Merge branch 'drm-patches' of master.kernel.org:/pub/scm/linux/kernel/git/airlied...
[linux-2.6] / arch / um / sys-i386 / bugs.c
1 /*
2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
3  * Licensed under the GPL
4  */
5
6 #include <unistd.h>
7 #include <errno.h>
8 #include <string.h>
9 #include <sys/signal.h>
10 #include <asm/ldt.h>
11 #include "kern_util.h"
12 #include "user.h"
13 #include "sysdep/ptrace.h"
14 #include "task.h"
15 #include "os.h"
16
17 #define MAXTOKEN 64
18
19 /* Set during early boot */
20 int host_has_cmov = 1;
21 int host_has_xmm = 0;
22
23 static char token(int fd, char *buf, int len, char stop)
24 {
25         int n;
26         char *ptr, *end, c;
27
28         ptr = buf;
29         end = &buf[len];
30         do {
31                 n = os_read_file(fd, ptr, sizeof(*ptr));
32                 c = *ptr++;
33                 if(n != sizeof(*ptr)){
34                         if(n == 0)
35                                 return 0;
36                         printk("Reading /proc/cpuinfo failed, err = %d\n", -n);
37                         if(n < 0)
38                                 return n;
39                         else return -EIO;
40                 }
41         } while((c != '\n') && (c != stop) && (ptr < end));
42
43         if(ptr == end){
44                 printk("Failed to find '%c' in /proc/cpuinfo\n", stop);
45                 return -1;
46         }
47         *(ptr - 1) = '\0';
48         return c;
49 }
50
51 static int find_cpuinfo_line(int fd, char *key, char *scratch, int len)
52 {
53         int n;
54         char c;
55
56         scratch[len - 1] = '\0';
57         while(1){
58                 c = token(fd, scratch, len - 1, ':');
59                 if(c <= 0)
60                         return 0;
61                 else if(c != ':'){
62                         printk("Failed to find ':' in /proc/cpuinfo\n");
63                         return 0;
64                 }
65
66                 if(!strncmp(scratch, key, strlen(key)))
67                         return 1;
68
69                 do {
70                         n = os_read_file(fd, &c, sizeof(c));
71                         if(n != sizeof(c)){
72                                 printk("Failed to find newline in "
73                                        "/proc/cpuinfo, err = %d\n", -n);
74                                 return 0;
75                         }
76                 } while(c != '\n');
77         }
78         return 0;
79 }
80
81 static int check_cpu_flag(char *feature, int *have_it)
82 {
83         char buf[MAXTOKEN], c;
84         int fd, len = ARRAY_SIZE(buf);
85
86         printk("Checking for host processor %s support...", feature);
87         fd = os_open_file("/proc/cpuinfo", of_read(OPENFLAGS()), 0);
88         if(fd < 0){
89                 printk("Couldn't open /proc/cpuinfo, err = %d\n", -fd);
90                 return 0;
91         }
92
93         *have_it = 0;
94         if(!find_cpuinfo_line(fd, "flags", buf, ARRAY_SIZE(buf)))
95                 goto out;
96
97         c = token(fd, buf, len - 1, ' ');
98         if(c < 0)
99                 goto out;
100         else if(c != ' '){
101                 printk("Failed to find ' ' in /proc/cpuinfo\n");
102                 goto out;
103         }
104
105         while(1){
106                 c = token(fd, buf, len - 1, ' ');
107                 if(c < 0)
108                         goto out;
109                 else if(c == '\n') break;
110
111                 if(!strcmp(buf, feature)){
112                         *have_it = 1;
113                         goto out;
114                 }
115         }
116  out:
117         if(*have_it == 0)
118                 printk("No\n");
119         else if(*have_it == 1)
120                 printk("Yes\n");
121         os_close_file(fd);
122         return 1;
123 }
124
125 #if 0 /* This doesn't work in tt mode, plus it's causing compilation problems
126        * for some people.
127        */
128 static void disable_lcall(void)
129 {
130         struct modify_ldt_ldt_s ldt;
131         int err;
132
133         bzero(&ldt, sizeof(ldt));
134         ldt.entry_number = 7;
135         ldt.base_addr = 0;
136         ldt.limit = 0;
137         err = modify_ldt(1, &ldt, sizeof(ldt));
138         if(err)
139                 printk("Failed to disable lcall7 - errno = %d\n", errno);
140 }
141 #endif
142
143 void arch_init_thread(void)
144 {
145 #if 0
146         disable_lcall();
147 #endif
148 }
149
150 void arch_check_bugs(void)
151 {
152         int have_it;
153
154         if(os_access("/proc/cpuinfo", OS_ACC_R_OK) < 0){
155                 printk("/proc/cpuinfo not available - skipping CPU capability "
156                        "checks\n");
157                 return;
158         }
159         if(check_cpu_flag("cmov", &have_it))
160                 host_has_cmov = have_it;
161         if(check_cpu_flag("xmm", &have_it))
162                 host_has_xmm = have_it;
163 }
164
165 int arch_handle_signal(int sig, union uml_pt_regs *regs)
166 {
167         unsigned char tmp[2];
168
169         /* This is testing for a cmov (0x0f 0x4x) instruction causing a
170          * SIGILL in init.
171          */
172         if((sig != SIGILL) || (TASK_PID(get_current()) != 1))
173                 return 0;
174
175         if (copy_from_user_proc(tmp, (void *) UPT_IP(regs), 2))
176                 panic("SIGILL in init, could not read instructions!\n");
177         if((tmp[0] != 0x0f) || ((tmp[1] & 0xf0) != 0x40))
178                 return 0;
179
180         if(host_has_cmov == 0)
181                 panic("SIGILL caused by cmov, which this processor doesn't "
182                       "implement, boot a filesystem compiled for older "
183                       "processors");
184         else if(host_has_cmov == 1)
185                 panic("SIGILL caused by cmov, which this processor claims to "
186                       "implement");
187         else if(host_has_cmov == -1)
188                 panic("SIGILL caused by cmov, couldn't tell if this processor "
189                       "implements it, boot a filesystem compiled for older "
190                       "processors");
191         else panic("Bad value for host_has_cmov (%d)", host_has_cmov);
192         return 0;
193 }