This is a note to let you know that I've just added the patch titled
x86/platform/uv: Skip UV runtime services mapping in the efi_runtime_disabled case
to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-platform-uv-skip-uv-runtime-services-mapping-in-the-efi_runtime_disabled-case.patch
and it can be found in the queue-4.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f72075c9eda8a43aeea2f9dbb8d187afd4a76f0b Mon Sep 17 00:00:00 2001
From: Alex Thorlton <athorlton@xxxxxxx>
Date: Thu, 11 Aug 2016 11:41:59 +0100
Subject: x86/platform/uv: Skip UV runtime services mapping in the efi_runtime_disabled case
From: Alex Thorlton <athorlton@xxxxxxx>
commit f72075c9eda8a43aeea2f9dbb8d187afd4a76f0b upstream.
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@xxxxxxx>
Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Travis <travis@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Russ Anderson <rja@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1470912120-22831-2-git-send-email-matt@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/platform/uv/bios_uv.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/platform/uv/bios_uv.c
+++ b/arch/x86/platform/uv/bios_uv.c
@@ -188,7 +188,8 @@ EXPORT_SYMBOL_GPL(uv_bios_set_legacy_vga
void uv_bios_init(void)
{
uv_systab = NULL;
- if ((efi.uv_systab == EFI_INVALID_TABLE_ADDR) || !efi.uv_systab) {
+ if ((efi.uv_systab == EFI_INVALID_TABLE_ADDR) ||
+ !efi.uv_systab || efi_runtime_disabled()) {
pr_crit("UV: UVsystab: missing\n");
return;
}
Patches currently in stable-queue which might be from athorlton@xxxxxxx are
queue-4.7/x86-platform-uv-skip-uv-runtime-services-mapping-in-the-efi_runtime_disabled-case.patch
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