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Diffstat (limited to 'arch/i386/kernel/cpu/bugs.c')
| -rw-r--r-- | arch/i386/kernel/cpu/bugs.c | 191 |
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 000000000000..54428a2500f3 --- /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(); +} |