The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/bsd/dev/i386/unix_signal.c

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    1 /*
    2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
    3  *
    4  * @APPLE_LICENSE_HEADER_START@
    5  * 
    6  * The contents of this file constitute Original Code as defined in and
    7  * are subject to the Apple Public Source License Version 1.1 (the
    8  * "License").  You may not use this file except in compliance with the
    9  * License.  Please obtain a copy of the License at
   10  * http://www.apple.com/publicsource and read it before using this file.
   11  * 
   12  * This Original Code and all software distributed under the License are
   13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
   14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
   15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
   16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
   17  * License for the specific language governing rights and limitations
   18  * under the License.
   19  * 
   20  * @APPLE_LICENSE_HEADER_END@
   21  */
   22 /* 
   23  * Copyright (c) 1992 NeXT, Inc.
   24  *
   25  * HISTORY
   26  * 13 May 1992 ? at NeXT
   27  *      Created.
   28  */
   29 
   30 #include <mach/mach_types.h>
   31 #include <mach/exception.h>
   32 
   33 #include <kern/thread.h>
   34 
   35 #include <sys/systm.h>
   36 #include <sys/param.h>
   37 #include <sys/proc_internal.h>
   38 #include <sys/user.h>
   39 #include <sys/sysproto.h>
   40 #include <sys/sysent.h>
   41 #include <mach/thread_act.h>    /* for thread_abort_safely */
   42 
   43 #include <i386/psl.h>
   44 #include <i386/seg.h>
   45 
   46 #include <mach/i386/thread_status.h>
   47 
   48 extern struct i386_saved_state *get_user_regs(thread_t);
   49 
   50 extern boolean_t valid_user_segment_selectors(uint16_t cs,
   51                                               uint16_t ss,
   52                                               uint16_t ds,
   53                                               uint16_t es,
   54                                               uint16_t fs,
   55                                               uint16_t gs);
   56 
   57 /* Forward: */
   58 extern boolean_t machine_exception(int, int, int, int *, int *);
   59 
   60 /* Signal handler flavors supported */
   61 /* These defns should match the Libc implmn */
   62 #define UC_TRAD                 1
   63 
   64 /*
   65  * Send an interrupt to process.
   66  *
   67  * Stack is set up to allow sigcode stored
   68  * in u. to call routine, followed by chmk
   69  * to sigreturn routine below.  After sigreturn
   70  * resets the signal mask, the stack, the frame 
   71  * pointer, and the argument pointer, it returns
   72  * to the user specified pc, psl.
   73  */
   74 void
   75 sendsig(p, catcher, sig, mask, code)
   76         struct proc *p;
   77         user_addr_t catcher;    /* sig_t */
   78         int sig, mask;
   79         u_long code;
   80 {
   81         struct sigframe {
   82                 int                     retaddr;
   83                 sig_t                   catcher;
   84                 int                     sigstyle;
   85                 int                     sig;
   86                 int                     code;
   87                 struct sigcontext *     scp;
   88         } frame, *fp;
   89         struct sigcontext               context, *scp;
   90         struct sigacts *ps = p->p_sigacts;
   91         int oonstack;
   92         thread_t thread = current_thread();
   93         struct uthread * ut;
   94         struct i386_saved_state * saved_state = get_user_regs(thread);
   95         sig_t trampact;
   96     
   97         ut = get_bsdthread_info(thread);
   98         oonstack = ps->ps_sigstk.ss_flags & SA_ONSTACK;
   99         if ((ps->ps_flags & SAS_ALTSTACK) && !oonstack &&
  100                 (ps->ps_sigonstack & sigmask(sig))) {
  101                         scp = ((struct sigcontext *)ps->ps_sigstk.ss_sp) - 1;
  102                         ps->ps_sigstk.ss_flags |= SA_ONSTACK;
  103         } else
  104                 scp = ((struct sigcontext *)saved_state->uesp) - 1;
  105         fp = ((struct sigframe *)scp) - 1;
  106 
  107         /* 
  108          * Build the argument list for the signal handler.
  109          */
  110 
  111         trampact = (sig_t)ps->ps_trampact[sig];
  112         /* Handler should call sigreturn to get out of it */
  113         frame.retaddr = 0xffffffff;     
  114         frame.catcher = CAST_DOWN(sig_t,catcher);       /* XXX LP64 */
  115         frame.sigstyle = UC_TRAD;
  116         frame.sig = sig;
  117 
  118         if (sig == SIGILL || sig == SIGFPE) {
  119                 frame.code = code;
  120         } else
  121                 frame.code = 0;
  122         frame.scp = scp;
  123         if (copyout((caddr_t)&frame, (user_addr_t)fp, sizeof (frame))) 
  124                 goto bad;
  125 
  126         /*
  127          * Build the signal context to be used by sigreturn.
  128          */
  129         context.sc_onstack = oonstack;
  130         context.sc_mask = mask;
  131         context.sc_eax = saved_state->eax;
  132         context.sc_ebx = saved_state->ebx;
  133         context.sc_ecx = saved_state->ecx;
  134         context.sc_edx = saved_state->edx;
  135         context.sc_edi = saved_state->edi;
  136         context.sc_esi = saved_state->esi;
  137         context.sc_ebp = saved_state->ebp;
  138         context.sc_esp = saved_state->uesp;
  139         context.sc_ss = saved_state->ss;
  140         context.sc_eflags = saved_state->efl;
  141         context.sc_eip = saved_state->eip;
  142         context.sc_cs = saved_state->cs;
  143         if (saved_state->efl & EFL_VM) {
  144                 context.sc_ds = saved_state->v86_segs.v86_ds;
  145                 context.sc_es = saved_state->v86_segs.v86_es;
  146                 context.sc_fs = saved_state->v86_segs.v86_fs;
  147                 context.sc_gs = saved_state->v86_segs.v86_gs;
  148 
  149                 saved_state->efl &= ~EFL_VM;
  150         } else {
  151                 context.sc_ds = saved_state->ds;
  152                 context.sc_es = saved_state->es;
  153                 context.sc_fs = saved_state->fs;
  154                 context.sc_gs = saved_state->gs;
  155         }
  156         if (copyout((caddr_t)&context, (user_addr_t)scp, sizeof (context))) 
  157                 goto bad;
  158 
  159         saved_state->eip = (unsigned int)trampact;
  160         saved_state->cs = USER_CS;
  161 
  162         saved_state->uesp = (unsigned int)fp;
  163         saved_state->ss = USER_DS;
  164 
  165         saved_state->ds = USER_DS;
  166         saved_state->es = USER_DS;
  167         saved_state->fs = NULL_SEG;
  168         saved_state->gs = USER_CTHREAD;
  169         return;
  170 
  171 bad:
  172         SIGACTION(p, SIGILL) = SIG_DFL;
  173         sig = sigmask(SIGILL);
  174         p->p_sigignore &= ~sig;
  175         p->p_sigcatch &= ~sig;
  176         ut->uu_sigmask &= ~sig;
  177         /* sendsig is called with signal lock held */
  178         psignal_lock(p, SIGILL, 0);
  179         return;
  180 }
  181 
  182 /*
  183  * System call to cleanup state after a signal
  184  * has been taken.  Reset signal mask and
  185  * stack state from context left by sendsig (above).
  186  * Return to previous pc and psl as specified by
  187  * context left by sendsig. Check carefully to
  188  * make sure that the user has not modified the
  189  * psl to gain improper priviledges or to cause
  190  * a machine fault.
  191  */
  192 /* ARGSUSED */
  193 int
  194 sigreturn(
  195         struct proc *p,
  196         struct sigreturn_args *uap,
  197         __unused int *retval)
  198 {
  199     struct sigcontext           context;
  200     thread_t                    thread = current_thread();
  201         int error;
  202     struct i386_saved_state*    saved_state = (struct i386_saved_state*)
  203                                                         get_user_regs(thread);  
  204         struct uthread * ut;
  205 
  206 
  207     
  208         if (saved_state == NULL) 
  209                 return EINVAL;
  210 
  211     if ((error = copyin(CAST_USER_ADDR_T(uap->sigcntxp), (void *)&context, 
  212                                 sizeof (context)))) 
  213                 return(error);
  214 
  215         /*
  216          * Validate segment selectors.
  217          * Bad values would result in kernel exception at context switch
  218          * back to user mode. If other state is invalid an exception will
  219          * occur in user context.
  220          */
  221         if (!valid_user_segment_selectors(context.sc_cs,
  222                                           context.sc_ss,
  223                                           context.sc_ds,
  224                                           context.sc_es,
  225                                           context.sc_fs,
  226                                           context.sc_gs)) {
  227                 return EINVAL;
  228         }
  229 
  230         ut = (struct uthread *)get_bsdthread_info(thread);
  231 
  232         if (context.sc_onstack & 01)
  233                 p->p_sigacts->ps_sigstk.ss_flags |= SA_ONSTACK;
  234         else
  235                 p->p_sigacts->ps_sigstk.ss_flags &= ~SA_ONSTACK;
  236 
  237         ut->uu_sigmask = context.sc_mask &~ sigcantmask;
  238         if(ut->uu_siglist & ~ut->uu_sigmask)
  239                 signal_setast(thread);
  240 
  241         saved_state->eax = context.sc_eax;
  242         saved_state->ebx = context.sc_ebx;
  243         saved_state->ecx = context.sc_ecx;
  244         saved_state->edx = context.sc_edx;
  245         saved_state->edi = context.sc_edi;
  246         saved_state->esi = context.sc_esi;
  247         saved_state->ebp = context.sc_ebp;
  248         saved_state->uesp = context.sc_esp;
  249         saved_state->ss = context.sc_ss;
  250         saved_state->efl = context.sc_eflags;
  251         saved_state->efl &= ~EFL_USERCLR;
  252         saved_state->efl |= EFL_USERSET;
  253         saved_state->eip = context.sc_eip;
  254         saved_state->cs = context.sc_cs;
  255 
  256         if (context.sc_eflags & EFL_VM) {
  257                 saved_state->ds = NULL_SEG;
  258                 saved_state->es = NULL_SEG;
  259                 saved_state->fs = NULL_SEG;
  260                 saved_state->gs = NULL_SEG;
  261                 saved_state->v86_segs.v86_ds = context.sc_ds;
  262                 saved_state->v86_segs.v86_es = context.sc_es;
  263                 saved_state->v86_segs.v86_fs = context.sc_fs;
  264                 saved_state->v86_segs.v86_gs = context.sc_gs;
  265 
  266                 saved_state->efl |= EFL_VM;
  267         }
  268         else {
  269                 saved_state->ds = context.sc_ds;
  270                 saved_state->es = context.sc_es;
  271                 saved_state->fs = context.sc_fs;
  272                 saved_state->gs = context.sc_gs;
  273         }
  274 
  275         return (EJUSTRETURN);
  276 }
  277 
  278 /*
  279  * machine_exception() performs MD translation
  280  * of a mach exception to a unix signal and code.
  281  */
  282 
  283 boolean_t
  284 machine_exception(
  285     int                 exception,
  286     int                 code,
  287     __unused int        subcode,
  288     int                 *unix_signal,
  289     int                 *unix_code
  290 )
  291 {
  292 
  293     switch(exception) {
  294 
  295     case EXC_BAD_INSTRUCTION:
  296         *unix_signal = SIGILL;
  297         *unix_code = code;
  298         break;
  299 
  300     case EXC_ARITHMETIC:
  301         *unix_signal = SIGFPE;
  302         *unix_code = code;
  303         break;
  304 
  305     default:
  306         return(FALSE);
  307     }
  308    
  309     return(TRUE);
  310 }
  311 
  312 #include <sys/systm.h>
  313 #include <sys/sysent.h>
  314 
  315 int __pthread_cset(struct sysent *);
  316 void __pthread_creset(struct sysent *);
  317 
  318 int
  319 __pthread_cset(struct sysent *callp)
  320 {
  321         unsigned int cancel_enable;
  322         thread_t thread;
  323         struct uthread * uthread; 
  324 
  325         thread = current_thread();
  326         uthread = get_bsdthread_info(thread);
  327 
  328         cancel_enable = callp->sy_cancel;
  329         if (cancel_enable == _SYSCALL_CANCEL_NONE) {
  330                 uthread->uu_flag |= UT_NOTCANCELPT;
  331         } else {
  332                 if((uthread->uu_flag & (UT_CANCELDISABLE | UT_CANCEL | UT_CANCELED)) == UT_CANCEL) {
  333                         if (cancel_enable == _SYSCALL_CANCEL_PRE)
  334                                 return(EINTR);
  335                         else
  336                                 thread_abort_safely(thread);
  337                 }
  338         }   
  339         return(0);
  340 }
  341 
  342 
  343 void
  344 __pthread_creset(struct sysent *callp)
  345 {
  346 
  347         unsigned int cancel_enable;
  348         thread_t thread;
  349         struct uthread * uthread; 
  350 
  351         thread = current_thread();
  352         uthread = get_bsdthread_info(thread);
  353         
  354         cancel_enable = callp->sy_cancel;
  355         if (!cancel_enable) 
  356                 uthread->uu_flag &= ~UT_NOTCANCELPT;
  357 
  358 }
  359 

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