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authorArvind Sankar <nivedita@alum.mit.edu>2020-05-23 18:15:13 -0400
committerArd Biesheuvel <ardb@kernel.org>2020-05-24 00:25:15 +0200
commit9241dfe7f2772fc73c82eb950afb1c795d2c012c (patch)
tree6c04350f6b935f54893741a27642dd4eaec9f68e /arch/x86/boot
parent6e99d3213b10ee18428d6d20715ad6c0e89ead4d (diff)
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efi/x86: Drop the special GDT for the EFI thunk
Instead of using efi_gdt64 to switch back to 64-bit mode and then switching to the real boot-time GDT, just switch to the boot-time GDT directly. The two GDT's are identical other than efi_gdt64 not including the 32-bit code segment. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200523221513.1642948-1-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Diffstat (limited to 'arch/x86/boot')
-rw-r--r--arch/x86/boot/compressed/efi_thunk_64.S19
1 files changed, 3 insertions, 16 deletions
diff --git a/arch/x86/boot/compressed/efi_thunk_64.S b/arch/x86/boot/compressed/efi_thunk_64.S
index 2b2049259619..c4bb0f9363f5 100644
--- a/arch/x86/boot/compressed/efi_thunk_64.S
+++ b/arch/x86/boot/compressed/efi_thunk_64.S
@@ -28,8 +28,6 @@ SYM_FUNC_START(__efi64_thunk)
push %rbx
leaq 1f(%rip), %rbp
- leaq efi_gdt64(%rip), %rbx
- movl %ebx, 2(%rbx) /* Fixup the gdt base address */
movl %ds, %eax
push %rax
@@ -48,7 +46,8 @@ SYM_FUNC_START(__efi64_thunk)
movl %r8d, 0xc(%rsp)
movl %r9d, 0x10(%rsp)
- sgdt 0x14(%rsp)
+ leaq 0x14(%rsp), %rbx
+ sgdt (%rbx)
/*
* Switch to gdt with 32-bit segments. This is the firmware GDT
@@ -68,8 +67,7 @@ SYM_FUNC_START(__efi64_thunk)
pushq %rax
lretq
-1: lgdt 0x14(%rsp)
- addq $32, %rsp
+1: addq $32, %rsp
movq %rdi, %rax
pop %rbx
@@ -175,14 +173,3 @@ SYM_DATA_END(efi32_boot_cs)
SYM_DATA_START(efi32_boot_ds)
.word 0
SYM_DATA_END(efi32_boot_ds)
-
-SYM_DATA_START(efi_gdt64)
- .word efi_gdt64_end - efi_gdt64
- .long 0 /* Filled out by user */
- .word 0
- .quad 0x0000000000000000 /* NULL descriptor */
- .quad 0x00af9a000000ffff /* __KERNEL_CS */
- .quad 0x00cf92000000ffff /* __KERNEL_DS */
- .quad 0x0080890000000000 /* TS descriptor */
- .quad 0x0000000000000000 /* TS continued */
-SYM_DATA_END_LABEL(efi_gdt64, SYM_L_LOCAL, efi_gdt64_end)