/* Machine independent support for SVR4 /proc (process file system) for GDB. Copyright (C) 1991 Free Software Foundation, Inc. Written by Fred Fish at Cygnus Support. This file is part of GDB. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /* N O T E S For information on the details of using /proc consult section proc(4) in the UNIX System V Release 4 System Administrator's Reference Manual. The general register and floating point register sets are manipulated by separate ioctl's. This file makes the assumption that if FP0_REGNUM is defined, then support for the floating point register set is desired, regardless of whether or not the actual target has floating point hardware. */ #include "param.h" #ifdef USE_PROC_FS /* Entire file goes away if not using /proc */ #include #include #include #include #include "defs.h" #include "ansidecl.h" #include "inferior.h" #include "target.h" #ifndef PROC_NAME_FMT #define PROC_NAME_FMT "/proc/%d" #endif extern void EXFUN(supply_gregset, (gregset_t *gregsetp)); extern void EXFUN(fill_gregset, (gregset_t *gresetp, int regno)); #if defined (FP0_REGNUM) extern void EXFUN(supply_fpregset, (fpregset_t *fpregsetp)); extern void EXFUN(fill_fpregset, (fpregset_t *fpresetp, int regno)); #endif #if 1 /* FIXME: Gross and ugly hack to resolve coredep.c global */ CORE_ADDR kernel_u_addr; #endif /* All access to the inferior, either one started by gdb or one that has been attached to, is controlled by an instance of a procinfo structure, defined below. Since gdb currently only handles one inferior at a time, the procinfo structure is statically allocated and only one exists at any given time. */ struct procinfo { int valid; /* Nonzero if pid, fd, & pathname are valid */ int pid; /* Process ID of inferior */ int fd; /* File descriptor for /proc entry */ char *pathname; /* Pathname to /proc entry */ int was_stopped; /* Nonzero if was stopped prior to attach */ prrun_t prrun; /* Control state when it is run */ prstatus_t prstatus; /* Current process status info */ gregset_t gregset; /* General register set */ fpregset_t fpregset; /* Floating point register set */ fltset_t fltset; /* Current traced hardware fault set */ sigset_t trace; /* Current traced signal set */ sysset_t exitset; /* Current traced system call exit set */ sysset_t entryset; /* Current traced system call entry set */ } pi; /* Forward declarations of static functions so we don't have to worry about ordering within this file. The EXFUN macro may be slightly misleading. Should probably be called DCLFUN instead, or something more intuitive, since it can be used for both static and external definitions. */ static void EXFUN(proc_init_failed, (char *why)); static int EXFUN(open_proc_file, (int pid)); static void EXFUN(close_proc_file, (void)); static void EXFUN(unconditionally_kill_inferior, (void)); /* GLOBAL FUNCTION ptrace -- override library version to force errors for /proc version SYNOPSIS int ptrace (int request, int pid, int arg3, int arg4) DESCRIPTION When gdb is configured to use /proc, it should not be calling or otherwise attempting to use ptrace. In order to catch errors where use of /proc is configured, but some routine is still calling ptrace, we provide a local version of a function with that name that does nothing but issue an error message. */ int DEFUN(ptrace, (request, pid, arg3, arg4), int request AND int pid AND int arg3 AND int arg4) { error ("internal error - there is a call to ptrace() somewhere"); /*NOTREACHED*/ } /* GLOBAL FUNCTION kill_inferior_fast -- kill inferior while gdb is exiting SYNOPSIS void kill_inferior_fast (void) DESCRIPTION This is used when GDB is exiting. It gives less chance of error. NOTES Don't attempt to kill attached inferiors since we may be called when gdb is in the process of aborting, and killing the attached inferior may be very anti-social. This is particularly true if we were attached just so we could use the /proc facilities to get detailed information about it's status. */ void DEFUN_VOID(kill_inferior_fast) { if (inferior_pid != 0 && !attach_flag) { unconditionally_kill_inferior (); } } /* GLOBAL FUNCTION kill_inferior - kill any currently inferior SYNOPSIS void kill_inferior (void) DESCRIPTION Kill any current inferior. NOTES Kills even attached inferiors. Presumably the user has already been prompted that the inferior is an attached one rather than one started by gdb. (FIXME?) */ void DEFUN_VOID(kill_inferior) { if (inferior_pid != 0) { unconditionally_kill_inferior (); target_mourn_inferior (); } } /* LOCAL FUNCTION unconditionally_kill_inferior - terminate the inferior SYNOPSIS static void unconditionally_kill_inferior (void) DESCRIPTION Kill the current inferior. Should not be called until it is at least tested that there is an inferior. NOTE A possibly useful enhancement would be to first try sending the inferior a terminate signal, politely asking it to commit suicide, before we murder it. */ static void DEFUN_VOID(unconditionally_kill_inferior) { int signo; signo = SIGKILL; (void) ioctl (pi.fd, PIOCKILL, &signo); close_proc_file (); wait ((int *) 0); } /* GLOBAL FUNCTION child_xfer_memory -- copy data to or from inferior memory space SYNOPSIS int child_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int dowrite, struct target_ops target) DESCRIPTION Copy LEN bytes to/from inferior's memory starting at MEMADDR from/to debugger memory starting at MYADDR. Copy from inferior if DOWRITE is zero or to inferior if DOWRITE is nonzero. Returns the length copied, which is either the LEN argument or zero. This xfer function does not do partial moves, since child_ops doesn't allow memory operations to cross below us in the target stack anyway. NOTES The /proc interface makes this an almost trivial task. */ int DEFUN(child_xfer_memory, (memaddr, myaddr, len, dowrite, target), CORE_ADDR memaddr AND char *myaddr AND int len AND int dowrite AND struct target_ops target /* ignored */) { int nbytes = 0; if (lseek (pi.fd, (off_t) memaddr, 0) == (off_t) memaddr) { if (dowrite) { nbytes = write (pi.fd, myaddr, len); } else { nbytes = read (pi.fd, myaddr, len); } if (nbytes < 0) { nbytes = 0; } } return (nbytes); } /* GLOBAL FUNCTION store_inferior_registers -- copy register values back to inferior SYNOPSIS void store_inferior_registers (int regno) DESCRIPTION Store our current register values back into the inferior. If REGNO is -1 then store all the register, otherwise store just the value specified by REGNO. NOTES If we are storing only a single register, we first have to get all the current values from the process, overwrite the desired register in the gregset with the one we want from gdb's registers, and then send the whole set back to the process. For writing all the registers, all we have to do is generate the gregset and send it to the process. Also note that the process has to be stopped on an event of interest for this to work, which basically means that it has to have been run under the control of one of the other /proc ioctl calls and not ptrace. Since we don't use ptrace anyway, we don't worry about this fine point, but it is worth noting for future reference. Gdb is confused about what this function is supposed to return. Some versions return a value, others return nothing. Some are declared to return a value and actually return nothing. Gdb ignores anything returned. (FIXME) */ void DEFUN(store_inferior_registers, (regno), int regno) { if (regno != -1) { (void) ioctl (pi.fd, PIOCGREG, &pi.gregset); } fill_gregset (&pi.gregset, regno); (void) ioctl (pi.fd, PIOCSREG, &pi.gregset); #if defined (FP0_REGNUM) /* Now repeat everything using the floating point register set, if the target has floating point hardware. Since we ignore the returned value, we'll never know whether it worked or not anyway. */ if (regno != -1) { (void) ioctl (pi.fd, PIOCGFPREG, &pi.fpregset); } fill_fpregset (&pi.fpregset, regno); (void) ioctl (pi.fd, PIOCSFPREG, &pi.fpregset); #endif /* FP0_REGNUM */ } /* GLOBAL FUNCTION inferior_proc_init - initialize access to a /proc entry SYNOPSIS void inferior_proc_init (int pid) DESCRIPTION When gdb starts an inferior, this function is called in the parent process immediately after the fork. It waits for the child to stop on the return from the exec system call (the child itself takes care of ensuring that this is set up), then sets up the set of signals and faults that are to be traced. NOTES If proc_init_failed ever gets called, control returns to the command processing loop via the standard error handling code. */ void DEFUN(inferior_proc_init, (int pid), int pid) { if (!open_proc_file (pid)) { proc_init_failed ("can't open process file"); } else { (void) memset (&pi.prrun, 0, sizeof (pi.prrun)); prfillset (&pi.prrun.pr_trace); prfillset (&pi.prrun.pr_fault); prdelset (&pi.prrun.pr_fault, FLTPAGE); if (ioctl (pi.fd, PIOCWSTOP, &pi.prstatus) < 0) { proc_init_failed ("PIOCWSTOP failed"); } else if (ioctl (pi.fd, PIOCSTRACE, &pi.prrun.pr_trace) < 0) { proc_init_failed ("PIOCSTRACE failed"); } else if (ioctl (pi.fd, PIOCSFAULT, &pi.prrun.pr_fault) < 0) { proc_init_failed ("PIOCSFAULT failed"); } } } /* GLOBAL FUNCTION proc_set_exec_trap -- arrange for exec'd child to halt at startup SYNOPSIS void proc_set_exec_trap (void) DESCRIPTION This function is called in the child process when starting up an inferior, prior to doing the exec of the actual inferior. It sets the child process's exitset to make exit from the exec system call an event of interest to stop on, and then simply returns. The child does the exec, the system call returns, and the child stops at the first instruction, ready for the gdb parent process to take control of it. NOTE We need to use all local variables since the child may be sharing it's data space with the parent, if vfork was used rather than fork. */ void DEFUN_VOID(proc_set_exec_trap) { sysset_t exitset; auto char procname[32]; int fd; (void) sprintf (procname, PROC_NAME_FMT, getpid ()); if ((fd = open (procname, O_RDWR)) < 0) { perror (procname); fflush (stderr); _exit (127); } premptyset (&exitset); praddset (&exitset, SYS_exec); praddset (&exitset, SYS_execve); if (ioctl (fd, PIOCSEXIT, &exitset) < 0) { perror (procname); fflush (stderr); _exit (127); } } #ifdef ATTACH_DETACH /* GLOBAL FUNCTION attach -- attach to an already existing process SYNOPSIS int attach (int pid) DESCRIPTION Attach to an already existing process with the specified process id. If the process is not already stopped, query whether to stop it or not. NOTES The option of stopping at attach time is specific to the /proc versions of gdb. Versions using ptrace force the attachee to stop. */ int DEFUN(attach, (pid), int pid) { if (!open_proc_file (pid)) { perror_with_name (pi.pathname); /* NOTREACHED */ } /* Get current status of process and if it is not already stopped, then stop it. Remember whether or not it was stopped when we first examined it. */ if (ioctl (pi.fd, PIOCSTATUS, &pi.prstatus) < 0) { print_sys_errmsg (pi.pathname, errno); close_proc_file (); error ("PIOCSTATUS failed"); } if (pi.prstatus.pr_flags & (PR_STOPPED | PR_ISTOP)) { pi.was_stopped = 1; } else { pi.was_stopped = 0; if (query ("Process is currently running, stop it? ")) { if (ioctl (pi.fd, PIOCSTOP, &pi.prstatus) < 0) { print_sys_errmsg (pi.pathname, errno); close_proc_file (); error ("PIOCSTOP failed"); } } } /* Remember some things about the inferior that we will, or might, change so that we can restore them when we detach. */ (void) ioctl (pi.fd, PIOCGTRACE, &pi.trace); (void) ioctl (pi.fd, PIOCGFAULT, &pi.fltset); (void) ioctl (pi.fd, PIOCGENTRY, &pi.entryset); (void) ioctl (pi.fd, PIOCGEXIT, &pi.exitset); /* Set up trace and fault sets, as gdb expects them. */ (void) memset (&pi.prrun, 0, sizeof (pi.prrun)); prfillset (&pi.prrun.pr_trace); prfillset (&pi.prrun.pr_fault); prdelset (&pi.prrun.pr_fault, FLTPAGE); if (ioctl (pi.fd, PIOCSFAULT, &pi.prrun.pr_fault)) { print_sys_errmsg ("PIOCSFAULT failed"); } if (ioctl (pi.fd, PIOCSTRACE, &pi.prrun.pr_trace)) { print_sys_errmsg ("PIOCSTRACE failed"); } attach_flag = 1; return (pid); } /* GLOBAL FUNCTION detach -- detach from an attached-to process SYNOPSIS void detach (int signal) DESCRIPTION Detach from the current attachee. If signal is non-zero, the attachee is started running again and sent the specified signal. If signal is zero and the attachee was not already stopped when we attached to it, then we make it runnable again when we detach. Otherwise, we query whether or not to make the attachee runnable again, since we may simply want to leave it in the state it was in when we attached. We report any problems, but do not consider them errors, since we MUST detach even if some things don't seem to go right. This may not be the ideal situation. (FIXME). */ void DEFUN(detach, (signal), int signal) { if (signal) { struct siginfo siginfo; siginfo.si_signo = signal; siginfo.si_code = 0; siginfo.si_errno = 0; if (ioctl (pi.fd, PIOCSSIG, &siginfo) < 0) { print_sys_errmsg (pi.pathname, errno); printf ("PIOCSSIG failed.\n"); } } if (ioctl (pi.fd, PIOCSEXIT, &pi.exitset) < 0) { print_sys_errmsg (pi.pathname, errno); printf ("PIOCSEXIT failed.\n"); } if (ioctl (pi.fd, PIOCSENTRY, &pi.entryset) < 0) { print_sys_errmsg (pi.pathname, errno); printf ("PIOCSENTRY failed.\n"); } if (ioctl (pi.fd, PIOCSTRACE, &pi.trace) < 0) { print_sys_errmsg (pi.pathname, errno); printf ("PIOCSTRACE failed.\n"); } if (ioctl (pi.fd, PIOCSFAULT, &pi.fltset) < 0) { print_sys_errmsg (pi.pathname, errno); printf ("PIOCSFAULT failed.\n"); } if (ioctl (pi.fd, PIOCSTATUS, &pi.prstatus) < 0) { print_sys_errmsg (pi.pathname, errno); printf ("PIOCSTATUS failed.\n"); } else { if (signal || (pi.prstatus.pr_flags & (PR_STOPPED | PR_ISTOP))) { if (signal || !pi.was_stopped || query ("Was stopped when attached, make it runnable again? ")) { (void) memset (&pi.prrun, 0, sizeof (pi.prrun)); pi.prrun.pr_flags = PRCFAULT; if (ioctl (pi.fd, PIOCRUN, &pi.prrun)) { print_sys_errmsg (pi.pathname, errno); printf ("PIOCRUN failed.\n"); } } } } close_proc_file (); attach_flag = 0; } /* GLOBAL FUNCTION proc_wait -- emulate wait() as much as possible SYNOPSIS int proc_wait (int *statloc) DESCRIPTION Try to emulate wait() as much as possible. Not sure why we can't just use wait(), but it seems to have problems when applied to a process being controlled with the /proc interface. NOTES We have a race problem here with no obvious solution. We need to let the inferior run until it stops on an event of interest, which means that we need to use the PIOCWSTOP ioctl. However, we cannot use this ioctl if the process is already stopped on something that is not an event of interest, or the call will hang indefinitely. Thus we first use PIOCSTATUS to see if the process is not stopped. If not, then we use PIOCWSTOP. But during the window between the two, if the process stops for any reason that is not an event of interest (such as a job control signal) then gdb will hang. One possible workaround is to set an alarm to wake up every minute of so and check to see if the process is still running, and if so, then reissue the PIOCWSTOP. But this is a real kludge, so has not been implemented. FIXME: investigate alternatives. FIXME: Investigate why wait() seems to have problems with programs being control by /proc routines. */ int DEFUN(proc_wait, (statloc), int *statloc) { short what; short why; int statval = 0; int checkerr = 0; int rtnval = -1; if (ioctl (pi.fd, PIOCSTATUS, &pi.prstatus) < 0) { checkerr++; } else if (!(pi.prstatus.pr_flags & (PR_STOPPED | PR_ISTOP))) { if (ioctl (pi.fd, PIOCWSTOP, &pi.prstatus) < 0) { checkerr++; } } if (checkerr) { if (errno == ENOENT) { rtnval = wait (&statval); if (rtnval != inferior_pid) { error ("PIOCWSTOP, wait failed, returned %d", rtnval); /* NOTREACHED */ } } else { print_sys_errmsg (pi.pathname, errno); error ("PIOCSTATUS or PIOCWSTOP failed."); /* NOTREACHED */ } } else if (pi.prstatus.pr_flags & (PR_STOPPED | PR_ISTOP)) { rtnval = pi.prstatus.pr_pid; why = pi.prstatus.pr_why; what = pi.prstatus.pr_what; if (why == PR_SIGNALLED) { statval = (what << 8) | 0177; } else if ((why == PR_SYSEXIT) && (what == SYS_exec || what == SYS_execve)) { statval = (SIGTRAP << 8) | 0177; } else if (why == PR_REQUESTED) { statval = (SIGSTOP << 8) | 0177; } else if (why == PR_JOBCONTROL) { statval = (what << 8) | 0177; } else if (why == PR_FAULTED) { switch (what) { case FLTPRIV: case FLTILL: statval = (SIGILL << 8) | 0177; break; case FLTBPT: case FLTTRACE: statval = (SIGTRAP << 8) | 0177; break; case FLTSTACK: case FLTACCESS: case FLTBOUNDS: statval = (SIGSEGV << 8) | 0177; break; case FLTIOVF: case FLTIZDIV: case FLTFPE: statval = (SIGFPE << 8) | 0177; break; case FLTPAGE: /* Recoverable page fault */ default: rtnval = -1; error ("PIOCWSTOP, unknown why %d, what %d", why, what); /* NOTREACHED */ } } else { rtnval = -1; error ("PIOCWSTOP, unknown why %d, what %d", why, what); /* NOTREACHED */ } } else { error ("PIOCWSTOP, stopped for unknown/unhandled reason, flags %#x", pi.prstatus.pr_flags); /* NOTREACHED */ } if (statloc) { *statloc = statval; } return (rtnval); } /* GLOBAL FUNCTION child_resume -- resume execution of the inferior process SYNOPSIS void child_resume (int step, int signal) DESCRIPTION Resume execution of the inferior process. If STEP is nozero, then just single step it. If SIGNAL is nonzero, restart it with that signal activated. NOTE It may not be absolutely necessary to specify the PC value for restarting, but to be safe we use the value that gdb considers to be current. One case where this might be necessary is if the user explicitly changes the PC value that gdb considers to be current. FIXME: Investigate if this is necessary or not. */ void DEFUN(child_resume, (step, signal), int step AND int signal) { errno = 0; pi.prrun.pr_flags = PRSVADDR | PRSTRACE | PRSFAULT | PRCFAULT; pi.prrun.pr_vaddr = (caddr_t) *(int *) ®isters[REGISTER_BYTE (PC_REGNUM)]; if (signal) { if (signal != pi.prstatus.pr_cursig) { struct siginfo siginfo; siginfo.si_signo = signal; siginfo.si_code = 0; siginfo.si_errno = 0; (void) ioctl (pi.fd, PIOCSSIG, &siginfo); } } else { pi.prrun.pr_flags |= PRCSIG; } if (step) { pi.prrun.pr_flags |= PRSTEP; } if (ioctl (pi.fd, PIOCRUN, &pi.prrun) != 0) { perror_with_name (pi.pathname); /* NOTREACHED */ } } /* GLOBAL FUNCTION fetch_inferior_registers -- fetch current registers from inferior SYNOPSIS void fetch_inferior_registers (void) DESCRIPTION Read the current values of the inferior's registers, both the general register set and floating point registers (if supported) and update gdb's idea of their current values. */ void DEFUN_VOID(fetch_inferior_registers) { if (ioctl (pi.fd, PIOCGREG, &pi.gregset) != -1) { supply_gregset (&pi.gregset); } #if defined (FP0_REGNUM) if (ioctl (pi.fd, PIOCGFPREG, &pi.fpregset) != -1) { supply_fpregset (&pi.fpregset); } #endif } #endif /* ATTACH_DETACH */ /* LOCAL FUNCTION proc_init_failed - called whenever /proc access initialization fails SYNOPSIS static void proc_init_failed (char *why) DESCRIPTION This function is called whenever initialization of access to a /proc entry fails. It prints a suitable error message, does some cleanup, and then invokes the standard error processing routine which dumps us back into the command loop. */ static void DEFUN(proc_init_failed, (why), char *why) { print_sys_errmsg (pi.pathname, errno); (void) kill (pi.pid, SIGKILL); close_proc_file (); error (why); /* NOTREACHED */ } /* LOCAL FUNCTION close_proc_file - close any currently open /proc entry SYNOPSIS static void close_proc_file (void) DESCRIPTION Close any currently open /proc entry and mark the process information entry as invalid. In order to ensure that we don't try to reuse any stale information, the pid, fd, and pathnames are explicitly invalidated, which may be overkill. */ static void DEFUN_VOID(close_proc_file) { pi.pid = 0; if (pi.valid) { (void) close (pi.fd); } pi.fd = -1; if (pi.pathname) { free (pi.pathname); pi.pathname = NULL; } pi.valid = 0; } /* LOCAL FUNCTION open_proc_file - open a /proc entry for a given process id SYNOPSIS static int open_proc_file (pid) DESCRIPTION Given a process id, close the existing open /proc entry (if any) and open one for the new process id. Once it is open, then mark the local process information structure as valid, which guarantees that the pid, fd, and pathname fields match an open /proc entry. Returns zero if the open fails, nonzero otherwise. Note that the pathname is left intact, even when the open fails, so that callers can use it to construct meaningful error messages rather than just "file open failed". */ static int DEFUN(open_proc_file, (pid), int pid) { pi.valid = 0; if (pi.valid) { (void) close (pi.fd); } if (pi.pathname == NULL) { pi.pathname = xmalloc (32); } sprintf (pi.pathname, PROC_NAME_FMT, pid); if ((pi.fd = open (pi.pathname, O_RDWR)) >= 0) { pi.valid = 1; pi.pid = pid; } return (pi.valid); } #endif /* USE_PROC_FS */