diff options
Diffstat (limited to 'arch/x86/cpu/cpu.c')
-rw-r--r-- | arch/x86/cpu/cpu.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c index 7a4de29..8c1eacc 100644 --- a/arch/x86/cpu/cpu.c +++ b/arch/x86/cpu/cpu.c @@ -275,3 +275,67 @@ void cpu_disable_paging_pae(void) : : "eax"); } + +static bool has_cpuid(void) +{ + unsigned long flag; + + asm volatile("pushf\n" \ + "pop %%eax\n" + "mov %%eax, %%ecx\n" /* ecx = flags */ + "xor %1, %%eax\n" + "push %%eax\n" + "popf\n" /* flags ^= $2 */ + "pushf\n" + "pop %%eax\n" /* eax = flags */ + "push %%ecx\n" + "popf\n" /* flags = ecx */ + "xor %%ecx, %%eax\n" + "mov %%eax, %0" + : "=r" (flag) + : "i" (1 << 21) + : "eax", "ecx", "memory"); + + return flag != 0; +} + +static bool can_detect_long_mode(void) +{ + unsigned long flag; + + asm volatile("mov $0x80000000, %%eax\n" + "cpuid\n" + "mov %%eax, %0" + : "=r" (flag) + : + : "eax", "ebx", "ecx", "edx", "memory"); + + return flag > 0x80000000UL; +} + +static bool has_long_mode(void) +{ + unsigned long flag; + + asm volatile("mov $0x80000001, %%eax\n" + "cpuid\n" + "mov %%edx, %0" + : "=r" (flag) + : + : "eax", "ebx", "ecx", "edx", "memory"); + + return flag & (1 << 29) ? true : false; +} + +int cpu_has_64bit(void) +{ + return has_cpuid() && can_detect_long_mode() && + has_long_mode(); +} + +int print_cpuinfo(void) +{ + printf("CPU: %s\n", cpu_has_64bit() ? "x86_64" : "x86"); + + return 0; +} |