gdb/gdb-6.3-threaded-watchpoints2-20050225.patch

2005-02-28  Jeff Johnston  <jjohnstn@redhat.com>

	* config/i386/nm-linux.h: Change dr register routines to
	accept a ptid_t first argument.  Change all calling macros
	to default the inferior_ptid for the first argument.
	(i386_linux_insert_watchpoint): New prototype.
	(i386_linux_remove_watchpoint, i386_linux_insert_hw_breakpoint): Ditto.
	(i386_linux_remove_hw_breakpoint): Ditto.
	(target_insert_watchpoint, target_remove_watchpoint): Undef and
	override.
	(target_insert_hw_breakpoint, target_remove_hw_breakpoint): Ditto.
	* config/i386/nm-linux64.h: Ditto except add amd64 versions of
	the watchpoint/hw-breakpoint insert/remove routines.
	* i386-nat.c: Include "inferior.h" to define inferior_ptid.
	* i386-linux-nat.c: Change all dr get/set routines to accept
	ptid_t as first argument and to use this argument to determine
	the tid for PTRACE.
	(i386_linux_set_debug_regs_for_thread): New function.
	(i386_linux_sync_debug_registers_callback): Ditto.
	(i386_linux_sync_debug_registers_across_threads): Ditto.
	(i386_linux_insert_watchpoint, i386_linux_remove_watchpoint): Ditto.
	(i386_linux_hw_breakpoint, i386_linux_remove_hw_breakpoint): Ditto.
	(i386_linux_new_thread): Ditto.
	(_initialize_i386_linux_nat): Ditto.
	* amd64-linux-nat.c: Change all dr get/set routines to accept
	ptid_t as first argument and to use this argument to determine
	the tid for PTRACE.
	(amd64_linux_set_debug_regs_for_thread): New function.
	(amd64_linux_sync_debug_registers_callback): Ditto.
	(amd64_linux_sync_debug_registers_across_threads): Ditto.
	(amd64_linux_insert_watchpoint, amd64_linux_remove_watchpoint): Ditto.
	(amd64_linux_hw_breakpoint, amd64_linux_remove_hw_breakpoint): Ditto.
	(amd64_linux_new_thread): Ditto.
	(_initialize_amd64_linux_nat): Register linux new thread observer.
	* testsuite/gdb.threads/watchthreads2.c: New test case.
	* testsuite/gdb.threads/watchthreads2.exp: Ditto.

2007-10-14  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Port to GDB-6.7.

Index: gdb-6.7/gdb/config/i386/nm-linux64.h
===================================================================
--- gdb-6.7.orig/gdb/config/i386/nm-linux64.h	2007-08-23 20:08:48.000000000 +0200
+++ gdb-6.7/gdb/config/i386/nm-linux64.h	2007-10-14 23:41:50.000000000 +0200
@@ -33,20 +33,58 @@
 
 /* Provide access to the i386 hardware debugging registers.  */
 
-extern void amd64_linux_dr_set_control (unsigned long control);
+extern void amd64_linux_dr_set_control (ptid_t ptid, unsigned long control);
 #define I386_DR_LOW_SET_CONTROL(control) \
-  amd64_linux_dr_set_control (control)
+  amd64_linux_dr_set_control (inferior_ptid, control)
 
-extern void amd64_linux_dr_set_addr (int regnum, CORE_ADDR addr);
+extern void amd64_linux_dr_set_addr (ptid_t ptid, int regnum, CORE_ADDR addr);
 #define I386_DR_LOW_SET_ADDR(regnum, addr) \
-  amd64_linux_dr_set_addr (regnum, addr)
+  amd64_linux_dr_set_addr (inferior_ptid, regnum, addr)
 
-extern void amd64_linux_dr_reset_addr (int regnum);
+extern void amd64_linux_dr_reset_addr (ptid_t ptid, int regnum);
 #define I386_DR_LOW_RESET_ADDR(regnum) \
-  amd64_linux_dr_reset_addr (regnum)
+  amd64_linux_dr_reset_addr (inferior_ptid, regnum)
 
-extern unsigned long amd64_linux_dr_get_status (void);
+extern unsigned long amd64_linux_dr_get_status (ptid_t ptid);
 #define I386_DR_LOW_GET_STATUS() \
-  amd64_linux_dr_get_status ()
+  amd64_linux_dr_get_status (inferior_ptid)
+
+/* Watchpoints and hardware breakpoints.  */
+
+/* Insert a watchpoint to watch a memory region which starts at
+ *  *    address ADDR and whose length is LEN bytes.  Watch memory accesses
+ *   *       of the type TYPE.  Return 0 on success, -1 on failure.  */
+extern int amd64_linux_insert_watchpoint (CORE_ADDR addr, int len, int type);
+
+/* Remove a watchpoint that watched the memory region which starts at
+ *  *    address ADDR, whose length is LEN bytes, and for accesses of the
+ *   *       type TYPE.  Return 0 on success, -1 on failure.  */
+extern int amd64_linux_remove_watchpoint (CORE_ADDR addr, int len, int type);
+
+/* Insert a hardware-assisted breakpoint at address ADDR.  SHADOW is
+ *  *    unused.  Return 0 on success, EBUSY on failure.  */
+extern int amd64_linux_insert_hw_breakpoint (struct bp_target_info *bp_tgt);
+
+/* Remove a hardware-assisted breakpoint at address ADDR.  SHADOW is
+ *  *    unused. Return 0 on success, -1 on failure.  */
+extern int  amd64_linux_remove_hw_breakpoint (struct bp_target_info *bp_tgt);
+
+/* Override basic amd64 macros for watchpoint and hardware breakpoint 
+ *    insertion/removal to support threads.  */
+#undef target_insert_watchpoint
+#define target_insert_watchpoint(addr, len, type) \
+  amd64_linux_insert_watchpoint (addr, len, type)
+
+#undef target_remove_watchpoint
+#define target_remove_watchpoint(addr, len, type) \
+  amd64_linux_remove_watchpoint (addr, len, type)
+
+#undef target_insert_hw_breakpoint
+#define target_insert_hw_breakpoint(bp_tgt) \
+  amd64_linux_insert_hw_breakpoint (bp_tgt)
+
+#undef target_remove_hw_breakpoint
+#define target_remove_hw_breakpoint(bp_tgt) \
+  amd64_linux_remove_hw_breakpoint (bp_tgt)
 
 #endif /* nm-linux64.h */
Index: gdb-6.7/gdb/config/i386/nm-linux.h
===================================================================
--- gdb-6.7.orig/gdb/config/i386/nm-linux.h	2007-08-23 20:08:48.000000000 +0200
+++ gdb-6.7/gdb/config/i386/nm-linux.h	2007-10-14 23:40:55.000000000 +0200
@@ -29,21 +29,60 @@
 
 /* Provide access to the i386 hardware debugging registers.  */
 
-extern void i386_linux_dr_set_control (unsigned long control);
+extern void i386_linux_dr_set_control (ptid_t ptid, unsigned long control);
 #define I386_DR_LOW_SET_CONTROL(control) \
-  i386_linux_dr_set_control (control)
+  i386_linux_dr_set_control (inferior_ptid, control)
 
-extern void i386_linux_dr_set_addr (int regnum, CORE_ADDR addr);
+extern void i386_linux_dr_set_addr (ptid_t ptid, int regnum, CORE_ADDR addr);
 #define I386_DR_LOW_SET_ADDR(regnum, addr) \
-  i386_linux_dr_set_addr (regnum, addr)
+  i386_linux_dr_set_addr (inferior_ptid, regnum, addr)
 
-extern void i386_linux_dr_reset_addr (int regnum);
+extern void i386_linux_dr_reset_addr (ptid_t ptid, int regnum);
 #define I386_DR_LOW_RESET_ADDR(regnum) \
-  i386_linux_dr_reset_addr (regnum)
+  i386_linux_dr_reset_addr (inferior_ptid, regnum)
 
-extern unsigned long i386_linux_dr_get_status (void);
+extern unsigned long i386_linux_dr_get_status (ptid_t ptid);
 #define I386_DR_LOW_GET_STATUS() \
-  i386_linux_dr_get_status ()
+  i386_linux_dr_get_status (inferior_ptid)
+
+/* Watchpoints and hardware breakpoints.  */
+
+/* Insert a watchpoint to watch a memory region which starts at
+ *    address ADDR and whose length is LEN bytes.  Watch memory accesses
+ *       of the type TYPE.  Return 0 on success, -1 on failure.  */
+extern int i386_linux_insert_watchpoint (CORE_ADDR addr, int len, int type);
+
+/* Remove a watchpoint that watched the memory region which starts at
+ *    address ADDR, whose length is LEN bytes, and for accesses of the
+ *       type TYPE.  Return 0 on success, -1 on failure.  */
+extern int i386_linux_remove_watchpoint (CORE_ADDR addr, int len, int type);
+
+/* Insert a hardware-assisted breakpoint at address ADDR.  SHADOW is
+ *    unused.  Return 0 on success, EBUSY on failure.  */
+extern int i386_linux_insert_hw_breakpoint (struct bp_target_info *bp_tgt);
+
+/* Remove a hardware-assisted breakpoint at address ADDR.  SHADOW is
+ *    unused. Return 0 on success, -1 on failure.  */
+extern int  i386_linux_remove_hw_breakpoint (struct bp_target_info *bp_tgt);
+
+/* Override basic i386 macros for watchpoint and hardware breakpoint 
+   insertion/removal to support threads.  */
+#undef target_insert_watchpoint
+#define target_insert_watchpoint(addr, len, type) \
+  i386_linux_insert_watchpoint (addr, len, type)
+
+#undef target_remove_watchpoint
+#define target_remove_watchpoint(addr, len, type) \
+  i386_linux_remove_watchpoint (addr, len, type)
+
+#undef target_insert_hw_breakpoint
+#define target_insert_hw_breakpoint(bp_tgt) \
+  i386_linux_insert_hw_breakpoint (bp_tgt)
+
+#undef target_remove_hw_breakpoint
+#define target_remove_hw_breakpoint(bp_tgt) \
+  i386_linux_remove_hw_breakpoint (bp_tgt)
+
 
 
 #ifdef HAVE_PTRACE_GETFPXREGS
Index: gdb-6.7/gdb/i386-nat.c
===================================================================
--- gdb-6.7.orig/gdb/i386-nat.c	2007-08-23 20:08:34.000000000 +0200
+++ gdb-6.7/gdb/i386-nat.c	2007-10-14 23:39:04.000000000 +0200
@@ -19,6 +19,7 @@
 
 #include "defs.h"
 #include "breakpoint.h"
+#include "inferior.h"
 #include "command.h"
 #include "gdbcmd.h"
 
Index: gdb-6.7/gdb/testsuite/gdb.threads/watchthreads2.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb-6.7/gdb/testsuite/gdb.threads/watchthreads2.c	2007-10-14 23:39:04.000000000 +0200
@@ -0,0 +1,66 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+
+   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.  
+ 
+   This file is copied from schedlock.c.  */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+void *thread_function(void *arg); /* Pointer to function executed by each thread */
+
+#define NUM 5
+
+unsigned int args[NUM+1];
+
+int main() {
+    int res;
+    pthread_t threads[NUM];
+    void *thread_result;
+    long i;
+
+    for (i = 0; i < NUM; i++)
+      {
+	args[i] = 1; /* Init value.  */
+	res = pthread_create(&threads[i],
+		             NULL,
+			     thread_function,
+			     (void *) i);
+      }
+
+    args[i] = 1;
+    thread_function ((void *) i);
+
+    exit(EXIT_SUCCESS);
+}
+
+void *thread_function(void *arg) {
+    int my_number =  (long) arg;
+    int *myp = (int *) &args[my_number];
+
+    /* Don't run forever.  Run just short of it :)  */
+    while (*myp > 0)
+      {
+	(*myp) ++; usleep (1); /* Loop increment.  */
+      }
+
+    pthread_exit(NULL);
+}
+
Index: gdb-6.7/gdb/testsuite/gdb.threads/watchthreads2.exp
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gdb-6.7/gdb/testsuite/gdb.threads/watchthreads2.exp	2007-10-14 23:39:04.000000000 +0200
@@ -0,0 +1,133 @@
+# This testcase is part of GDB, the GNU debugger.
+
+# Copyright 2005 Free Software Foundation, Inc.
+
+# 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.  
+
+# Check that GDB can support multiple watchpoints across threads.
+
+if $tracelevel {
+    strace $tracelevel
+}
+
+set prms_id 0
+set bug_id 0
+
+# This test verifies that a watchpoint is detected in the proper thread
+# so the test is only meaningful on a system with hardware watchpoints.
+if [target_info exists gdb,no_hardware_watchpoints] {
+    return 0;
+}
+
+set testfile "watchthreads2"
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable [list debug "incdir=${objdir}"]] != "" } {
+    return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+gdb_test "set can-use-hw-watchpoints 1" "" ""
+
+#
+# Run to `main' where we begin our tests.
+#
+
+if ![runto_main] then {
+    gdb_suppress_tests
+}
+
+set args_2 0
+set args_3 0
+
+gdb_breakpoint "thread_function"
+gdb_continue_to_breakpoint "thread_function"
+gdb_test "disable 2" ""
+
+gdb_test_multiple "p args\[2\]" "get initial args2" {
+  -re "\\\$\[0-9\]* = (.*)$gdb_prompt $" {
+    set init_args_2 $expect_out(1,string)
+    pass "get initial args2"
+  }
+}
+
+gdb_test_multiple "p args\[3\]" "get initial args3" {
+  -re "\\\$\[0-9\]* = (.*)$gdb_prompt $" {
+    set init_args_3 $expect_out(1,string)
+    pass "get initial args3"
+  }
+}
+
+set args_2 $init_args_2
+set args_3 $init_args_3
+
+# Watch values that will be modified by distinct threads.
+gdb_test "watch args\[2\]" "Hardware watchpoint 3: args\\\[2\\\]"
+gdb_test "watch args\[3\]" "Hardware watchpoint 4: args\\\[3\\\]"
+
+set init_line [expr [gdb_get_line_number "Init value"]+1]
+set inc_line [gdb_get_line_number "Loop increment"]
+
+# Loop and continue to allow both watchpoints to be triggered.
+for {set i 0} {$i < 30} {incr i} {
+  set test_flag 0
+  gdb_test_multiple "continue" "threaded watch loop" {
+    -re "Hardware watchpoint 3: args\\\[2\\\].*Old value = 0.*New value = 1.*main \\\(\\\) at .*watchthreads2.c:$init_line.*$gdb_prompt $"
+       { set args_2 1; set test_flag 1 }
+    -re "Hardware watchpoint 4: args\\\[3\\\].*Old value = 0.*New value = 1.*main \\\(\\\) at .*watchthreads2.c:$init_line.*$gdb_prompt $"
+       { set args_3 1; set test_flag 1 }
+    -re "Hardware watchpoint 3: args\\\[2\\\].*Old value = $args_2.*New value = [expr $args_2+1].*in thread_function \\\(arg=0x2\\\) at .*watchthreads2.c:$inc_line.*$gdb_prompt $"
+       { set args_2 [expr $args_2+1]; set test_flag 1 }
+    -re "Hardware watchpoint 4: args\\\[3\\\].*Old value = $args_3.*New value = [expr $args_3+1].*in thread_function \\\(arg=0x3\\\) at .*watchthreads2.c:$inc_line.*$gdb_prompt $"
+       { set args_3 [expr $args_3+1]; set test_flag 1 }
+  }
+  # If we fail above, don't bother continuing loop
+  if { $test_flag == 0 } {
+    set i 30;
+  }
+}
+
+# Print success message if loop succeeded.
+if { $test_flag == 1 } {
+  pass "threaded watch loop"
+}
+
+# Verify that we hit first watchpoint in child thread.
+set message "watchpoint on args\[2\] hit in thread"
+if { $args_2 > 1 } {
+  pass $message 
+} else {
+  fail $message
+}
+
+# Verify that we hit second watchpoint in child thread.
+set message "watchpoint on args\[3\] hit in thread"
+if { $args_3 > 1 } {
+  pass $message 
+} else {
+  fail $message 
+}
+
+# Verify that all watchpoint hits are accounted for.
+set message "combination of threaded watchpoints = 30 + initial values"
+if { [expr $args_2+$args_3] == [expr [expr 30+$init_args_2]+$init_args_3] } {
+  pass $message 
+} else {
+  fail $message 
+}
Index: gdb-6.7/gdb/i386-linux-nat.c
===================================================================
--- gdb-6.7.orig/gdb/i386-linux-nat.c	2007-10-13 05:09:50.000000000 +0200
+++ gdb-6.7/gdb/i386-linux-nat.c	2007-10-14 23:39:04.000000000 +0200
@@ -22,6 +22,7 @@
 #include "inferior.h"
 #include "gdbcore.h"
 #include "regcache.h"
+#include "observer.h"
 #include "target.h"
 #include "linux-nat.h"
 
@@ -580,14 +581,14 @@ i386_linux_store_inferior_registers (str
 /* Support for debug registers.  */
 
 static unsigned long
-i386_linux_dr_get (int regnum)
+i386_linux_dr_get (ptid_t ptid, int regnum)
 {
   int tid;
   unsigned long value;
 
-  tid = TIDGET (inferior_ptid);
+  tid = TIDGET (ptid);
   if (tid == 0)
-    tid = PIDGET (inferior_ptid);
+    tid = PIDGET (ptid);
 
   /* FIXME: kettenis/2001-03-27: Calling perror_with_name if the
      ptrace call fails breaks debugging remote targets.  The correct
@@ -608,13 +609,13 @@ i386_linux_dr_get (int regnum)
 }
 
 static void
-i386_linux_dr_set (int regnum, unsigned long value)
+i386_linux_dr_set (ptid_t ptid, int regnum, unsigned long value)
 {
   int tid;
 
-  tid = TIDGET (inferior_ptid);
+  tid = TIDGET (ptid);
   if (tid == 0)
-    tid = PIDGET (inferior_ptid);
+    tid = PIDGET (ptid);
 
   errno = 0;
   ptrace (PTRACE_POKEUSER, tid,
@@ -624,34 +625,158 @@ i386_linux_dr_set (int regnum, unsigned 
 }
 
 void
-i386_linux_dr_set_control (unsigned long control)
+i386_linux_dr_set_control (ptid_t ptid, unsigned long control)
 {
-  i386_linux_dr_set (DR_CONTROL, control);
+  i386_linux_dr_set (ptid, DR_CONTROL, control);
 }
 
 void
-i386_linux_dr_set_addr (int regnum, CORE_ADDR addr)
+i386_linux_dr_set_addr (ptid_t ptid, int regnum, CORE_ADDR addr)
 {
   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
 
-  i386_linux_dr_set (DR_FIRSTADDR + regnum, addr);
+  i386_linux_dr_set (ptid, DR_FIRSTADDR + regnum, addr);
 }
 
 void
-i386_linux_dr_reset_addr (int regnum)
+i386_linux_dr_reset_addr (ptid_t ptid, int regnum)
 {
   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
 
-  i386_linux_dr_set (DR_FIRSTADDR + regnum, 0L);
+  i386_linux_dr_set (ptid, DR_FIRSTADDR + regnum, 0L);
 }
 
 unsigned long
-i386_linux_dr_get_status (void)
+i386_linux_dr_get_status (ptid_t ptid)
 {
-  return i386_linux_dr_get (DR_STATUS);
+  return i386_linux_dr_get (ptid, DR_STATUS);
 }
 
 
+/* Structure used to sync debug registers for all threads.  */
+struct i386_debug_register_state
+{
+  int tid;
+  CORE_ADDR addr[DR_LASTADDR - DR_FIRSTADDR + 1];
+  unsigned long control;
+};
+
+static void
+i386_linux_set_debug_regs_for_thread (ptid_t ptid,
+				      struct i386_debug_register_state *dbs)
+{
+  int i;
+  for (i = 0; i < (DR_LASTADDR - DR_FIRSTADDR) + 1; ++i)
+    i386_linux_dr_set_addr (ptid, i, dbs->addr[i]);
+  i386_linux_dr_set_control (ptid, dbs->control);
+}
+
+/* Iterator function to support syncing debug registers across all threads.  */
+static int
+i386_linux_sync_debug_registers_callback (struct lwp_info *lwp, void *data)
+{
+  struct i386_debug_register_state *args = data;
+  int i, tid;
+
+  tid = TIDGET (lwp->ptid);
+  if (tid == 0)
+    tid = PIDGET (lwp->ptid);
+
+  if (tid != args->tid)
+    i386_linux_set_debug_regs_for_thread (lwp->ptid, args);
+  return 0;
+}
+
+/* Sync the debug registers for all known threads to the current
+   thread that has just performed an operation.  This is required
+   because the debug registers are thread-specific.  We want
+   watchpoints and hardware breakpoints to be treated globally
+   across all threads.  */
+static int
+i386_linux_sync_debug_registers_across_threads (void)
+{
+  int i, tid;
+  struct i386_debug_register_state args;
+
+  tid = TIDGET (inferior_ptid);
+  if (tid == 0)
+    tid = PIDGET (inferior_ptid);
+
+  args.tid = tid;
+  for (i = 0; i < (DR_LASTADDR - DR_FIRSTADDR) + 1; ++i)
+    args.addr[i] = i386_linux_dr_get (inferior_ptid, DR_FIRSTADDR + i);
+  args.control = i386_linux_dr_get (inferior_ptid, DR_CONTROL);
+
+  iterate_over_lwps (&i386_linux_sync_debug_registers_callback, &args);
+
+  return 0;
+}
+
+/* Insert a watchpoint to watch a memory region which starts at
+   address ADDR and whose length is LEN bytes.  Watch memory accesses
+   of the type TYPE.  Return 0 on success, -1 on failure.  */
+int
+i386_linux_insert_watchpoint (CORE_ADDR addr, int len, int type)
+{
+  int rc;
+  rc = i386_insert_watchpoint (addr, len, type);
+  if (!rc)
+    i386_linux_sync_debug_registers_across_threads ();
+  return rc;
+}
+
+/* Remove a watchpoint that watched the memory region which starts at
+   address ADDR, whose length is LEN bytes, and for accesses of the
+   type TYPE.  Return 0 on success, -1 on failure.  */
+int
+i386_linux_remove_watchpoint (CORE_ADDR addr, int len, int type)
+{
+  int rc;
+  rc = i386_remove_watchpoint (addr, len, type);
+  if (!rc)
+    i386_linux_sync_debug_registers_across_threads ();
+  return rc;
+}
+
+/* Insert a hardware-assisted breakpoint at address ADDR.  SHADOW is
+   unused.  Return 0 on success, EBUSY on failure.  */
+int
+i386_linux_insert_hw_breakpoint (struct bp_target_info *bp_tgt)
+{
+  int rc;
+  rc = i386_insert_hw_breakpoint (bp_tgt);
+  if (!rc)
+    i386_linux_sync_debug_registers_across_threads ();
+  return rc;
+}
+
+/* Remove a hardware-assisted breakpoint at address ADDR.  SHADOW is
+   unused.  Return 0 on success, -1 on failure.  */
+int
+i386_linux_remove_hw_breakpoint (struct bp_target_info *bp_tgt)
+{
+  int rc;
+  rc = i386_remove_hw_breakpoint (bp_tgt);
+  if (!rc)
+    i386_linux_sync_debug_registers_across_threads ();
+  return rc;
+}
+
+/* Observer function for a new thread attach.  We need to insert
+   existing watchpoints and hardware breakpoints on the new thread.  */
+static void
+i386_linux_new_thread (ptid_t ptid)
+{
+  int i;
+  struct i386_debug_register_state dbs;
+
+  for (i = 0; i < (DR_LASTADDR - DR_FIRSTADDR) + 1; ++i)
+    dbs.addr[i] = i386_linux_dr_get (inferior_ptid, DR_FIRSTADDR + i);
+  dbs.control = i386_linux_dr_get (inferior_ptid, DR_CONTROL);
+
+  i386_linux_set_debug_regs_for_thread (ptid, &dbs);
+}
+
 /* Called by libthread_db.  Returns a pointer to the thread local
    storage (or its descriptor).  */
 
@@ -816,4 +941,6 @@ _initialize_i386_linux_nat (void)
 
   /* Register the target.  */
   linux_nat_add_target (t);
+
+  observer_attach_linux_new_thread (i386_linux_new_thread);
 }
Index: gdb-6.7/gdb/amd64-linux-nat.c
===================================================================
--- gdb-6.7.orig/gdb/amd64-linux-nat.c	2007-10-13 05:09:50.000000000 +0200
+++ gdb-6.7/gdb/amd64-linux-nat.c	2007-10-14 23:39:04.000000000 +0200
@@ -23,6 +23,7 @@
 #include "inferior.h"
 #include "gdbcore.h"
 #include "regcache.h"
+#include "observer.h"
 #include "linux-nat.h"
 #include "amd64-linux-tdep.h"
 
@@ -235,14 +236,14 @@ amd64_linux_store_inferior_registers (st
 
 
 static unsigned long
-amd64_linux_dr_get (int regnum)
+amd64_linux_dr_get (ptid_t ptid, int regnum)
 {
   int tid;
   unsigned long value;
 
-  tid = TIDGET (inferior_ptid);
+  tid = TIDGET (ptid);
   if (tid == 0)
-    tid = PIDGET (inferior_ptid);
+    tid = PIDGET (ptid);
 
   /* FIXME: kettenis/2001-03-27: Calling perror_with_name if the
      ptrace call fails breaks debugging remote targets.  The correct
@@ -263,13 +264,13 @@ amd64_linux_dr_get (int regnum)
 }
 
 static void
-amd64_linux_dr_set (int regnum, unsigned long value)
+amd64_linux_dr_set (ptid_t ptid, int regnum, unsigned long value)
 {
   int tid;
 
-  tid = TIDGET (inferior_ptid);
+  tid = TIDGET (ptid);
   if (tid == 0)
-    tid = PIDGET (inferior_ptid);
+    tid = PIDGET (ptid);
 
   errno = 0;
   ptrace (PT_WRITE_U, tid, offsetof (struct user, u_debugreg[regnum]), value);
@@ -278,34 +279,158 @@ amd64_linux_dr_set (int regnum, unsigned
 }
 
 void
-amd64_linux_dr_set_control (unsigned long control)
+amd64_linux_dr_set_control (ptid_t ptid, unsigned long control)
 {
-  amd64_linux_dr_set (DR_CONTROL, control);
+  amd64_linux_dr_set (ptid, DR_CONTROL, control);
 }
 
 void
-amd64_linux_dr_set_addr (int regnum, CORE_ADDR addr)
+amd64_linux_dr_set_addr (ptid_t ptid, int regnum, CORE_ADDR addr)
 {
   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
 
-  amd64_linux_dr_set (DR_FIRSTADDR + regnum, addr);
+  amd64_linux_dr_set (ptid, DR_FIRSTADDR + regnum, addr);
 }
 
 void
-amd64_linux_dr_reset_addr (int regnum)
+amd64_linux_dr_reset_addr (ptid_t ptid, int regnum)
 {
   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
 
-  amd64_linux_dr_set (DR_FIRSTADDR + regnum, 0L);
+  amd64_linux_dr_set (ptid, DR_FIRSTADDR + regnum, 0L);
 }
 
 unsigned long
-amd64_linux_dr_get_status (void)
+amd64_linux_dr_get_status (ptid_t ptid)
 {
-  return amd64_linux_dr_get (DR_STATUS);
+  return amd64_linux_dr_get (ptid, DR_STATUS);
 }
 
 
+/* Structure used to sync debug registers for all threads.  */
+struct amd64_debug_register_state
+{
+  int tid;
+  CORE_ADDR addr[DR_LASTADDR - DR_FIRSTADDR + 1];
+  unsigned long control;
+};
+
+static void
+amd64_linux_set_debug_regs_for_thread (ptid_t ptid,
+				       struct amd64_debug_register_state *dbs)
+{
+  int i;
+  for (i = 0; i < (DR_LASTADDR - DR_FIRSTADDR) + 1; ++i)
+    amd64_linux_dr_set_addr (ptid, i, dbs->addr[i]);
+  amd64_linux_dr_set_control (ptid, dbs->control);
+}
+
+/* Iterator function to support syncing debug registers across all threads.  */
+static int
+amd64_linux_sync_debug_registers_callback (struct lwp_info *lwp, void *data)
+{
+  struct amd64_debug_register_state *args = data;
+  int i, tid;
+
+  tid = TIDGET (lwp->ptid);
+  if (tid == 0)
+    tid = PIDGET (lwp->ptid);
+
+  if (tid != args->tid)
+    amd64_linux_set_debug_regs_for_thread (lwp->ptid, args);
+  return 0;
+}
+
+/* Sync the debug registers for all known threads to the current
+   thread that has just performed an operation.  This is required
+   because the debug registers are thread-specific.  We want
+   watchpoints and hardware breakpoints to be treated globally
+   across all threads.  */
+static int
+amd64_linux_sync_debug_registers_across_threads (void)
+{
+  int i, tid;
+  struct amd64_debug_register_state args;
+
+  tid = TIDGET (inferior_ptid);
+  if (tid == 0)
+    tid = PIDGET (inferior_ptid);
+
+  args.tid = tid;
+  for (i = 0; i < (DR_LASTADDR - DR_FIRSTADDR) + 1; ++i)
+    args.addr[i] = amd64_linux_dr_get (inferior_ptid, DR_FIRSTADDR + i);
+  args.control = amd64_linux_dr_get (inferior_ptid, DR_CONTROL);
+
+  iterate_over_lwps (&amd64_linux_sync_debug_registers_callback, &args);
+
+  return 0;
+}
+
+/* Insert a watchpoint to watch a memory region which starts at
+   address ADDR and whose length is LEN bytes.  Watch memory accesses
+   of the type TYPE.  Return 0 on success, -1 on failure.  */
+int
+amd64_linux_insert_watchpoint (CORE_ADDR addr, int len, int type)
+{
+  int rc;
+  rc = i386_insert_watchpoint (addr, len, type);
+  if (!rc)
+    amd64_linux_sync_debug_registers_across_threads ();
+  return rc;
+}
+
+/* Remove a watchpoint that watched the memory region which starts at
+   address ADDR, whose length is LEN bytes, and for accesses of the
+   type TYPE.  Return 0 on success, -1 on failure.  */
+int
+amd64_linux_remove_watchpoint (CORE_ADDR addr, int len, int type)
+{
+  int rc;
+  rc = i386_remove_watchpoint (addr, len, type);
+  if (!rc)
+    amd64_linux_sync_debug_registers_across_threads ();
+  return rc;
+}
+
+/* Insert a hardware-assisted breakpoint at address ADDR.  SHADOW is
+   unused.  Return 0 on success, EBUSY on failure.  */
+int
+amd64_linux_insert_hw_breakpoint (struct bp_target_info *bp_tgt)
+{
+  int rc;
+  rc = i386_insert_hw_breakpoint (bp_tgt);
+  if (!rc)
+    amd64_linux_sync_debug_registers_across_threads ();
+  return rc;
+}
+
+/* Remove a hardware-assisted breakpoint at address ADDR.  SHADOW is
+   unused.  Return 0 on success, -1 on failure.  */
+int
+amd64_linux_remove_hw_breakpoint (struct bp_target_info *bp_tgt)
+{
+  int rc;
+  rc = i386_remove_hw_breakpoint (bp_tgt);
+  if (!rc)
+    amd64_linux_sync_debug_registers_across_threads ();
+  return rc;
+}
+
+/* Observer function for a new thread attach.  We need to insert
+   existing watchpoints and hardware breakpoints on the new thread.  */
+static void
+amd64_linux_new_thread (ptid_t ptid)
+{
+  int i;
+  struct amd64_debug_register_state dbs;
+
+  for (i = 0; i < (DR_LASTADDR - DR_FIRSTADDR) + 1; ++i)
+    dbs.addr[i] = amd64_linux_dr_get (inferior_ptid, DR_FIRSTADDR + i);
+  dbs.control = amd64_linux_dr_get (inferior_ptid, DR_CONTROL);
+
+  amd64_linux_set_debug_regs_for_thread (ptid, &dbs);
+}
+
 /* This function is called by libthread_db as part of its handling of
    a request for a thread's local storage address.  */
 
@@ -406,4 +531,6 @@ _initialize_amd64_linux_nat (void)
 
   /* Register the target.  */
   linux_nat_add_target (t);
+
+  observer_attach_linux_new_thread (amd64_linux_new_thread);
 }
Index: gdb-6.7/gdb/testsuite/gdb.threads/watchthreads.c
===================================================================
--- gdb-6.7.orig/gdb/testsuite/gdb.threads/watchthreads.c	2007-08-23 20:08:50.000000000 +0200
+++ gdb-6.7/gdb/testsuite/gdb.threads/watchthreads.c	2007-10-14 23:39:04.000000000 +0200
@@ -56,7 +56,7 @@ void *thread_function(void *arg) {
     /* Don't run forever.  Run just short of it :)  */
     while (*myp > 0)
       {
-	(*myp) ++;  /* Loop increment.  */
+	(*myp) ++; usleep (1); /* Loop increment.  */
       }
 
     pthread_exit(NULL);