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