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-rw-r--r--arch/x86/boot/cpucheck.c268
1 files changed, 268 insertions, 0 deletions
diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c
new file mode 100644
index 00000000000..e655a89c551
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+++ b/arch/x86/boot/cpucheck.c
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+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright 2007 rPath, Inc. - All Rights Reserved
+ *
+ * This file is part of the Linux kernel, and is made available under
+ * the terms of the GNU General Public License version 2.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * arch/i386/boot/cpucheck.c
+ *
+ * Check for obligatory CPU features and abort if the features are not
+ * present. This code should be compilable as 16-, 32- or 64-bit
+ * code, so be very careful with types and inline assembly.
+ *
+ * This code should not contain any messages; that requires an
+ * additional wrapper.
+ *
+ * As written, this code is not safe for inclusion into the kernel
+ * proper (after FPU initialization, in particular).
+ */
+
+#ifdef _SETUP
+# include "boot.h"
+# include "bitops.h"
+#endif
+#include <linux/types.h>
+#include <asm/cpufeature.h>
+#include <asm/processor-flags.h>
+#include <asm/required-features.h>
+#include <asm/msr-index.h>
+
+struct cpu_features {
+ int level; /* Family, or 64 for x86-64 */
+ int model;
+ u32 flags[NCAPINTS];
+};
+
+static struct cpu_features cpu;
+static u32 cpu_vendor[3];
+static u32 err_flags[NCAPINTS];
+
+#ifdef CONFIG_X86_64
+static const int req_level = 64;
+#elif defined(CONFIG_X86_MINIMUM_CPU_FAMILY)
+static const int req_level = CONFIG_X86_MINIMUM_CPU_FAMILY;
+#else
+static const int req_level = 3;
+#endif
+
+static const u32 req_flags[NCAPINTS] =
+{
+ REQUIRED_MASK0,
+ REQUIRED_MASK1,
+ REQUIRED_MASK2,
+ REQUIRED_MASK3,
+ REQUIRED_MASK4,
+ REQUIRED_MASK5,
+ REQUIRED_MASK6,
+ REQUIRED_MASK7,
+};
+
+#define A32(a,b,c,d) (((d) << 24)+((c) << 16)+((b) << 8)+(a))
+
+static int is_amd(void)
+{
+ return cpu_vendor[0] == A32('A','u','t','h') &&
+ cpu_vendor[1] == A32('e','n','t','i') &&
+ cpu_vendor[2] == A32('c','A','M','D');
+}
+
+static int is_centaur(void)
+{
+ return cpu_vendor[0] == A32('C','e','n','t') &&
+ cpu_vendor[1] == A32('a','u','r','H') &&
+ cpu_vendor[2] == A32('a','u','l','s');
+}
+
+static int is_transmeta(void)
+{
+ return cpu_vendor[0] == A32('G','e','n','u') &&
+ cpu_vendor[1] == A32('i','n','e','T') &&
+ cpu_vendor[2] == A32('M','x','8','6');
+}
+
+static int has_fpu(void)
+{
+ u16 fcw = -1, fsw = -1;
+ u32 cr0;
+
+ asm("movl %%cr0,%0" : "=r" (cr0));
+ if (cr0 & (X86_CR0_EM|X86_CR0_TS)) {
+ cr0 &= ~(X86_CR0_EM|X86_CR0_TS);
+ asm volatile("movl %0,%%cr0" : : "r" (cr0));
+ }
+
+ asm volatile("fninit ; fnstsw %0 ; fnstcw %1"
+ : "+m" (fsw), "+m" (fcw));
+
+ return fsw == 0 && (fcw & 0x103f) == 0x003f;
+}
+
+static int has_eflag(u32 mask)
+{
+ u32 f0, f1;
+
+ asm("pushfl ; "
+ "pushfl ; "
+ "popl %0 ; "
+ "movl %0,%1 ; "
+ "xorl %2,%1 ; "
+ "pushl %1 ; "
+ "popfl ; "
+ "pushfl ; "
+ "popl %1 ; "
+ "popfl"
+ : "=&r" (f0), "=&r" (f1)
+ : "ri" (mask));
+
+ return !!((f0^f1) & mask);
+}
+
+static void get_flags(void)
+{
+ u32 max_intel_level, max_amd_level;
+ u32 tfms;
+
+ if (has_fpu())
+ set_bit(X86_FEATURE_FPU, cpu.flags);
+
+ if (has_eflag(X86_EFLAGS_ID)) {
+ asm("cpuid"
+ : "=a" (max_intel_level),
+ "=b" (cpu_vendor[0]),
+ "=d" (cpu_vendor[1]),
+ "=c" (cpu_vendor[2])
+ : "a" (0));
+
+ if (max_intel_level >= 0x00000001 &&
+ max_intel_level <= 0x0000ffff) {
+ asm("cpuid"
+ : "=a" (tfms),
+ "=c" (cpu.flags[4]),
+ "=d" (cpu.flags[0])
+ : "a" (0x00000001)
+ : "ebx");
+ cpu.level = (tfms >> 8) & 15;
+ cpu.model = (tfms >> 4) & 15;
+ if (cpu.level >= 6)
+ cpu.model += ((tfms >> 16) & 0xf) << 4;
+ }
+
+ asm("cpuid"
+ : "=a" (max_amd_level)
+ : "a" (0x80000000)
+ : "ebx", "ecx", "edx");
+
+ if (max_amd_level >= 0x80000001 &&
+ max_amd_level <= 0x8000ffff) {
+ u32 eax = 0x80000001;
+ asm("cpuid"
+ : "+a" (eax),
+ "=c" (cpu.flags[6]),
+ "=d" (cpu.flags[1])
+ : : "ebx");
+ }
+ }
+}
+
+/* Returns a bitmask of which words we have error bits in */
+static int check_flags(void)
+{
+ u32 err;
+ int i;
+
+ err = 0;
+ for (i = 0; i < NCAPINTS; i++) {
+ err_flags[i] = req_flags[i] & ~cpu.flags[i];
+ if (err_flags[i])
+ err |= 1 << i;
+ }
+
+ return err;
+}
+
+/*
+ * Returns -1 on error.
+ *
+ * *cpu_level is set to the current CPU level; *req_level to the required
+ * level. x86-64 is considered level 64 for this purpose.
+ *
+ * *err_flags_ptr is set to the flags error array if there are flags missing.
+ */
+int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr)
+{
+ int err;
+
+ memset(&cpu.flags, 0, sizeof cpu.flags);
+ cpu.level = 3;
+
+ if (has_eflag(X86_EFLAGS_AC))
+ cpu.level = 4;
+
+ get_flags();
+ err = check_flags();
+
+ if (test_bit(X86_FEATURE_LM, cpu.flags))
+ cpu.level = 64;
+
+ if (err == 0x01 &&
+ !(err_flags[0] &
+ ~((1 << X86_FEATURE_XMM)|(1 << X86_FEATURE_XMM2))) &&
+ is_amd()) {
+ /* If this is an AMD and we're only missing SSE+SSE2, try to
+ turn them on */
+
+ u32 ecx = MSR_K7_HWCR;
+ u32 eax, edx;
+
+ asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx));
+ eax &= ~(1 << 15);
+ asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx));
+
+ get_flags(); /* Make sure it really did something */
+ err = check_flags();
+ } else if (err == 0x01 &&
+ !(err_flags[0] & ~(1 << X86_FEATURE_CX8)) &&
+ is_centaur() && cpu.model >= 6) {
+ /* If this is a VIA C3, we might have to enable CX8
+ explicitly */
+
+ u32 ecx = MSR_VIA_FCR;
+ u32 eax, edx;
+
+ asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx));
+ eax |= (1<<1)|(1<<7);
+ asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx));
+
+ set_bit(X86_FEATURE_CX8, cpu.flags);
+ err = check_flags();
+ } else if (err == 0x01 && is_transmeta()) {
+ /* Transmeta might have masked feature bits in word 0 */
+
+ u32 ecx = 0x80860004;
+ u32 eax, edx;
+ u32 level = 1;
+
+ asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx));
+ asm("wrmsr" : : "a" (~0), "d" (edx), "c" (ecx));
+ asm("cpuid"
+ : "+a" (level), "=d" (cpu.flags[0])
+ : : "ecx", "ebx");
+ asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx));
+
+ err = check_flags();
+ }
+
+ if (err_flags_ptr)
+ *err_flags_ptr = err ? err_flags : NULL;
+ if (cpu_level_ptr)
+ *cpu_level_ptr = cpu.level;
+ if (req_level_ptr)
+ *req_level_ptr = req_level;
+
+ return (cpu.level < req_level || err) ? -1 : 0;
+}
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