Import 2.3.18pre1

[davej-history.git] / include / asm-i386 / bugs.h

/*
 *  include/asm-i386/bugs.h
 *
 *  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).
 */

/*
 * This is included by init/main.c to check for architecture-dependent bugs.
 *
 * Needs:
 *      void check_bugs(void);
 */

#include <linux/config.h>
#include <asm/processor.h>
#include <asm/msr.h>

#define CONFIG_BUGi386

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 char __initdata fpu_error = 0;

static void __init copro_timeout(void)
{
        fpu_error = 1;
        timer_table[COPRO_TIMER].expires = jiffies+HZ;
        timer_active |= 1<<COPRO_TIMER;
        printk(KERN_ERR "387 failed: trying to reset\n");
        send_sig(SIGFPE, current, 1);
        outb_p(0,0xf1);
        outb_p(0,0xf0);
}

static double __initdata x = 4195835.0;
static double __initdata y = 3145727.0;

static void __init check_fpu(void)
{
        unsigned short control_word;

        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;
        }
        if (mca_pentium_flag) {
                /* The IBM Model 95 machines with pentiums lock up on
                 * fpu test, so we avoid it. All pentiums have inbuilt
                 * FPU and thus should use exception 16. We still do
                 * the FDIV test, although I doubt there where ever any
                 * MCA boxes built with non-FDIV-bug cpus.
                 */
                __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));
                printk("mca-pentium specified, avoiding FPU coupling test... ");
                if (!boot_cpu_data.fdiv_bug)
                        printk("??? No FDIV bug? Lucky you...\n");
                else
                        printk("detected FDIV bug though.\n");
                return;
        }
        /*
         * check if exception 16 works correctly.. This is truly evil
         * code: it disables the high 8 interrupts to make sure that
         * the irq13 doesn't happen. But as this will lead to a lockup
         * if no exception16 arrives, it depends on the fact that the
         * high 8 interrupts will be re-enabled by the next timer tick.
         * So the irq13 will happen eventually, but the exception 16
         * should get there first..
         */
        printk(KERN_INFO "Checking 386/387 coupling... ");
        timer_table[COPRO_TIMER].expires = jiffies+HZ/2;
        timer_table[COPRO_TIMER].fn = copro_timeout;
        timer_active |= 1<<COPRO_TIMER;
        __asm__("clts ; fninit ; fnstcw %0 ; fwait":"=m" (*&control_word));
        control_word &= 0xffc0;
        __asm__("fldcw %0 ; fwait": :"m" (*&control_word));
        outb_p(inb_p(0x21) | (1 << 2), 0x21);
        __asm__("fldz ; fld1 ; fdiv %st,%st(1) ; fwait");
        timer_active &= ~(1<<COPRO_TIMER);
        if (fpu_error)
                return;
        if (!ignore_irq13) {
                printk("OK, FPU using old IRQ 13 error reporting\n");
                return;
        }
        __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("OK, FPU using exception 16 error reporting.\n");
        else
                printk("Hmm, FPU using exception 16 error reporting with FDIV bug.\n");
}

static void __init check_hlt(void)
{
        printk(KERN_INFO "Checking 'hlt' instruction... ");
        if (!boot_cpu_data.hlt_works_ok) {
                printk("disabled\n");
                return;
        }
        __asm__ __volatile__("hlt ; hlt ; hlt ; hlt");
        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
}

/*
 *      B step AMD K6 before B 9730xxxx have hardware bugs that can cause
 *      misexecution of code under Linux. Owners of such processors should
 *      contact AMD for precise details and a CPU swap.
 *
 *      See     http://www.mygale.com/~poulot/k6bug.html
 *              http://www.amd.com/K6/k6docs/revgd.html
 *
 *      The following test is erm.. interesting. AMD neglected to up
 *      the chip setting when fixing the bug but they also tweaked some
 *      performance at the same time..
 */
 
extern void vide(void);
__asm__(".align 4\nvide: ret");

static void __init check_amd_k6(void)
{
        if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
            boot_cpu_data.x86_model == 6 &&
            boot_cpu_data.x86_mask == 1)
        {
                int n;
                void (*f_vide)(void);
                unsigned long d, d2;

                printk(KERN_INFO "AMD K6 stepping B detected - ");

#define K6_BUG_LOOP 1000000

                /*
                 * It looks like AMD fixed the 2.6.2 bug and improved indirect 
                 * calls at the same time.
                 */

                n = K6_BUG_LOOP;
                f_vide = vide;
                rdtscl(d);
                while (n--) 
                        f_vide();
                rdtscl(d2);
                d = d2-d;

                /* Knock these two lines out if it debugs out ok */
                printk(KERN_INFO "K6 BUG %ld %d (Report these if test report is incorrect)\n", d, 20*K6_BUG_LOOP);
                printk(KERN_INFO "AMD K6 stepping B detected - ");
                /* -- cut here -- */
                if (d > 20*K6_BUG_LOOP) 
                        printk("system stability may be impaired when more than 32 MB are used.\n");
                else 
                        printk("probably OK (after B9730xxxx).\n");
                printk(KERN_INFO "Please see http://www.mygale.com/~poulot/k6bug.html\n");
        }
}

/*
 * All current models of Pentium and Pentium with MMX technology CPUs
 * have the F0 0F bug, which lets nonpriviledged users lock up the system:
 */

extern void trap_init_f00f_bug(void);

static void __init check_pentium_f00f(void)
{
        /*
         * Pentium and Pentium MMX
         */
        boot_cpu_data.f00f_bug = 0;
        if (boot_cpu_data.x86 == 5 && boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
                printk(KERN_INFO "Intel Pentium with F0 0F bug - workaround enabled.\n");
                boot_cpu_data.f00f_bug = 1;
                trap_init_f00f_bug();
        }
}

/*
 * Perform the Cyrix 5/2 test. A Cyrix won't change
 * the flags, while other 486 chips will.
 */

static inline int test_cyrix_52div(void)
{
        unsigned int test;

        __asm__ __volatile__(
             "sahf\n\t"         /* clear flags (%eax = 0x0005) */
             "div %b2\n\t"      /* divide 5 by 2 */
             "lahf"             /* store flags into %ah */
             : "=a" (test)
             : "0" (5), "q" (2)
             : "cc");

        /* AH is 0x02 on Cyrix after the divide.. */
        return (unsigned char) (test >> 8) == 0x02;
}

/*
 * Fix cpuid problems with Cyrix CPU's:
 *   -- on the Cx686(L) the cpuid is disabled on power up.
 *   -- braindamaged BIOS disable cpuid on the Cx686MX.
 */

extern unsigned char Cx86_dir0_msb;  /* exported HACK from cyrix_model() */

static void __init check_cx686_cpuid(void)
{
        if (boot_cpu_data.cpuid_level == -1 &&
            ((Cx86_dir0_msb == 5) || (Cx86_dir0_msb == 3))) {
                int eax, dummy;
                unsigned char ccr3, ccr4;
                __u32 old_cap;

                cli();
                ccr3 = getCx86(CX86_CCR3);
                setCx86(CX86_CCR3, (ccr3 & 0x0f) | 0x10); /* enable MAPEN  */
                ccr4 = getCx86(CX86_CCR4);
                setCx86(CX86_CCR4, ccr4 | 0x80);          /* enable cpuid  */
                setCx86(CX86_CCR3, ccr3);                 /* disable MAPEN */
                sti();

                /* we have up to level 1 available on the Cx6x86(L|MX) */
                boot_cpu_data.cpuid_level = 1;
                /*  Need to preserve some externally computed capabilities  */
                old_cap = boot_cpu_data.x86_capability & X86_FEATURE_MTRR;
                cpuid(1, &eax, &dummy, &dummy,
                      &boot_cpu_data.x86_capability);
                boot_cpu_data.x86_capability |= old_cap;

                boot_cpu_data.x86 = (eax >> 8) & 15;
                /*
                 * we already have a cooked step/rev number from DIR1
                 * so we don't use the cpuid-provided ones.
                 */
        }
}

/*
 * Reset the slow-loop (SLOP) bit on the 686(L) which is set by some old
 * BIOSes for compatability with DOS games.  This makes the udelay loop
 * work correctly, and improves performance.
 */

extern void calibrate_delay(void) __init;

static void __init check_cx686_slop(void)
{
        if (Cx86_dir0_msb == 3) {
                unsigned char ccr3, ccr5;

                cli();
                ccr3 = getCx86(CX86_CCR3);
                setCx86(CX86_CCR3, (ccr3 & 0x0f) | 0x10); /* enable MAPEN  */
                ccr5 = getCx86(CX86_CCR5);
                if (ccr5 & 2)
                        setCx86(CX86_CCR5, ccr5 & 0xfd);  /* reset SLOP */
                setCx86(CX86_CCR3, ccr3);                 /* disable MAPEN */
                sti();

                if (ccr5 & 2) { /* possible wrong calibration done */
                        printk(KERN_INFO "Recalibrating delay loop with SLOP bit reset\n");
                        calibrate_delay();
                        boot_cpu_data.loops_per_sec = loops_per_sec;
                }
        }
}

/*
 * Cyrix CPUs without cpuid or with cpuid not yet enabled can be detected
 * by the fact that they preserve the flags across the division of 5/2.
 * PII and PPro exhibit this behavior too, but they have cpuid available.
 */

static void __init check_cyrix_cpu(void)
{
        if ((boot_cpu_data.cpuid_level == -1) && (boot_cpu_data.x86 == 4)
            && test_cyrix_52div()) {

                strcpy(boot_cpu_data.x86_vendor_id, "CyrixInstead");
        }
}
 
/*
 * In setup.c's cyrix_model() we have set the boot_cpu_data.coma_bug
 * on certain processors that we know contain this bug and now we
 * enable the workaround for it.
 */

static void __init check_cyrix_coma(void)
{
}
 
/*
 * Check wether 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 work on a Pentium/SMP machine, we need to be
 *   compiled for a Pentium or lower, as a PPro 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 (!(boot_cpu_data.x86_capability & X86_FEATURE_TSC))
                panic("Kernel compiled for Pentium+, requires TSC");
#endif

/*
 * If we were told we had a good APIC for SMP, we'd better be a PPro
 */
#if defined(CONFIG_X86_GOOD_APIC) && defined(CONFIG_SMP)
        if (smp_found_config && boot_cpu_data.x86 <= 5)
                panic("Kernel compiled for PPro+, assumes local APIC without read-before-write bug");
#endif
}

static void __init check_bugs(void)
{
        check_cyrix_cpu();
        identify_cpu(&boot_cpu_data);
        check_cx686_cpuid();
        check_cx686_slop();
#ifndef __SMP__
        printk("CPU: ");
        print_cpu_info(&boot_cpu_data);
#endif
        check_config();
        check_fpu();
        check_hlt();
        check_popad();
        check_amd_k6();
        check_pentium_f00f();
        check_cyrix_coma();
        system_utsname.machine[1] = '0' + boot_cpu_data.x86;
}