arch/alpha/kernel/traps.c

/* */
This source file includes following definitions.
die_if_kernel
do_entArith
do_entIF
do_entUna
do_entUnaUser
do_entSys
trap_init
   1 /*
   2  * kernel/traps.c
   3  *
   4  * (C) Copyright 1994 Linus Torvalds
   5  */
   6 
   7 /*
   8  * This file initializes the trap entry points
   9  */
  10 
  11 #include <linux/mm.h>
  12 #include <linux/sched.h>
  13 #include <linux/tty.h>
  14 
  15 #include <asm/unaligned.h>
  16 
  17 void die_if_kernel(char * str, struct pt_regs * regs, long err)
     /*  */
  18 {
  19         long i;
  20         unsigned long sp;
  21         unsigned int * pc;
  22 
  23         if (regs->ps & 8)
  24                 return;
  25         printk("%s(%d): %s %ld\n", current->comm, current->pid, str, err);
  26         sp = (unsigned long) (regs+1);
  27         printk("pc = %lx ps = %04lx\n", regs->pc, regs->ps);
  28         printk("rp = %lx sp = %lx\n", regs->r26, sp);
  29         printk("r0=%lx r1=%lx r2=%lx r3=%lx\n",
  30                 regs->r0, regs->r1, regs->r2, regs->r3);
  31         printk("r8=%lx\n", regs->r8);
  32         printk("r16=%lx r17=%lx r18=%lx r19=%lx\n",
  33                 regs->r16, regs->r17, regs->r18, regs->r19);
  34         printk("r20=%lx r21=%lx r22=%lx r23=%lx\n",
  35                 regs->r20, regs->r21, regs->r22, regs->r23);
  36         printk("r24=%lx r25=%lx r26=%lx r27=%lx\n",
  37                 regs->r24, regs->r25, regs->r26, regs->r27);
  38         printk("r28=%lx r29=%lx r30=%lx\n",
  39                 regs->r28, regs->gp, sp);
  40         printk("Code:");
  41         pc = (unsigned int *) regs->pc;
  42         for (i = -3; i < 6; i++)
  43                 printk("%c%08x%c",i?' ':'<',pc[i],i?' ':'>');
  44         printk("\n");
  45         do_exit(SIGSEGV);
  46 }
  47 
  48 asmlinkage void do_entArith(unsigned long summary, unsigned long write_mask,
     /*  */
  49         unsigned long a2, unsigned long a3, unsigned long a4, unsigned long a5,
  50         struct pt_regs regs)
  51 {
  52         printk("Arithmetic trap: %02lx %016lx\n", summary, write_mask);
  53         die_if_kernel("Arithmetic fault", &regs, 0);
  54         send_sig(SIGFPE, current, 1);
  55 }
  56 
  57 asmlinkage void do_entIF(unsigned long type, unsigned long a1, unsigned long a2,
     /*  */
  58         unsigned long a3, unsigned long a4, unsigned long a5,
  59         struct pt_regs regs)
  60 {
  61         extern int ptrace_cancel_bpt (struct task_struct *who);
  62 
  63         die_if_kernel("Instruction fault", &regs, type);
  64         switch (type) {
  65               case 0: /* breakpoint */
  66                 if (ptrace_cancel_bpt(current)) {
  67                         regs.pc -= 4;   /* make pc point to former bpt */
  68                 }
  69                 send_sig(SIGTRAP, current, 1);
  70                 break;
  71 
  72               case 1: /* bugcheck */
  73               case 2: /* gentrap */
  74               case 3: /* FEN fault */
  75               case 4: /* opDEC */
  76                 send_sig(SIGILL, current, 1);
  77                 break;
  78 
  79               default:
  80                 panic("do_entIF: unexpected instruction-fault type");
  81         }
  82 }
  83 
  84 /*
  85  * entUna has a different register layout to be reasonably simple. It
  86  * needs access to all the integer registers (the kernel doesn't use
  87  * fp-regs), and it needs to have them in order for simpler access.
  88  *
  89  * Due to the non-standard register layout (and because we don't want
  90  * to handle floating-point regs), user-mode unaligned accesses are
  91  * handled separately by do_entUnaUser below.
  92  *
  93  * Oh, btw, we don't handle the "gp" register correctly, but if we fault
  94  * on a gp-register unaligned load/store, something is _very_ wrong
  95  * in the kernel anyway..
  96  */
  97 struct allregs {
  98         unsigned long regs[32];
  99         unsigned long ps, pc, gp, a0, a1, a2;
 100 };
 101 
 102 struct unaligned_stat {
 103         unsigned long count, va, pc;
 104 } unaligned[2];
 105 
 106 asmlinkage void do_entUna(void * va, unsigned long opcode, unsigned long reg,
     /*  */
 107         unsigned long a3, unsigned long a4, unsigned long a5,
 108         struct allregs regs)
 109 {
 110         static int cnt = 0;
 111         static long last_time = 0;
 112 
 113         if (cnt >= 5 && jiffies - last_time > 5*HZ) {
 114                 cnt = 0;
 115         }
 116         if (++cnt < 5) {
 117                 printk("kernel: unaligned trap at %016lx: %p %lx %ld\n",
 118                        regs.pc - 4, va, opcode, reg);
 119         }
 120         last_time = jiffies;
 121 
 122         ++unaligned[0].count;
 123         unaligned[0].va = (unsigned long) va - 4;
 124         unaligned[0].pc = regs.pc;
 125 
 126         /* $16-$18 are PAL-saved, and are offset by 19 entries */
 127         if (reg >= 16 && reg <= 18)
 128                 reg += 19;
 129         switch (opcode) {
 130                 case 0x28: /* ldl */
 131                         *(reg+regs.regs) = (int) ldl_u(va);
 132                         return;
 133                 case 0x29: /* ldq */
 134                         *(reg+regs.regs) = ldq_u(va);
 135                         return;
 136                 case 0x2c: /* stl */
 137                         stl_u(*(reg+regs.regs), va);
 138                         return;
 139                 case 0x2d: /* stq */
 140                         stq_u(*(reg+regs.regs), va);
 141                         return;
 142         }
 143         printk("Bad unaligned kernel access at %016lx: %p %lx %ld\n",
 144                 regs.pc, va, opcode, reg);
 145         do_exit(SIGSEGV);
 146 }
 147 
 148 /*
 149  * Handle user-level unaligned fault.  Handling user-level unaligned
 150  * faults is *extremely* slow and produces nasty messages.  A user
 151  * program *should* fix unaligned faults ASAP.
 152  *
 153  * Notice that we have (almost) the regular kernel stack layout here,
 154  * so finding the appropriate registers is a little more difficult
 155  * than in the kernel case.
 156  *
 157  * Finally, we handle regular integer load/stores only.  In
 158  * particular, load-linked/store-conditionally and floating point
 159  * load/stores are not supported.  The former make no sense with
 160  * unaligned faults (they are guaranteed to fail) and I don't think
 161  * the latter will occur in any decent program.
 162  */
 163 asmlinkage void do_entUnaUser(void * va, unsigned long opcode, unsigned long reg,
     /*  */
 164                               unsigned long * frame)
 165 {
 166         long dir, size;
 167         unsigned long *reg_addr, *pc_addr, usp, zero = 0;
 168         static int cnt = 0;
 169         static long last_time = 0;
 170 
 171         pc_addr = frame + 7 + 20 + 1;                   /* pc in PAL frame */
 172 
 173         if (cnt >= 5 && jiffies - last_time > 5*HZ) {
 174                 cnt = 0;
 175         }
 176         if (++cnt < 5) {
 177                 printk("%s(%d): unaligned trap at %016lx: %p %lx %ld\n",
 178                        current->comm, current->pid,
 179                        *pc_addr - 4, va, opcode, reg);
 180         }
 181         last_time = jiffies;
 182 
 183         ++unaligned[1].count;
 184         unaligned[1].va = (unsigned long) va - 4;
 185         unaligned[1].pc = *pc_addr;
 186 
 187         dir = VERIFY_READ;
 188         if (opcode > 0x29) {
 189                 /* it's a stl or stq */
 190                 dir = VERIFY_WRITE;
 191         }
 192         size = 4;
 193         if (opcode & 1) {
 194                 /* it's a quadword op */
 195                 size = 8;
 196         }
 197         if (verify_area(dir, va, size)) {
 198                 *pc_addr -= 4;  /* make pc point to faulting insn */
 199                 send_sig(SIGSEGV, current, 1);
 200                 return;
 201         }
 202 
 203         reg_addr = frame;
 204         if (reg < 9) {
 205                 reg_addr += 7 + reg;                    /* v0-t7 in SAVE_ALL frame */
 206         } else if (reg < 16) {
 207                 reg_addr += (reg - 9);                  /* s0-s6 in entUna frame */
 208         } else if (reg < 19) {
 209                 reg_addr += 7 + 20 + 3 + (reg - 16);    /* a0-a2 in PAL frame */
 210         } else if (reg < 29) {
 211                 reg_addr += 7 + 9 + (reg - 19);         /* a3-at in SAVE_ALL frame */
 212         } else {
 213                 switch (reg) {
 214                         case 29:                        /* gp in PAL frame */
 215                                 reg_addr += 7 + 20 + 2;
 216                                 break;
 217                         case 30:                        /* usp in PAL regs */
 218                                 usp = rdusp();
 219                                 reg_addr = &usp;
 220                                 break;
 221                         case 31:                        /* zero "register" */
 222                                 reg_addr = &zero;
 223                                 break;
 224                 }
 225         }
 226 
 227         switch (opcode) {
 228                 case 0x28: *reg_addr = (int) ldl_u(va); break;  /* ldl */
 229                 case 0x29: *reg_addr = ldq_u(va);       break;  /* ldq */
 230                 case 0x2c: stl_u(*reg_addr, va);        break;  /* stl */
 231                 case 0x2d: stq_u(*reg_addr, va);        break;  /* stq */
 232                 default:
 233                         *pc_addr -= 4;  /* make pc point to faulting insn */
 234                         send_sig(SIGBUS, current, 1);
 235                         return;
 236         }
 237 
 238         if (reg == 30 && dir == VERIFY_WRITE) {
 239                 wrusp(usp);
 240         } 
 241 }
 242 
 243 /*
 244  * DEC means people to use the "retsys" instruction for return from
 245  * a system call, but they are clearly misguided about this. We use
 246  * "rti" in all cases, and fill in the stack with the return values.
 247  * That should make signal handling etc much cleaner.
 248  *
 249  * Even more horribly, DEC doesn't allow system calls from kernel mode.
 250  * "Security" features letting the user do something the kernel can't
 251  * are a thinko. DEC palcode is strange. The PAL-code designers probably
 252  * got terminally tainted by VMS at some point.
 253  */
 254 asmlinkage long do_entSys(unsigned long a0, unsigned long a1, unsigned long a2,
     /*  */
 255         unsigned long a3, unsigned long a4, unsigned long a5, struct pt_regs regs)
 256 {
 257         if (regs.r0 != 112)
 258           printk("<sc %ld(%lx,%lx,%lx)>", regs.r0, a0, a1, a2);
 259         return -1;
 260 }
 261 
 262 extern asmlinkage void entMM(void);
 263 extern asmlinkage void entIF(void);
 264 extern asmlinkage void entArith(void);
 265 extern asmlinkage void entUna(void);
 266 extern asmlinkage void entSys(void);
 267 
 268 void trap_init(void)
     /*  */
 269 {
 270         unsigned long gptr;
 271 
 272         /*
 273          * Tell PAL-code what global pointer we want in the kernel..
 274          */
 275         __asm__("br %0,___tmp\n"
 276                 "___tmp:\tldgp %0,0(%0)"
 277                 : "=r" (gptr));
 278         wrkgp(gptr);
 279 
 280         wrent(entArith, 1);
 281         wrent(entMM, 2);
 282         wrent(entIF, 3);
 283         wrent(entUna, 4);
 284         wrent(entSys, 5);
 285 }
/* */
root/arch/alpha/kernel/traps.c

DEFINITIONS
