ia64/xen-unstable

view linux-2.6.11-xen-sparse/include/asm-xen/asm-i386/bugs.h @ 5377:99d9ce2c0a65

bitkeeper revision 1.1159.258.164 (42a7277bdZm8DZjc_UHJ0TWuobiRXw)

reenable TS flag after testing for fdiv bug. fix the fpu corruption that some config have

Signed-off: Vincent Hanquez <vincent@xensource.com>
author vh249@arcadians.cl.cam.ac.uk
date Wed Jun 08 17:14:35 2005 +0000 (2005-06-08)
parents
children 936540389715
line source
1 /*
2 * include/asm-i386/bugs.h
3 *
4 * Copyright (C) 1994 Linus Torvalds
5 *
6 * Cyrix stuff, June 1998 by:
7 * - Rafael R. Reilova (moved everything from head.S),
8 * <rreilova@ececs.uc.edu>
9 * - Channing Corn (tests & fixes),
10 * - Andrew D. Balsa (code cleanup).
11 *
12 * Pentium III FXSR, SSE support
13 * Gareth Hughes <gareth@valinux.com>, May 2000
14 */
16 /*
17 * This is included by init/main.c to check for architecture-dependent bugs.
18 *
19 * Needs:
20 * void check_bugs(void);
21 */
23 #include <linux/config.h>
24 #include <linux/init.h>
25 #include <asm/processor.h>
26 #include <asm/i387.h>
27 #include <asm/msr.h>
29 static int __init no_halt(char *s)
30 {
31 boot_cpu_data.hlt_works_ok = 0;
32 return 1;
33 }
35 __setup("no-hlt", no_halt);
37 static int __init mca_pentium(char *s)
38 {
39 mca_pentium_flag = 1;
40 return 1;
41 }
43 __setup("mca-pentium", mca_pentium);
45 static int __init no_387(char *s)
46 {
47 boot_cpu_data.hard_math = 0;
48 write_cr0(0xE | read_cr0());
49 return 1;
50 }
52 __setup("no387", no_387);
54 static double __initdata x = 4195835.0;
55 static double __initdata y = 3145727.0;
57 /*
58 * This used to check for exceptions..
59 * However, it turns out that to support that,
60 * the XMM trap handlers basically had to
61 * be buggy. So let's have a correct XMM trap
62 * handler, and forget about printing out
63 * some status at boot.
64 *
65 * We should really only care about bugs here
66 * anyway. Not features.
67 */
68 static void __init check_fpu(void)
69 {
70 if (!boot_cpu_data.hard_math) {
71 #ifndef CONFIG_MATH_EMULATION
72 printk(KERN_EMERG "No coprocessor found and no math emulation present.\n");
73 printk(KERN_EMERG "Giving up.\n");
74 for (;;) ;
75 #endif
76 return;
77 }
79 /* Enable FXSR and company _before_ testing for FP problems. */
80 /*
81 * Verify that the FXSAVE/FXRSTOR data will be 16-byte aligned.
82 */
83 if (offsetof(struct task_struct, thread.i387.fxsave) & 15) {
84 extern void __buggy_fxsr_alignment(void);
85 __buggy_fxsr_alignment();
86 }
87 if (cpu_has_fxsr) {
88 printk(KERN_INFO "Enabling fast FPU save and restore... ");
89 set_in_cr4(X86_CR4_OSFXSR);
90 printk("done.\n");
91 }
92 if (cpu_has_xmm) {
93 printk(KERN_INFO "Enabling unmasked SIMD FPU exception support... ");
94 set_in_cr4(X86_CR4_OSXMMEXCPT);
95 printk("done.\n");
96 }
98 /* Test for the divl bug.. */
99 __asm__("fninit\n\t"
100 "fldl %1\n\t"
101 "fdivl %2\n\t"
102 "fmull %2\n\t"
103 "fldl %1\n\t"
104 "fsubp %%st,%%st(1)\n\t"
105 "fistpl %0\n\t"
106 "fwait\n\t"
107 "fninit"
108 : "=m" (*&boot_cpu_data.fdiv_bug)
109 : "m" (*&x), "m" (*&y));
110 stts();
111 if (boot_cpu_data.fdiv_bug)
112 printk("Hmm, FPU with FDIV bug.\n");
113 }
115 static void __init check_hlt(void)
116 {
117 printk(KERN_INFO "Checking 'hlt' instruction... ");
118 if (!boot_cpu_data.hlt_works_ok) {
119 printk("disabled\n");
120 return;
121 }
122 __asm__ __volatile__("hlt ; hlt ; hlt ; hlt");
123 printk("OK.\n");
124 }
126 /*
127 * Most 386 processors have a bug where a POPAD can lock the
128 * machine even from user space.
129 */
131 static void __init check_popad(void)
132 {
133 #ifndef CONFIG_X86_POPAD_OK
134 int res, inp = (int) &res;
136 printk(KERN_INFO "Checking for popad bug... ");
137 __asm__ __volatile__(
138 "movl $12345678,%%eax; movl $0,%%edi; pusha; popa; movl (%%edx,%%edi),%%ecx "
139 : "=&a" (res)
140 : "d" (inp)
141 : "ecx", "edi" );
142 /* If this fails, it means that any user program may lock the CPU hard. Too bad. */
143 if (res != 12345678) printk( "Buggy.\n" );
144 else printk( "OK.\n" );
145 #endif
146 }
148 /*
149 * Check whether we are able to run this kernel safely on SMP.
150 *
151 * - In order to run on a i386, we need to be compiled for i386
152 * (for due to lack of "invlpg" and working WP on a i386)
153 * - In order to run on anything without a TSC, we need to be
154 * compiled for a i486.
155 * - In order to support the local APIC on a buggy Pentium machine,
156 * we need to be compiled with CONFIG_X86_GOOD_APIC disabled,
157 * which happens implicitly if compiled for a Pentium or lower
158 * (unless an advanced selection of CPU features is used) as an
159 * otherwise config implies a properly working local APIC without
160 * the need to do extra reads from the APIC.
161 */
163 static void __init check_config(void)
164 {
165 /*
166 * We'd better not be a i386 if we're configured to use some
167 * i486+ only features! (WP works in supervisor mode and the
168 * new "invlpg" and "bswap" instructions)
169 */
170 #if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || defined(CONFIG_X86_BSWAP)
171 if (boot_cpu_data.x86 == 3)
172 panic("Kernel requires i486+ for 'invlpg' and other features");
173 #endif
175 /*
176 * If we configured ourselves for a TSC, we'd better have one!
177 */
178 #ifdef CONFIG_X86_TSC
179 if (!cpu_has_tsc)
180 panic("Kernel compiled for Pentium+, requires TSC feature!");
181 #endif
183 /*
184 * If we were told we had a good local APIC, check for buggy Pentia,
185 * i.e. all B steppings and the C2 stepping of P54C when using their
186 * integrated APIC (see 11AP erratum in "Pentium Processor
187 * Specification Update").
188 */
189 #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_GOOD_APIC)
190 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL
191 && cpu_has_apic
192 && boot_cpu_data.x86 == 5
193 && boot_cpu_data.x86_model == 2
194 && (boot_cpu_data.x86_mask < 6 || boot_cpu_data.x86_mask == 11))
195 panic("Kernel compiled for PMMX+, assumes a local APIC without the read-before-write bug!");
196 #endif
197 }
199 extern void alternative_instructions(void);
201 static void __init check_bugs(void)
202 {
203 identify_cpu(&boot_cpu_data);
204 #ifndef CONFIG_SMP
205 printk("CPU: ");
206 print_cpu_info(&boot_cpu_data);
207 #endif
208 check_config();
209 check_fpu();
210 check_hlt();
211 check_popad();
212 system_utsname.machine[1] = '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
213 alternative_instructions();
214 }