This is a note to let you know that I've just added the patch titled
x86/boot/compressed: Simplify IDT/GDT preserve/restore in the EFI thunk
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-boot-compressed-simplify-idt-gdt-preserve-restore-in-the-efi-thunk.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 630f337f0c4fd80390e8600adcab31550aea33df Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@xxxxxxxxxx>
Date: Tue, 22 Nov 2022 17:10:08 +0100
Subject: x86/boot/compressed: Simplify IDT/GDT preserve/restore in the EFI thunk
From: Ard Biesheuvel <ardb@xxxxxxxxxx>
commit 630f337f0c4fd80390e8600adcab31550aea33df upstream.
Tweak the asm and remove some redundant instructions. While at it,
fix the associated comment for style and correctness.
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lore.kernel.org/r/20221122161017.2426828-9-ardb@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/boot/compressed/efi_mixed.S | 20 +++++++-------------
1 file changed, 7 insertions(+), 13 deletions(-)
--- a/arch/x86/boot/compressed/efi_mixed.S
+++ b/arch/x86/boot/compressed/efi_mixed.S
@@ -96,24 +96,20 @@ SYM_FUNC_START(__efi64_thunk)
leaq 0x20(%rsp), %rbx
sgdt (%rbx)
-
- addq $16, %rbx
- sidt (%rbx)
+ sidt 16(%rbx)
leaq 1f(%rip), %rbp
/*
- * Switch to IDT and GDT with 32-bit segments. This is the firmware GDT
- * and IDT that was installed when the kernel started executing. The
- * pointers were saved by the efi32_entry() routine below.
+ * Switch to IDT and GDT with 32-bit segments. These are the firmware
+ * GDT and IDT that were installed when the kernel started executing.
+ * The pointers were saved by the efi32_entry() routine below.
*
* Pass the saved DS selector to the 32-bit code, and use far return to
* restore the saved CS selector.
*/
- leaq efi32_boot_idt(%rip), %rax
- lidt (%rax)
- leaq efi32_boot_gdt(%rip), %rax
- lgdt (%rax)
+ lidt efi32_boot_idt(%rip)
+ lgdt efi32_boot_gdt(%rip)
movzwl efi32_boot_ds(%rip), %edx
movzwq efi32_boot_cs(%rip), %rax
@@ -187,9 +183,7 @@ SYM_FUNC_START_LOCAL(efi_enter32)
*/
cli
- lidtl (%ebx)
- subl $16, %ebx
-
+ lidtl 16(%ebx)
lgdtl (%ebx)
movl %cr4, %eax
Patches currently in stable-queue which might be from ardb@xxxxxxxxxx are
queue-6.1/x86-boot-compressed-avoid-touching-ecx-in-startup32_set_idt_entry.patch
queue-6.1/x86-boot-compressed-only-build-mem_encrypt.s-if-amd_mem_encrypt-y.patch
queue-6.1/efi-capsule-loader-fix-incorrect-allocation-size.patch
queue-6.1/x86-decompressor-move-global-symbol-references-to-c-code.patch
queue-6.1/x86-boot-compressed-move-startup32_load_idt-into-.text-section.patch
queue-6.1/x86-decompressor-only-call-the-trampoline-when-changing-paging-levels.patch
queue-6.1/x86-boot-compressed-rename-efi_thunk_64.s-to-efi-mixed.s.patch
queue-6.1/x86-decompressor-merge-trampoline-cleanup-with-switching-code.patch
queue-6.1/x86-boot-compressed-move-efi32_pe_entry-out-of-head_64.s.patch
queue-6.1/efi-verify-that-variable-services-are-supported.patch
queue-6.1/x86-decompressor-call-trampoline-directly-from-c-code.patch
queue-6.1/x86-boot-compressed-pull-global-variable-reference-into-startup32_load_idt.patch
queue-6.1/x86-boot-compressed-simplify-idt-gdt-preserve-restore-in-the-efi-thunk.patch
queue-6.1/x86-decompressor-assign-paging-related-global-variables-earlier.patch
queue-6.1/x86-boot-compressed-move-32-bit-entrypoint-code-into-.text-section.patch
queue-6.1/x86-boot-compressed-move-efi32_pe_entry-into-.text-section.patch
queue-6.1/x86-decompressor-avoid-the-need-for-a-stack-in-the-32-bit-trampoline.patch
queue-6.1/x86-boot-compressed-move-startup32_check_sev_cbit-out-of-head_64.s.patch
queue-6.1/x86-boot-compressed-efi-merge-multiple-definitions-of-image_offset-into-one.patch
queue-6.1/x86-boot-compressed-move-startup32_load_idt-out-of-head_64.s.patch
queue-6.1/decompress-use-8-byte-alignment.patch
queue-6.1/x86-boot-compressed-move-efi32_entry-out-of-head_64.s.patch
queue-6.1/efi-libstub-use-efi_loader_code-region-when-moving-the-kernel-in-memory.patch
queue-6.1/crypto-arm64-neonbs-fix-out-of-bounds-access-on-short-input.patch
queue-6.1/x86-boot-compressed-move-bootargs-parsing-out-of-32-bit-startup-code.patch
queue-6.1/efivarfs-request-at-most-512-bytes-for-variable-names.patch
queue-6.1/x86-boot-compressed-adhere-to-calling-convention-in-get_sev_encryption_bit.patch
queue-6.1/x86-boot-compressed-move-startup32_check_sev_cbit-into-.text.patch
queue-6.1/x86-decompressor-store-boot_params-pointer-in-callee-save-register.patch
queue-6.1/x86-efistub-branch-straight-to-kernel-entry-point-from-c-code.patch
queue-6.1/x86-decompressor-call-trampoline-as-a-normal-function.patch
queue-6.1/x86-decompressor-pass-pgtable-address-to-trampoline-directly.patch
queue-6.1/x86-decompressor-use-standard-calling-convention-for-trampoline.patch
queue-6.1/x86-efi-make-the-deprecated-efi-handover-protocol-optional.patch
