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) return(0);
  35                         printk("Reading /proc/cpuinfo failed, err = %d\n", -n);
  36                         if(n < 0)
  37                                 return(n);
  38                         else
  39                                 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 int cpu_feature(char *what, char *buf, int len)
  82 {
  83         int fd, ret = 0;
  84
  85         fd = os_open_file("/proc/cpuinfo", of_read(OPENFLAGS()), 0);
  86         if(fd < 0){
  87                 printk("Couldn't open /proc/cpuinfo, err = %d\n", -fd);
  88                 return(0);
  89         }
  90
  91         if(!find_cpuinfo_line(fd, what, buf, len)){
  92                 printk("Couldn't find '%s' line in /proc/cpuinfo\n", what);
  93                 goto out_close;
  94         }
  95
  96         token(fd, buf, len, '\n');
  97         ret = 1;
  98
  99  out_close:
 100         os_close_file(fd);
 101         return(ret);
 102 }
 103
 104 static int check_cpu_flag(char *feature, int *have_it)
 105 {
 106         char buf[MAXTOKEN], c;
 107         int fd, len = sizeof(buf)/sizeof(buf[0]);
 108
 109         printk("Checking for host processor %s support...", feature);
 110         fd = os_open_file("/proc/cpuinfo", of_read(OPENFLAGS()), 0);
 111         if(fd < 0){
 112                 printk("Couldn't open /proc/cpuinfo, err = %d\n", -fd);
 113                 return(0);
 114         }
 115
 116         *have_it = 0;
 117         if(!find_cpuinfo_line(fd, "flags", buf, sizeof(buf) / sizeof(buf[0])))
 118                 goto out;
 119
 120         c = token(fd, buf, len - 1, ' ');
 121         if(c < 0) goto out;
 122         else if(c != ' '){
 123                 printk("Failed to find ' ' in /proc/cpuinfo\n");
 124                 goto out;
 125         }
 126
 127         while(1){
 128                 c = token(fd, buf, len - 1, ' ');
 129                 if(c < 0) goto out;
 130                 else if(c == '\n') break;
 131
 132                 if(!strcmp(buf, feature)){
 133                         *have_it = 1;
 134                         goto out;
 135                 }
 136         }
 137  out:
 138         if(*have_it == 0) printk("No\n");
 139         else if(*have_it == 1) printk("Yes\n");
 140         os_close_file(fd);
 141         return(1);
 142 }
 143
 144 #if 0 /* This doesn't work in tt mode, plus it's causing compilation problems
 145        * for some people.
 146        */
 147 static void disable_lcall(void)
 148 {
 149         struct modify_ldt_ldt_s ldt;
 150         int err;
 151
 152         bzero(&ldt, sizeof(ldt));
 153         ldt.entry_number = 7;
 154         ldt.base_addr = 0;
 155         ldt.limit = 0;
 156         err = modify_ldt(1, &ldt, sizeof(ldt));
 157         if(err)
 158                 printk("Failed to disable lcall7 - errno = %d\n", errno);
 159 }
 160 #endif
 161
 162 void arch_init_thread(void)
 163 {
 164 #if 0
 165         disable_lcall();
 166 #endif
 167 }
 168
 169 void arch_check_bugs(void)
 170 {
 171         int have_it;
 172
 173         if(os_access("/proc/cpuinfo", OS_ACC_R_OK) < 0){
 174                 printk("/proc/cpuinfo not available - skipping CPU capability "
 175                        "checks\n");
 176                 return;
 177         }
 178         if(check_cpu_flag("cmov", &have_it))
 179                 host_has_cmov = have_it;
 180         if(check_cpu_flag("xmm", &have_it))
 181                 host_has_xmm = have_it;
 182 }
 183
 184 int arch_handle_signal(int sig, union uml_pt_regs *regs)
 185 {
 186         unsigned char tmp[2];
 187
 188         /* This is testing for a cmov (0x0f 0x4x) instruction causing a
 189          * SIGILL in init.
 190          */
 191         if((sig != SIGILL) || (TASK_PID(get_current()) != 1)) return(0);
 192
 193         if (copy_from_user_proc(tmp, (void *) UPT_IP(regs), 2))
 194                 panic("SIGILL in init, could not read instructions!\n");
 195         if((tmp[0] != 0x0f) || ((tmp[1] & 0xf0) != 0x40))
 196                 return(0);
 197
 198         if(host_has_cmov == 0)
 199                 panic("SIGILL caused by cmov, which this processor doesn't "
 200                       "implement, boot a filesystem compiled for older "
 201                       "processors");
 202         else if(host_has_cmov == 1)
 203                 panic("SIGILL caused by cmov, which this processor claims to "
 204                       "implement");
 205         else if(host_has_cmov == -1)
 206                 panic("SIGILL caused by cmov, couldn't tell if this processor "
 207                       "implements it, boot a filesystem compiled for older "
 208                       "processors");
 209         else panic("Bad value for host_has_cmov (%d)", host_has_cmov);
 210         return(0);
 211 }
 212
 213 /*
 214  * Overrides for Emacs so that we follow Linus's tabbing style.
 215  * Emacs will notice this stuff at the end of the file and automatically
 216  * adjust the settings for this buffer only.  This must remain at the end
 217  * of the file.
 218  * ---------------------------------------------------------------------------
 219  * Local variables:
 220  * c-file-style: "linux"
 221  * End:
 222  */