diff options
| author | Arvind Sankar <nivedita@alum.mit.edu> | 2020-02-26 18:00:31 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-02-29 10:19:35 +0100 |
| commit | c98a76eabbb6e7755f3d4a4c33f8fe869dda6383 (patch) | |
| tree | 8d9f30d143d1b6d68863cf08d88cfc0fd2c5dff3 | |
| parent | 3e03dca500ca65b37dff0a205893095dca74f054 (diff) | |
x86/boot/compressed: Fix reloading of GDTR post-relocation
The following commit:
ef5a7b5eb13e ("efi/x86: Remove GDT setup from efi_main")
introduced GDT setup into the 32-bit kernel's startup_32, and reloads
the GDTR after relocating the kernel for paranoia's sake.
A followup commit:
32d009137a56 ("x86/boot: Reload GDTR after copying to the end of the buffer")
introduced a similar GDTR reload in the 64-bit kernel as well.
The GDTR is adjusted by (init_size-_end), however this may not be the
correct offset to apply if the kernel was loaded at a misaligned address
or below LOAD_PHYSICAL_ADDR, as in that case the decompression buffer
has an additional offset from the original load address.
This should never happen for a conformant bootloader, but we're being
paranoid anyway, so just store the new GDT address in there instead of
adding any offsets, which is simpler as well.
Fixes: ef5a7b5eb13e ("efi/x86: Remove GDT setup from efi_main")
Fixes: 32d009137a56 ("x86/boot: Reload GDTR after copying to the end of the buffer")
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-efi@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Link: https://lore.kernel.org/r/20200226230031.3011645-2-nivedita@alum.mit.edu
| -rw-r--r-- | arch/x86/boot/compressed/head_32.S | 9 | ||||
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 4 |
2 files changed, 6 insertions, 7 deletions
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index 356060c5332c..2f8138b71ea9 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -139,12 +139,11 @@ SYM_FUNC_START(startup_32) /* * The GDT may get overwritten either during the copy we just did or * during extract_kernel below. To avoid any issues, repoint the GDTR - * to the new copy of the GDT. EAX still contains the previously - * calculated relocation offset of init_size - _end. + * to the new copy of the GDT. */ - leal gdt(%ebx), %edx - addl %eax, 2(%edx) - lgdt (%edx) + leal gdt(%ebx), %eax + movl %eax, 2(%eax) + lgdt (%eax) /* * Jump to the relocated address. diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index f7bacc4c1494..fcf8feaa57ea 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -456,8 +456,8 @@ trampoline_return: * to the new copy of the GDT. */ leaq gdt64(%rbx), %rax - subq %rbp, 2(%rax) - addq %rbx, 2(%rax) + leaq gdt(%rbx), %rdx + movq %rdx, 2(%rax) lgdt (%rax) /* |