linux_dsm_epyc7002/drivers/firmware/efi
Ard Biesheuvel c8f325a59c efi/fdt: Avoid FDT manipulation after ExitBootServices()
Some AArch64 UEFI implementations disable the MMU in ExitBootServices(),
after which unaligned accesses to RAM are no longer supported.

Commit:

  abfb7b686a ("efi/libstub/arm*: Pass latest memory map to the kernel")

fixed an issue in the memory map handling of the stub FDT code, but
inadvertently created an issue with such firmware, by moving some
of the FDT manipulation to after the invocation of ExitBootServices().

Given that the stub's libfdt implementation uses the ordinary, accelerated
string functions, which rely on hardware handling of unaligned accesses,
manipulating the FDT with the MMU off may result in alignment faults.

So fix the situation by moving the update_fdt_memmap() call into the
callback function invoked by efi_exit_boot_services() right before it
calls the ExitBootServices() UEFI service (which is arguably a better
place for it anyway)

Note that disabling the MMU in ExitBootServices() is not compliant with
the UEFI spec, and carries great risk due to the fact that switching from
cached to uncached memory accesses halfway through compiler generated code
(i.e., involving a stack) can never be done in a way that is architecturally
safe.

Fixes: abfb7b686a ("efi/libstub/arm*: Pass latest memory map to the kernel")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Riku Voipio <riku.voipio@linaro.org>
Cc: <stable@vger.kernel.org>
Cc: mark.rutland@arm.com
Cc: linux-efi@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: leif.lindholm@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1485971102-23330-2-git-send-email-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-02-01 21:17:49 +01:00
..
libstub efi/fdt: Avoid FDT manipulation after ExitBootServices() 2017-02-01 21:17:49 +01:00
test efi/efi_test: Use memdup_user() as a cleanup 2016-10-18 17:11:19 +02:00
apple-properties.c x86/efi: Retrieve and assign Apple device properties 2016-11-13 08:23:16 +01:00
arm-init.c efi/arm*: Fix efi_init() error handling 2016-10-18 17:11:17 +02:00
arm-runtime.c arm64: dump: Make ptdump debugfs a separate option 2016-11-07 18:15:04 +00:00
capsule-loader.c efi/capsule: Allocate whole capsule into virtual memory 2016-08-11 13:55:36 +02:00
capsule.c efi/capsule: Allocate whole capsule into virtual memory 2016-08-11 13:55:36 +02:00
cper.c efi: Handle memory error structures produced based on old versions of standard 2015-07-15 13:30:38 +01:00
dev-path-parser.c efi: Add device path parser 2016-11-13 08:23:15 +01:00
efi-pstore.c Fix bug in module unloading. 2016-10-06 15:16:16 -07:00
efi.c efi: Add support for seeding the RNG from a UEFI config table 2016-11-13 08:23:14 +01:00
efibc.c efibc: Report more information in the error messages 2016-06-27 13:06:54 +02:00
efivars.c efi: Don't use spinlocks for efi vars 2016-09-09 16:08:42 +01:00
esrt.c efi/esrt: Use memremap not ioremap to access ESRT table in memory 2016-09-09 16:08:39 +01:00
fake_mem.c x86/efi: Don't allocate memmap through memblock after mm_init() 2017-01-07 08:58:07 +01:00
Kconfig x86/efi: Retrieve and assign Apple device properties 2016-11-13 08:23:16 +01:00
Makefile x86/efi: Retrieve and assign Apple device properties 2016-11-13 08:23:16 +01:00
memattr.c efi: Implement generic support for the Memory Attributes table 2016-04-28 11:33:54 +02:00
memmap.c x86/efi: Don't allocate memmap through memblock after mm_init() 2017-01-07 08:58:07 +01:00
reboot.c efi: Add 'capsule' update support 2016-04-28 11:34:03 +02:00
runtime-map.c efi/runtime-map: Use efi.memmap directly instead of a copy 2016-09-09 16:08:36 +01:00
runtime-wrappers.c efi: Replace runtime services spinlock with semaphore 2016-09-09 16:08:43 +01:00
vars.c efi: Don't use spinlocks for efi vars 2016-09-09 16:08:42 +01:00