diff options
Diffstat (limited to 'arch/x86_64/kernel/trampoline.S')
| -rw-r--r-- | arch/x86_64/kernel/trampoline.S | 51 |
1 files changed, 3 insertions, 48 deletions
diff --git a/arch/x86_64/kernel/trampoline.S b/arch/x86_64/kernel/trampoline.S index 13eee63c7bb..e7e2764c461 100644 --- a/arch/x86_64/kernel/trampoline.S +++ b/arch/x86_64/kernel/trampoline.S @@ -54,6 +54,8 @@ r_base = . movw $(trampoline_stack_end - r_base), %sp call verify_cpu # Verify the cpu supports long mode + testl %eax, %eax # Check for return code + jnz no_longmode mov %cs, %ax movzx %ax, %esi # Find the 32bit trampoline location @@ -121,57 +123,10 @@ startup_64: jmp *%rax .code16 -verify_cpu: - pushl $0 # Kill any dangerous flags - popfl - - /* minimum CPUID flags for x86-64 */ - /* see http://www.x86-64.org/lists/discuss/msg02971.html */ -#define REQUIRED_MASK1 ((1<<0)|(1<<3)|(1<<4)|(1<<5)|(1<<6)|(1<<8)|\ - (1<<13)|(1<<15)|(1<<24)|(1<<25)|(1<<26)) -#define REQUIRED_MASK2 (1<<29) - - pushfl # check for cpuid - popl %eax - movl %eax, %ebx - xorl $0x200000,%eax - pushl %eax - popfl - pushfl - popl %eax - pushl %ebx - popfl - cmpl %eax, %ebx - jz no_longmode - - xorl %eax, %eax # See if cpuid 1 is implemented - cpuid - cmpl $0x1, %eax - jb no_longmode - - movl $0x01, %eax # Does the cpu have what it takes? - cpuid - andl $REQUIRED_MASK1, %edx - xorl $REQUIRED_MASK1, %edx - jnz no_longmode - - movl $0x80000000, %eax # See if extended cpuid is implemented - cpuid - cmpl $0x80000001, %eax - jb no_longmode - - movl $0x80000001, %eax # Does the cpu have what it takes? - cpuid - andl $REQUIRED_MASK2, %edx - xorl $REQUIRED_MASK2, %edx - jnz no_longmode - - ret # The cpu supports long mode - no_longmode: hlt jmp no_longmode - +#include "verify_cpu.S" # Careful these need to be in the same 64K segment as the above; tidt: |