diff options
| author | Matt Fleming <matt.fleming@intel.com> | 2012-04-15 16:06:04 +0100 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2012-04-16 11:41:44 -0700 |
| commit | b1994304fc399f5d3a5368c81111d713490c4799 (patch) | |
| tree | fda4b1fa900378abddf71bc8d815543a49783fee /arch/x86/boot/compressed/head_64.S | |
| parent | d7de8649f34d45041409d1af4ba4a521971a9075 (diff) | |
x86, efi: Add dedicated EFI stub entry point
The method used to work out whether we were booted by EFI firmware or
via a boot loader is broken. Because efi_main() is always executed
when booting from a boot loader we will dereference invalid pointers
either on the stack (CONFIG_X86_32) or contained in %rdx
(CONFIG_X86_64) when searching for an EFI System Table signature.
Instead of dereferencing these invalid system table pointers, add a
new entry point that is only used when booting from EFI firmware, when
we know the pointer arguments will be valid. With this change legacy
boot loaders will no longer execute efi_main(), but will instead skip
EFI stub initialisation completely.
[ hpa: Marking this for urgent/stable since it is a regression when
the option is enabled; without the option the patch has no effect ]
Signed-off-by: Matt Fleming <matt.hfleming@intel.com>
Link: http://lkml.kernel.org/r/1334584744.26997.14.camel@mfleming-mobl1.ger.corp.intel.com
Reported-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> v3.3
Diffstat (limited to 'arch/x86/boot/compressed/head_64.S')
| -rw-r--r-- | arch/x86/boot/compressed/head_64.S | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 558d76ce23bc..87e03a13d8e3 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -200,18 +200,28 @@ ENTRY(startup_64) * entire text+data+bss and hopefully all of memory. */ #ifdef CONFIG_EFI_STUB - pushq %rsi + /* + * The entry point for the PE/COFF executable is 0x210, so only + * legacy boot loaders will execute this jmp. + */ + jmp preferred_addr + + .org 0x210 mov %rcx, %rdi mov %rdx, %rsi call efi_main - popq %rsi - cmpq $0,%rax - je preferred_addr movq %rax,%rsi - call 1f + cmpq $0,%rax + jne 2f 1: + /* EFI init failed, so hang. */ + hlt + jmp 1b +2: + call 3f +3: popq %rax - subq $1b, %rax + subq $3b, %rax subq BP_pref_address(%rsi), %rax add BP_code32_start(%esi), %eax leaq preferred_addr(%rax), %rax |