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gdb/remote: do not check for null_ptid in stop reply 

A gdbserver does not report a ptid in a 'W' or 'X' packet if multi-process
extensions are not supported or turned off.  See

https://sourceware.org/gdb/current/onlinedocs/gdb/General-Query-Packets.html#multiprocess-extensions
https://sourceware.org/gdb/current/onlinedocs/gdb/Stop-Reply-Packets.html#Stop-Reply-Packets

GDB's remote packet parser checks for whether a stop-reply packet
contains a ptid if the target is non-stop, and issues an error if no
ptid is included:

  if (target_is_non_stop_p () && event->ptid == null_ptid)
    error (_("No process or thread specified in stop reply: %s"), buf);

This leads to the following error when the non-stop
mode is turned on but multi-process extensions are off:

  $ gdb
  (gdb) set non-stop on
  (gdb) set remote multiprocess-feature-packet off
  (gdb) target remote | gdbserver - ./foo
  Remote debugging using | gdbserver - ./foo
  stdin/stdout redirected
  Process ./foo created; pid = 3712
  ...
  (gdb) continue
  Continuing.
  ...
  No process or thread specified in stop reply: W2a
  (gdb)

Because the check is done for stop reply packets in general, a similar
situation occurs if the 'T' or 'Tthread' packet is disabled in
gdbserver (i.e.  via --disable-packet=T).  E.g:

  $ gdb
  (gdb) set non-stop on
  (gdb) target remote | gdbserver --disable-packet=Tthread - ./foo
  ...
  No process or thread specified in stop reply: T0506:0000000000000000;07:10e2ffffff7f0000;10:9060ddf7ff7f0000;

or

  $ gdb
  (gdb) set non-stop on
  (gdb) target remote | gdbserver --disable-packet=T - ./foo
  ...
  No process or thread specified in stop reply: S05

The commit

  commit cada5fc921
  Date:   Wed Mar 11 12:30:13 2020 +0000

      gdb: Handle W and X remote packets without giving a warning

and its predecessor

  commit 24ed6739b6
  Date:   Thu Jan 30 14:35:40 2020 +0000

      gdb/remote: Restore support for 'S' stop reply packet

added warnings for when GDB has to make a guess for a missing ptid in
case of multiple threads/inferiors.  These warnings should suffice.
So, the simple solution is to remove the check completely.

Regression-tested on X86_64 Linux.

gdb/ChangeLog:
2020-04-01  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* remote.c (remote_target::remote_parse_stop_reply): Remove the
	check for no ptid in the stop reply when the target is non-stop.

gdb/testsuite/ChangeLog:
2020-04-01  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* gdb.server/stop-reply-no-thread.exp: Enhance the test
	scenario to cover execution until the end and also the case
	when no packet is disabled when starting gdbserver.
This commit is contained in:
Tankut Baris Aktemur 2020-04-01 16:57:39 +02:00
parent e0802d5996
commit e139a727be
4 changed files with 30 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
gdb/ChangeLog
View File

@ -1,3 +1,8 @@
2020-04-01 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
* remote.c (remote_target::remote_parse_stop_reply): Remove the
check for no ptid in the stop reply when the target is non-stop.
2020-04-01 Tom Tromey <tromey@adacore.com>
* symtab.h (class lookup_name_info) <lookup_name_info>: Change

3
gdb/remote.c
View File

@ -7561,9 +7561,6 @@ Packet: '%s'\n"),
event->ptid = minus_one_ptid;
break;
}
if (target_is_non_stop_p () && event->ptid == null_ptid)
error (_("No process or thread specified in stop reply: %s"), buf);
}
/* When the stub wants to tell GDB about a new notification reply, it

5
gdb/testsuite/ChangeLog
View File

@ -1,3 +1,8 @@
2020-04-01 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
* gdb.server/stop-reply-no-thread.exp: Enhance the test
scenario to cover execution until the end and also the case
2020-03-31 Tom de Vries <tdevries@suse.de>
* gdb.base/c-linkage-name.exp: Fix test-case comment. Set language to

24
gdb/testsuite/gdb.server/stop-reply-no-thread.exp
View File

@ -33,7 +33,7 @@ if [prepare_for_testing "failed to prepare" $testfile $srcfile] {
}
# Run the tests with different features of GDBserver disabled.
proc run_test { disable_feature } {
proc run_test { disable_feature target_nonstop } {
global binfile gdb_prompt decimal
clean_restart ${binfile}
@ -42,7 +42,11 @@ proc run_test { disable_feature } {
# extended-remote board, therefore already connected.
gdb_test "disconnect" ".*"
set res [gdbserver_start "--disable-packet=${disable_feature}" $binfile]
set packet_arg ""
if { $disable_feature != "" } {
set packet_arg "--disable-packet=${disable_feature}"
}
set res [gdbserver_start $packet_arg $binfile]
set gdbserver_protocol [lindex $res 0]
set gdbserver_gdbport [lindex $res 1]
@ -50,6 +54,9 @@ proc run_test { disable_feature } {
gdb_test_no_output "set remote threads-packet off"
gdb_test_no_output "set remote multiprocess-feature-packet off"
# Set target-nonstop mode.
gdb_test_no_output "maint set target-non-stop ${target_nonstop}"
set res [gdb_target_cmd $gdbserver_protocol $gdbserver_gdbport]
if ![gdb_assert {$res == 0} "connect"] {
return
@ -76,6 +83,13 @@ proc run_test { disable_feature } {
# Cannot execute this command without a live selected thread.
# (gdb)
gdb_test "c" "Breakpoint $decimal, main.*" "continue to main"
# Continue until exit. The server sends a 'W' with no PID.
# Bad GDB gave an error like below when target is nonstop:
# (gdb) c
# Continuing.
# No process or thread specified in stop reply: W00
gdb_continue_to_end "" continue 1
}
# Disable different features within gdbserver:
@ -85,6 +99,8 @@ proc run_test { disable_feature } {
#
# T: Start GDBserver with the entire 'T' stop reply packet disabled,
# GDBserver will instead send the 'S' stop reply.
foreach_with_prefix to_disable { Tthread T } {
run_test $to_disable
foreach_with_prefix to_disable { "" Tthread T } {
foreach_with_prefix t_nonstop { off on } {
run_test $to_disable $t_nonstop
}
}