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authorAlex Thorlton <athorlton@sgi.com>2016-08-11 11:41:59 +0100
committerIngo Molnar <mingo@kernel.org>2016-08-11 13:55:36 +0200
commitf72075c9eda8a43aeea2f9dbb8d187afd4a76f0b (patch)
tree35e167963b95224700177f1cbe4a0fd81ee4190d /Documentation
parent85e97be32c6242c98dbbc7a241b4a78c1b93327b (diff)
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>
Diffstat (limited to 'Documentation')
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