diff options
Diffstat (limited to 'arch/x86/boot/cpuflags.c')
-rw-r--r-- | arch/x86/boot/cpuflags.c | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/arch/x86/boot/cpuflags.c b/arch/x86/boot/cpuflags.c new file mode 100644 index 0000000..b02544a --- /dev/null +++ b/arch/x86/boot/cpuflags.c @@ -0,0 +1,104 @@ +#include <linux/types.h> +#include "bitops.h" + +#include <asm/processor-flags.h> +#include <asm/required-features.h> +#include <asm/msr-index.h> +#include "cpuflags.h" + +struct cpu_features cpu; +u32 cpu_vendor[3]; + +static bool loaded_flags; + +static int has_fpu(void) +{ + u16 fcw = -1, fsw = -1; + unsigned long cr0; + + asm volatile("mov %%cr0,%0" : "=r" (cr0)); + if (cr0 & (X86_CR0_EM|X86_CR0_TS)) { + cr0 &= ~(X86_CR0_EM|X86_CR0_TS); + asm volatile("mov %0,%%cr0" : : "r" (cr0)); + } + + asm volatile("fninit ; fnstsw %0 ; fnstcw %1" + : "+m" (fsw), "+m" (fcw)); + + return fsw == 0 && (fcw & 0x103f) == 0x003f; +} + +int has_eflag(unsigned long mask) +{ + unsigned long f0, f1; + + asm volatile("pushf \n\t" + "pushf \n\t" + "pop %0 \n\t" + "mov %0,%1 \n\t" + "xor %2,%1 \n\t" + "push %1 \n\t" + "popf \n\t" + "pushf \n\t" + "pop %1 \n\t" + "popf" + : "=&r" (f0), "=&r" (f1) + : "ri" (mask)); + + return !!((f0^f1) & mask); +} + +/* Handle x86_32 PIC using ebx. */ +#if defined(__i386__) && defined(__PIC__) +# define EBX_REG "=r" +#else +# define EBX_REG "=b" +#endif + +static inline void cpuid(u32 id, u32 *a, u32 *b, u32 *c, u32 *d) +{ + asm volatile(".ifnc %%ebx,%3 ; movl %%ebx,%3 ; .endif \n\t" + "cpuid \n\t" + ".ifnc %%ebx,%3 ; xchgl %%ebx,%3 ; .endif \n\t" + : "=a" (*a), "=c" (*c), "=d" (*d), EBX_REG (*b) + : "a" (id) + ); +} + +void get_flags(void) +{ + u32 max_intel_level, max_amd_level; + u32 tfms; + u32 ignored; + + if (loaded_flags) + return; + loaded_flags = true; + + if (has_fpu()) + set_bit(X86_FEATURE_FPU, cpu.flags); + + if (has_eflag(X86_EFLAGS_ID)) { + cpuid(0x0, &max_intel_level, &cpu_vendor[0], &cpu_vendor[2], + &cpu_vendor[1]); + + if (max_intel_level >= 0x00000001 && + max_intel_level <= 0x0000ffff) { + cpuid(0x1, &tfms, &ignored, &cpu.flags[4], + &cpu.flags[0]); + cpu.level = (tfms >> 8) & 15; + cpu.model = (tfms >> 4) & 15; + if (cpu.level >= 6) + cpu.model += ((tfms >> 16) & 0xf) << 4; + } + + cpuid(0x80000000, &max_amd_level, &ignored, &ignored, + &ignored); + + if (max_amd_level >= 0x80000001 && + max_amd_level <= 0x8000ffff) { + cpuid(0x80000001, &ignored, &ignored, &cpu.flags[6], + &cpu.flags[1]); + } + } +} |