gdb: Avoid using W_STOPCODE(0) as this is ambiguous on MIPS

The MIPS target supports 127 signals, and this can create an ambiguity
in process wait statuses.  A status value of 0x007f could potentially
indicate a process that has exited with signal 127, or a process that
has stopped with signal 0.

In uClibc-ng the interpretation of 0x007f is that the process has
exited with signal 127 rather than stopped with signal 0, and so,
WIFSTOPPED (W_STOPCODE (0)) will be false rather than true as it would
be on most other platforms.

Given that it's pretty easy to avoid using W_STOPCODE (0), lets do that.

gdb/ChangeLog:

	* linux-nat.c (linux_nat_target::follow_fork): Avoid using
	'W_STOPCODE (0)' as this could be ambiguous.
This commit is contained in:
Andrew Burgess 2018-07-03 19:02:48 +01:00
parent e968fc9b63
commit 9534733755
2 changed files with 17 additions and 4 deletions

View File

@ -1,3 +1,9 @@
2018-08-06 Sergey Korolev <s.korolev@ndmsystems.com>
Andrew Burgess <andrew.burgess@embecosm.com>
* linux-nat.c (linux_nat_target::follow_fork): Avoid using
'W_STOPCODE (0)' as this could be ambiguous.
2018-08-03 Sergio Durigan Junior <sergiodj@redhat.com>
* ser-tcp.c (net_open): Fix thinko when deciding whether to

View File

@ -445,7 +445,6 @@ linux_nat_target::follow_fork (int follow_child, int detach_fork)
if (!follow_child)
{
struct lwp_info *child_lp = NULL;
int status = W_STOPCODE (0);
int has_vforked;
ptid_t parent_ptid, child_ptid;
int parent_pid, child_pid;
@ -465,6 +464,8 @@ linux_nat_target::follow_fork (int follow_child, int detach_fork)
/* Detach new forked process? */
if (detach_fork)
{
int child_stop_signal = 0;
bool detach_child = true;
struct cleanup *old_chain = make_cleanup (delete_lwp_cleanup,
child_lp);
@ -484,18 +485,24 @@ linux_nat_target::follow_fork (int follow_child, int detach_fork)
if (!gdbarch_software_single_step_p (target_thread_architecture
(parent_ptid)))
{
int status;
linux_disable_event_reporting (child_pid);
if (ptrace (PTRACE_SINGLESTEP, child_pid, 0, 0) < 0)
perror_with_name (_("Couldn't do single step"));
if (my_waitpid (child_pid, &status, 0) < 0)
perror_with_name (_("Couldn't wait vfork process"));
else
{
detach_child = WIFSTOPPED (status);
child_stop_signal = WSTOPSIG (status);
}
}
if (WIFSTOPPED (status))
if (detach_child)
{
int signo;
int signo = child_stop_signal;
signo = WSTOPSIG (status);
if (signo != 0
&& !signal_pass_state (gdb_signal_from_host (signo)))
signo = 0;