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| author | Ard Biesheuvel <ardb@kernel.org> | 2022-11-22 17:10:09 +0100 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2022-11-24 08:57:41 +0100 |
| commit | 6aac80a8da46d70f2ae7ff97c9f45a15c7c9b3ef (patch) | |
| tree | 51f732d9fbf3408585c126dc3a8deabd69646f0a /arch/x86/boot | |
| parent | x86/boot/compressed: Simplify IDT/GDT preserve/restore in the EFI thunk (diff) | |
| download | linux-6aac80a8da46d70f2ae7ff97c9f45a15c7c9b3ef.tar.xz linux-6aac80a8da46d70f2ae7ff97c9f45a15c7c9b3ef.zip | |
x86/boot/compressed: Avoid touching ECX in startup32_set_idt_entry()
Avoid touching register %ecx in startup32_set_idt_entry(), by folding
the MOV, SHL and ORL instructions into a single ORL which no longer
requires a temp register.
This permits ECX to be used as a function argument in a subsequent
patch.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221122161017.2426828-10-ardb@kernel.org
Diffstat (limited to 'arch/x86/boot')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 8 |
1 files changed, 2 insertions, 6 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 34d03953b08c..a2d1c0317944 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -733,7 +733,6 @@ SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLOBAL, boot32_idt_end) */ SYM_FUNC_START(startup32_set_idt_entry) push %ebx - push %ecx /* IDT entry address to %ebx */ leal rva(boot32_idt)(%ebp), %ebx @@ -742,10 +741,8 @@ SYM_FUNC_START(startup32_set_idt_entry) /* Build IDT entry, lower 4 bytes */ movl %eax, %edx - andl $0x0000ffff, %edx # Target code segment offset [15:0] - movl $__KERNEL32_CS, %ecx # Target code segment selector - shl $16, %ecx - orl %ecx, %edx + andl $0x0000ffff, %edx # Target code segment offset [15:0] + orl $(__KERNEL32_CS << 16), %edx # Target code segment selector /* Store lower 4 bytes to IDT */ movl %edx, (%ebx) @@ -758,7 +755,6 @@ SYM_FUNC_START(startup32_set_idt_entry) /* Store upper 4 bytes to IDT */ movl %edx, 4(%ebx) - pop %ecx pop %ebx RET SYM_FUNC_END(startup32_set_idt_entry) |