054 32190318 (b94002c0)
> ---[ end trace c46ed37f9651c58e ]---
> Kernel panic - not syncing: Fatal exception
> Rebooting in 10 seconds..
>
> (diagnosis)
> * This fault is a data abort, alignment fault (ESR=0x96000021)
> during reading out ACPI table.
> * Initial ACPI tables are normally stored in system ram and marked as
> "ACPI Reclaim memory" by the firmware.
> * After the commit f56ab9a5b73c ("efi/arm: Don't mark ACPI reclaim
> memory as MEMBLOCK_NOMAP"), those regions' attribute were changed
> removing NOMAP bit and they are instead "memblock-reserved".
> * When crash dump kernel boots up, it tries to accesses ACPI tables by
> ioremap'ing them (through acpi_os_ioremap()).
> * Since those regions are not included in device tree's
> "usable-memory-range" and so not recognized as part of crash dump
> kernel's system ram, ioremap() will create a non-cacheable mapping here.
Ugh, because acpi_os_ioremap() looks at the efi memory map through the prism of
what we pulled into memblock, which is different during kdump.
Is an alternative to teach acpi_os_ioremap() to ask
efi_mem_attributes() directly for the attributes to use?
(e.g. arch_apei_get_mem_attribute())
> * ACPI accessor/helper functions are compiled in without unaligned access
> support (ACPI_MISALIGNMENT_NOT_SUPPORTED), eventually ending up a fatal
> panic when accessing ACPI tables.
>
> With this patch, all the reserved memory regions, as well as NOMAP-
> attributed ones which are presumably ACPI runtime code and data, are set
> to be retained in system ram even if they are outside of usable memory
> range specified by device tree blob. Accordingly, ACPI tables are mapped
> as cacheable and can be safely accessed without causing unaligned access
> faults.
Thanks,
James
next prev parent reply other threads:[~2018-01-10 11:26 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-10 10:09 [PATCH] arm64: kdump: retain reserved memory regions AKASHI Takahiro
2018-01-10 11:09 ` Ard Biesheuvel
2018-01-11 11:32 ` AKASHI Takahiro
2018-01-10 11:26 ` James Morse [this message]
2018-01-11 11:38 ` AKASHI Takahiro
2018-01-19 11:39 ` James Morse
2018-01-29 8:12 ` AKASHI Takahiro
2018-01-29 12:11 ` Ard Biesheuvel
2018-01-31 5:50 ` Bhupesh Sharma
2018-01-31 6:23 ` AKASHI Takahiro
2018-01-23 1:19 ` Goel, Sameer
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