/* * 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/bugs.h> #include <asm/processor.h> #include <asm/processor-flags.h> #include <asm/i387.h> #include <asm/msr.h> #include <asm/paravirt.h> #include <asm/alternative.h> static int __init no_halt(char *s) { WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n"); boot_cpu_data.hlt_works_ok = 0; return 1; } __setup("no-hlt", no_halt); static int __init no_387(char *s) { boot_cpu_data.hard_math = 0; write_cr0(X86_CR0_TS | X86_CR0_EM | X86_CR0_MP | 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) { s32 fdiv_bug; if (!boot_cpu_data.hard_math) { #ifndef CONFIG_MATH_EMULATION pr_emerg("No coprocessor found and no math emulation present\n"); pr_emerg("Giving up\n"); for (;;) ; #endif return; } kernel_fpu_begin(); /* * 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" (*&fdiv_bug) : "m" (*&x), "m" (*&y)); kernel_fpu_end(); boot_cpu_data.fdiv_bug = fdiv_bug; if (boot_cpu_data.fdiv_bug) pr_warn("Hmm, FPU with FDIV bug\n"); } static void __init check_hlt(void) { if (boot_cpu_data.x86 >= 5 || paravirt_enabled()) return; pr_info("Checking 'hlt' instruction... "); if (!boot_cpu_data.hlt_works_ok) { pr_cont("disabled\n"); return; } halt(); halt(); halt(); halt(); pr_cont("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; pr_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) pr_cont("Buggy\n"); else pr_cont("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. */ 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 } void __init check_bugs(void) { identify_boot_cpu(); #ifndef CONFIG_SMP pr_info("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(); }