o Remove the obscure tid command, because it does what the thread

   command does, but worse.
o  Remove the obscure proc command, because it does what the thread
   command does, but not unambigously.
o  Move the PID to the extra thread info, where it makes sense and
   where it doesn't confuse users. The extra thread info holds some
   process information, to which the PID belongs.
o  Implement the to_find_new_threads target method by having it call
   the target beneath us if we're not using KVM. This makes sure that
   new threads are found when using the remote target.

o  Fix various core dump scenarios:
   -  Implement the to_files_info target method. Previously the
      'info target' command would cause a NULL pointer dereference.
   -  Don't assume there's a current thread. We're not initialized
      in all cases. This prevents a NULL pointer dereference.
   -  When we're not ussing KVM, have the to_xfer_memory target
      method call the target beneath us. This avoids calling into
      KVM with a NULL pointer.

MFC after: 1 week

1 files changed, 41 insertions, 100 deletions

diff --git a/gnu/usr.bin/gdb/kgdb/trgt.c b/gnu/usr.bin/gdb/kgdb/trgt.c
index 93cac11..87487ce 100644
--- a/gnu/usr.bin/gdb/kgdb/trgt.c
+++ b/gnu/usr.bin/gdb/kgdb/trgt.c
@@ -44,36 +44,40 @@ __FBSDID("$FreeBSD$");
 
 static struct target_ops kgdb_trgt_ops;
 
-#define	KERNOFF		(kgdb_kernbase ())
-#define	INKERNEL(x)	((x) >= KERNOFF)
-
-static CORE_ADDR
-kgdb_kernbase (void)
+static char *
+kgdb_trgt_extra_thread_info(struct thread_info *ti)
 {
-	static CORE_ADDR kernbase;
-	struct minimal_symbol *sym;
- 
-	if (kernbase == 0)
-	{
-		sym = lookup_minimal_symbol ("kernbase", NULL, NULL);
-		if (sym == NULL) {
-			kernbase = KERNBASE;
-		} else {
-			kernbase = SYMBOL_VALUE_ADDRESS (sym);
-		}
-	}
-	return kernbase;
+	static char buf[64];
+	char *p, *s;
+
+	p = buf + snprintf(buf, sizeof(buf), "PID=%d", ptid_get_pid(ti->ptid));
+	s = kgdb_thr_extra_thread_info(ptid_get_tid(ti->ptid));
+	if (s != NULL)
+		snprintf(p, sizeof(buf) - (p - buf), ": %s", s);
+	return (buf);
 }
 
-static char *
-kgdb_trgt_extra_thread_info(struct thread_info *ti)
+static void
+kgdb_trgt_files_info(struct target_ops *target)
 {
-	return (kgdb_thr_extra_thread_info(ptid_get_tid(ti->ptid)));
+	struct target_ops *tb;
+
+	tb = find_target_beneath(target);
+	if (tb->to_files_info != NULL)
+		tb->to_files_info(tb);
 }
 
 static void
 kgdb_trgt_find_new_threads(void)
 {
+	struct target_ops *tb;
+
+	if (kvm != NULL)
+		return;
+
+	tb = find_target_beneath(&kgdb_trgt_ops);
+	if (tb->to_find_new_threads != NULL)
+		tb->to_find_new_threads();
 }
 
 static char *
@@ -81,8 +85,7 @@ kgdb_trgt_pid_to_str(ptid_t ptid)
 {
 	static char buf[33];
 
-	snprintf(buf, sizeof(buf), "PID %5d TID %5ld", ptid_get_pid(ptid),
-		ptid_get_tid(ptid));
+	snprintf(buf, sizeof(buf), "Thread %ld", ptid_get_tid(ptid));
 	return (buf);
 }
 
@@ -94,80 +97,20 @@ kgdb_trgt_thread_alive(ptid_t ptid)
 
 static int
 kgdb_trgt_xfer_memory(CORE_ADDR memaddr, char *myaddr, int len, int write,
-    struct mem_attrib *attrib __unused, struct target_ops *target __unused)
+    struct mem_attrib *attrib, struct target_ops *target)
 {
-	if (len == 0)
-		return (0);
-
-	if (!write)
-		return (kvm_read(kvm, memaddr, myaddr, len));
-	else
-		return (kvm_write(kvm, memaddr, myaddr, len));
-}
-
-static void
-kgdb_switch_to_thread(struct kthr *thr)
-{
-	if (thr->tid == ptid_get_tid(inferior_ptid))
-		return;
-
-	inferior_ptid = ptid_build(thr->pid, 0, thr->tid);
-	flush_cached_frames ();
-	registers_changed ();
-	stop_pc = read_pc ();
-	select_frame (get_current_frame ());
-}
-
-static void
-kgdb_set_proc_cmd (char *arg, int from_tty)
-{
-	CORE_ADDR addr;
-	struct kthr *thr;
-
-	if (!arg)
-		error_no_arg ("proc address for the new context");
-
-	if (kvm == NULL)
-		error ("no kernel core file");
-
-	addr = (CORE_ADDR) parse_and_eval_address (arg);
-
-	if (!INKERNEL (addr)) {
-		thr = kgdb_thr_lookup_pid((int)addr);
-		if (thr == NULL)
-			error ("invalid pid");
-	} else {
-		thr = kgdb_thr_lookup_paddr(addr);
-		if (thr == NULL)
-			error("invalid proc address");
-	}
-	kgdb_switch_to_thread(thr);
-}
-
-static void
-kgdb_set_tid_cmd (char *arg, int from_tty)
-{
-	CORE_ADDR addr;
-	struct kthr *thr;
-
-	if (!arg)
-		error_no_arg ("TID or thread address for the new context");
-
-	if (kvm == NULL)
-		error ("no kernel core file");
-
-	addr = (CORE_ADDR) parse_and_eval_address (arg);
-
-	if (!INKERNEL (addr)) {
-		thr = kgdb_thr_lookup_tid((int)addr);
-		if (thr == NULL)
-			error ("invalid TID");
-	} else {
-		thr = kgdb_thr_lookup_taddr(addr);
-		if (thr == NULL)
-			error("invalid thread address");
+	struct target_ops *tb;
+
+	if (kvm != NULL) {
+		if (len == 0)
+			return (0);
+		if (!write)
+			return (kvm_read(kvm, memaddr, myaddr, len));
+		else
+			return (kvm_write(kvm, memaddr, myaddr, len));
 	}
-	kgdb_switch_to_thread(thr);
+	tb = find_target_beneath(target);
+	return (tb->to_xfer_memory(memaddr, myaddr, len, write, attrib, tb));
 }
 
 void
@@ -187,6 +130,7 @@ kgdb_target(void)
 
 	kgdb_trgt_ops.to_extra_thread_info = kgdb_trgt_extra_thread_info;
 	kgdb_trgt_ops.to_fetch_registers = kgdb_trgt_fetch_registers;
+	kgdb_trgt_ops.to_files_info = kgdb_trgt_files_info;
 	kgdb_trgt_ops.to_find_new_threads = kgdb_trgt_find_new_threads;
 	kgdb_trgt_ops.to_pid_to_str = kgdb_trgt_pid_to_str;
 	kgdb_trgt_ops.to_store_registers = kgdb_trgt_store_registers;
@@ -200,9 +144,6 @@ kgdb_target(void)
 		ti = add_thread(ptid_build(kt->pid, 0, kt->tid));
 		kt = kgdb_thr_next(kt);
 	}
-	inferior_ptid = ptid_build(curkthr->pid, 0, curkthr->tid);
-	add_com ("proc", class_obscure, kgdb_set_proc_cmd,
-	   "Set current process context");
-	add_com ("tid", class_obscure, kgdb_set_tid_cmd,
-	   "Set current process context");
+	if (curkthr != 0)
+		inferior_ptid = ptid_build(curkthr->pid, 0, curkthr->tid);
 }