@@ -27,12 +27,9 @@ SYM_FUNC_START(__efi64_thunk)
push %rbp
push %rbx
- subq $8, %rsp
- leaq 1f(%rip), %rax
- movl %eax, 4(%rsp)
- leaq efi_gdt64(%rip), %rax
- movl %eax, (%rsp)
- movl %eax, 2(%rax) /* Fixup the gdt base address */
+ leaq 1f(%rip), %rbp
+ leaq efi_gdt64(%rip), %rbx
+ movl %ebx, 2(%rbx) /* Fixup the gdt base address */
movl %ds, %eax
push %rax
@@ -48,12 +45,10 @@ SYM_FUNC_START(__efi64_thunk)
movl %esi, 0x0(%rsp)
movl %edx, 0x4(%rsp)
movl %ecx, 0x8(%rsp)
- movq %r8, %rsi
- movl %esi, 0xc(%rsp)
- movq %r9, %rsi
- movl %esi, 0x10(%rsp)
+ movl %r8d, 0xc(%rsp)
+ movl %r9d, 0x10(%rsp)
- sgdt save_gdt(%rip)
+ sgdt 0x14(%rsp)
/*
* Switch to gdt with 32-bit segments. This is the firmware GDT
@@ -68,11 +63,10 @@ SYM_FUNC_START(__efi64_thunk)
pushq %rax
lretq
-1: addq $32, %rsp
+1: lgdt 0x14(%rsp)
+ addq $32, %rsp
movq %rdi, %rax
- lgdt save_gdt(%rip)
-
pop %rbx
movl %ebx, %ss
pop %rbx
@@ -83,15 +77,9 @@ SYM_FUNC_START(__efi64_thunk)
/*
* Convert 32-bit status code into 64-bit.
*/
- test %rax, %rax
- jz 1f
- movl %eax, %ecx
- andl $0x0fffffff, %ecx
- andl $0xf0000000, %eax
- shl $32, %rax
- or %rcx, %rax
-1:
- addq $8, %rsp
+ roll $1, %eax
+ rorq $1, %rax
+
pop %rbx
pop %rbp
ret
@@ -135,9 +123,7 @@ SYM_FUNC_START_LOCAL(efi_enter32)
*/
cli
- movl 56(%esp), %eax
- movl %eax, 2(%eax)
- lgdtl (%eax)
+ lgdtl (%ebx)
movl %cr4, %eax
btsl $(X86_CR4_PAE_BIT), %eax
@@ -154,9 +140,8 @@ SYM_FUNC_START_LOCAL(efi_enter32)
xorl %eax, %eax
lldt %ax
- movl 60(%esp), %eax
pushl $__KERNEL_CS
- pushl %eax
+ pushl %ebp
/* Enable paging */
movl %cr0, %eax
@@ -172,11 +157,6 @@ SYM_DATA_START(efi32_boot_gdt)
.quad 0
SYM_DATA_END(efi32_boot_gdt)
-SYM_DATA_START_LOCAL(save_gdt)
- .word 0
- .quad 0
-SYM_DATA_END(save_gdt)
-
SYM_DATA_START(efi_gdt64)
.word efi_gdt64_end - efi_gdt64
.long 0 /* Filled out by user */
Reduce the stack frame of the EFI stub's mixed mode thunk routine by 8 bytes, by moving the GDT and return addresses to EBP and EBX, which we need to preserve anyway, since their top halves will be cleared by the call into 32-bit firmware code. Doing so results in the UEFI code being entered with a 16 byte aligned stack, as mandated by the UEFI spec, fixing the last occurrence in the 64-bit kernel where we violate this requirement. Also, move the saved GDT from a global variable to an unused part of the stack frame, and touch up some other parts of the code. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/x86/boot/compressed/efi_thunk_64.S | 46 +++++++------------------ 1 file changed, 13 insertions(+), 33 deletions(-)