e0d22d03c0
The fdiv detection code writes s32 integer into the boot_cpu_data.fdiv_bug. However, the boot_cpu_data.fdiv_bug is only char (s8) field so the detection overwrites already set fields for other bugs, e.g. the f00f bug field. Use local s32 variable to receive result. This is a partial fix to Bugzilla #9928 - fixes wrong information about the f00f bug (tested) and probably for coma bug (I have no cpu to test this). Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
170 lines
3.6 KiB
C
170 lines
3.6 KiB
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_halt(char *s)
|
|
{
|
|
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
|
|
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" (*&fdiv_bug)
|
|
: "m" (*&x), "m" (*&y));
|
|
|
|
boot_cpu_data.fdiv_bug = fdiv_bug;
|
|
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.
|
|
*/
|
|
|
|
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
|
|
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();
|
|
}
|