Commit f9ecf422 authored by Dave Young's avatar Dave Young Committed by Greg Kroah-Hartman

efi/bgrt: Skip efi_bgrt_init() in case of non-EFI boot

commit 7425826f upstream.

Sabrina Dubroca reported an early panic:

  BUG: unable to handle kernel paging request at ffffffffff240001
  IP: efi_bgrt_init+0xdc/0x134

  [...]

  ---[ end Kernel panic - not syncing: Attempted to kill the idle task!

... which was introduced by:

  7b0a9114 ("efi/x86: Move the EFI BGRT init code to early init code")

The cause is that on this machine the firmware provides the EFI ACPI BGRT
table even on legacy non-EFI bootups - which table should be EFI only.

The garbage BGRT data causes the efi_bgrt_init() panic.

Add a check to skip efi_bgrt_init() in case non-EFI bootup to work around
this firmware bug.
Tested-by: default avatarSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: default avatarDave Young <dyoung@redhat.com>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarMatt Fleming <matt@codeblueprint.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Fixes: 7b0a9114 ("efi/x86: Move the EFI BGRT init code to early init code")
Link: http://lkml.kernel.org/r/20170526113652.21339-6-matt@codeblueprint.co.uk
[ Rewrote the changelog to be more readable. ]
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c76a4a07
...@@ -36,6 +36,9 @@ void __init efi_bgrt_init(struct acpi_table_header *table) ...@@ -36,6 +36,9 @@ void __init efi_bgrt_init(struct acpi_table_header *table)
if (acpi_disabled) if (acpi_disabled)
return; return;
if (!efi_enabled(EFI_BOOT))
return;
if (table->length < sizeof(bgrt_tab)) { if (table->length < sizeof(bgrt_tab)) {
pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n", pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n",
table->length, sizeof(bgrt_tab)); table->length, sizeof(bgrt_tab));
......
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