diff options
| author | Ard Biesheuvel <[email protected]> | 2019-12-24 14:29:09 +0100 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2019-12-25 10:46:07 +0100 |
| commit | 4911ee401b7ceff8f38e0ac597cbf503d71e690c (patch) | |
| tree | e7aac326086466d51f3d67b74ea3f76cdf771f47 | |
| parent | 818c7ce724770fbcdcd43725c81f2b3535f82b76 (diff) | |
x86/efistub: Disable paging at mixed mode entry
The EFI mixed mode entry code goes through the ordinary startup_32()
routine before jumping into the kernel's EFI boot code in 64-bit
mode. The 32-bit startup code must be entered with paging disabled,
but this is not documented as a requirement for the EFI handover
protocol, and so we should disable paging explicitly when entering
the kernel from 32-bit EFI firmware.
Signed-off-by: Ard Biesheuvel <[email protected]>
Cc: <[email protected]>
Cc: Arvind Sankar <[email protected]>
Cc: Hans de Goede <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 58a512e33d8d..ee60b81944a7 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -244,6 +244,11 @@ SYM_FUNC_START(efi32_stub_entry) leal efi32_config(%ebp), %eax movl %eax, efi_config(%ebp) + /* Disable paging */ + movl %cr0, %eax + btrl $X86_CR0_PG_BIT, %eax + movl %eax, %cr0 + jmp startup_32 SYM_FUNC_END(efi32_stub_entry) #endif |