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 #include "user_util.h"
  17
  18 #define MAXTOKEN 64
  19
  20 /* Set during early boot */
  21 int host_has_cmov = 1;
  22 int host_has_xmm = 0;
  23
  24 static char token(int fd, char *buf, int len, char stop)
  25 {
  26         int n;
  27         char *ptr, *end, c;
  28
  29         ptr = buf;
  30         end = &buf[len];
  31         do {
  32                 n = os_read_file(fd, ptr, sizeof(*ptr));
  33                 c = *ptr++;
  34                 if(n != sizeof(*ptr)){
  35                         if(n == 0) return(0);
  36                         printk("Reading /proc/cpuinfo failed, err = %d\n", -n);
  37                         if(n < 0)
  38                                 return(n);
  39                         else
  40                                 return(-EIO);
  41                 }
  42         } while((c != '\n') && (c != stop) && (ptr < end));
  43
  44         if(ptr == end){
  45                 printk("Failed to find '%c' in /proc/cpuinfo\n", stop);
  46                 return(-1);
  47         }
  48         *(ptr - 1) = '\0';
  49         return(c);
  50 }
  51
  52 static int find_cpuinfo_line(int fd, char *key, char *scratch, int len)
  53 {
  54         int n;
  55         char c;
  56
  57         scratch[len - 1] = '\0';
  58         while(1){
  59                 c = token(fd, scratch, len - 1, ':');
  60                 if(c <= 0)
  61                         return(0);
  62                 else if(c != ':'){
  63                         printk("Failed to find ':' in /proc/cpuinfo\n");
  64                         return(0);
  65                 }
  66
  67                 if(!strncmp(scratch, key, strlen(key)))
  68                         return(1);
  69
  70                 do {
  71                         n = os_read_file(fd, &c, sizeof(c));
  72                         if(n != sizeof(c)){
  73                                 printk("Failed to find newline in "
  74                                        "/proc/cpuinfo, err = %d\n", -n);
  75                                 return(0);
  76                         }
  77                 } while(c != '\n');
  78         }
  79         return(0);
  80 }
  81
  82 int cpu_feature(char *what, char *buf, int len)
  83 {
  84         int fd, ret = 0;
  85
  86         fd = os_open_file("/proc/cpuinfo", of_read(OPENFLAGS()), 0);
  87         if(fd < 0){
  88                 printk("Couldn't open /proc/cpuinfo, err = %d\n", -fd);
  89                 return(0);
  90         }
  91
  92         if(!find_cpuinfo_line(fd, what, buf, len)){
  93                 printk("Couldn't find '%s' line in /proc/cpuinfo\n", what);
  94                 goto out_close;
  95         }
  96
  97         token(fd, buf, len, '\n');
  98         ret = 1;
  99
 100  out_close:
 101         os_close_file(fd);
 102         return(ret);
 103 }
 104
 105 static int check_cpu_flag(char *feature, int *have_it)
 106 {
 107         char buf[MAXTOKEN], c;
 108         int fd, len = ARRAY_SIZE(buf);
 109
 110         printk("Checking for host processor %s support...", feature);
 111         fd = os_open_file("/proc/cpuinfo", of_read(OPENFLAGS()), 0);
 112         if(fd < 0){
 113                 printk("Couldn't open /proc/cpuinfo, err = %d\n", -fd);
 114                 return 0;
 115         }
 116
 117         *have_it = 0;
 118         if(!find_cpuinfo_line(fd, "flags", buf, ARRAY_SIZE(buf)))
 119                 goto out;
 120
 121         c = token(fd, buf, len - 1, ' ');
 122         if(c < 0) goto out;
 123         else if(c != ' '){
 124                 printk("Failed to find ' ' in /proc/cpuinfo\n");
 125                 goto out;
 126         }
 127
 128         while(1){
 129                 c = token(fd, buf, len - 1, ' ');
 130                 if(c < 0) goto out;
 131                 else if(c == '\n') break;
 132
 133                 if(!strcmp(buf, feature)){
 134                         *have_it = 1;
 135                         goto out;
 136                 }
 137         }
 138  out:
 139         if(*have_it == 0) printk("No\n");
 140         else if(*have_it == 1) printk("Yes\n");
 141         os_close_file(fd);
 142         return 1;
 143 }
 144
 145 #if 0 /* This doesn't work in tt mode, plus it's causing compilation problems
 146        * for some people.
 147        */
 148 static void disable_lcall(void)
 149 {
 150         struct modify_ldt_ldt_s ldt;
 151         int err;
 152
 153         bzero(&ldt, sizeof(ldt));
 154         ldt.entry_number = 7;
 155         ldt.base_addr = 0;
 156         ldt.limit = 0;
 157         err = modify_ldt(1, &ldt, sizeof(ldt));
 158         if(err)
 159                 printk("Failed to disable lcall7 - errno = %d\n", errno);
 160 }
 161 #endif
 162
 163 void arch_init_thread(void)
 164 {
 165 #if 0
 166         disable_lcall();
 167 #endif
 168 }
 169
 170 void arch_check_bugs(void)
 171 {
 172         int have_it;
 173
 174         if(os_access("/proc/cpuinfo", OS_ACC_R_OK) < 0){
 175                 printk("/proc/cpuinfo not available - skipping CPU capability "
 176                        "checks\n");
 177                 return;
 178         }
 179         if(check_cpu_flag("cmov", &have_it))
 180                 host_has_cmov = have_it;
 181         if(check_cpu_flag("xmm", &have_it))
 182                 host_has_xmm = have_it;
 183 }
 184
 185 int arch_handle_signal(int sig, union uml_pt_regs *regs)
 186 {
 187         unsigned char tmp[2];
 188
 189         /* This is testing for a cmov (0x0f 0x4x) instruction causing a
 190          * SIGILL in init.
 191          */
 192         if((sig != SIGILL) || (TASK_PID(get_current()) != 1)) return(0);
 193
 194         if (copy_from_user_proc(tmp, (void *) UPT_IP(regs), 2))
 195                 panic("SIGILL in init, could not read instructions!\n");
 196         if((tmp[0] != 0x0f) || ((tmp[1] & 0xf0) != 0x40))
 197                 return(0);
 198
 199         if(host_has_cmov == 0)
 200                 panic("SIGILL caused by cmov, which this processor doesn't "
 201                       "implement, boot a filesystem compiled for older "
 202                       "processors");
 203         else if(host_has_cmov == 1)
 204                 panic("SIGILL caused by cmov, which this processor claims to "
 205                       "implement");
 206         else if(host_has_cmov == -1)
 207                 panic("SIGILL caused by cmov, couldn't tell if this processor "
 208                       "implements it, boot a filesystem compiled for older "
 209                       "processors");
 210         else panic("Bad value for host_has_cmov (%d)", host_has_cmov);
 211         return(0);
 212 }
 213
 214 /*
 215  * Overrides for Emacs so that we follow Linus's tabbing style.
 216  * Emacs will notice this stuff at the end of the file and automatically
 217  * adjust the settings for this buffer only.  This must remain at the end
 218  * of the file.
 219  * ---------------------------------------------------------------------------
 220  * Local variables:
 221  * c-file-style: "linux"
 222  * End:
 223  */