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-rw-r--r--arch/x86/boot/cpuflags.c119
1 files changed, 119 insertions, 0 deletions
diff --git a/arch/x86/boot/cpuflags.c b/arch/x86/boot/cpuflags.c
new file mode 100644
index 0000000000..d75237ba7c
--- /dev/null
+++ b/arch/x86/boot/cpuflags.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0
+#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;
+}
+
+/*
+ * For building the 16-bit code we want to explicitly specify 32-bit
+ * push/pop operations, rather than just saying 'pushf' or 'popf' and
+ * letting the compiler choose. But this is also included from the
+ * compressed/ directory where it may be 64-bit code, and thus needs
+ * to be 'pushfq' or 'popfq' in that case.
+ */
+#ifdef __x86_64__
+#define PUSHF "pushfq"
+#define POPF "popfq"
+#else
+#define PUSHF "pushfl"
+#define POPF "popfl"
+#endif
+
+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);
+}
+
+void cpuid_count(u32 id, u32 count, u32 *a, u32 *b, u32 *c, u32 *d)
+{
+ asm volatile("cpuid"
+ : "=a" (*a), "=b" (*b), "=c" (*c), "=d" (*d)
+ : "0" (id), "2" (count)
+ );
+}
+
+#define cpuid(id, a, b, c, d) cpuid_count(id, 0, a, b, c, d)
+
+void get_cpuflags(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.family = cpu.level;
+ cpu.model = (tfms >> 4) & 15;
+ if (cpu.level >= 6)
+ cpu.model += ((tfms >> 16) & 0xf) << 4;
+ }
+
+ if (max_intel_level >= 0x00000007) {
+ cpuid_count(0x00000007, 0, &ignored, &ignored,
+ &cpu.flags[16], &ignored);
+ }
+
+ 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]);
+ }
+ }
+}