linux/arch/x86/platform
Alex Thorlton f72075c9ed x86/platform/uv: Skip UV runtime services mapping in the efi_runtime_disabled case
This problem has actually been in the UV code for a while, but we didn't
catch it until recently, because we had been relying on EFI_OLD_MEMMAP
to allow our systems to boot for a period of time.  We noticed the issue
when trying to kexec a recent community kernel, where we hit this NULL
pointer dereference in efi_sync_low_kernel_mappings():

 [    0.337515] BUG: unable to handle kernel NULL pointer dereference at 0000000000000880
 [    0.346276] IP: [<ffffffff8105df8d>] efi_sync_low_kernel_mappings+0x5d/0x1b0

The problem doesn't show up with EFI_OLD_MEMMAP because we skip the
chunk of setup_efi_state() that sets the efi_loader_signature for the
kexec'd kernel.  When the kexec'd kernel boots, it won't set EFI_BOOT in
setup_arch, so we completely avoid the bug.

We always kexec with noefi on the command line, so this shouldn't be an
issue, but since we're not actually checking for efi_runtime_disabled in
uv_bios_init(), we end up trying to do EFI runtime callbacks when we
shouldn't be. This patch just adds a check for efi_runtime_disabled in
uv_bios_init() so that we don't map in uv_systab when runtime_disabled ==
true.

Signed-off-by: Alex Thorlton <athorlton@sgi.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: <stable@vger.kernel.org> # v4.7
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Travis <travis@sgi.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russ Anderson <rja@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1470912120-22831-2-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-08-11 13:55:36 +02:00
..
atom x86/platform/atom/punit: Enable support for Merrifield 2016-06-14 12:44:51 +02:00
ce4100 x86/ce4100: Remove duplicated include from ce4100.c 2016-07-19 16:02:17 +02:00
efi RTC for 4.8 2016-08-05 09:48:22 -04:00
geode x86/platform: Make platform/geode/net5501.c explicitly non-modular 2016-02-16 09:11:09 +01:00
goldfish
intel x86/platform/iosf_mbi: Add Intel Tangier PCI id 2015-07-16 17:48:48 +02:00
intel-mid RTC for 4.8 2016-08-05 09:48:22 -04:00
intel-quark x86/platform/intel/quark: Drop IMR lock bit support 2016-02-23 07:37:23 +01:00
iris x86: platform: iris: drop owner assignment from platform_drivers 2014-10-20 16:20:15 +02:00
olpc x86/platform: Audit and remove any unnecessary uses of module.h 2016-07-14 15:06:59 +02:00
scx200
sfi x86: Cleanup irq_domain ops 2015-04-24 15:36:55 +02:00
ts5500 x86/platform: Delete extraneous MODULE_* tags fromm ts5500 2016-07-16 22:41:00 +02:00
uv x86/platform/uv: Skip UV runtime services mapping in the efi_runtime_disabled case 2016-08-11 13:55:36 +02:00
Makefile x86/platform/iosf_mbi: Move to dedicated folder 2015-07-16 17:48:47 +02:00