Fix for newer kernels with: t (tracing stop)
Commit Message
Hi,
I did provide wrong ptrace data which should fail on their write.
error (_("Unexpected error setting hardware debug registers"));
But GDB did not print that error, only inferior did hang, because the data was
not written.
It is because this error/exception gets suppressed by:
linux_resume_one_lwp():
1578 if (!check_ptrace_stopped_lwp_gone (lp))
1579 throw_exception (ex);
Which happens because check_ptrace_stopped_lwp_gone()
expects 'T (tracing stop)' while recent Linux kernels
provide 't (tracing stop)' instad.
What does lowercase t means in ps state code
http://stackoverflow.com/questions/35895886/what-does-lowercase-t-means-in-ps-state-code
Found it on:
kernel-4.4.6-301.fc23.aarch64
by:
gdb/nat/aarch64-linux-hw-point.c
- ctrl |= ((1 << len) - 1) << 5;
+ ctrl |= (((1 << len) - 1)&~1) << 5;
It does not change testsuite results on that F-23.aarch64 machine.
I see no real regessions on rawhide.x86_64 machine (with F-23 kernel) although
there were some fuzzy results I will need to check more.
OK for check-in?
Thanks,
Jan
gdb/ChangeLog
2016-06-04 Jan Kratochvil <jan.kratochvil@redhat.com>
* nat/linux-procfs.c (linux_proc_pid_has_state): Add parameter state2.
(linux_proc_pid_is_stopped): Update caller.
(linux_proc_pid_is_trace_stopped_nowarn): Add 't (tracing stop)'.
(linux_proc_pid_is_zombie_maybe_warn): Update caller.
Comments
On 06/04/2016 01:29 PM, Jan Kratochvil wrote:
> Hi,
>
> I did provide wrong ptrace data which should fail on their write.
> error (_("Unexpected error setting hardware debug registers"));
> But GDB did not print that error, only inferior did hang, because the data was
> not written.
>
> It is because this error/exception gets suppressed by:
> linux_resume_one_lwp():
> 1578 if (!check_ptrace_stopped_lwp_gone (lp))
> 1579 throw_exception (ex);
>
> Which happens because check_ptrace_stopped_lwp_gone()
> expects 'T (tracing stop)' while recent Linux kernels
> provide 't (tracing stop)' instad.
> What does lowercase t means in ps state code
> http://stackoverflow.com/questions/35895886/what-does-lowercase-t-means-in-ps-state-code
Eh, I'm not sure how I ended up with "T (tracing stop)"
in the first place last year, as I think I was on Fedora 20,
and lowercase "t (tracing stop)" is around since 2009.
>
> Found it on:
> kernel-4.4.6-301.fc23.aarch64
> by:
> gdb/nat/aarch64-linux-hw-point.c
> - ctrl |= ((1 << len) - 1) << 5;
> + ctrl |= (((1 << len) - 1)&~1) << 5;
>
> It does not change testsuite results on that F-23.aarch64 machine.
> I see no real regessions on rawhide.x86_64 machine (with F-23 kernel) although
> there were some fuzzy results I will need to check more.
>
> OK for check-in?
OK.
I wonder whether it wouldn't simplify things to parse the
state into some new enum lwp_state instead of the current scheme
of passing state strings around. I may give that a try as follow up.
Thanks,
Pedro Alves
@@ -129,17 +129,20 @@ linux_proc_pid_is_gone (pid_t pid)
}
}
-/* Return non-zero if 'State' of /proc/PID/status contains STATE. If
- WARN, warn on failure to open the /proc file. */
+/* Return non-zero if 'State' of /proc/PID/status contains STATE or STATE2.
+ STATE2 can be NULL. If WARN, warn on failure to open the /proc file. */
static int
-linux_proc_pid_has_state (pid_t pid, const char *state, int warn)
+linux_proc_pid_has_state (pid_t pid, const char *state, const char *state2,
+ int warn)
{
char buffer[100];
int have_state;
have_state = linux_proc_pid_get_state (pid, buffer, sizeof buffer, warn);
- return (have_state > 0 && strstr (buffer, state) != NULL);
+ return (have_state > 0
+ && (strstr (buffer, state) != NULL
+ || (state2 != NULL && strstr (buffer, state2) != NULL)));
}
/* Detect `T (stopped)' in `/proc/PID/status'.
@@ -148,16 +151,18 @@ linux_proc_pid_has_state (pid_t pid, const char *state, int warn)
int
linux_proc_pid_is_stopped (pid_t pid)
{
- return linux_proc_pid_has_state (pid, "T (stopped)", 1);
+ return linux_proc_pid_has_state (pid, "T (stopped)", NULL, 1);
}
-/* Detect `T (tracing stop)' in `/proc/PID/status'.
- Other states including `T (stopped)' are reported as false. */
+/* Detect `t (tracing stop)' or `T (tracing stop)' (present in older
+ kernels) in `/proc/PID/status'. Other states including `T (stopped)'
+ are reported as false. */
int
linux_proc_pid_is_trace_stopped_nowarn (pid_t pid)
{
- return linux_proc_pid_has_state (pid, "T (tracing stop)", 1);
+ return linux_proc_pid_has_state (pid, "t (tracing stop)", "T (tracing stop)",
+ 1);
}
/* Return non-zero if PID is a zombie. If WARN, warn on failure to
@@ -166,7 +171,7 @@ linux_proc_pid_is_trace_stopped_nowarn (pid_t pid)
static int
linux_proc_pid_is_zombie_maybe_warn (pid_t pid, int warn)
{
- return linux_proc_pid_has_state (pid, "Z (zombie)", warn);
+ return linux_proc_pid_has_state (pid, "Z (zombie)", NULL, warn);
}
/* See linux-procfs.h declaration. */