[linux-2.6-block.git] / arch / x86 / kernel / 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/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_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");
}

/*
 * Check whether we are able to run this kernel safely on SMP.
 *
 * - i386 is no longer supported.
 * - In order to run on anything without a TSC, we need to be
 *   compiled for a i486.
 */

static void __init check_config(void)
{
	if (boot_cpu_data.x86 < 4)
		panic("Kernel requires i486+ for 'invlpg' and other features");
}


void __init check_bugs(void)
{
	identify_boot_cpu();
#ifndef CONFIG_SMP
	pr_info("CPU: ");
	print_cpu_info(&boot_cpu_data);
#endif
	check_config();
	init_utsname()->machine[1] =
		'0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
	alternative_instructions();

	/*
	 * kernel_fpu_begin/end() in check_fpu() relies on the patched
	 * alternative instructions.
	 */
	check_fpu();
}
Commit	Line	Data
1353ebb4	1	/*
1353ebb4 JF	2	* Copyright (C) 1994 Linus Torvalds
	3	*
	4	* Cyrix stuff, June 1998 by:
	5	* - Rafael R. Reilova (moved everything from head.S),
	6	* <rreilova@ececs.uc.edu>
	7	* - Channing Corn (tests & fixes),
	8	* - Andrew D. Balsa (code cleanup).
	9	*/
	10	#include <linux/init.h>
	11	#include <linux/utsname.h>
91eb1b79	12	#include <asm/bugs.h>
1353ebb4	13	#include <asm/processor.h>
7ebad705	14	#include <asm/processor-flags.h>
1353ebb4 JF	15	#include <asm/i387.h>
	16	#include <asm/msr.h>
	17	#include <asm/paravirt.h>
	18	#include <asm/alternative.h>
	19
1353ebb4 JF	20	static int __init no_387(char *s)
	21	{
	22	boot_cpu_data.hard_math = 0;
7ebad705	23	write_cr0(X86_CR0_TS \| X86_CR0_EM \| X86_CR0_MP \| read_cr0());
1353ebb4 JF	24	return 1;
	25	}
	26
	27	__setup("no387", no_387);
	28
	29	static double __initdata x = 4195835.0;
	30	static double __initdata y = 3145727.0;
	31
	32	/*
	33	* This used to check for exceptions..
	34	* However, it turns out that to support that,
	35	* the XMM trap handlers basically had to
	36	* be buggy. So let's have a correct XMM trap
	37	* handler, and forget about printing out
	38	* some status at boot.
	39	*
	40	* We should really only care about bugs here
	41	* anyway. Not features.
	42	*/
	43	static void __init check_fpu(void)
	44	{
e0d22d03 KH	45	s32 fdiv_bug;
e0d22d03 KH	46
1353ebb4 JF	47	if (!boot_cpu_data.hard_math) {
1353ebb4 JF	48	#ifndef CONFIG_MATH_EMULATION
c767a54b JP	49	pr_emerg("No coprocessor found and no math emulation present\n");
c767a54b JP	50	pr_emerg("Giving up\n");
1353ebb4 JF	51	for (;;) ;
	52	#endif
	53	return;
	54	}
	55
3e7cf5b0 SS	56	kernel_fpu_begin();
3e7cf5b0 SS	57
bfe4bb15 MV	58	/*
	59	* trap_init() enabled FXSR and company _before_ testing for FP
	60	* problems here.
	61	*
	62	* Test for the divl bug..
	63	*/
1353ebb4 JF	64	__asm__("fninit\n\t"
	65	"fldl %1\n\t"
	66	"fdivl %2\n\t"
	67	"fmull %2\n\t"
	68	"fldl %1\n\t"
	69	"fsubp %%st,%%st(1)\n\t"
	70	"fistpl %0\n\t"
	71	"fwait\n\t"
	72	"fninit"
e0d22d03	73	: "=m" (*&fdiv_bug)
1353ebb4	74	: "m" (&x), "m" (&y));
e0d22d03	75
3e7cf5b0 SS	76	kernel_fpu_end();
3e7cf5b0 SS	77
e0d22d03	78	boot_cpu_data.fdiv_bug = fdiv_bug;
1353ebb4	79	if (boot_cpu_data.fdiv_bug)
c767a54b	80	pr_warn("Hmm, FPU with FDIV bug\n");
1353ebb4 JF	81	}
1353ebb4 JF	82
1353ebb4 JF	83	/*
	84	* Check whether we are able to run this kernel safely on SMP.
	85	*
e5bb8ad8	86	* - i386 is no longer supported.
1353ebb4 JF	87	* - In order to run on anything without a TSC, we need to be
1353ebb4 JF	88	* compiled for a i486.
593f4a78	89	*/
1353ebb4 JF	90
	91	static void __init check_config(void)
	92	{
e5bb8ad8	93	if (boot_cpu_data.x86 < 4)
1353ebb4	94	panic("Kernel requires i486+ for 'invlpg' and other features");
1353ebb4 JF	95	}
	96
	97
	98	void __init check_bugs(void)
	99	{
	100	identify_boot_cpu();
	101	#ifndef CONFIG_SMP
c767a54b	102	pr_info("CPU: ");
1353ebb4 JF	103	print_cpu_info(&boot_cpu_data);
	104	#endif
	105	check_config();
bfe4bb15 MV	106	init_utsname()->machine[1] =
bfe4bb15 MV	107	'0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
1353ebb4	108	alternative_instructions();
304bceda SS	109
	110	/*
	111	* kernel_fpu_begin/end() in check_fpu() relies on the patched
	112	* alternative instructions.
	113	*/
	114	check_fpu();
1353ebb4	115	}