1 files changed, 191 insertions, 0 deletions

diff --git a/arch/i386/kernel/cpu/bugs.c b/arch/i386/kernel/cpu/bugs.c
new file mode 100644
index 00000000000..54428a2500f
--- /dev/null
+++ b/arch/i386/kernel/cpu/bugs.c
@@ -0,0 +1,191 @@
+/*
+ *  arch/i386/cpu/bugs.c
+ *
+ *  Copyright (C) 1994  Linus Torvalds
+ *
+ *  Cyrix stuff, June 1998 by:
+ *      - Rafael R. Reilova (moved everything from head.S),
+ *        <rreilova@ececs.uc.edu>
+ *      - Channing Corn (tests & fixes),
+ *      - Andrew D. Balsa (code cleanup).
+ */
+#include <linux/init.h>
+#include <linux/utsname.h>
+#include <asm/processor.h>
+#include <asm/i387.h>
+#include <asm/msr.h>
+#include <asm/paravirt.h>
+#include <asm/alternative.h>
+
+static int __init no_halt(char *s)
+{
+        boot_cpu_data.hlt_works_ok = 0;
+        return 1;
+}
+
+__setup("no-hlt", no_halt);
+
+static int __init mca_pentium(char *s)
+{
+        mca_pentium_flag = 1;
+        return 1;
+}
+
+__setup("mca-pentium", mca_pentium);
+
+static int __init no_387(char *s)
+{
+        boot_cpu_data.hard_math = 0;
+        write_cr0(0xE | read_cr0());
+        return 1;
+}
+
+__setup("no387", no_387);
+
+static double __initdata x = 4195835.0;
+static double __initdata y = 3145727.0;
+
+/*
+ * This used to check for exceptions..
+ * However, it turns out that to support that,
+ * the XMM trap handlers basically had to
+ * be buggy. So let's have a correct XMM trap
+ * handler, and forget about printing out
+ * some status at boot.
+ *
+ * We should really only care about bugs here
+ * anyway. Not features.
+ */
+static void __init check_fpu(void)
+{
+        if (!boot_cpu_data.hard_math) {
+#ifndef CONFIG_MATH_EMULATION
+                printk(KERN_EMERG "No coprocessor found and no math emulation present.\n");
+                printk(KERN_EMERG "Giving up.\n");
+                for (;;) ;
+#endif
+                return;
+        }
+
+/* trap_init() enabled FXSR and company _before_ testing for FP problems here. */
+        /* Test for the divl bug.. */
+        __asm__("fninit\n\t"
+                "fldl %1\n\t"
+                "fdivl %2\n\t"
+                "fmull %2\n\t"
+                "fldl %1\n\t"
+                "fsubp %%st,%%st(1)\n\t"
+                "fistpl %0\n\t"
+                "fwait\n\t"
+                "fninit"
+                : "=m" (*&boot_cpu_data.fdiv_bug)
+                : "m" (*&x), "m" (*&y));
+        if (boot_cpu_data.fdiv_bug)
+                printk("Hmm, FPU with FDIV bug.\n");
+}
+
+static void __init check_hlt(void)
+{
+        if (paravirt_enabled())
+                return;
+
+        printk(KERN_INFO "Checking 'hlt' instruction... ");
+        if (!boot_cpu_data.hlt_works_ok) {
+                printk("disabled\n");
+                return;
+        }
+        halt();
+        halt();
+        halt();
+        halt();
+        printk("OK.\n");
+}
+
+/*
+ *      Most 386 processors have a bug where a POPAD can lock the
+ *      machine even from user space.
+ */
+
+static void __init check_popad(void)
+{
+#ifndef CONFIG_X86_POPAD_OK
+        int res, inp = (int) &res;
+
+        printk(KERN_INFO "Checking for popad bug... ");
+        __asm__ __volatile__(
+          "movl $12345678,%%eax; movl $0,%%edi; pusha; popa; movl (%%edx,%%edi),%%ecx "
+          : "=&a" (res)
+          : "d" (inp)
+          : "ecx", "edi" );
+        /* If this fails, it means that any user program may lock the CPU hard. Too bad. */
+        if (res != 12345678) printk( "Buggy.\n" );
+                        else printk( "OK.\n" );
+#endif
+}
+
+/*
+ * Check whether we are able to run this kernel safely on SMP.
+ *
+ * - In order to run on a i386, we need to be compiled for i386
+ *   (for due to lack of "invlpg" and working WP on a i386)
+ * - In order to run on anything without a TSC, we need to be
+ *   compiled for a i486.
+ * - In order to support the local APIC on a buggy Pentium machine,
+ *   we need to be compiled with CONFIG_X86_GOOD_APIC disabled,
+ *   which happens implicitly if compiled for a Pentium or lower
+ *   (unless an advanced selection of CPU features is used) as an
+ *   otherwise config implies a properly working local APIC without
+ *   the need to do extra reads from the APIC.
+*/
+
+static void __init check_config(void)
+{
+/*
+ * We'd better not be a i386 if we're configured to use some
+ * i486+ only features! (WP works in supervisor mode and the
+ * new "invlpg" and "bswap" instructions)
+ */
+#if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || defined(CONFIG_X86_BSWAP)
+        if (boot_cpu_data.x86 == 3)
+                panic("Kernel requires i486+ for 'invlpg' and other features");
+#endif
+
+/*
+ * If we configured ourselves for a TSC, we'd better have one!
+ */
+#ifdef CONFIG_X86_TSC
+        if (!cpu_has_tsc && !tsc_disable)
+                panic("Kernel compiled for Pentium+, requires TSC feature!");
+#endif
+
+/*
+ * If we were told we had a good local APIC, check for buggy Pentia,
+ * i.e. all B steppings and the C2 stepping of P54C when using their
+ * integrated APIC (see 11AP erratum in "Pentium Processor
+ * Specification Update").
+ */
+#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_GOOD_APIC)
+        if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL
+            && cpu_has_apic
+            && boot_cpu_data.x86 == 5
+            && boot_cpu_data.x86_model == 2
+            && (boot_cpu_data.x86_mask < 6 || boot_cpu_data.x86_mask == 11))
+                panic("Kernel compiled for PMMX+, assumes a local APIC without the read-before-write bug!");
+#endif
+}
+
+
+void __init check_bugs(void)
+{
+        identify_boot_cpu();
+#ifndef CONFIG_SMP
+        printk("CPU: ");
+        print_cpu_info(&boot_cpu_data);
+#endif
+        check_config();
+        check_fpu();
+        check_hlt();
+        check_popad();
+        init_utsname()->machine[1] = '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
+        alternative_instructions();
+}