linux-stable/drivers/firmware/efi
Sai Praneeth 3425d934fc efi/x86: Handle page faults occurring while running EFI runtime services
Memory accesses performed by UEFI runtime services should be limited to:
- reading/executing from EFI_RUNTIME_SERVICES_CODE memory regions
- reading/writing from/to EFI_RUNTIME_SERVICES_DATA memory regions
- reading/writing by-ref arguments
- reading/writing from/to the stack.

Accesses outside these regions may cause the kernel to hang because the
memory region requested by the firmware isn't mapped in efi_pgd, which
causes a page fault in ring 0 and the kernel fails to handle it, leading
to die(). To save kernel from hanging, add an EFI specific page fault
handler which recovers from such faults by
1. If the efi runtime service is efi_reset_system(), reboot the machine
   through BIOS.
2. If the efi runtime service is _not_ efi_reset_system(), then freeze
   efi_rts_wq and schedule a new process.

The EFI page fault handler offers us two advantages:
1. Avoid potential hangs caused by buggy firmware.
2. Shout loud that the firmware is buggy and hence is not a kernel bug.

Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Suggested-by: Matt Fleming <matt@codeblueprint.co.uk>
Based-on-code-from: Ricardo Neri <ricardo.neri@intel.com>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
[ardb: clarify commit log]
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
2018-09-26 12:14:55 +02:00
..
libstub efi/libstub: arm: support building with clang 2018-09-26 12:03:58 +02:00
test efi/efi_test: add exporting ResetSystem runtime service 2018-09-26 12:04:00 +02:00
apple-properties.c device property: Get rid of union aliasing 2018-05-17 12:47:21 +02:00
arm-init.c efi/arm: preserve early mapping of UEFI memory map longer for BGRT 2018-07-23 15:33:18 +01:00
arm-runtime.c efi/arm: map UEFI memory map even w/o runtime services enabled 2018-07-23 15:34:11 +01:00
capsule-loader.c efi/capsule-loader: Don't output reset log when reset flags are not set 2018-05-14 08:57:49 +02:00
capsule.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
cper-arm.c efi/cper: Remove the INDENT_SP silliness 2018-05-14 08:57:47 +02:00
cper-x86.c efi: Decode IA32/X64 Context Info structure 2018-05-14 08:57:48 +02:00
cper.c efi/cper: Use consistent types for UUIDs 2018-07-22 14:13:43 +02:00
dev-path-parser.c efi: Add device path parser 2016-11-13 08:23:15 +01:00
efi-bgrt.c efi/bgrt: Drop __initdata from bgrt_image_size 2018-07-03 17:43:10 +02:00
efi-pstore.c pstore: Convert internal records to timespec64 2018-06-05 16:57:31 -07:00
efi.c efi: add API to reserve memory persistently across kexec reboot 2018-09-26 12:03:57 +02:00
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: Only call efi_mem_reserve() for boot services memory 2018-07-17 09:15:05 +02:00
fake_mem.c x86/efi: Don't allocate memmap through memblock after mm_init() 2017-01-07 08:58:07 +01:00
Kconfig efi/libstub/arm: Add opt-in Kconfig option for the DTB loader 2018-07-16 00:43:12 +02:00
Makefile efi: Decode IA32/X64 Processor Error Section 2018-05-14 08:57:47 +02:00
memattr.c x86/efi: Add support for EFI_MEMORY_ATTRIBUTES_TABLE 2017-02-01 08:45:44 +01:00
memmap.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
reboot.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
runtime-map.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
runtime-wrappers.c efi/x86: Handle page faults occurring while running EFI runtime services 2018-09-26 12:14:55 +02:00
tpm.c efi: call get_event_log before ExitBootServices 2018-01-08 12:58:35 +02:00
vars.c efi: Don't use spinlocks for efi vars 2016-09-09 16:08:42 +01:00