This is a note to let you know that I've just added the patch titled
x86/boot/compressed: Move bootargs parsing out of 32-bit startup code
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-move-bootargs-parsing-out-of-32-bit-startup-code.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 5c3a85f35b583259cf5ca0344cd79c8899ba1bb7 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@xxxxxxxxxx>
Date: Tue, 22 Nov 2022 17:10:03 +0100
Subject: x86/boot/compressed: Move bootargs parsing out of 32-bit startup code
From: Ard Biesheuvel <ardb@xxxxxxxxxx>
commit 5c3a85f35b583259cf5ca0344cd79c8899ba1bb7 upstream.
Move the logic that chooses between the different EFI entrypoints out of
the 32-bit boot path, and into a 64-bit helper that can perform the same
task much more cleanly. While at it, document the mixed mode boot flow
in a code comment.
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lore.kernel.org/r/20221122161017.2426828-4-ardb@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/boot/compressed/efi_mixed.S | 43 +++++++++++++++++++++++++++++++++++
arch/x86/boot/compressed/head_64.S | 24 +++----------------
2 files changed, 47 insertions(+), 20 deletions(-)
--- a/arch/x86/boot/compressed/efi_mixed.S
+++ b/arch/x86/boot/compressed/efi_mixed.S
@@ -22,6 +22,49 @@
.code64
.text
+/*
+ * When booting in 64-bit mode on 32-bit EFI firmware, startup_64_mixed_mode()
+ * is the first thing that runs after switching to long mode. Depending on
+ * whether the EFI handover protocol or the compat entry point was used to
+ * enter the kernel, it will either branch to the 64-bit EFI handover
+ * entrypoint at offset 0x390 in the image, or to the 64-bit EFI PE/COFF
+ * entrypoint efi_pe_entry(). In the former case, the bootloader must provide a
+ * struct bootparams pointer as the third argument, so the presence of such a
+ * pointer is used to disambiguate.
+ *
+ * +--------------+
+ * +------------------+ +------------+ +------>| efi_pe_entry |
+ * | efi32_pe_entry |---->| | | +-----------+--+
+ * +------------------+ | | +------+----------------+ |
+ * | startup_32 |---->| startup_64_mixed_mode | |
+ * +------------------+ | | +------+----------------+ V
+ * | efi32_stub_entry |---->| | | +------------------+
+ * +------------------+ +------------+ +---->| efi64_stub_entry |
+ * +-------------+----+
+ * +------------+ +----------+ |
+ * | startup_64 |<----| efi_main |<--------------+
+ * +------------+ +----------+
+ */
+SYM_FUNC_START(startup_64_mixed_mode)
+ lea efi32_boot_args(%rip), %rdx
+ mov 0(%rdx), %edi
+ mov 4(%rdx), %esi
+ mov 8(%rdx), %edx // saved bootparams pointer
+ test %edx, %edx
+ jnz efi64_stub_entry
+ /*
+ * efi_pe_entry uses MS calling convention, which requires 32 bytes of
+ * shadow space on the stack even if all arguments are passed in
+ * registers. We also need an additional 8 bytes for the space that
+ * would be occupied by the return address, and this also results in
+ * the correct stack alignment for entry.
+ */
+ sub $40, %rsp
+ mov %rdi, %rcx // MS calling convention
+ mov %rsi, %rdx
+ jmp efi_pe_entry
+SYM_FUNC_END(startup_64_mixed_mode)
+
SYM_FUNC_START(__efi64_thunk)
push %rbp
push %rbx
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -261,25 +261,9 @@ SYM_FUNC_START(startup_32)
*/
leal rva(startup_64)(%ebp), %eax
#ifdef CONFIG_EFI_MIXED
- movl rva(efi32_boot_args)(%ebp), %edi
- testl %edi, %edi
- jz 1f
- leal rva(efi64_stub_entry)(%ebp), %eax
- movl rva(efi32_boot_args+4)(%ebp), %esi
- movl rva(efi32_boot_args+8)(%ebp), %edx // saved bootparams pointer
- testl %edx, %edx
- jnz 1f
- /*
- * efi_pe_entry uses MS calling convention, which requires 32 bytes of
- * shadow space on the stack even if all arguments are passed in
- * registers. We also need an additional 8 bytes for the space that
- * would be occupied by the return address, and this also results in
- * the correct stack alignment for entry.
- */
- subl $40, %esp
- leal rva(efi_pe_entry)(%ebp), %eax
- movl %edi, %ecx // MS calling convention
- movl %esi, %edx
+ cmpb $1, rva(efi_is64)(%ebp)
+ je 1f
+ leal rva(startup_64_mixed_mode)(%ebp), %eax
1:
#endif
/* Check if the C-bit position is correct when SEV is active */
@@ -795,7 +779,7 @@ SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLO
SYM_DATA(image_offset, .long 0)
#endif
#ifdef CONFIG_EFI_MIXED
-SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0)
+SYM_DATA(efi32_boot_args, .long 0, 0, 0)
SYM_DATA(efi_is64, .byte 1)
#define ST32_boottime 60 // offsetof(efi_system_table_32_t, boottime)
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
