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Redecorating
60 lines
2.6 KiB
Diff
60 lines
2.6 KiB
Diff
From b6740001d1adbfe84768b859bee038ceeccdc50c Mon Sep 17 00:00:00 2001
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From: "Ard Biesheuvel" <ardb@kernel.org>
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Subject: [PATCH] efi: runtime: avoid EFIv2 runtime services on Apple x86 machines
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Date: Wed, 12 Jan 2022 21:14:13 +1100
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Aditya reports [0] that his recent MacbookPro crashes in the firmware
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when using the variable services at runtime. The culprit appears to be a
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call to QueryVariableInfo(), which we did not use to call on Apple x86
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machines in the past as they only upgraded from EFI v1.10 to EFI v2.40
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firmware fairly recently, and QueryVariableInfo() (along with
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UpdateCapsule() et al) was added in EFI v2.00.
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The only runtime service introduced in EFI v2.00 that we actually use in
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Linux is QueryVariableInfo(), as the capsule based ones are optional,
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generally not used at runtime (all the LVFS/fwupd firmware update
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infrastructure uses helper EFI programs that invoke capsule update at
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boot time, not runtime), and not implemented by Apple machines in the
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first place. QueryVariableInfo() is used to 'safely' set variables,
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i.e., only when there is enough space. This prevents machines with buggy
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firmwares from corrupting their NVRAMs when they run out of space.
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Given that Apple machines have been using EFI v1.10 services only for
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the longest time (the EFI v2.0 spec was released in 2006, and Linux
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support for the newly introduced runtime services was added in 2011, but
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the MacbookPro12,1 released in 2015 still claims to be EFI v1.10 only),
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let's avoid the EFI v2.0 ones on all Apple x86 machines.
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[0] https://lore.kernel.org/all/6D757C75-65B1-468B-842D-10410081A8E4@live.com/
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Cc: <stable@vger.kernel.org>
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Cc: Jeremy Kerr <jk@ozlabs.org>
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Cc: Matthew Garrett <mjg59@srcf.ucam.org>
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Reported-by: Aditya Garg <gargaditya08@live.com>
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Tested-by: Orlando Chamberlain <redecorating@protonmail.com>
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Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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---
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drivers/firmware/efi/efi.c | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
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index ae79c3300129..7de3f5b6e8d0 100644
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--- a/drivers/firmware/efi/efi.c
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+++ b/drivers/firmware/efi/efi.c
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@@ -722,6 +722,13 @@ void __init efi_systab_report_header(const efi_table_hdr_t *systab_hdr,
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systab_hdr->revision >> 16,
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systab_hdr->revision & 0xffff,
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vendor);
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+
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+ if (IS_ENABLED(CONFIG_X86_64) &&
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+ systab_hdr->revision > EFI_1_10_SYSTEM_TABLE_REVISION &&
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+ !strcmp(vendor, "Apple")) {
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+ pr_info("Apple Mac detected, using EFI v1.10 runtime services only\n");
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+ efi.runtime_version = EFI_1_10_SYSTEM_TABLE_REVISION;
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+ }
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}
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static __initdata char memory_type_name[][13] = {
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--
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2.30.2
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