This is a note to let you know that I've just added the patch titled
x86/decompressor: Avoid magic offsets for EFI handover entrypoint
to the 6.1-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-decompressor-avoid-magic-offsets-for-efi-handover-entrypoint.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From stable+bounces-25897-greg=kroah.com@xxxxxxxxxxxxxxx Mon Mar 4 12:20:51 2024
From: Ard Biesheuvel <ardb+git@xxxxxxxxxx>
Date: Mon, 4 Mar 2024 12:19:42 +0100
Subject: x86/decompressor: Avoid magic offsets for EFI handover entrypoint
To: stable@xxxxxxxxxxxxxxx
Cc: linux-efi@xxxxxxxxxxxxxxx, Ard Biesheuvel <ardb@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>
Message-ID: <20240304111937.2556102-24-ardb+git@xxxxxxxxxx>
From: Ard Biesheuvel <ardb+git@xxxxxxxxxx>
From: Ard Biesheuvel <ardb@xxxxxxxxxx>
[ Commit 12792064587623065250069d1df980e2c9ac3e67 upstream ]
The native 32-bit or 64-bit EFI handover protocol entrypoint offset
relative to the respective startup_32/64 address is described in
boot_params as handover_offset, so that the special Linux/x86 aware EFI
loader can find it there.
When mixed mode is enabled, this single field has to describe this
offset for both the 32-bit and 64-bit entrypoints, so their respective
relative offsets have to be identical. Given that startup_32 and
startup_64 are 0x200 bytes apart, and the EFI handover entrypoint
resides at a fixed offset, the 32-bit and 64-bit versions of those
entrypoints must be exactly 0x200 bytes apart as well.
Currently, hard-coded fixed offsets are used to ensure this, but it is
sufficient to emit the 64-bit entrypoint 0x200 bytes after the 32-bit
one, wherever it happens to reside. This allows this code (which is now
EFI mixed mode specific) to be moved into efi_mixed.S and out of the
startup code in head_64.S.
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230807162720.545787-6-ardb@xxxxxxxxxx
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/boot/compressed/efi_mixed.S | 20 +++++++++++++++++++-
arch/x86/boot/compressed/head_64.S | 18 ------------------
2 files changed, 19 insertions(+), 19 deletions(-)
--- a/arch/x86/boot/compressed/efi_mixed.S
+++ b/arch/x86/boot/compressed/efi_mixed.S
@@ -146,6 +146,16 @@ SYM_FUNC_START(__efi64_thunk)
SYM_FUNC_END(__efi64_thunk)
.code32
+#ifdef CONFIG_EFI_HANDOVER_PROTOCOL
+SYM_FUNC_START(efi32_stub_entry)
+ add $0x4, %esp /* Discard return address */
+ popl %ecx
+ popl %edx
+ popl %esi
+ jmp efi32_entry
+SYM_FUNC_END(efi32_stub_entry)
+#endif
+
/*
* EFI service pointer must be in %edi.
*
@@ -226,7 +236,7 @@ SYM_FUNC_END(efi_enter32)
* stub may still exit and return to the firmware using the Exit() EFI boot
* service.]
*/
-SYM_FUNC_START(efi32_entry)
+SYM_FUNC_START_LOCAL(efi32_entry)
call 1f
1: pop %ebx
@@ -326,6 +336,14 @@ SYM_FUNC_START(efi32_pe_entry)
RET
SYM_FUNC_END(efi32_pe_entry)
+#ifdef CONFIG_EFI_HANDOVER_PROTOCOL
+ .org efi32_stub_entry + 0x200
+ .code64
+SYM_FUNC_START_NOALIGN(efi64_stub_entry)
+ jmp efi_stub_entry
+SYM_FUNC_END(efi64_stub_entry)
+#endif
+
.section ".rodata"
/* EFI loaded image protocol GUID */
.balign 4
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -286,17 +286,6 @@ SYM_FUNC_START(startup_32)
lret
SYM_FUNC_END(startup_32)
-#if IS_ENABLED(CONFIG_EFI_MIXED) && IS_ENABLED(CONFIG_EFI_HANDOVER_PROTOCOL)
- .org 0x190
-SYM_FUNC_START(efi32_stub_entry)
- add $0x4, %esp /* Discard return address */
- popl %ecx
- popl %edx
- popl %esi
- jmp efi32_entry
-SYM_FUNC_END(efi32_stub_entry)
-#endif
-
.code64
.org 0x200
SYM_CODE_START(startup_64)
@@ -474,13 +463,6 @@ SYM_CODE_START(startup_64)
jmp *%rax
SYM_CODE_END(startup_64)
-#if IS_ENABLED(CONFIG_EFI_MIXED) && IS_ENABLED(CONFIG_EFI_HANDOVER_PROTOCOL)
- .org 0x390
-SYM_FUNC_START(efi64_stub_entry)
- jmp efi_stub_entry
-SYM_FUNC_END(efi64_stub_entry)
-#endif
-
.text
SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
Patches currently in stable-queue which might be from kroah.com@xxxxxxxxxxxxxxx are
queue-6.1/x86-decompressor-avoid-magic-offsets-for-efi-handover-entrypoint.patch
queue-6.1/x86-efistub-avoid-placing-the-kernel-below-load_physical_addr.patch
queue-6.1/x86-efistub-avoid-legacy-decompressor-when-doing-efi-boot.patch
queue-6.1/x86-efistub-perform-4-5-level-paging-switch-from-the-stub.patch
queue-6.1/x86-boot-rename-conflicting-boot_params-pointer-to-boot_params_ptr.patch
queue-6.1/x86-efistub-perform-snp-feature-test-while-running-in-the-firmware.patch
queue-6.1/x86-efistub-simplify-and-clean-up-handover-entry-code.patch
queue-6.1/efi-libstub-add-memory-attribute-protocol-definitions.patch
queue-6.1/efi-libstub-add-limit-argument-to-efi_random_alloc.patch
queue-6.1/efi-x86-fix-the-missing-kaslr_flag-bit-in-boot_params-hdr.loadflags.patch
queue-6.1/arm64-efi-limit-allocations-to-48-bit-addressable-physical-region.patch
queue-6.1/x86-efistub-prefer-efi-memory-attributes-protocol-over-dxe-services.patch
queue-6.1/efi-efivars-prevent-double-registration.patch
queue-6.1/x86-boot-efistub-assign-global-boot_params-variable.patch
queue-6.1/x86-efistub-clear-bss-in-efi-handover-protocol-entrypoint.patch
queue-6.1/x86-decompressor-factor-out-kernel-decompression-and-relocation.patch
queue-6.1/efi-x86-avoid-physical-kaslr-on-older-dell-systems.patch
