From 7425826f4f7ac60f2538b06a7f0a5d1006405159 Mon Sep 17 00:00:00 2001 From: Dave Young Date: Fri, 26 May 2017 12:36:51 +0100 Subject: [PATCH] efi/bgrt: Skip efi_bgrt_init() in case of non-EFI boot 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: 7b0a911478c7 ("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: Sabrina Dubroca Signed-off-by: Dave Young Signed-off-by: Ard Biesheuvel Signed-off-by: Matt Fleming Cc: # v4.11+ Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Fixes: 7b0a911478c7 ("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: Ingo Molnar --- drivers/firmware/efi/efi-bgrt.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/firmware/efi/efi-bgrt.c b/drivers/firmware/efi/efi-bgrt.c index 04ca8764f0c0..8bf27323f7a3 100644 --- a/drivers/firmware/efi/efi-bgrt.c +++ b/drivers/firmware/efi/efi-bgrt.c @@ -36,6 +36,9 @@ void __init efi_bgrt_init(struct acpi_table_header *table) if (acpi_disabled) return; + if (!efi_enabled(EFI_BOOT)) + return; + if (table->length < sizeof(bgrt_tab)) { pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n", table->length, sizeof(bgrt_tab)); -- GitLab