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/mm.h>
   9 #include <linux/kernel.h>
  10 #include <linux/signal.h>
  11 #include <linux/errno.h>
  12 #include <linux/wait.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/unistd.h>
  15 
  16 #include <asm/segment.h>
  17 
  18 #define _S(nr) (1<<((nr)-1))
  19 
  20 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
  21 
  22 asmlinkage int sys_waitpid(pid_t pid,unsigned long * stat_addr, int options);
  23 asmlinkage int do_signal(unsigned long oldmask, struct pt_regs * regs);
  24 
  25 /*
  26  * atomically swap in the new signal mask, and wait for a signal.
  27  */
  28 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, unsigned long set)
     /*  */
  29 {
  30         unsigned long mask;
  31         struct pt_regs * regs = (struct pt_regs *) &restart;
  32 
  33         mask = current->blocked;
  34         current->blocked = set & _BLOCKABLE;
  35         regs->eax = -EINTR;
  36         while (1) {
  37                 current->state = TASK_INTERRUPTIBLE;
  38                 schedule();
  39                 if (do_signal(mask,regs))
  40                         return -EINTR;
  41         }
  42 }
  43 
  44 /*
  45  * This sets regs->esp even though we don't actually use sigstacks yet..
  46  */
  47 asmlinkage int sys_sigreturn(unsigned long __unused)
     /*  */
  48 {
  49 #define COPY(x) regs->x = context.x
  50 #define COPY_SEG(x) \
  51 if ((context.x & 0xfffc) && (context.x & 3) != 3) goto badframe; COPY(x);
  52 #define COPY_SEG_STRICT(x) \
  53 if (!(context.x & 0xfffc) || (context.x & 3) != 3) goto badframe; COPY(x);
  54         struct sigcontext_struct context;
  55         struct pt_regs * regs;
  56 
  57         regs = (struct pt_regs *) &__unused;
  58         if (verify_area(VERIFY_READ, (void *) regs->esp, sizeof(context)))
  59                 goto badframe;
  60         memcpy_fromfs(&context,(void *) regs->esp, sizeof(context));
  61         current->blocked = context.oldmask & _BLOCKABLE;
  62         COPY_SEG(ds);
  63         COPY_SEG(es);
  64         COPY_SEG(fs);
  65         COPY_SEG(gs);
  66         COPY_SEG_STRICT(ss);
  67         COPY_SEG_STRICT(cs);
  68         COPY(eip);
  69         COPY(ecx); COPY(edx);
  70         COPY(ebx);
  71         COPY(esp); COPY(ebp);
  72         COPY(edi); COPY(esi);
  73         regs->eflags &= ~0x40DD5;
  74         regs->eflags |= context.eflags & 0x40DD5;
  75         regs->orig_eax = -1;            /* disable syscall checks */
  76         return context.eax;
  77 badframe:
  78         do_exit(SIGSEGV);
  79 }
  80 
  81 /*
  82  * Set up a signal frame... Make the stack look the way iBCS2 expects
  83  * it to look.
  84  */
  85 void setup_frame(struct sigaction * sa, unsigned long ** fp, unsigned long eip,
     /*  */
  86         struct pt_regs * regs, int signr, unsigned long oldmask)
  87 {
  88         unsigned long * frame;
  89 
  90 #define __CODE ((unsigned long)(frame+24))
  91 #define CODE(x) ((unsigned long *) ((x)+__CODE))
  92         frame = *fp;
  93         if (regs->ss != USER_DS && sa->sa_restorer)
  94                 frame = (unsigned long *) sa->sa_restorer;
  95         frame -= 32;
  96         if (verify_area(VERIFY_WRITE,frame,32*4))
  97                 do_exit(SIGSEGV);
  98 /* set up the "normal" stack seen by the signal handler (iBCS2) */
  99         put_fs_long(__CODE,frame);
 100         if (current->exec_domain && current->exec_domain->signal_invmap)
 101                 put_fs_long(current->exec_domain->signal_invmap[signr], frame+1);
 102         else
 103                 put_fs_long(signr, frame+1);
 104         put_fs_long(regs->gs, frame+2);
 105         put_fs_long(regs->fs, frame+3);
 106         put_fs_long(regs->es, frame+4);
 107         put_fs_long(regs->ds, frame+5);
 108         put_fs_long(regs->edi, frame+6);
 109         put_fs_long(regs->esi, frame+7);
 110         put_fs_long(regs->ebp, frame+8);
 111         put_fs_long((long)*fp, frame+9);
 112         put_fs_long(regs->ebx, frame+10);
 113         put_fs_long(regs->edx, frame+11);
 114         put_fs_long(regs->ecx, frame+12);
 115         put_fs_long(regs->eax, frame+13);
 116         put_fs_long(current->tss.trap_no, frame+14);
 117         put_fs_long(current->tss.error_code, frame+15);
 118         put_fs_long(eip, frame+16);
 119         put_fs_long(regs->cs, frame+17);
 120         put_fs_long(regs->eflags, frame+18);
 121         put_fs_long(regs->esp, frame+19);
 122         put_fs_long(regs->ss, frame+20);
 123         put_fs_long(0,frame+21);                /* 387 state pointer - not implemented*/
 124 /* non-iBCS2 extensions.. */
 125         put_fs_long(oldmask, frame+22);
 126         put_fs_long(current->tss.cr2, frame+23);
 127 /* set up the return code... */
 128         put_fs_long(0x0000b858, CODE(0));       /* popl %eax ; movl $,%eax */
 129         put_fs_long(0x80cd0000, CODE(4));       /* int $0x80 */
 130         put_fs_long(__NR_sigreturn, CODE(2));
 131         *fp = frame;
 132 #undef __CODE
 133 #undef CODE
 134 }
 135 
 136 /*
 137  * Note that 'init' is a special process: it doesn't get signals it doesn't
 138  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 139  * mistake.
 140  *
 141  * Note that we go through the signals twice: once to check the signals that
 142  * the kernel can handle, and then we build all the user-level signal handling
 143  * stack-frames in one go after that.
 144  */
 145 asmlinkage int do_signal(unsigned long oldmask, struct pt_regs * regs)
     /*  */
 146 {
 147         unsigned long mask = ~current->blocked;
 148         unsigned long handler_signal = 0;
 149         unsigned long *frame = NULL;
 150         unsigned long eip = 0;
 151         unsigned long signr;
 152         struct sigaction * sa;
 153 
 154         while ((signr = current->signal & mask)) {
 155                 __asm__("bsf %3,%1\n\t"
 156                         "btrl %1,%0"
 157                         :"=m" (current->signal),"=r" (signr)
 158                         :"0" (current->signal), "1" (signr));
 159                 sa = current->sig->action + signr;
 160                 signr++;
 161                 if ((current->flags & PF_PTRACED) && signr != SIGKILL) {
 162                         current->exit_code = signr;
 163                         current->state = TASK_STOPPED;
 164                         notify_parent(current);
 165                         schedule();
 166                         if (!(signr = current->exit_code))
 167                                 continue;
 168                         current->exit_code = 0;
 169                         if (signr == SIGSTOP)
 170                                 continue;
 171                         if (_S(signr) & current->blocked) {
 172                                 current->signal |= _S(signr);
 173                                 continue;
 174                         }
 175                         sa = current->sig->action + signr - 1;
 176                 }
 177                 if (sa->sa_handler == SIG_IGN) {
 178                         if (signr != SIGCHLD)
 179                                 continue;
 180                         /* check for SIGCHLD: it's special */
 181                         while (sys_waitpid(-1,NULL,WNOHANG) > 0)
 182                                 /* nothing */;
 183                         continue;
 184                 }
 185                 if (sa->sa_handler == SIG_DFL) {
 186                         if (current->pid == 1)
 187                                 continue;
 188                         switch (signr) {
 189                         case SIGCONT: case SIGCHLD: case SIGWINCH:
 190                                 continue;
 191 
 192                         case SIGSTOP: case SIGTSTP: case SIGTTIN: case SIGTTOU:
 193                                 if (current->flags & PF_PTRACED)
 194                                         continue;
 195                                 current->state = TASK_STOPPED;
 196                                 current->exit_code = signr;
 197                                 if (!(current->p_pptr->sig->action[SIGCHLD-1].sa_flags & 
 198                                                 SA_NOCLDSTOP))
 199                                         notify_parent(current);
 200                                 schedule();
 201                                 continue;
 202 
 203                         case SIGQUIT: case SIGILL: case SIGTRAP:
 204                         case SIGABRT: case SIGFPE: case SIGSEGV:
 205                                 if (current->binfmt && current->binfmt->core_dump) {
 206                                         if (current->binfmt->core_dump(signr, regs))
 207                                                 signr |= 0x80;
 208                                 }
 209                                 /* fall through */
 210                         default:
 211                                 current->signal |= _S(signr & 0x7f);
 212                                 do_exit(signr);
 213                         }
 214                 }
 215                 /*
 216                  * OK, we're invoking a handler
 217                  */
 218                 if (regs->orig_eax >= 0) {
 219                         if (regs->eax == -ERESTARTNOHAND ||
 220                            (regs->eax == -ERESTARTSYS && !(sa->sa_flags & SA_RESTART)))
 221                                 regs->eax = -EINTR;
 222                 }
 223                 handler_signal |= 1 << (signr-1);
 224                 mask &= ~sa->sa_mask;
 225         }
 226         if (regs->orig_eax >= 0 &&
 227             (regs->eax == -ERESTARTNOHAND ||
 228              regs->eax == -ERESTARTSYS ||
 229              regs->eax == -ERESTARTNOINTR)) {
 230                 regs->eax = regs->orig_eax;
 231                 regs->eip -= 2;
 232         }
 233         if (!handler_signal)            /* no handler will be called - return 0 */
 234                 return 0;
 235         eip = regs->eip;
 236         frame = (unsigned long *) regs->esp;
 237         signr = 1;
 238         sa = current->sig->action;
 239         for (mask = 1 ; mask ; sa++,signr++,mask += mask) {
 240                 if (mask > handler_signal)
 241                         break;
 242                 if (!(mask & handler_signal))
 243                         continue;
 244                 setup_frame(sa,&frame,eip,regs,signr,oldmask);
 245                 eip = (unsigned long) sa->sa_handler;
 246                 if (sa->sa_flags & SA_ONESHOT)
 247                         sa->sa_handler = NULL;
 248 /* force a supervisor-mode page-in of the signal handler to reduce races */
 249                 __asm__("testb $0,%%fs:%0": :"m" (*(char *) eip));
 250                 regs->cs = USER_CS; regs->ss = USER_DS;
 251                 regs->ds = USER_DS; regs->es = USER_DS;
 252                 regs->gs = USER_DS; regs->fs = USER_DS;
 253                 current->blocked |= sa->sa_mask;
 254                 oldmask |= sa->sa_mask;
 255         }
 256         regs->esp = (unsigned long) frame;
 257         regs->eip = eip;                /* "return" to the first handler */
 258         regs->eflags &= ~TF_MASK;
 259         current->tss.trap_no = current->tss.error_code = 0;
 260         return 1;
 261 }
/* */
root/arch/i386/kernel/signal.c

DEFINITIONS
