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 000000000000..b02544a2bce0
--- /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]);
+                }
+        }
+}