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 }