kernel-ark/include/asm-i386/bugs.h
Rusty Russell 4f205fd45a [PATCH] paravirt: Allow selected bug checks to be
Allow selected bug checks to be skipped by paravirt kernels.  The two most
important are the F00F workaround (which is either done by the hypervisor,
or not required), and the 'hlt' instruction check, which can break under
some hypervisors.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
2006-12-07 02:14:08 +01:00

199 lines
4.9 KiB
C

/*
* 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/init.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/msr.h>
#include <asm/paravirt.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)
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();
init_utsname()->machine[1] = '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
alternative_instructions();
}