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09ffcb0d71
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."
(kernel messages after panic kicked off kdump)
(snip...)
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 f56ab9a5b7 ("efi/arm: Don't mark ACPI reclaim
memory as MEMBLOCK_NOMAP"), those regions are differently handled
as they are "memblock-reserved", without NOMAP bit.
* So they are now excluded from device tree's "usable-memory-range"
which kexec-tools determines based on a current view of /proc/iomem.
* When crash dump kernel boots up, it tries to accesses ACPI tables by
mapping them with ioremap(), not ioremap_cache(), in acpi_os_ioremap()
since they are no longer part of mapped system ram.
* Given that ACPI accessor/helper functions are compiled in without
unaligned access support (ACPI_MISALIGNMENT_NOT_SUPPORTED),
any unaligned access to ACPI tables can cause a fatal panic.
With this patch, acpi_os_ioremap() always honors memory attribute
information provided by the firmware (EFI) and retaining cacheability
allows the kernel safe access to ACPI tables.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: James Morse <james.morse@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reported-by and Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Linux kernel
============
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In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
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