arch/i386/kernel/signal.c

/* */
This source file includes following definitions.
sys_sigsuspend
sys_sigreturn
setup_frame
do_signal
   1 /*
   2  *  linux/arch/i386/kernel/signal.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 #include <linux/sched.h>
   8 #include <linux/kernel.h>
   9 #include <linux/signal.h>
  10 #include <linux/errno.h>
  11 #include <linux/wait.h>
  12 #include <linux/ptrace.h>
  13 #include <linux/unistd.h>
  14 
  15 #include <asm/segment.h>
  16 
  17 #define _S(nr) (1<<((nr)-1))
  18 
  19 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
  20 
  21 asmlinkage int sys_waitpid(pid_t pid,unsigned long * stat_addr, int options);
  22 
  23 /*
  24  * atomically swap in the new signal mask, and wait for a signal.
  25  */
  26 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, unsigned long set)
     /*  */
  27 {
  28         unsigned long mask;
  29         struct pt_regs * regs = (struct pt_regs *) &restart;
  30 
  31         mask = current->blocked;
  32         current->blocked = set & _BLOCKABLE;
  33         regs->eax = -EINTR;
  34         while (1) {
  35                 current->state = TASK_INTERRUPTIBLE;
  36                 schedule();
  37                 if (do_signal(mask,regs))
  38                         return -EINTR;
  39         }
  40 }
  41 
  42 /*
  43  * This sets regs->esp even though we don't actually use sigstacks yet..
  44  */
  45 asmlinkage int sys_sigreturn(unsigned long __unused)
     /*  */
  46 {
  47 #define COPY(x) regs->x = context.x
  48 #define COPY_SEG(x) \
  49 if ((context.x & 0xfffc) && (context.x & 3) != 3) goto badframe; COPY(x);
  50 #define COPY_SEG_STRICT(x) \
  51 if (!(context.x & 0xfffc) || (context.x & 3) != 3) goto badframe; COPY(x);
  52         struct sigcontext_struct context;
  53         struct pt_regs * regs;
  54 
  55         regs = (struct pt_regs *) &__unused;
  56         if (verify_area(VERIFY_READ, (void *) regs->esp, sizeof(context)))
  57                 goto badframe;
  58         memcpy_fromfs(&context,(void *) regs->esp, sizeof(context));
  59         current->blocked = context.oldmask & _BLOCKABLE;
  60         COPY_SEG(ds);
  61         COPY_SEG(es);
  62         COPY_SEG(fs);
  63         COPY_SEG(gs);
  64         COPY_SEG_STRICT(ss);
  65         COPY_SEG_STRICT(cs);
  66         COPY(eip);
  67         COPY(ecx); COPY(edx);
  68         COPY(ebx);
  69         COPY(esp); COPY(ebp);
  70         COPY(edi); COPY(esi);
  71         regs->eflags &= ~0x40DD5;
  72         regs->eflags |= context.eflags & 0x40DD5;
  73         regs->orig_eax = -1;            /* disable syscall checks */
  74         return context.eax;
  75 badframe:
  76         do_exit(SIGSEGV);
  77 }
  78 
  79 /*
  80  * Set up a signal frame... Make the stack look the way iBCS2 expects
  81  * it to look.
  82  */
  83 void setup_frame(struct sigaction * sa, unsigned long ** fp, unsigned long eip,
     /*  */
  84         struct pt_regs * regs, int signr, unsigned long oldmask)
  85 {
  86         unsigned long * frame;
  87 
  88 #define __CODE ((unsigned long)(frame+24))
  89 #define CODE(x) ((unsigned long *) ((x)+__CODE))
  90         frame = *fp;
  91         if (regs->ss != USER_DS)
  92                 frame = (unsigned long *) sa->sa_restorer;
  93         frame -= 32;
  94         if (verify_area(VERIFY_WRITE,frame,32*4))
  95                 do_exit(SIGSEGV);
  96 /* set up the "normal" stack seen by the signal handler (iBCS2) */
  97         put_fs_long(__CODE,frame);
  98         if (current->exec_domain && current->exec_domain->signal_invmap)
  99                 put_fs_long(current->exec_domain->signal_invmap[signr], frame+1);
 100         else
 101                 put_fs_long(signr, frame+1);
 102         put_fs_long(regs->gs, frame+2);
 103         put_fs_long(regs->fs, frame+3);
 104         put_fs_long(regs->es, frame+4);
 105         put_fs_long(regs->ds, frame+5);
 106         put_fs_long(regs->edi, frame+6);
 107         put_fs_long(regs->esi, frame+7);
 108         put_fs_long(regs->ebp, frame+8);
 109         put_fs_long((long)*fp, frame+9);
 110         put_fs_long(regs->ebx, frame+10);
 111         put_fs_long(regs->edx, frame+11);
 112         put_fs_long(regs->ecx, frame+12);
 113         put_fs_long(regs->eax, frame+13);
 114         put_fs_long(current->tss.trap_no, frame+14);
 115         put_fs_long(current->tss.error_code, frame+15);
 116         put_fs_long(eip, frame+16);
 117         put_fs_long(regs->cs, frame+17);
 118         put_fs_long(regs->eflags, frame+18);
 119         put_fs_long(regs->esp, frame+19);
 120         put_fs_long(regs->ss, frame+20);
 121         put_fs_long(0,frame+21);                /* 387 state pointer - not implemented*/
 122 /* non-iBCS2 extensions.. */
 123         put_fs_long(oldmask, frame+22);
 124         put_fs_long(current->tss.cr2, frame+23);
 125 /* set up the return code... */
 126         put_fs_long(0x0000b858, CODE(0));       /* popl %eax ; movl $,%eax */
 127         put_fs_long(0x80cd0000, CODE(4));       /* int $0x80 */
 128         put_fs_long(__NR_sigreturn, CODE(2));
 129         *fp = frame;
 130 #undef __CODE
 131 #undef CODE
 132 }
 133 
 134 /*
 135  * Note that 'init' is a special process: it doesn't get signals it doesn't
 136  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 137  * mistake.
 138  *
 139  * Note that we go through the signals twice: once to check the signals that
 140  * the kernel can handle, and then we build all the user-level signal handling
 141  * stack-frames in one go after that.
 142  */
 143 asmlinkage int do_signal(unsigned long oldmask, struct pt_regs * regs)
     /*  */
 144 {
 145         unsigned long mask = ~current->blocked;
 146         unsigned long handler_signal = 0;
 147         unsigned long *frame = NULL;
 148         unsigned long eip = 0;
 149         unsigned long signr;
 150         struct sigaction * sa;
 151 
 152         while ((signr = current->signal & mask)) {
 153                 __asm__("bsf %2,%1\n\t"
 154                         "btrl %1,%0"
 155                         :"=m" (current->signal),"=r" (signr)
 156                         :"1" (signr));
 157                 sa = current->sigaction + signr;
 158                 signr++;
 159                 if ((current->flags & PF_PTRACED) && signr != SIGKILL) {
 160                         current->exit_code = signr;
 161                         current->state = TASK_STOPPED;
 162                         notify_parent(current);
 163                         schedule();
 164                         if (!(signr = current->exit_code))
 165                                 continue;
 166                         current->exit_code = 0;
 167                         if (signr == SIGSTOP)
 168                                 continue;
 169                         if (_S(signr) & current->blocked) {
 170                                 current->signal |= _S(signr);
 171                                 continue;
 172                         }
 173                         sa = current->sigaction + signr - 1;
 174                 }
 175                 if (sa->sa_handler == SIG_IGN) {
 176                         if (signr != SIGCHLD)
 177                                 continue;
 178                         /* check for SIGCHLD: it's special */
 179                         while (sys_waitpid(-1,NULL,WNOHANG) > 0)
 180                                 /* nothing */;
 181                         continue;
 182                 }
 183                 if (sa->sa_handler == SIG_DFL) {
 184                         if (current->pid == 1)
 185                                 continue;
 186                         switch (signr) {
 187                         case SIGCONT: case SIGCHLD: case SIGWINCH:
 188                                 continue;
 189 
 190                         case SIGSTOP: case SIGTSTP: case SIGTTIN: case SIGTTOU:
 191                                 if (current->flags & PF_PTRACED)
 192                                         continue;
 193                                 current->state = TASK_STOPPED;
 194                                 current->exit_code = signr;
 195                                 if (!(current->p_pptr->sigaction[SIGCHLD-1].sa_flags & 
 196                                                 SA_NOCLDSTOP))
 197                                         notify_parent(current);
 198                                 schedule();
 199                                 continue;
 200 
 201                         case SIGQUIT: case SIGILL: case SIGTRAP:
 202                         case SIGIOT: case SIGFPE: case SIGSEGV:
 203                                 if (current->binfmt && current->binfmt->core_dump) {
 204                                         if (current->binfmt->core_dump(signr, regs))
 205                                                 signr |= 0x80;
 206                                 }
 207                                 /* fall through */
 208                         default:
 209                                 current->signal |= _S(signr & 0x7f);
 210                                 do_exit(signr);
 211                         }
 212                 }
 213                 /*
 214                  * OK, we're invoking a handler
 215                  */
 216                 if (regs->orig_eax >= 0) {
 217                         if (regs->eax == -ERESTARTNOHAND ||
 218                            (regs->eax == -ERESTARTSYS && !(sa->sa_flags & SA_RESTART)))
 219                                 regs->eax = -EINTR;
 220                 }
 221                 handler_signal |= 1 << (signr-1);
 222                 mask &= ~sa->sa_mask;
 223         }
 224         if (regs->orig_eax >= 0 &&
 225             (regs->eax == -ERESTARTNOHAND ||
 226              regs->eax == -ERESTARTSYS ||
 227              regs->eax == -ERESTARTNOINTR)) {
 228                 regs->eax = regs->orig_eax;
 229                 regs->eip -= 2;
 230         }
 231         if (!handler_signal)            /* no handler will be called - return 0 */
 232                 return 0;
 233         eip = regs->eip;
 234         frame = (unsigned long *) regs->esp;
 235         signr = 1;
 236         sa = current->sigaction;
 237         for (mask = 1 ; mask ; sa++,signr++,mask += mask) {
 238                 if (mask > handler_signal)
 239                         break;
 240                 if (!(mask & handler_signal))
 241                         continue;
 242                 setup_frame(sa,&frame,eip,regs,signr,oldmask);
 243                 eip = (unsigned long) sa->sa_handler;
 244                 if (sa->sa_flags & SA_ONESHOT)
 245                         sa->sa_handler = NULL;
 246 /* force a supervisor-mode page-in of the signal handler to reduce races */
 247                 __asm__("testb $0,%%fs:%0": :"m" (*(char *) eip));
 248                 regs->cs = USER_CS; regs->ss = USER_DS;
 249                 regs->ds = USER_DS; regs->es = USER_DS;
 250                 regs->gs = USER_DS; regs->fs = USER_DS;
 251                 current->blocked |= sa->sa_mask;
 252                 oldmask |= sa->sa_mask;
 253         }
 254         regs->esp = (unsigned long) frame;
 255         regs->eip = eip;                /* "return" to the first handler */
 256         current->tss.trap_no = current->tss.error_code = 0;
 257         return 1;
 258 }
/* */
root/arch/i386/kernel/signal.c

DEFINITIONS
