Reserving a runtime region results in splitting the EFI memory
descriptors for the runtime region. This results in runtime region
descriptors with bogus memory mappings, leading to interesting crashes
like the following during a kexec:
general protection fault: 0000 [#1] SMP
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.11.0-rc1 #53
Hardware name: Wiwynn Leopard-Orv2/Leopard-DDR BW, BIOS LBM05 09/30/2016
RIP: 0010:virt_efi_set_variable()
...
Call Trace:
efi_delete_dummy_variable()
efi_enter_virtual_mode()
start_kernel()
? set_init_arg()
x86_64_start_reservations()
x86_64_start_kernel()
start_cpu()
...
Kernel panic - not syncing: Fatal exception
Runtime regions will not be freed and do not need to be reserved, so
skip the memmap modification in this case.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: <stable@vger.kernel.org> # v4.9+
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Fixes: 8e80632fb2 ("efi/esrt: Use efi_mem_reserve() and avoid a kmalloc()")
Link: http://lkml.kernel.org/r/20170412152719.9779-2-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
6f6266a561