arch/i386/kernel/signal.c

/* */
This source file includes following definitions.
sys_sigsuspend
restore_i387_hard
restore_i387
sys_sigreturn
save_i387_hard
save_i387
setup_frame
handle_signal
do_signal
   1 /*
   2  *  linux/arch/i386/kernel/signal.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 #include <linux/config.h>
   8 
   9 #include <linux/sched.h>
  10 #include <linux/mm.h>
  11 #include <linux/kernel.h>
  12 #include <linux/signal.h>
  13 #include <linux/errno.h>
  14 #include <linux/wait.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/unistd.h>
  17 
  18 #include <asm/segment.h>
  19 
  20 #define _S(nr) (1<<((nr)-1))
  21 
  22 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
  23 
  24 asmlinkage int sys_waitpid(pid_t pid,unsigned long * stat_addr, int options);
  25 asmlinkage int do_signal(unsigned long oldmask, struct pt_regs * regs);
  26 
  27 /*
  28  * atomically swap in the new signal mask, and wait for a signal.
  29  */
  30 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, unsigned long set)
     /*  */
  31 {
  32         unsigned long mask;
  33         struct pt_regs * regs = (struct pt_regs *) &restart;
  34 
  35         mask = current->blocked;
  36         current->blocked = set & _BLOCKABLE;
  37         regs->eax = -EINTR;
  38         while (1) {
  39                 current->state = TASK_INTERRUPTIBLE;
  40                 schedule();
  41                 if (do_signal(mask,regs))
  42                         return -EINTR;
  43         }
  44 }
  45 
  46 static inline void restore_i387_hard(struct _fpstate *buf)
     /*  */
  47 {
  48 #ifdef __SMP__
  49         if (current->flags & PF_USEDFPU) {
  50                 stts();
  51         }
  52 #else
  53         if (current == last_task_used_math) {
  54                 last_task_used_math = NULL;
  55                 stts();
  56         }
  57 #endif
  58         current->used_math = 1;
  59         current->flags &= ~PF_USEDFPU;
  60         memcpy_fromfs(&current->tss.i387.hard, buf, sizeof(*buf));
  61 }
  62 
  63 static void restore_i387(struct _fpstate *buf)
     /*  */
  64 {
  65 #ifndef CONFIG_MATH_EMULATION
  66         restore_i387_hard(buf);
  67 #else
  68         if (hard_math) {
  69                 restore_i387_hard(buf);
  70                 return;
  71         }
  72         restore_i387_soft(buf);
  73 #endif  
  74 }
  75         
  76 
  77 /*
  78  * This sets regs->esp even though we don't actually use sigstacks yet..
  79  */
  80 asmlinkage int sys_sigreturn(unsigned long __unused)
     /*  */
  81 {
  82 #define COPY(x) regs->x = context.x
  83 #define COPY_SEG(x) \
  84 if ((context.x & 0xfffc) && (context.x & 3) != 3) goto badframe; COPY(x);
  85 #define COPY_SEG_STRICT(x) \
  86 if (!(context.x & 0xfffc) || (context.x & 3) != 3) goto badframe; COPY(x);
  87         struct sigcontext_struct context;
  88         struct pt_regs * regs;
  89 
  90         regs = (struct pt_regs *) &__unused;
  91         if (verify_area(VERIFY_READ, (void *) regs->esp, sizeof(context)))
  92                 goto badframe;
  93         memcpy_fromfs(&context,(void *) regs->esp, sizeof(context));
  94         current->blocked = context.oldmask & _BLOCKABLE;
  95         COPY_SEG(ds);
  96         COPY_SEG(es);
  97         COPY_SEG(fs);
  98         COPY_SEG(gs);
  99         COPY_SEG_STRICT(ss);
 100         COPY_SEG_STRICT(cs);
 101         COPY(eip);
 102         COPY(ecx); COPY(edx);
 103         COPY(ebx);
 104         COPY(esp); COPY(ebp);
 105         COPY(edi); COPY(esi);
 106         regs->eflags &= ~0x40DD5;
 107         regs->eflags |= context.eflags & 0x40DD5;
 108         regs->orig_eax = -1;            /* disable syscall checks */
 109         if (context.fpstate) {
 110                 struct _fpstate * buf = context.fpstate;
 111                 if (verify_area(VERIFY_READ, buf, sizeof(*buf)))
 112                         goto badframe;
 113                 restore_i387(buf);
 114         }
 115         return context.eax;
 116 badframe:
 117         do_exit(SIGSEGV);
 118 }
 119 
 120 static inline struct _fpstate * save_i387_hard(struct _fpstate * buf)
     /*  */
 121 {
 122 #ifdef __SMP__
 123         if (current->flags & PF_USEDFPU) {
 124                 __asm__ __volatile__("fnsave %0":"=m" (current->tss.i387.hard));
 125                 stts();
 126                 current->flags &= ~PF_USEDFPU;
 127         }
 128 #else
 129         if (current == last_task_used_math) {
 130                 __asm__ __volatile__("fnsave %0":"=m" (current->tss.i387.hard));
 131                 last_task_used_math = NULL;
 132                 __asm__ __volatile__("fwait");  /* not needed on 486+ */
 133                 stts();
 134         }
 135 #endif
 136         current->tss.i387.hard.status = current->tss.i387.hard.swd;
 137         memcpy_tofs(buf, &current->tss.i387.hard, sizeof(*buf));
 138         current->used_math = 0;
 139         return buf;
 140 }
 141 
 142 static struct _fpstate * save_i387(struct _fpstate * buf)
     /*  */
 143 {
 144         if (!current->used_math)
 145                 return NULL;
 146 
 147 #ifndef CONFIG_MATH_EMULATION
 148         return save_i387_hard(buf);
 149 #else
 150         if (hard_math)
 151                 return save_i387_hard(buf);
 152         return save_i387_soft(buf);
 153 #endif
 154 }
 155 
 156 /*
 157  * Set up a signal frame... Make the stack look the way iBCS2 expects
 158  * it to look.
 159  */
 160 static void setup_frame(struct sigaction * sa,
     /*  */
 161         struct pt_regs * regs, int signr,
 162         unsigned long oldmask)
 163 {
 164         unsigned long * frame;
 165 
 166         frame = (unsigned long *) regs->esp;
 167         if (regs->ss != USER_DS && sa->sa_restorer)
 168                 frame = (unsigned long *) sa->sa_restorer;
 169         frame -= 64;
 170         if (verify_area(VERIFY_WRITE,frame,64*4))
 171                 do_exit(SIGSEGV);
 172 
 173 /* set up the "normal" stack seen by the signal handler (iBCS2) */
 174 #define __CODE ((unsigned long)(frame+24))
 175 #define CODE(x) ((unsigned long *) ((x)+__CODE))
 176         put_user(__CODE,frame);
 177         if (current->exec_domain && current->exec_domain->signal_invmap)
 178                 put_user(current->exec_domain->signal_invmap[signr], frame+1);
 179         else
 180                 put_user(signr, frame+1);
 181         put_user(regs->gs, frame+2);
 182         put_user(regs->fs, frame+3);
 183         put_user(regs->es, frame+4);
 184         put_user(regs->ds, frame+5);
 185         put_user(regs->edi, frame+6);
 186         put_user(regs->esi, frame+7);
 187         put_user(regs->ebp, frame+8);
 188         put_user(regs->esp, frame+9);
 189         put_user(regs->ebx, frame+10);
 190         put_user(regs->edx, frame+11);
 191         put_user(regs->ecx, frame+12);
 192         put_user(regs->eax, frame+13);
 193         put_user(current->tss.trap_no, frame+14);
 194         put_user(current->tss.error_code, frame+15);
 195         put_user(regs->eip, frame+16);
 196         put_user(regs->cs, frame+17);
 197         put_user(regs->eflags, frame+18);
 198         put_user(regs->esp, frame+19);
 199         put_user(regs->ss, frame+20);
 200         put_user(save_i387((struct _fpstate *)(frame+32)),frame+21);
 201 /* non-iBCS2 extensions.. */
 202         put_user(oldmask, frame+22);
 203         put_user(current->tss.cr2, frame+23);
 204 /* set up the return code... */
 205         put_user(0x0000b858, CODE(0));  /* popl %eax ; movl $,%eax */
 206         put_user(0x80cd0000, CODE(4));  /* int $0x80 */
 207         put_user(__NR_sigreturn, CODE(2));
 208 #undef __CODE
 209 #undef CODE
 210 
 211         /* Set up registers for signal handler */
 212         regs->esp = (unsigned long) frame;
 213         regs->eip = (unsigned long) sa->sa_handler;
 214         regs->cs = USER_CS; regs->ss = USER_DS;
 215         regs->ds = USER_DS; regs->es = USER_DS;
 216         regs->gs = USER_DS; regs->fs = USER_DS;
 217         regs->eflags &= ~TF_MASK;
 218 }
 219 
 220 /*
 221  * OK, we're invoking a handler
 222  */     
 223 static void handle_signal(unsigned long signr, struct sigaction *sa,
     /*  */
 224         unsigned long oldmask, struct pt_regs * regs)
 225 {
 226         /* are we from a system call? */
 227         if (regs->orig_eax >= 0) {
 228                 /* If so, check system call restarting.. */
 229                 switch (regs->eax) {
 230                         case -ERESTARTNOHAND:
 231                                 regs->eax = -EINTR;
 232                                 break;
 233 
 234                         case -ERESTARTSYS:
 235                                 if (!(sa->sa_flags & SA_RESTART)) {
 236                                         regs->eax = -EINTR;
 237                                         break;
 238                                 }
 239                         /* fallthrough */
 240                         case -ERESTARTNOINTR:
 241                                 regs->eax = regs->orig_eax;
 242                                 regs->eip -= 2;
 243                 }
 244         }
 245 
 246         /* set up the stack frame */
 247         setup_frame(sa, regs, signr, oldmask);
 248 
 249         if (sa->sa_flags & SA_ONESHOT)
 250                 sa->sa_handler = NULL;
 251         current->blocked |= sa->sa_mask;
 252 }
 253 
 254 /*
 255  * Note that 'init' is a special process: it doesn't get signals it doesn't
 256  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 257  * mistake.
 258  *
 259  * Note that we go through the signals twice: once to check the signals that
 260  * the kernel can handle, and then we build all the user-level signal handling
 261  * stack-frames in one go after that.
 262  */
 263 asmlinkage int do_signal(unsigned long oldmask, struct pt_regs * regs)
     /*  */
 264 {
 265         unsigned long mask = ~current->blocked;
 266         unsigned long signr;
 267         struct sigaction * sa;
 268 
 269         while ((signr = current->signal & mask)) {
 270                 /*
 271                  *      This stops gcc flipping out. Otherwise the assembler
 272                  *      including volatiles for the inline function to get
 273                  *      current combined with this gets it confused.
 274                  */
 275                 struct task_struct *t=current;
 276                 __asm__("bsf %3,%1\n\t"
 277                         "btrl %1,%0"
 278                         :"=m" (t->signal),"=r" (signr)
 279                         :"0" (t->signal), "1" (signr));
 280                 sa = current->sig->action + signr;
 281                 signr++;
 282                 if ((current->flags & PF_PTRACED) && signr != SIGKILL) {
 283                         current->exit_code = signr;
 284                         current->state = TASK_STOPPED;
 285                         notify_parent(current);
 286                         schedule();
 287                         if (!(signr = current->exit_code))
 288                                 continue;
 289                         current->exit_code = 0;
 290                         if (signr == SIGSTOP)
 291                                 continue;
 292                         if (_S(signr) & current->blocked) {
 293                                 current->signal |= _S(signr);
 294                                 continue;
 295                         }
 296                         sa = current->sig->action + signr - 1;
 297                 }
 298                 if (sa->sa_handler == SIG_IGN) {
 299                         if (signr != SIGCHLD)
 300                                 continue;
 301                         /* check for SIGCHLD: it's special */
 302                         while (sys_waitpid(-1,NULL,WNOHANG) > 0)
 303                                 /* nothing */;
 304                         continue;
 305                 }
 306                 if (sa->sa_handler == SIG_DFL) {
 307                         if (current->pid == 1)
 308                                 continue;
 309                         switch (signr) {
 310                         case SIGCONT: case SIGCHLD: case SIGWINCH:
 311                                 continue;
 312 
 313                         case SIGSTOP: case SIGTSTP: case SIGTTIN: case SIGTTOU:
 314                                 if (current->flags & PF_PTRACED)
 315                                         continue;
 316                                 current->state = TASK_STOPPED;
 317                                 current->exit_code = signr;
 318                                 if (!(current->p_pptr->sig->action[SIGCHLD-1].sa_flags & 
 319                                                 SA_NOCLDSTOP))
 320                                         notify_parent(current);
 321                                 schedule();
 322                                 continue;
 323 
 324                         case SIGQUIT: case SIGILL: case SIGTRAP:
 325                         case SIGABRT: case SIGFPE: case SIGSEGV:
 326                                 if (current->binfmt && current->binfmt->core_dump) {
 327                                         if (current->binfmt->core_dump(signr, regs))
 328                                                 signr |= 0x80;
 329                                 }
 330                                 /* fall through */
 331                         default:
 332                                 current->signal |= _S(signr & 0x7f);
 333                                 current->flags |= PF_SIGNALED;
 334                                 do_exit(signr);
 335                         }
 336                 }
 337                 handle_signal(signr, sa, oldmask, regs);
 338                 return 1;
 339         }
 340 
 341         /* Did we come from a system call? */
 342         if (regs->orig_eax >= 0) {
 343                 /* Restart the system call - no handlers present */
 344                 if (regs->eax == -ERESTARTNOHAND ||
 345                     regs->eax == -ERESTARTSYS ||
 346                     regs->eax == -ERESTARTNOINTR) {
 347                         regs->eax = regs->orig_eax;
 348                         regs->eip -= 2;
 349                 }
 350         }
 351         return 0;
 352 }
/* */
root/arch/i386/kernel/signal.c

DEFINITIONS
