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[PATCH] New Linux threads support
- To: gdb-patches at sourceware dot cygnus dot com
- Subject: [PATCH] New Linux threads support
- From: Mark Kettenis <kettenis at wins dot uva dot nl>
- Date: Sun, 3 Sep 2000 20:57:40 +0200
OK, here is the new Linux threads stuff I've been taling about. There
are basically three new files:
* proc-service.c: Implementation of the Solaris <proc_service.h>
interfaces that is also used by the Linux libthread_db. I moved
this to its own module since it isn't really thread-specific, the
same interface is used for the Solaris librtld_db. With a little
more effort this module could replace parts of sol-thread.c. It
contains one Linux-specific function.
* thread-db.c: The generic threads layer. Again this code should be
usable for Solaris, and can replace even more stuff in
sol-thread.c. There are a few Linux-specific hooks.
* lin-lwp.c: The Linux LWP layer. Takes a bunch of Linux processes
and presents them to GDB as LWP's similar to the various
SVR4-derived systems have. This is the hairy bit, and contains a
fair amount of debugging code that is still enabled. It can serve
as the basis for support for other threads libraries, and could
even be useful on its own. However it needs to be integrated
better for that purpose. Perhaps we need an additional LWP stratum
in the target vector for that.
There are no regressions on i586-pc-linux-gnu, and it shouldn't affect
the other Linux targets yet (those still use the old code).
I hope that checking this code in will make sure that it gets tested.
I will send a notice to the people who've complained about the current
threads code. If it has been proven to work reliably on Linux/x86, we
can convert the other Linux targets.
Mark
2000-09-03 Mark Kettenis <kettenis@gnu.org>
* config/i386/nm-linux.h (PREPARE_TO_PROCEED, ATTCH_LWP,
GET_THREAD_SIGNALS): New defines.
* config/i386/linux.mh (NATDEPFILES): Remove lin-thread.o and
linux-threads.o. Add proc-service.o, thread-db.o and lin-lwp.o.
* proc-service.c: New file.
* thread-db.c: New file.
* lin-lwp.c: New file.
Index: config/i386/nm-linux.h
===================================================================
RCS file: /cvs/src/src/gdb/config/i386/nm-linux.h,v
retrieving revision 1.4
diff -u -p -r1.4 nm-linux.h
--- config/i386/nm-linux.h 2000/05/28 01:12:35 1.4
+++ config/i386/nm-linux.h 2000/09/03 18:36:56
@@ -1,5 +1,5 @@
-/* Native support for GNU/Linux, for GDB, the GNU debugger.
- Copyright (C) 1986, 1987, 1989, 1992, 1996, 1998, 2000
+/* Native support for Linux/x86.
+ Copyright 1986, 1987, 1989, 1992, 1996, 1998, 2000
Free Software Foundation, Inc.
This file is part of GDB.
@@ -79,4 +79,18 @@ extern CORE_ADDR i386_stopped_by_watchpo
extern int i386_insert_watchpoint (int pid, CORE_ADDR addr, int len, int rw);
extern int i386_remove_watchpoint (int pid, CORE_ADDR addr, int len);
-#endif /* #ifndef NM_LINUX_H */
+/* FIXME: kettenis/2000-09-03: This should be moved to ../nm-linux.h
+ once we have converted all Linux targets to use the new threads
+ stuff (without the #undef of course). */
+
+extern int lin_lwp_prepare_to_proceed (void);
+#undef PREPARE_TO_PROCEED
+#define PREPARE_TO_PROCEED(select_it) lin_lwp_prepare_to_proceed ()
+
+extern void lin_lwp_attach_lwp (int pid, int verbose);
+#define ATTACH_LWP(pid, verbose) lin_lwp_attach_lwp ((pid), (verbose))
+
+extern void lin_thread_get_thread_signals (sigset_t *mask);
+#define GET_THREAD_SIGNALS(mask) lin_thread_get_thread_signals (mask)
+
+#endif /* nm_linux.h */
Index: config/i386/linux.mh
===================================================================
RCS file: /cvs/src/src/gdb/config/i386/linux.mh,v
retrieving revision 1.3
diff -u -p -r1.3 linux.mh
--- config/i386/linux.mh 2000/08/10 17:04:33 1.3
+++ config/i386/linux.mh 2000/09/03 18:36:56
@@ -5,7 +5,7 @@ XDEPFILES=
NAT_FILE= nm-linux.h
NATDEPFILES= infptrace.o solib.o inftarg.o fork-child.o corelow.o \
- core-aout.o i386v-nat.o i386-linux-nat.o linux-thread.o lin-thread.o \
- i387-nat.o
+ core-aout.o i386v-nat.o i386-linux-nat.o i387-nat.o \
+ proc-service.o thread-db.o lin-lwp.o
LOADLIBES = -ldl -rdynamic
--- /dev/null Thu Feb 19 16:30:24 1998
+++ proc-service.c Sun Sep 3 17:29:25 2000
@@ -0,0 +1,333 @@
+/* <proc_service.h> implementation.
+ Copyright 1999, 2000 Free Software Foundation, Inc.
+
+ 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., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+#include "defs.h"
+
+#include "gdb_proc_service.h"
+#include <sys/procfs.h>
+
+#include "inferior.h"
+#include "symtab.h"
+#include "target.h"
+
+/* Prototypes for supply_gregset etc. */
+#include "gregset.h"
+
+
+/* Fix-up some broken systems. */
+
+/* The prototypes in <proc_service.h> are slightly different on older
+ systems. Compensate for the discrepancies. */
+
+#ifdef PROC_SERVICE_IS_OLD
+typedef const struct ps_prochandle *gdb_ps_prochandle_t;
+typedef char *gdb_ps_read_buf_t;
+typedef char *gdb_ps_write_buf_t;
+typedef int gdb_ps_size_t;
+#else
+typedef struct ps_prochandle *gdb_ps_prochandle_t;
+typedef void *gdb_ps_read_buf_t;
+typedef const void *gdb_ps_write_buf_t;
+typedef size_t gdb_ps_size_t;
+#endif
+
+
+/* Building process ids. */
+
+#ifndef MERGEPID
+#define MERGEPID(PID, TID) (((PID) & 0xffff) | ((TID) << 16))
+#endif
+
+#define BUILD_LWP(tid, pid) MERGEPID (pid, tid)
+
+
+/* Helper functions. */
+
+static void
+restore_inferior_pid (void *arg)
+{
+ int *saved_pid_ptr = arg;
+ inferior_pid = *saved_pid_ptr;
+ free (arg);
+}
+
+static struct cleanup *
+save_inferior_pid (void)
+{
+ int *saved_pid_ptr;
+
+ saved_pid_ptr = xmalloc (sizeof (int));
+ *saved_pid_ptr = inferior_pid;
+ return make_cleanup (restore_inferior_pid, saved_pid_ptr);
+}
+
+/* Transfer LEN bytes of memory between BUF and address ADDR in the
+ process specified by PH. If WRITE, transfer them to the process,
+ else transfer them from the process. Returns PS_OK for success,
+ PS_ERR on failure.
+
+ This is a helper function for ps_pdread, ps_pdwrite, ps_ptread and
+ ps_ptwrite. */
+
+static ps_err_e
+ps_xfer_memory (const struct ps_prochandle *ph, paddr_t addr,
+ char *buf, size_t len, int write)
+{
+ struct cleanup *old_chain = save_inferior_pid ();
+ int ret;
+
+ inferior_pid = ph->pid;
+
+ if (write)
+ ret = target_write_memory (addr, buf, len);
+ else
+ ret = target_read_memory (addr, buf, len);
+
+ do_cleanups (old_chain);
+
+ return (ret == 0 ? PS_OK : PS_ERR);
+}
+
+
+/* Stop the target process PH. */
+
+ps_err_e
+ps_pstop (gdb_ps_prochandle_t ph)
+{
+ /* The process is always stopped when under control of GDB. */
+ return PS_OK;
+}
+
+/* Resume the target process PH. */
+
+ps_err_e
+ps_pcontinue (gdb_ps_prochandle_t ph)
+{
+ /* Pretend we did successfully continue the process. GDB will take
+ care of it later on. */
+ return PS_OK;
+}
+
+/* Stop the lightweight process LWPID within the target process PH. */
+
+ps_err_e
+ps_lstop (gdb_ps_prochandle_t ph, lwpid_t lwpid)
+{
+ /* All lightweight processes are stopped when under control of GDB. */
+ return PS_OK;
+}
+
+/* Resume the lightweight process (LWP) LWPID within the target
+ process PH. */
+
+ps_err_e
+ps_lcontinue (gdb_ps_prochandle_t ph, lwpid_t lwpid)
+{
+ /* Pretend we did successfully continue LWPID. GDB will take care
+ of it later on. */
+ return PS_OK;
+}
+
+/* Get the size of the architecture-dependent extra state registers
+ for LWP LWPID within the target process PH and return it in
+ *XREGSIZE. */
+
+ps_err_e
+ps_lgetxregsize (gdb_ps_prochandle_t ph, lwpid_t lwpid, int *xregsize)
+{
+ /* FIXME: Not supported yet. */
+ return PS_OK;
+}
+
+/* Get the extra state registers of LWP LWPID within the target
+ process PH and store them in XREGSET. */
+
+ps_err_e
+ps_lgetxregs (gdb_ps_prochandle_t ph, lwpid_t lwpid, caddr_t xregset)
+{
+ /* FIXME: Not supported yet. */
+ return PS_OK;
+}
+
+/* Set the extra state registers of LWP LWPID within the target
+ process PH from XREGSET. */
+
+ps_err_e
+ps_lsetxregs (gdb_ps_prochandle_t ph, lwpid_t lwpid, caddr_t xregset)
+{
+ /* FIXME: Not supported yet. */
+ return PS_OK;
+}
+
+/* Log (additional) diognostic information. */
+
+void
+ps_plog (const char *fmt, ...)
+{
+ va_list args;
+
+ va_start (args, fmt);
+ vfprintf_filtered (gdb_stderr, fmt, args);
+}
+
+/* Search for the symbol named NAME within the object named OBJ within
+ the target process PH. If the symbol is found the address of the
+ symbol is stored in SYM_ADDR. */
+
+ps_err_e
+ps_pglobal_lookup (gdb_ps_prochandle_t ph, const char *obj,
+ const char *name, paddr_t *sym_addr)
+{
+ struct minimal_symbol *ms;
+
+ /* FIXME: kettenis/2000-09-03: What should we do with OBJ? */
+ ms = lookup_minimal_symbol (name, NULL, NULL);
+ if (ms == NULL)
+ return PS_NOSYM;
+
+ *sym_addr = SYMBOL_VALUE_ADDRESS (ms);
+ return PS_OK;
+}
+
+/* Read SIZE bytes from the target process PH at address ADDR and copy
+ them into BUF. */
+
+ps_err_e
+ps_pdread (gdb_ps_prochandle_t ph, paddr_t addr,
+ gdb_ps_read_buf_t buf, gdb_ps_size_t size)
+{
+ return ps_xfer_memory (ph, addr, buf, size, 0);
+}
+
+/* Write SIZE bytes from BUF into the target process PH at address ADDR. */
+
+ps_err_e
+ps_pdwrite (gdb_ps_prochandle_t ph, paddr_t addr,
+ gdb_ps_write_buf_t buf, gdb_ps_size_t size)
+{
+ return ps_xfer_memory (ph, addr, (char *) buf, size, 1);
+}
+
+/* Read SIZE bytes from the target process PH at address ADDR and copy
+ them into BUF. */
+
+ps_err_e
+ps_ptread (gdb_ps_prochandle_t ph, paddr_t addr,
+ gdb_ps_read_buf_t buf, gdb_ps_size_t size)
+{
+ return ps_xfer_memory (ph, addr, buf, size, 0);
+}
+
+/* Write SIZE bytes from BUF into the target process PH at address ADDR. */
+
+ps_err_e
+ps_ptwrite (gdb_ps_prochandle_t ph, paddr_t addr,
+ gdb_ps_write_buf_t buf, gdb_ps_size_t size)
+{
+ return ps_xfer_memory (ph, addr, (char *) buf, size, 1);
+}
+
+/* Get the general registers of LWP LWPID within the target process PH
+ and store them in GREGSET. */
+
+ps_err_e
+ps_lgetregs (gdb_ps_prochandle_t ph, lwpid_t lwpid, prgregset_t gregset)
+{
+ struct cleanup *old_chain = save_inferior_pid ();
+
+ inferior_pid = BUILD_LWP (lwpid, ph->pid);
+
+ target_fetch_registers (-1);
+ fill_gregset ((gdb_gregset_t *) gregset, -1);
+
+ do_cleanups (old_chain);
+ return PS_OK;
+}
+
+/* Set the general registers of LWP LWPID within the target process PH
+ from GREGSET. */
+
+ps_err_e
+ps_lsetregs (gdb_ps_prochandle_t ph, lwpid_t lwpid, const prgregset_t gregset)
+{
+ struct cleanup *old_chain = save_inferior_pid ();
+
+ inferior_pid = BUILD_LWP (lwpid, ph->pid);
+
+ /* FIXME: We should really make supply_gregset const-correct. */
+ supply_gregset ((gdb_gregset_t *) gregset);
+ target_store_registers (-1);
+
+ do_cleanups (old_chain);
+ return PS_OK;
+}
+
+/* Get the floating-point registers of LWP LWPID within the target
+ process PH and store them in FPREGSET. */
+
+ps_err_e
+ps_lgetfpregs (gdb_ps_prochandle_t ph, lwpid_t lwpid,
+ gdb_prfpregset_t *fpregset)
+{
+ struct cleanup *old_chain = save_inferior_pid ();
+
+ inferior_pid = BUILD_LWP (lwpid, ph->pid);
+
+ target_fetch_registers (-1);
+ fill_fpregset ((gdb_fpregset_t *) fpregset, -1);
+
+ do_cleanups (old_chain);
+ return PS_OK;
+}
+
+/* Set the floating-point registers of LWP LWPID within the target
+ process PH from FPREGSET. */
+
+ps_err_e
+ps_lsetfpregs (gdb_ps_prochandle_t ph, lwpid_t lwpid,
+ const gdb_prfpregset_t *fpregset)
+{
+ struct cleanup *old_chain = save_inferior_pid ();
+
+ inferior_pid = BUILD_LWP (lwpid, ph->pid);
+
+ /* FIXME: We should really make supply_fpregset const-correct. */
+ supply_fpregset ((gdb_fpregset_t *) fpregset);
+ target_store_registers (-1);
+
+ do_cleanups (old_chain);
+ return PS_OK;
+}
+
+/* Return overall process id of the target PH.
+ Special for Linux -- not used on Solaris. */
+
+pid_t
+ps_getpid (gdb_ps_prochandle_t ph)
+{
+ return ph->pid;
+}
+
+void
+_initialize_proc_service (void)
+{
+ /* This function solely exists to make sure this module is linked
+ into the final binary. */
+}
--- /dev/null Thu Feb 19 16:30:24 1998
+++ thread-db.c Sun Sep 3 17:27:16 2000
@@ -0,0 +1,992 @@
+/* libthread_db assisted debugging support, generic parts.
+ Copyright 1999, 2000 Free Software Foundation, Inc.
+
+ 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., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+#include "defs.h"
+
+#include "gdb_assert.h"
+#include <dlfcn.h>
+#include "gdb_proc_service.h"
+#include "gdb_thread_db.h"
+
+#include "gdbthread.h"
+#include "inferior.h"
+#include "target.h"
+
+#ifndef LIBTHREAD_DB_SO
+#define LIBTHREAD_DB_SO "libthread_db.so.1"
+#endif
+
+/* If we're running on Linux, we must explicitly attach to any new threads. */
+
+/* FIXME: There is certainly some room for improvements:
+ - Cache LWP ids.
+ - Bypass libthread_db when fetching or storing registers for
+ threads bound to a LWP. */
+
+/* This module's target vector. */
+static struct target_ops thread_db_ops;
+
+/* The target vector that we call for things this module can't handle. */
+static struct target_ops *target_beneath;
+
+/* Pointer to the next function on the objfile event chain. */
+static void (*target_new_objfile_chain) (struct objfile *objfile);
+
+/* Non-zero if we're using this module's target vector. */
+static int using_thread_db;
+
+/* Non-zero if we have determined the signals used by the threads
+ library. */
+static int thread_signals;
+static sigset_t thread_stop_set;
+static sigset_t thread_print_set;
+
+/* Structure that identifies the child process for the
+ <proc_service.h> interface. */
+static struct ps_prochandle proc_handle;
+
+/* Connection to the libthread_db library. */
+static td_thragent_t *thread_agent;
+
+/* Pointers to the libthread_db functions. */
+
+static td_err_e (*td_init_p) (void);
+
+static td_err_e (*td_ta_new_p) (struct ps_prochandle *ps, td_thragent_t **ta);
+static td_err_e (*td_ta_map_id2thr_p) (const td_thragent_t *ta, thread_t pt,
+ td_thrhandle_t *__th);
+static td_err_e (*td_ta_map_lwp2thr_p) (const td_thragent_t *ta, lwpid_t lwpid,
+ td_thrhandle_t *th);
+static td_err_e (*td_ta_thr_iter_p) (const td_thragent_t *ta,
+ td_thr_iter_f *callback,
+ void *cbdata_p, td_thr_state_e state,
+ int ti_pri, sigset_t *ti_sigmask_p,
+ unsigned int ti_user_flags);
+static td_err_e (*td_ta_event_addr_p) (const td_thragent_t *ta,
+ td_event_e event, td_notify_t *ptr);
+static td_err_e (*td_ta_set_event_p) (const td_thragent_t *ta,
+ td_thr_events_t *event);
+static td_err_e (*td_ta_event_getmsg_p) (const td_thragent_t *ta,
+ td_event_msg_t *msg);
+
+static td_err_e (*td_thr_validate_p) (const td_thrhandle_t *th);
+static td_err_e (*td_thr_get_info_p) (const td_thrhandle_t *th,
+ td_thrinfo_t *infop);
+static td_err_e (*td_thr_getfpregs_p) (const td_thrhandle_t *th,
+ gdb_prfpregset_t *regset);
+static td_err_e (*td_thr_getgregs_p) (const td_thrhandle_t *th,
+ prgregset_t gregs);
+static td_err_e (*td_thr_setfpregs_p) (const td_thrhandle_t *th,
+ const gdb_prfpregset_t *fpregs);
+static td_err_e (*td_thr_setgregs_p) (const td_thrhandle_t *th,
+ prgregset_t gregs);
+static td_err_e (*td_thr_event_enable_p) (const td_thrhandle_t *th, int event);
+
+/* Location of the thread creation event breakpoint. The code at this
+ location in the child process will be called by the pthread library
+ whenever a new thread is created. By setting a special breakpoint
+ at this location, GDB can detect when a new thread is created. We
+ obtain this location via the td_ta_event_addr call. */
+static CORE_ADDR td_create_bp_addr;
+
+/* Location of the thread death event breakpoint. */
+static CORE_ADDR td_death_bp_addr;
+
+/* Prototypes for local functions. */
+static int find_new_threads_callback (const td_thrhandle_t *th_p, void *data);
+
+
+/* Building process ids. */
+
+#ifndef TIDGET
+#define TIDGET(PID) (((PID) & 0x7fffffff) >> 16)
+#define PIDGET(PID) (((PID) & 0xffff))
+#define MERGEPID(PID, TID) (((PID) & 0xffff) | ((TID) << 16))
+#endif
+
+#define THREAD_FLAG 0x80000000
+
+#define is_lwp(pid) (((pid) & THREAD_FLAG) == 0 && TIDGET (pid))
+#define is_thread(pid) ((pid) & THREAD_FLAG)
+
+#define GET_PID(pid) PIDGET (pid)
+#define GET_LWP(pid) TIDGET (pid)
+#define GET_THREAD(pid) TIDGET (pid)
+
+#define BUILD_LWP(tid, pid) MERGEPID (pid, tid)
+#define BUILD_THREAD(tid, pid) (MERGEPID (pid, tid) | THREAD_FLAG)
+
+
+struct private_thread_info
+{
+ /* Cached LWP id. Must come first, see lin-lwp.c. */
+ lwpid_t lwpid;
+};
+
+
+/* Helper functions. */
+
+static void
+restore_inferior_pid (void *arg)
+{
+ int *saved_pid_ptr = arg;
+ inferior_pid = *saved_pid_ptr;
+ free (arg);
+}
+
+static struct cleanup *
+save_inferior_pid (void)
+{
+ int *saved_pid_ptr;
+
+ saved_pid_ptr = xmalloc (sizeof (int));
+ *saved_pid_ptr = inferior_pid;
+ return make_cleanup (restore_inferior_pid, saved_pid_ptr);
+}
+
+
+static char *
+thread_db_err_str (td_err_e err)
+{
+ static char buf[64];
+
+ switch (err)
+ {
+ case TD_OK:
+ return "generic 'call succeeded'";
+ case TD_ERR:
+ return "generic error";
+ case TD_NOTHR:
+ return "no thread to satisfy query";
+ case TD_NOSV:
+ return "no sync handle to satisfy query";
+ case TD_NOLWP:
+ return "no LWP to satisfy query";
+ case TD_BADPH:
+ return "invalid process handle";
+ case TD_BADTH:
+ return "invalid thread handle";
+ case TD_BADSH:
+ return "invalid synchronization handle";
+ case TD_BADTA:
+ return "invalid thread agent";
+ case TD_BADKEY:
+ return "invalid key";
+ case TD_NOMSG:
+ return "no event message for getmsg";
+ case TD_NOFPREGS:
+ return "FPU register set not available";
+ case TD_NOLIBTHREAD:
+ return "application not linked with libthread";
+ case TD_NOEVENT:
+ return "requested event is not supported";
+ case TD_NOCAPAB:
+ return "capability not available";
+ case TD_DBERR:
+ return "debugger service failed";
+ case TD_NOAPLIC:
+ return "operation not applicable to";
+ case TD_NOTSD:
+ return "no thread-specific data for this thread";
+ case TD_MALLOC:
+ return "malloc failed";
+ case TD_PARTIALREG:
+ return "only part of register set was written/read";
+ case TD_NOXREGS:
+ return "X register set not available for this thread";
+ default:
+ snprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err);
+ return buf;
+ }
+}
+
+static char *
+thread_db_state_str (td_thr_state_e state)
+{
+ static char buf[64];
+
+ switch (state)
+ {
+ case TD_THR_STOPPED:
+ return "stopped by debugger";
+ case TD_THR_RUN:
+ return "runnable";
+ case TD_THR_ACTIVE:
+ return "active";
+ case TD_THR_ZOMBIE:
+ return "zombie";
+ case TD_THR_SLEEP:
+ return "sleeping";
+ case TD_THR_STOPPED_ASLEEP:
+ return "stopped by debugger AND blocked";
+ default:
+ snprintf (buf, sizeof (buf), "unknown thread_db state %d", state);
+ return buf;
+ }
+}
+
+
+/* Convert between user-level thread ids and LWP ids. */
+
+static int
+thread_from_lwp (int pid)
+{
+ td_thrinfo_t ti;
+ td_thrhandle_t th;
+ td_err_e err;
+
+ if (GET_LWP (pid) == 0)
+ pid = BUILD_LWP (pid, pid);
+
+ gdb_assert (is_lwp (pid));
+
+ err = td_ta_map_lwp2thr_p (thread_agent, GET_LWP (pid), &th);
+ if (err != TD_OK)
+ error ("Cannot find user-level thread for LWP %d: %s",
+ GET_LWP (pid), thread_db_err_str (err));
+
+ err = td_thr_get_info_p (&th, &ti);
+ if (err != TD_OK)
+ error ("Cannot get thread info: %s", thread_db_err_str (err));
+
+ return BUILD_THREAD (ti.ti_tid, GET_PID (pid));
+}
+
+static int
+lwp_from_thread (int pid)
+{
+ td_thrinfo_t ti;
+ td_thrhandle_t th;
+ td_err_e err;
+
+ if (! is_thread (pid))
+ return pid;
+
+ err = td_ta_map_id2thr_p (thread_agent, GET_THREAD (pid), &th);
+ if (err != TD_OK)
+ error ("Cannot find thread %ld: %s",
+ (long) GET_THREAD (pid), thread_db_err_str (err));
+
+ err = td_thr_get_info_p (&th, &ti);
+ if (err != TD_OK)
+ error ("Cannot get thread info: %s", thread_db_err_str (err));
+
+ return BUILD_LWP (ti.ti_lid, GET_PID (pid));
+}
+
+
+void
+thread_db_init (struct target_ops *target)
+{
+ target_beneath = target;
+}
+
+static int
+thread_db_load (void)
+{
+ void *handle;
+ td_err_e err;
+
+ handle = dlopen (LIBTHREAD_DB_SO, RTLD_NOW);
+ if (handle == NULL)
+ return 0;
+
+ /* Initialize pointers to the dynamic library functions we will use.
+ Essential functions first. */
+
+ td_init_p = dlsym (handle, "td_init");
+ if (td_init_p == NULL)
+ return 0;
+
+ td_ta_new_p = dlsym (handle, "td_ta_new");
+ if (td_ta_new_p == NULL)
+ return 0;
+
+ td_ta_map_id2thr_p = dlsym (handle, "td_ta_map_id2thr");
+ if (td_ta_map_id2thr_p == NULL)
+ return 0;
+
+ td_ta_map_lwp2thr_p = dlsym (handle, "td_ta_map_lwp2thr");
+ if (td_ta_map_lwp2thr_p == NULL)
+ return 0;
+
+ td_ta_thr_iter_p = dlsym (handle, "td_ta_thr_iter");
+ if (td_ta_thr_iter_p == NULL)
+ return 0;
+
+ td_thr_validate_p = dlsym (handle, "td_thr_validate");
+ if (td_thr_validate_p == NULL)
+ return 0;
+
+ td_thr_get_info_p = dlsym (handle, "td_thr_get_info");
+ if (td_thr_get_info_p == NULL)
+ return 0;
+
+ td_thr_getfpregs_p = dlsym (handle, "td_thr_getfpregs");
+ if (td_thr_getfpregs_p == NULL)
+ return 0;
+
+ td_thr_getgregs_p = dlsym (handle, "td_thr_getgregs");
+ if (td_thr_getgregs_p == NULL)
+ return 0;
+
+ td_thr_setfpregs_p = dlsym (handle, "td_thr_setfpregs");
+ if (td_thr_setfpregs_p == NULL)
+ return 0;
+
+ td_thr_setgregs_p = dlsym (handle, "td_thr_setgregs");
+ if (td_thr_setgregs_p == NULL)
+ return 0;
+
+ /* Initialize the library. */
+ err = td_init_p ();
+ if (err != TD_OK)
+ {
+ warning ("Cannot initialize libthread_db: %s", thread_db_err_str (err));
+ return 0;
+ }
+
+ /* These are not essential. */
+ td_ta_event_addr_p = dlsym (handle, "td_ta_event_addr");
+ td_ta_set_event_p = dlsym (handle, "td_ta_set_event");
+ td_ta_event_getmsg_p = dlsym (handle, "td_ta_event_getmsg");
+ td_thr_event_enable_p = dlsym (handle, "td_thr_event_enable");
+
+ return 1;
+}
+
+static void
+enable_thread_event_reporting (void)
+{
+ td_thr_events_t events;
+ td_notify_t notify;
+ td_err_e err;
+
+ /* We cannot use the thread event reporting facility if these
+ functions aren't available. */
+ if (td_ta_event_addr_p == NULL || td_ta_set_event_p == NULL
+ || td_ta_event_getmsg_p == NULL || td_thr_event_enable_p == NULL)
+ return;
+
+ /* Set the process wide mask saying which events we're interested in. */
+ td_event_emptyset (&events);
+ td_event_addset (&events, TD_CREATE);
+#if 0
+ /* FIXME: kettenis/2000-04-23: The event reporting facility is
+ broken for TD_DEATH events in glibc 2.1.3, so don't enable it for
+ now. */
+ td_event_addset (&events, TD_DEATH);
+#endif
+
+ err = td_ta_set_event_p (thread_agent, &events);
+ if (err != TD_OK)
+ {
+ warning ("Unable to set global thread event mask: %s",
+ thread_db_err_str (err));
+ return;
+ }
+
+ /* Delete previous thread event breakpoints, if any. */
+ remove_thread_event_breakpoints ();
+
+ /* Get address for thread creation breakpoint. */
+ err = td_ta_event_addr_p (thread_agent, TD_CREATE, ¬ify);
+ if (err != TD_OK)
+ {
+ warning ("Unable to get location for thread creation breakpoint: %s",
+ thread_db_err_str (err));
+ return;
+ }
+
+ /* Set up the breakpoint. */
+ td_create_bp_addr = (CORE_ADDR) notify.u.bptaddr;
+ create_thread_event_breakpoint (td_create_bp_addr);
+
+ /* Get address for thread death breakpoint. */
+ err = td_ta_event_addr_p (thread_agent, TD_DEATH, ¬ify);
+ if (err != TD_OK)
+ {
+ warning ("Unable to get location for thread creation breakpoint: %s",
+ thread_db_err_str (err));
+ return;
+ }
+
+ /* Set up the breakpoint. */
+ td_death_bp_addr = (CORE_ADDR) notify.u.bptaddr;
+ create_thread_event_breakpoint (td_death_bp_addr);
+}
+
+static void
+disable_thread_event_reporting (void)
+{
+ td_thr_events_t events;
+
+ /* Set the process wide mask saying we aren't interested in any
+ events anymore. */
+ td_event_emptyset (&events);
+ td_ta_set_event_p (thread_agent, &events);
+
+ /* Delete thread event breakpoints, if any. */
+ remove_thread_event_breakpoints ();
+ td_create_bp_addr = 0;
+ td_death_bp_addr = 0;
+}
+
+static void
+check_thread_signals (void)
+{
+#ifdef GET_THREAD_SIGNALS
+ if (! thread_signals)
+ {
+ sigset_t mask;
+ int i;
+
+ GET_THREAD_SIGNALS (&mask);
+ sigemptyset (&thread_stop_set);
+ sigemptyset (&thread_print_set);
+
+ for (i = 0; i < NSIG; i++)
+ {
+ if (sigismember (&mask, i))
+ {
+ if (signal_stop_update (target_signal_from_host (i), 0))
+ sigaddset (&thread_stop_set, i);
+ if (signal_print_update (target_signal_from_host (i), 0))
+ sigaddset (&thread_print_set, i);
+ thread_signals = 1;
+ }
+ }
+ }
+#endif
+}
+
+static void
+disable_thread_signals (void)
+{
+#ifdef GET_THREAD_SIGNALS
+ if (thread_signals)
+ {
+ int i;
+
+ for (i = 0; i < NSIG; i++)
+ {
+ if (sigismember (&thread_stop_set, i))
+ signal_stop_update (target_signal_from_host (i), 1);
+ if (sigismember (&thread_print_set, i))
+ signal_print_update (target_signal_from_host (i), 1);
+ }
+
+ thread_signals = 0;
+ }
+#endif
+}
+
+static void
+thread_db_push_target (void)
+{
+ using_thread_db = 1;
+
+ /* Push this target vector. */
+ push_target (&thread_db_ops);
+
+ enable_thread_event_reporting ();
+}
+
+static void
+thread_db_unpush_target (void)
+{
+ /* Unpush this target vector. */
+ unpush_target (&thread_db_ops);
+
+ using_thread_db = 0;
+}
+
+static void
+thread_db_new_objfile (struct objfile *objfile)
+{
+ td_err_e err;
+
+ if (using_thread_db)
+ /* Nothing to do. The thread library was already detected and the
+ target vector was already activated. */
+ goto quit;
+
+ if (objfile == NULL)
+ /* Un-interesting object file. */
+ goto quit;
+
+ /* Initialize the structure that identifies the child process. */
+ proc_handle.pid = GET_PID (inferior_pid);
+
+ /* Now attempt to open a connection to the thread library running in
+ the child process. */
+ err = td_ta_new_p (&proc_handle, &thread_agent);
+ switch (err)
+ {
+ case TD_NOLIBTHREAD:
+ /* No thread library found in the child process, probably
+ because the child process isn't running yet. */
+ break;
+
+ case TD_OK:
+ /* The thread library was detected in the child; we go live now! */
+ thread_db_push_target ();
+
+ /* Find all user-space threads. */
+ err = td_ta_thr_iter_p (thread_agent, find_new_threads_callback,
+ &inferior_pid, TD_THR_ANY_STATE,
+ TD_THR_LOWEST_PRIORITY, TD_SIGNO_MASK,
+ TD_THR_ANY_USER_FLAGS);
+ if (err != TD_OK)
+ error ("Finding new threads failed: %s", thread_db_err_str (err));
+ break;
+
+ default:
+ warning ("Cannot initialize thread debugging library: %s",
+ thread_db_err_str (err));
+ break;
+ }
+
+ quit:
+ if (target_new_objfile_chain)
+ target_new_objfile_chain (objfile);
+}
+
+static void
+attach_thread (int pid, const td_thrhandle_t *th_p,
+ const td_thrinfo_t *ti_p, int verbose)
+{
+ struct thread_info *tp;
+ td_err_e err;
+
+ check_thread_signals ();
+
+ if (verbose)
+ printf_unfiltered ("[New %s]\n", target_pid_to_str (pid));
+
+ /* Add the thread to GDB's thread list. */
+ tp = add_thread (pid);
+ tp->private = xmalloc (sizeof (struct private_thread_info));
+ tp->private->lwpid = ti_p->ti_lid;
+
+ /* Under Linux, we have to attach to each and every thread. */
+#ifdef ATTACH_LWP
+ if (ti_p->ti_lid != GET_PID (pid))
+ ATTACH_LWP (BUILD_LWP (ti_p->ti_lid, GET_PID (pid)), 0);
+#endif
+
+ /* Enable thread event reporting for this thread. */
+ err = td_thr_event_enable_p (th_p, 1);
+ if (err != TD_OK)
+ error ("Cannot enable thread event reporting for %s: %s",
+ target_pid_to_str (pid), thread_db_err_str (err));
+}
+
+static void
+detach_thread (int pid, int verbose)
+{
+ if (verbose)
+ printf_unfiltered ("[%s exited]\n", target_pid_to_str (pid));
+}
+
+static void
+thread_db_detach (char *args, int from_tty)
+{
+ disable_thread_event_reporting ();
+ thread_db_unpush_target ();
+
+ target_beneath->to_detach (args, from_tty);
+}
+
+static void
+thread_db_resume (int pid, int step, enum target_signal signo)
+{
+ struct cleanup *old_chain = save_inferior_pid ();
+
+ if (pid == -1)
+ inferior_pid = lwp_from_thread (inferior_pid);
+ else if (is_thread (pid))
+ pid = lwp_from_thread (pid);
+
+ target_beneath->to_resume (pid, step, signo);
+
+ do_cleanups (old_chain);
+}
+
+/* Check if PID is currently stopped at the location of a thread event
+ breakpoint location. If it is, read the event message and act upon
+ the event. */
+
+static void
+check_event (int pid)
+{
+ td_event_msg_t msg;
+ td_thrinfo_t ti;
+ td_err_e err;
+ CORE_ADDR stop_pc;
+
+ /* Bail out early if we're not at a thread event breakpoint. */
+ stop_pc = read_pc_pid (pid) - DECR_PC_AFTER_BREAK;
+ if (stop_pc != td_create_bp_addr && stop_pc != td_death_bp_addr)
+ return;
+
+ err = td_ta_event_getmsg_p (thread_agent, &msg);
+ if (err != TD_OK)
+ {
+ if (err == TD_NOMSG)
+ return;
+
+ error ("Cannot get thread event message: %s", thread_db_err_str (err));
+ }
+
+ err = td_thr_get_info_p (msg.th_p, &ti);
+ if (err != TD_OK)
+ error ("Cannot get thread info: %s", thread_db_err_str (err));
+
+ pid = BUILD_THREAD (ti.ti_tid, GET_PID (pid));
+
+ switch (msg.event)
+ {
+ case TD_CREATE:
+#if 0
+ /* FIXME: kettenis/2000-08-26: Since we use td_ta_event_getmsg,
+ there is no guarantee that the breakpoint will match the
+ event. Should we use td_thr_event_getmsg instead? */
+
+ if (stop_pc != td_create_bp_addr)
+ error ("Thread creation event doesn't match breakpoint.");
+#endif
+
+ if (in_thread_list (pid))
+ error ("Spurious thread creation event.");
+
+ attach_thread (pid, msg.th_p, &ti, 1);
+ return;
+
+ case TD_DEATH:
+#if 0
+ /* FIXME: See TD_CREATE. */
+
+ if (stop_pc != td_death_bp_addr)
+ error ("Thread death event doesn't match breakpoint.");
+#endif
+
+ if (! in_thread_list (pid))
+ error ("Spurious thread death event.");
+
+ detach_thread (pid, 1);
+ return;
+
+ default:
+ error ("Spurious thread event.");
+ }
+}
+
+static int
+thread_db_wait (int pid, struct target_waitstatus *ourstatus)
+{
+ extern int trap_pid;
+
+ if (pid != -1 && is_thread (pid))
+ pid = lwp_from_thread (pid);
+
+ pid = target_beneath->to_wait (pid, ourstatus);
+
+ if (ourstatus->kind == TARGET_WAITKIND_EXITED)
+ return -1;
+
+ if (ourstatus->kind == TARGET_WAITKIND_STOPPED
+ && ourstatus->value.sig == TARGET_SIGNAL_TRAP)
+ /* Check for a thread event. */
+ check_event (pid);
+
+ if (trap_pid)
+ trap_pid = thread_from_lwp (trap_pid);
+
+ return thread_from_lwp (pid);
+}
+
+static int
+thread_db_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int write,
+ struct target_ops *target)
+{
+ struct cleanup *old_chain = save_inferior_pid ();
+ int xfer;
+
+ if (is_thread (inferior_pid))
+ {
+ /* FIXME: This seems to be necessary to make sure breakpoints
+ are removed. */
+ if (! target_thread_alive (inferior_pid))
+ inferior_pid = GET_PID (inferior_pid);
+ else
+ inferior_pid = lwp_from_thread (inferior_pid);
+ }
+
+ xfer = target_beneath->to_xfer_memory (memaddr, myaddr, len, write, target);
+
+ do_cleanups (old_chain);
+ return xfer;
+}
+
+static void
+thread_db_fetch_registers (int regno)
+{
+ td_thrhandle_t th;
+ prgregset_t gregset;
+ gdb_prfpregset_t fpregset;
+ td_err_e err;
+
+ if (! is_thread (inferior_pid))
+ {
+ /* Pass the request to the target beneath us. */
+ target_beneath->to_fetch_registers (regno);
+ return;
+ }
+
+ err = td_ta_map_id2thr_p (thread_agent, GET_THREAD (inferior_pid), &th);
+ if (err != TD_OK)
+ error ("Cannot find thread %ld: %s",
+ (long) GET_THREAD (inferior_pid), thread_db_err_str (err));
+
+ err = td_thr_getgregs_p (&th, gregset);
+ if (err != TD_OK)
+ error ("Cannot fetch general-purpose registers for thread %ld: %s",
+ (long) GET_THREAD (inferior_pid), thread_db_err_str (err));
+
+ err = td_thr_getfpregs_p (&th, &fpregset);
+ if (err != TD_OK)
+ error ("Cannot get floating-point registers for thread %ld: %s",
+ (long) GET_THREAD (inferior_pid), thread_db_err_str (err));
+
+ /* Note that we must call supply_gregset after calling the thread_db
+ routines because the thread_db routines call ps_lgetgregs and
+ friends which clobber GDB's register cache. */
+ supply_gregset ((gdb_gregset_t *) gregset);
+ supply_fpregset (&fpregset);
+}
+
+static void
+thread_db_store_registers (int regno)
+{
+ td_thrhandle_t th;
+ prgregset_t gregset;
+ gdb_prfpregset_t fpregset;
+ td_err_e err;
+
+ if (! is_thread (inferior_pid))
+ {
+ /* Pass the request to the target beneath us. */
+ target_beneath->to_store_registers (regno);
+ return;
+ }
+
+ err = td_ta_map_id2thr_p (thread_agent, GET_THREAD (inferior_pid), &th);
+ if (err != TD_OK)
+ error ("Cannot find thread %ld: %s",
+ (long) GET_THREAD (inferior_pid), thread_db_err_str (err));
+
+ if (regno != -1)
+ {
+ char raw[MAX_REGISTER_RAW_SIZE];
+
+ read_register_gen (regno, raw);
+ thread_db_fetch_registers (-1);
+ supply_register (regno, raw);
+ }
+
+ fill_gregset ((gdb_gregset_t *) gregset, -1);
+ fill_fpregset (&fpregset, -1);
+
+ err = td_thr_setgregs_p (&th, gregset);
+ if (err != TD_OK)
+ error ("Cannot store general-purpose registers for thread %ld: %s",
+ (long) GET_THREAD (inferior_pid), thread_db_err_str (err));
+ err = td_thr_setfpregs_p (&th, &fpregset);
+ if (err != TD_OK)
+ error ("Cannot store floating-point registers for thread %ld: %s",
+ (long) GET_THREAD (inferior_pid), thread_db_err_str (err));
+}
+
+static void
+thread_db_kill (void)
+{
+ target_beneath->to_kill ();
+}
+
+static void
+thread_db_create_inferior (char *exec_file, char *allargs, char **env)
+{
+ /* We never want to actually create the inferior! If this is ever
+ called, it means we were on the target stack when the user said
+ "run". But we don't want to be on the new inferior's target
+ stack until the libthread_db connection is ready to be made. So
+ we unpush ourselves from the stack, and then invoke
+ find_default_create_inferior, which will invoke the appropriate
+ process_stratum target to do the create. */
+
+ thread_db_unpush_target ();
+
+ find_default_create_inferior (exec_file, allargs, env);
+}
+
+static void
+thread_db_mourn_inferior (void)
+{
+ remove_thread_event_breakpoints ();
+ thread_db_unpush_target ();
+
+ target_beneath->to_mourn_inferior ();
+}
+
+static int
+thread_db_thread_alive (int pid)
+{
+ if (is_thread (pid))
+ {
+ td_thrhandle_t th;
+ td_err_e err;
+
+ err = td_ta_map_id2thr_p (thread_agent, GET_THREAD (pid), &th);
+ if (err != TD_OK)
+ return 0;
+
+ err = td_thr_validate_p (&th);
+ if (err != TD_OK)
+ return 0;
+
+ return 1;
+ }
+
+ if (target_beneath->to_thread_alive)
+ return target_beneath->to_thread_alive (pid);
+
+ return 0;
+}
+
+static int
+find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
+{
+ td_thrinfo_t ti;
+ td_err_e err;
+ int pid;
+
+ err = td_thr_get_info_p (th_p, &ti);
+ if (err != TD_OK)
+ error ("Cannot get thread info: %s", thread_db_err_str (err));
+
+ pid = BUILD_THREAD (ti.ti_tid, GET_PID (inferior_pid));
+
+ if (! in_thread_list (pid))
+ attach_thread (pid, th_p, &ti, 1);
+
+ return 0;
+}
+
+static void
+thread_db_find_new_threads (void)
+{
+ td_err_e err;
+
+ /* Iterate over all user-space threads to discover new threads. */
+ err = td_ta_thr_iter_p (thread_agent, find_new_threads_callback, NULL,
+ TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
+ TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
+ if (err != TD_OK)
+ error ("Cannot find new threads: %s", thread_db_err_str (err));
+}
+
+static char *
+thread_db_pid_to_str (int pid)
+{
+ if (is_thread (pid))
+ {
+ static char buf[64];
+ td_thrhandle_t th;
+ td_thrinfo_t ti;
+ td_err_e err;
+
+ err = td_ta_map_id2thr_p (thread_agent, GET_THREAD (pid), &th);
+ if (err != TD_OK)
+ error ("Cannot find thread %ld: %s",
+ (long) GET_THREAD (pid), thread_db_err_str (err));
+
+ err = td_thr_get_info_p (&th, &ti);
+ if (err != TD_OK)
+ error ("Cannot get thread info for thread %ld: %s",
+ (long) GET_THREAD (pid), thread_db_err_str (err));
+
+ if (ti.ti_state == TD_THR_ACTIVE && ti.ti_lid != 0)
+ {
+ snprintf (buf, sizeof (buf), "Thread %ld (LWP %d)",
+ (long) ti.ti_tid, ti.ti_lid);
+ }
+ else
+ {
+ snprintf (buf, sizeof (buf), "Thread %ld (%s)",
+ (long) ti.ti_tid, thread_db_state_str (ti.ti_state));
+ }
+
+ return buf;
+ }
+
+ if (target_beneath->to_pid_to_str (pid))
+ return target_beneath->to_pid_to_str (pid);
+
+ return normal_pid_to_str (pid);
+}
+
+static void
+init_thread_db_ops (void)
+{
+ thread_db_ops.to_shortname = "multi-thread";
+ thread_db_ops.to_longname = "multi-threaded child process.";
+ thread_db_ops.to_doc = "Threads and pthreads support.";
+ thread_db_ops.to_detach = thread_db_detach;
+ thread_db_ops.to_resume = thread_db_resume;
+ thread_db_ops.to_wait = thread_db_wait;
+ thread_db_ops.to_fetch_registers = thread_db_fetch_registers;
+ thread_db_ops.to_store_registers = thread_db_store_registers;
+ thread_db_ops.to_xfer_memory = thread_db_xfer_memory;
+ thread_db_ops.to_kill = thread_db_kill;
+ thread_db_ops.to_create_inferior = thread_db_create_inferior;
+ thread_db_ops.to_mourn_inferior = thread_db_mourn_inferior;
+ thread_db_ops.to_thread_alive = thread_db_thread_alive;
+ thread_db_ops.to_find_new_threads = thread_db_find_new_threads;
+ thread_db_ops.to_pid_to_str = thread_db_pid_to_str;
+ thread_db_ops.to_stratum = thread_stratum;
+ thread_db_ops.to_has_thread_control = tc_schedlock;
+ thread_db_ops.to_magic = OPS_MAGIC;
+}
+
+void
+_initialize_thread_db (void)
+{
+ /* Only initialize the module if we can load libthread_db. */
+ if (thread_db_load ())
+ {
+ init_thread_db_ops ();
+ add_target (&thread_db_ops);
+
+ /* Add ourselves to objfile event chain. */
+ target_new_objfile_chain = target_new_objfile_hook;
+ target_new_objfile_hook = thread_db_new_objfile;
+ }
+}
--- /dev/null Thu Feb 19 16:30:24 1998
+++ lin-lwp.c Sun Sep 3 19:38:15 2000
@@ -0,0 +1,1048 @@
+/* Multi-threaded debugging support for Linux (LWP layer).
+ Copyright 2000 Free Software Foundation, Inc.
+
+ 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., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+#include "defs.h"
+
+#include "gdb_assert.h"
+#include <errno.h>
+#include <signal.h>
+#include <sys/ptrace.h>
+#include "gdb_wait.h"
+
+#include "gdbthread.h"
+#include "inferior.h"
+#include "target.h"
+
+#define DEBUG 1
+
+#if DEBUG
+extern const char *strsignal (int sig);
+#endif
+
+/* On Linux there are no real LWP's. The closest thing to LWP's are
+ processes sharing the same VM space. A multi-threaded process is
+ basically a group of such processes. However, such a grouping is
+ almost entirely a user-space issue; the kernel doesn't enforce such
+ a grouping at all (this might change in the future). In general,
+ we'll rely on the threads library (i.e. the LinuxThreads library)
+ to provide such a grouping.
+
+ It is perfectly well possible to write a multi-threaded application
+ without the assistance of a threads library, by using the clone
+ system call directly. This module should be able to give some
+ rudimentary support for debugging such applications if developers
+ specify the CLONE_PTRACE flag in the clone system call, and are
+ using Linux 2.4 or above.
+
+ Note that there are some peculiarities in Linux that affect this
+ code:
+
+ - In general one should specify the __WCLONE flag to waitpid in
+ order to make it report events for any of the cloned processes.
+ However, if a cloned process has exited the exit status is only
+ reported if the __WCLONE flag is absent.
+
+ - When a traced, cloned process exits and is waited for by the
+ debugger, the kernel reassigns it to the origional parent and
+ keeps it around as a "zombie". Somehow, the LinuxThreads library
+ doesn't notice this, which leads to the "zombie problem": When
+ debugged a multi-threaded process that spawns a lot of threads
+ will run out of processes, even if the threads exit, because the
+ "zombies" stay around. */
+
+/* Structure describing a LWP. */
+struct lwp_info
+{
+ /* The process id of the LWP. This is a combination of the LWP id
+ and overall process id. */
+ int pid;
+
+ /* Non-zero if we sent this LWP a SIGSTOP (but the LWP didn't report
+ it back yet). */
+ int signalled;
+
+ /* Non-zero if this LWP is stopped. */
+ int stopped;
+
+ /* If non-zero, a pending wait status. */
+ int status;
+
+ /* Non-zero if we were stepping this LWP. */
+ int step;
+
+ /* Next LWP in list. */
+ struct lwp_info *next;
+};
+
+/* List of known LWPs. */
+static struct lwp_info *lwp_list;
+
+/* Number of LWPs in the list. */
+static int num_lwps;
+
+/* Non-zero if we're running in "threaded" mode. */
+static int threaded;
+
+
+#ifndef TIDGET
+#define TIDGET(PID) (((PID) & 0x7fffffff) >> 16)
+#define PIDGET(PID) (((PID) & 0xffff))
+#define MERGEPID(PID, TID) (((PID) & 0xffff) | ((TID) << 16))
+#endif
+
+#define THREAD_FLAG 0x80000000
+#define is_lwp(pid) (((pid) & THREAD_FLAG) == 0 && TIDGET (pid))
+#define GET_LWP(pid) TIDGET (pid)
+#define GET_PID(pid) PIDGET (pid)
+#define BUILD_LWP(tid, pid) MERGEPID (pid, tid)
+
+#define is_cloned(pid) (GET_LWP (pid) != GET_PID (pid))
+
+/* If the last reported event was a SIGTRAP, this variable is set to
+ the process id of the LWP/thread that got it. */
+int trap_pid;
+
+
+/* This module's target-specific operations. */
+static struct target_ops lin_lwp_ops;
+
+/* The standard child operations. */
+extern struct target_ops child_ops;
+
+/* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in
+ _initialize_lin_lwp. */
+static sigset_t suspend_mask;
+
+
+/* Prototypes for local functions. */
+static void lin_lwp_mourn_inferior (void);
+
+
+/* Initialize the list of LWPs. */
+
+static void
+init_lwp_list (void)
+{
+ struct lwp_info *lp, *lpnext;
+
+ for (lp = lwp_list; lp; lp = lpnext)
+ {
+ lpnext = lp->next;
+ free (lp);
+ }
+
+ lwp_list = NULL;
+ num_lwps = 0;
+ threaded = 0;
+}
+
+/* Add the LWP specified by PID to the list. If this causes the
+ number of LWPs to become larger than one, go into "threaded" mode.
+ Return a pointer to the structure describing the new LWP. */
+
+static struct lwp_info *
+add_lwp (int pid)
+{
+ struct lwp_info *lp;
+
+ gdb_assert (is_lwp (pid));
+
+ lp = (struct lwp_info *) xmalloc (sizeof (struct lwp_info));
+
+ memset (lp, 0, sizeof (struct lwp_info));
+
+ lp->pid = pid;
+
+ lp->next = lwp_list;
+ lwp_list = lp;
+ if (++num_lwps > 1)
+ threaded = 1;
+
+ return lp;
+}
+
+/* Remove the LWP specified by PID from the list. */
+
+static void
+delete_lwp (int pid)
+{
+ struct lwp_info *lp, *lpprev;
+
+ lpprev = NULL;
+
+ for (lp = lwp_list; lp; lpprev = lp, lp = lp->next)
+ if (lp->pid == pid)
+ break;
+
+ if (!lp)
+ return;
+
+ /* We don't go back to "non-threaded" mode if the number of threads
+ becomes less than two. */
+ num_lwps--;
+
+ if (lpprev)
+ lpprev->next = lp->next;
+ else
+ lwp_list = lp->next;
+
+ free (lp);
+}
+
+/* Return a pointer to the structure describing the LWP corresponding
+ to PID. If no corresponding LWP could be found, return NULL. */
+
+static struct lwp_info *
+find_lwp_pid (int pid)
+{
+ struct lwp_info *lp;
+
+ if (is_lwp (pid))
+ pid = GET_LWP (pid);
+
+ for (lp = lwp_list; lp; lp = lp->next)
+ if (pid == GET_LWP (lp->pid))
+ return lp;
+
+ return NULL;
+}
+
+/* Call CALLBACK with its second argument set to DATA for every LWP in
+ the list. If CALLBACK returns 1 for a particular LWP, return a
+ pointer to the structure describing that LWP immediately.
+ Otherwise return NULL. */
+
+struct lwp_info *
+iterate_over_lwps (int (*callback) (struct lwp_info *, void *), void *data)
+{
+ struct lwp_info *lp;
+
+ for (lp = lwp_list; lp; lp = lp->next)
+ if ((*callback) (lp, data))
+ return lp;
+
+ return NULL;
+}
+
+
+/* Helper functions. */
+
+static void
+restore_inferior_pid (void *arg)
+{
+ int *saved_pid_ptr = arg;
+ inferior_pid = *saved_pid_ptr;
+ free (arg);
+}
+
+static struct cleanup *
+save_inferior_pid (void)
+{
+ int *saved_pid_ptr;
+
+ saved_pid_ptr = xmalloc (sizeof (int));
+ *saved_pid_ptr = inferior_pid;
+ return make_cleanup (restore_inferior_pid, saved_pid_ptr);
+}
+
+
+/* Implementation of the PREPARE_TO_PROCEED hook for the Linux LWP layer. */
+
+int
+lin_lwp_prepare_to_proceed (void)
+{
+ if (trap_pid && inferior_pid != trap_pid)
+ {
+ /* Switched over from TRAP_PID. */
+ CORE_ADDR stop_pc = read_pc ();
+ CORE_ADDR trap_pc;
+
+ /* Avoid switching where it wouldn't do any good, i.e. if both
+ threads are at the same breakpoint. */
+ trap_pc = read_pc_pid (trap_pid);
+ if (trap_pc != stop_pc && breakpoint_here_p (trap_pc))
+ {
+ /* User hasn't deleted the breakpoint. Return non-zero, and
+ switch back to TRAP_PID. */
+ inferior_pid = trap_pid;
+
+ /* FIXME: Is this stuff really necessary? */
+ flush_cached_frames ();
+ registers_changed ();
+
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+
+#if 0
+static void
+lin_lwp_open (char *args, int from_tty)
+{
+ push_target (&lin_lwp_ops);
+}
+#endif
+
+/* Attach to the LWP specified by PID. If VERBOSE is non-zero, print
+ a message telling the user that a new LWP has been added to the
+ process. */
+
+void
+lin_lwp_attach_lwp (int pid, int verbose)
+{
+ struct lwp_info *lp;
+
+ gdb_assert (is_lwp (pid));
+
+ if (verbose)
+ printf_filtered ("[New %s]\n", target_pid_to_str (pid));
+
+ if (ptrace (PTRACE_ATTACH, GET_LWP (pid), 0, 0) < 0)
+ error ("Can't attach %s: %s", target_pid_to_str (pid), strerror (errno));
+
+ lp = add_lwp (pid);
+ lp->signalled = 1;
+}
+
+static void
+lin_lwp_attach (char *args, int from_tty)
+{
+ /* FIXME: We should probably accept a list of process id's, and
+ attach all of them. */
+ error("Not implemented yet");
+}
+
+static void
+lin_lwp_detach (char *args, int from_tty)
+{
+ /* FIXME: Provide implementation when we implement lin_lwp_attach. */
+ error ("Not implemented yet");
+}
+
+
+struct private_thread_info
+{
+ int lwpid;
+};
+
+/* Return non-zero if TP corresponds to the LWP specified by DATA
+ (which is assumed to be a pointer to a `struct lwp_info'. */
+
+static int
+find_lwp_callback (struct thread_info *tp, void *data)
+{
+ struct lwp_info *lp = data;
+
+ if (tp->private->lwpid == GET_LWP (lp->pid))
+ return 1;
+
+ return 0;
+}
+
+/* Resume LP. */
+
+static int
+resume_callback (struct lwp_info *lp, void *data)
+{
+ if (lp->stopped && lp->status == 0)
+ {
+ struct thread_info *tp;
+
+#if 1
+ /* FIXME: kettenis/2000-08-26: This should really be handled
+ properly by core GDB. */
+
+ tp = find_thread_pid (lp->pid);
+ if (tp == NULL)
+ tp = iterate_over_threads (find_lwp_callback, lp);
+ gdb_assert (tp);
+
+ /* If we were previously stepping the thread, and now continue
+ the thread we must invalidate the stepping range. However,
+ if there is a step_resume breakpoint for this thread, we must
+ preserve the stepping range to make it possible to continue
+ stepping once we hit it. */
+ if (tp->step_range_end && tp->step_resume_breakpoint == NULL)
+ {
+ gdb_assert (lp->step);
+ tp->step_range_start = tp->step_range_end = 0;
+ }
+#endif
+
+ child_resume (GET_LWP (lp->pid), 0, TARGET_SIGNAL_0);
+ lp->stopped = 0;
+ lp->step = 0;
+ }
+
+ return 0;
+}
+
+static void
+lin_lwp_resume (int pid, int step, enum target_signal signo)
+{
+ struct lwp_info *lp;
+ int resume_all;
+
+ /* Apparently the interpretation of PID is dependent on STEP: If
+ STEP is non-zero, a specific PID means `step only this process
+ id'. But if STEP is zero, then PID means `continue *all*
+ processes, but give the signal only to this one'. */
+ resume_all = (pid == -1) || !step;
+
+ /* If PID is -1, it's the current inferior that should be
+ handled special. */
+ if (pid == -1)
+ pid = inferior_pid;
+
+ lp = find_lwp_pid (pid);
+ if (lp)
+ {
+ pid = GET_LWP (lp->pid);
+
+ /* Mark LWP as not stopped to prevent it from being continued by
+ resume_callback. */
+ lp->stopped = 0;
+
+ /* Remember if we're stepping. */
+ lp->step = step;
+
+ /* If we have a pending wait status for this thread, there is no
+ point in resuming the process. */
+ if (lp->status)
+ {
+ /* FIXME: What should we do if we are supposed to continue
+ this thread with a signal? */
+ gdb_assert (signo == TARGET_SIGNAL_0);
+ return;
+ }
+ }
+
+ if (resume_all)
+ iterate_over_lwps (resume_callback, NULL);
+
+ child_resume (pid, step, signo);
+}
+
+
+/* Send a SIGSTOP to LP. */
+
+static int
+stop_callback (struct lwp_info *lp, void *data)
+{
+ if (! lp->stopped && ! lp->signalled)
+ {
+ int ret;
+
+ ret = kill (GET_LWP (lp->pid), SIGSTOP);
+ gdb_assert (ret == 0);
+
+ lp->signalled = 1;
+ gdb_assert (lp->status == 0);
+ }
+
+ return 0;
+}
+
+/* Wait until LP is stopped. */
+
+static int
+stop_wait_callback (struct lwp_info *lp, void *data)
+{
+ if (! lp->stopped && lp->signalled)
+ {
+ pid_t pid;
+ int status;
+
+ gdb_assert (lp->status == 0);
+
+ pid = waitpid (GET_LWP (lp->pid), &status,
+ is_cloned (lp->pid) ? __WCLONE : 0);
+ if (pid == -1 && errno == ECHILD)
+ /* OK, the proccess has disappeared. We'll catch the actual
+ exit event in lin_lwp_wait. */
+ return 0;
+
+ gdb_assert (pid == GET_LWP (lp->pid));
+
+ if (WIFEXITED (status) || WIFSIGNALED (status))
+ {
+ gdb_assert (num_lwps > 1);
+ gdb_assert (! is_cloned (lp->pid));
+
+ gdb_assert (in_thread_list (lp->pid));
+ if (lp->pid != inferior_pid)
+ delete_thread (lp->pid);
+ printf_unfiltered ("[%s exited]\n",
+ target_pid_to_str (lp->pid));
+
+ delete_lwp (lp->pid);
+ return 0;
+ }
+
+ gdb_assert (WIFSTOPPED (status));
+ lp->stopped = 1;
+
+ if (WSTOPSIG (status) != SIGSTOP)
+ {
+ if (WSTOPSIG (status) == SIGTRAP
+ && breakpoint_inserted_here_p (read_pc_pid (pid)
+ - DECR_PC_AFTER_BREAK))
+ {
+ /* If a LWP other than the LWP that we're reporting an
+ event for has hit a GDB breakpoint (as opposed to
+ some random trap signal), then just arrange for it to
+ hit it again later. We don't keep the SIGTRAP status
+ and don't forward the SIGTRAP signal to the LWP. We
+ will handle the current event, eventually we will
+ resume all LWPs, and this one will get its breakpoint
+ trap again.
+
+ If we do not do this, then we run the risk that the
+ user will delete or disable the breakpoint, but the
+ thread will have already tripped on it. */
+#if DEBUG
+ printf ("Tripped breakpoint at %lx in LWP %d"
+ " while waiting for SIGSTOP.\n",
+ (long) read_pc_pid (lp->pid), pid);
+#endif
+ /* Set the PC to before the trap. */
+ if (DECR_PC_AFTER_BREAK)
+ write_pc_pid (read_pc_pid (pid) - DECR_PC_AFTER_BREAK, pid);
+ }
+ else
+ {
+#if DEBUG
+ printf ("Received %s in LWP %d while waiting for SIGSTOP.\n",
+ strsignal (WSTOPSIG (status)), pid);
+#endif
+ /* The thread was stopped with a signal other than
+ SIGSTOP, and didn't accidentiliy trip a breakpoint.
+ Record the wait status. */
+ lp->status = status;
+ }
+ }
+ else
+ {
+ /* We caught the SIGSTOP that we intended to catch, so
+ there's no SIGSTOP pending. */
+ lp->signalled = 0;
+ }
+ }
+
+ return 0;
+}
+
+/* Return non-zero if LP has a wait status pending. */
+
+static int
+status_callback (struct lwp_info *lp, void *data)
+{
+ return (lp->status != 0);
+}
+
+/* Return non-zero if LP isn't stopped. */
+
+static int
+running_callback (struct lwp_info *lp, void *data)
+{
+ return (lp->stopped == 0);
+}
+
+static int
+lin_lwp_wait (int pid, struct target_waitstatus *ourstatus)
+{
+ struct lwp_info *lp = NULL;
+ int options = 0;
+ int status = 0;
+
+ retry:
+
+ /* First check if there is a LWP with a wait status pending. */
+ if (pid == -1)
+ {
+ /* Any LWP will do. */
+ lp = iterate_over_lwps (status_callback, NULL);
+ if (lp)
+ {
+#if DEBUG
+ printf ("Using pending wait status for LWP %d.\n",
+ GET_LWP (lp->pid));
+#endif
+ status = lp->status;
+ lp->status = 0;
+ }
+
+ /* But if we don't fine one, we'll have to wait, and check both
+ cloned and uncloned processes. We start with the cloned
+ processes. */
+ options = __WCLONE | WNOHANG;
+ }
+ else if (is_lwp (pid))
+ {
+#if DEBUG
+ printf ("Waiting for specific LWP %d.\n", GET_LWP (pid));
+#endif
+ /* We have a specific LWP to check. */
+ lp = find_lwp_pid (GET_LWP (pid));
+ gdb_assert (lp);
+ status = lp->status;
+ lp->status = 0;
+#if DEBUG
+ if (status)
+ printf ("Using pending wait status for LWP %d.\n",
+ GET_LWP (lp->pid));
+#endif
+
+ /* If we have to wait, take into account whether PID is a cloned
+ process or not. And we have to convert it to something that
+ the layer beneath us can understand. */
+ options = is_cloned (lp->pid) ? __WCLONE : 0;
+ pid = GET_LWP (pid);
+ }
+
+ if (status && lp->signalled)
+ {
+ /* A pending SIGSTOP may interfere with the normal stream of
+ events. In a typical case where interference is a problem,
+ we have a SIGSTOP signal pending for LWP A while
+ single-stepping it, encounter an event in LWP B, and take the
+ pending SIGSTOP while trying to stop LWP A. After processing
+ the event in LWP B, LWP A is continued, and we'll never see
+ the SIGTRAP associated with the last time we were
+ single-stepping LWP A. */
+
+ /* Resume the thread. It should halt immediately returning the
+ pending SIGSTOP. */
+ child_resume (GET_LWP (lp->pid), lp->step, TARGET_SIGNAL_0);
+ lp->stopped = 0;
+
+ /* This should catch the pending SIGSTOP. */
+ stop_wait_callback (lp, NULL);
+ }
+
+ set_sigint_trap (); /* Causes SIGINT to be passed on to the
+ attached process. */
+ set_sigio_trap ();
+
+ while (status == 0)
+ {
+ pid_t lwpid;
+
+ lwpid = waitpid (pid, &status, options);
+ if (lwpid > 0)
+ {
+ gdb_assert (pid == -1 || lwpid == pid);
+
+ lp = find_lwp_pid (lwpid);
+ if (! lp)
+ {
+ lp = add_lwp (BUILD_LWP (lwpid, inferior_pid));
+ if (threaded)
+ {
+ gdb_assert (WIFSTOPPED (status) && WSTOPSIG (status) == SIGSTOP);
+ lp->signalled = 1;
+
+ if (! in_thread_list (inferior_pid))
+ {
+ inferior_pid = BUILD_LWP (inferior_pid, inferior_pid);
+ add_thread (inferior_pid);
+ }
+
+ add_thread (lp->pid);
+ printf_unfiltered ("[New %s]\n",
+ target_pid_to_str (lp->pid));
+ }
+ }
+
+ /* Make sure we don't report a TARGET_WAITKIND_EXITED or
+ TARGET_WAITKIND_SIGNALLED event if there are still LWP's
+ left in the process. */
+ if ((WIFEXITED (status) || WIFSIGNALED (status)) && num_lwps > 1)
+ {
+ if (in_thread_list (lp->pid))
+ {
+ /* Core GDB cannot deal with us deeting the current
+ thread. */
+ if (lp->pid != inferior_pid)
+ delete_thread (lp->pid);
+ printf_unfiltered ("[%s exited]\n",
+ target_pid_to_str (lp->pid));
+ }
+#if DEBUG
+ printf ("%s exited.\n", target_pid_to_str (lp->pid));
+#endif
+ delete_lwp (lp->pid);
+
+ /* Make sure there is at least one thread running. */
+ gdb_assert (iterate_over_lwps (running_callback, NULL));
+
+ /* Discard the event. */
+ status = 0;
+ continue;
+ }
+
+ /* Make sure we don't report a SIGSTOP that we sent
+ ourselves in an attempt to stop an LWP. */
+ if (lp->signalled && WIFSTOPPED (status)
+ && WSTOPSIG (status) == SIGSTOP)
+ {
+#if DEBUG
+ printf ("Delayed SIGSTOP caught for %s.\n",
+ target_pid_to_str (lp->pid));
+#endif
+ /* This is a delayed SIGSTOP. */
+ lp->signalled = 0;
+
+ child_resume (GET_LWP (lp->pid), lp->step, TARGET_SIGNAL_0);
+ lp->stopped = 0;
+
+ /* Discard the event. */
+ status = 0;
+ continue;
+ }
+
+ break;
+ }
+
+ if (pid == -1)
+ {
+ /* Alternate between checking cloned and uncloned processes. */
+ options ^= __WCLONE;
+
+ /* And suspend every time we have checked both. */
+ if (options & __WCLONE)
+ sigsuspend (&suspend_mask);
+ }
+
+ /* We shouldn't end up here unless we want to try again. */
+ gdb_assert (status == 0);
+ }
+
+ clear_sigio_trap ();
+ clear_sigint_trap ();
+
+ gdb_assert (lp);
+
+ /* Don't report signals that GDB isn't interested in, such as
+ signals that are neither printed nor stopped upon. Stopping all
+ threads can be a bit time-consuming so if we want decent
+ performance with heavily multi-threaded programs, especially when
+ they're using a high frequency timer, we'd better avoid it if we
+ can. */
+
+ if (WIFSTOPPED (status))
+ {
+ int signo = target_signal_from_host (WSTOPSIG (status));
+
+ if (signal_stop_state (signo) == 0
+ && signal_print_state (signo) == 0
+ && signal_pass_state (signo) == 1)
+ {
+ child_resume (GET_LWP (lp->pid), lp->step, signo);
+ lp->stopped = 0;
+ status = 0;
+ goto retry;
+ }
+ }
+
+ /* This LWP is stopped now. */
+ lp->stopped = 1;
+
+ /* Now stop all other LWP's ... */
+ iterate_over_lwps (stop_callback, NULL);
+
+ /* ... and wait until all of them have reported back that they're no
+ longer running. */
+ iterate_over_lwps (stop_wait_callback, NULL);
+
+ /* If we're not running in "threaded" mode, we'll report the bare
+ process id. */
+
+ if (WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP)
+ trap_pid = (threaded ? lp->pid : GET_LWP (lp->pid));
+ else
+ trap_pid = 0;
+
+ store_waitstatus (ourstatus, status);
+ return (threaded ? lp->pid : GET_LWP (lp->pid));
+}
+
+static int
+kill_callback (struct lwp_info *lp, void *data)
+{
+ ptrace (PTRACE_KILL, GET_LWP (lp->pid), 0, 0);
+ return 0;
+}
+
+static int
+kill_wait_callback (struct lwp_info *lp, void *data)
+{
+ pid_t pid;
+
+ /* We must make sure that there are no pending events (delayed
+ SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
+ program doesn't interfere with any following debugging session. */
+
+ /* For cloned processes we must check both with __WCLONE and
+ without, since the exit status of a cloned process isn't reported
+ with __WCLONE. */
+ if (is_cloned (lp->pid))
+ {
+ do
+ {
+ pid = waitpid (GET_LWP (lp->pid), NULL, __WCLONE);
+ }
+ while (pid == GET_LWP (lp->pid));
+
+ gdb_assert (pid == -1 && errno == ECHILD);
+ }
+
+ do
+ {
+ pid = waitpid (GET_LWP (lp->pid), NULL, 0);
+ }
+ while (pid == GET_LWP (lp->pid));
+
+ gdb_assert (pid == -1 && errno == ECHILD);
+ return 0;
+}
+
+static void
+lin_lwp_kill (void)
+{
+ /* Kill all LWP's ... */
+ iterate_over_lwps (kill_callback, NULL);
+
+ /* ... and wait until we've flushed all events. */
+ iterate_over_lwps (kill_wait_callback, NULL);
+
+ target_mourn_inferior ();
+}
+
+static void
+lin_lwp_create_inferior (char *exec_file, char *allargs, char **env)
+{
+ struct target_ops *target_beneath;
+
+ init_lwp_list ();
+
+#if 0
+ target_beneath = find_target_beneath (&lin_lwp_ops);
+#else
+ target_beneath = &child_ops;
+#endif
+ target_beneath->to_create_inferior (exec_file, allargs, env);
+}
+
+static void
+lin_lwp_mourn_inferior (void)
+{
+ struct target_ops *target_beneath;
+
+ init_lwp_list ();
+
+ trap_pid = 0;
+
+#if 0
+ target_beneath = find_target_beneath (&lin_lwp_ops);
+#else
+ target_beneath = &child_ops;
+#endif
+ target_beneath->to_mourn_inferior ();
+}
+
+static void
+lin_lwp_fetch_registers (int regno)
+{
+ struct cleanup *old_chain = save_inferior_pid ();
+
+ if (is_lwp (inferior_pid))
+ inferior_pid = GET_LWP (inferior_pid);
+
+ fetch_inferior_registers (regno);
+
+ do_cleanups (old_chain);
+}
+
+static void
+lin_lwp_store_registers (int regno)
+{
+ struct cleanup *old_chain = save_inferior_pid ();
+
+ if (is_lwp (inferior_pid))
+ inferior_pid = GET_LWP (inferior_pid);
+
+ store_inferior_registers (regno);
+
+ do_cleanups (old_chain);
+}
+
+static int
+lin_lwp_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int write,
+ struct target_ops *target)
+{
+ struct cleanup *old_chain = save_inferior_pid ();
+ int xfer;
+
+ if (is_lwp (inferior_pid))
+ inferior_pid = GET_LWP (inferior_pid);
+
+ xfer = child_xfer_memory (memaddr, myaddr, len, write, target);
+
+ do_cleanups (old_chain);
+ return xfer;
+}
+
+static int
+lin_lwp_thread_alive (int pid)
+{
+ gdb_assert (is_lwp (pid));
+
+ errno = 0;
+ ptrace (PTRACE_PEEKUSER, GET_LWP (pid), 0, 0);
+ if (errno)
+ return 0;
+
+ return 1;
+}
+
+static char *
+lin_lwp_pid_to_str (int pid)
+{
+ static char buf[64];
+
+ if (is_lwp (pid))
+ {
+ snprintf (buf, sizeof (buf), "LWP %d", GET_LWP (pid));
+ return buf;
+ }
+
+ return normal_pid_to_str (pid);
+}
+
+static void
+init_lin_lwp_ops (void)
+{
+#if 0
+ lin_lwp_ops.to_open = lin_lwp_open;
+#endif
+ lin_lwp_ops.to_shortname = "lwp-layer";
+ lin_lwp_ops.to_longname = "lwp-layer";
+ lin_lwp_ops.to_doc = "Low level threads support (LWP layer)";
+ lin_lwp_ops.to_attach = lin_lwp_attach;
+ lin_lwp_ops.to_detach = lin_lwp_detach;
+ lin_lwp_ops.to_resume = lin_lwp_resume;
+ lin_lwp_ops.to_wait = lin_lwp_wait;
+ lin_lwp_ops.to_fetch_registers = lin_lwp_fetch_registers;
+ lin_lwp_ops.to_store_registers = lin_lwp_store_registers;
+ lin_lwp_ops.to_xfer_memory = lin_lwp_xfer_memory;
+ lin_lwp_ops.to_kill = lin_lwp_kill;
+ lin_lwp_ops.to_create_inferior = lin_lwp_create_inferior;
+ lin_lwp_ops.to_mourn_inferior = lin_lwp_mourn_inferior;
+ lin_lwp_ops.to_thread_alive = lin_lwp_thread_alive;
+ lin_lwp_ops.to_pid_to_str = lin_lwp_pid_to_str;
+ lin_lwp_ops.to_stratum = thread_stratum;
+ lin_lwp_ops.to_has_thread_control = tc_schedlock;
+ lin_lwp_ops.to_magic = OPS_MAGIC;
+}
+
+static void
+sigchld_handler (int signo)
+{
+ /* Do nothing. The only reason for this handler is that it allows
+ us to use sigsuspend in lin_lwp_wait above to wait for the
+ arrival of a SIGCHLD. */
+}
+
+void
+_initialize_lin_lwp (void)
+{
+ struct sigaction action;
+ sigset_t mask;
+
+ extern void thread_db_init (struct target_ops *);
+
+ init_lin_lwp_ops ();
+ add_target (&lin_lwp_ops);
+ thread_db_init (&lin_lwp_ops);
+
+ action.sa_handler = sigchld_handler;
+ sigemptyset (&action.sa_mask);
+ action.sa_flags = 0;
+ sigaction (SIGCHLD, &action, NULL);
+
+ /* We block SIGCHLD throughout this code ... */
+ sigemptyset (&mask);
+ sigaddset (&mask, SIGCHLD);
+ sigprocmask (SIG_BLOCK, &mask, &suspend_mask);
+
+ /* ... except during a sigsuspend. */
+ sigdelset (&suspend_mask, SIGCHLD);
+}
+
+
+/* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
+ the LinuxThreads library and therefore doesn't really belong here. */
+
+/* Read variable NAME in the target and return its value if found.
+ Otherwise return zero. It is assumed that the type of the variable
+ is `int'. */
+
+static int
+get_signo (const char *name)
+{
+ struct minimal_symbol *ms;
+ int signo;
+
+ ms = lookup_minimal_symbol (name, NULL, NULL);
+ if (ms == NULL)
+ return 0;
+
+ if (target_read_memory (SYMBOL_VALUE_ADDRESS (ms), (char *) &signo,
+ sizeof (signo)) != 0)
+ return 0;
+
+ return signo;
+}
+
+/* Return the set of signals used by the threads library in *SET. */
+
+void
+lin_thread_get_thread_signals (sigset_t *set)
+{
+ int restart;
+ int cancel;
+
+ sigemptyset (set);
+
+ restart = get_signo ("__pthread_sig_restart");
+ if (restart == 0)
+ return;
+
+ cancel = get_signo ("__pthread_sig_cancel");
+ if (cancel == 0)
+ return;
+
+ sigaddset (set, restart);
+ sigaddset (set, cancel);
+}