Commit ef5a7b5eb13e ("efi/x86: Remove GDT setup from efi_main")
introduced GDT setup into startup_32, and reloads the GDTR after
relocating the kernel for paranoia's sake.
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.
Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>
Fixes: ef5a7b5eb13e ("efi/x86: Remove GDT setup from efi_main")
---
arch/x86/boot/compressed/head_32.S | 9 ++++-----
1 file changed, 4 insertions(+), 5 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.
--
2.24.1
