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/* * 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 <linux/init.h> #include <asm/processor.h> #include <asm/i387.h> #include <asm/msr.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) { 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) 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 } extern void alternative_instructions(void); static void __init check_bugs(void) { identify_cpu(&boot_cpu_data); #ifndef CONFIG_SMP printk("CPU: "); print_cpu_info(&boot_cpu_data); #endif check_config(); check_fpu(); check_hlt(); check_popad(); system_utsname.machine[1] = '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86); alternative_instructions(); }