First, PL_FLAG_FORKED events now also set a PL_FLAG_VFORKED flag when
the new child was created via vfork() rather than fork(). Second, a
new PL_FLAG_VFORK_DONE event can now be enabled via the PTRACE_VFORK
event mask. This new stop is reported after the vfork parent resumes
due to the child calling exit or exec. Debuggers can use this stop to
reinsert breakpoints in the vfork parent process before it resumes.
Reviewed by: kib
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D7045
ptrace() now stores a mask of optional events in p_ptevents. Currently
this mask is a single integer, but it can be expanded into an array of
integers in the future.
Two new ptrace requests can be used to manipulate the event mask:
PT_GET_EVENT_MASK fetches the current event mask and PT_SET_EVENT_MASK
sets the current event mask.
The current set of events include:
- PTRACE_EXEC: trace calls to execve().
- PTRACE_SCE: trace system call entries.
- PTRACE_SCX: trace syscam call exits.
- PTRACE_FORK: trace forks and auto-attach to new child processes.
- PTRACE_LWP: trace LWP events.
The S_PT_SCX and S_PT_SCE events in the procfs p_stops flags have
been replaced by PTRACE_SCE and PTRACE_SCX. PTRACE_FORK replaces
P_FOLLOW_FORK and PTRACE_LWP replaces P2_LWP_EVENTS.
The PT_FOLLOW_FORK and PT_LWP_EVENTS ptrace requests remain for
compatibility but now simply toggle corresponding flags in the
event mask.
While here, document that PT_SYSCALL, PT_TO_SCE, and PT_TO_SCX both
modify the event mask and continue the traced process.
Reviewed by: kib
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D7044
Rather than pushing all eight possible arguments into dtrace_probe()'s
stack frame, make the syscall_args struct for the current syscall available
via the current thread. Using a custom getargval method for the systrace
provider, this allows any syscall argument to be fetched, even in kernels
that have modified the maximum number of system call arguments.
Sponsored by: EMC / Isilon Storage Division
For CloudABI we need to initialize the registers of new threads
differently based on whether the thread got created through a fork or
through simple thread creation.
Add a flag, TDP_FORKING, that is set by do_fork() and cleared by
fork_exit(). This can be tested against in schedtail.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D3973
- Always set td_dbg_sc_* when P_TRACED is set on system call entry
even if the debugger is not tracing system call entries. This
ensures the fields are valid when reporting other stops that
occur at system call boundaries such as for PT_FOLLOW_FORKS or
when only tracing system call exits.
- Set TDB_SCX when reporting the stop for a new child process in
fork_return(). This causes the event to be reported as a system
call exit.
- Report a system call exit event in fork_return() for new threads in
a traced process.
- Copy td_dbg_sc_* to new threads instead of zeroing. This ensures
that td_dbg_sc_code in particular will report the system call that
created the new thread or process when it reports a system call
exit event in fork_return().
- Add new ptrace tests to verify that new child processes and threads
report system call exit events with a valid pl_syscall_code via
PT_LWPINFO.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D3822
TDB_USERWR flag may still be set after a debugger detaches from a
process via PT_DETACH. Previously the flag would never be cleared
forcing a double fetch of the system call arguments for each system
call. Note that the flag cannot be cleared at PT_DETACH time in case
one of the threads in the process is currently stopped in
syscallenter() and the debugger has modified the arguments for that
pending system call before detaching.
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D3678
and exit events. procfs stop events for system call tracing report these
values (argument count for system call entry and code for system call exit),
but ptrace() does not provide this information. (Note that while the system
call code can be determined in an ABI-specific manner during system call
entry, it is not generally available during system call exit.)
The values are exported via new fields at the end of struct ptrace_lwpinfo
available via PT_LWPINFO.
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D3536
Thread credentials are maintained as follows: each thread has a pointer to
creds and a reference on them. The pointer is compared with proc's creds on
userspace<->kernel boundary and updated if needed.
This patch introduces a counter which can be compared instead, so that more
structures can use this scheme without adding more comparisons on the boundary.
for the suspension.
Currently, the loop performs uninterruptible cv_wait(9) call, which
prevents suspension until child allows further execution of parent.
If child is stopped, suspension or single-threading is delayed
indefinitely.
Create a helper thread_suspend_check_needed() to identify the need for
a call to thread_suspend_check(). It is required since call to the
thread_suspend_check() cannot be safely done while owning the child
(p2) process lock. Only when suspension is needed, drop p2 lock and
call thread_suspend_check(). Perform wait for cv with timeout, in
case suspend is requested after wait started; I do not see a better
way to interrupt the wait.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
further refinement is required as some device drivers intended to be
portable over FreeBSD versions rely on __FreeBSD_version to decide whether
to include capability.h.
MFC after: 3 weeks
option, unbreak the lock tracing release semantic by embedding
calls to LOCKSTAT_PROFILE_RELEASE_LOCK() direclty in the inlined
version of the releasing functions for mutex, rwlock and sxlock.
Failing to do so skips the lockstat_probe_func invokation for
unlocking.
- As part of the LOCKSTAT support is inlined in mutex operation, for
kernel compiled without lock debugging options, potentially every
consumer must be compiled including opt_kdtrace.h.
Fix this by moving KDTRACE_HOOKS into opt_global.h and remove the
dependency by opt_kdtrace.h for all files, as now only KDTRACE_FRAMES
is linked there and it is only used as a compile-time stub [0].
[0] immediately shows some new bug as DTRACE-derived support for debug
in sfxge is broken and it was never really tested. As it was not
including correctly opt_kdtrace.h before it was never enabled so it
was kept broken for a while. Fix this by using a protection stub,
leaving sfxge driver authors the responsibility for fixing it
appropriately [1].
Sponsored by: EMC / Isilon storage division
Discussed with: rstone
[0] Reported by: rstone
[1] Discussed with: philip
- Use this new format to automatically handle syscalls and VOPs. This
changes the earlier format but is still human readable.
Sponsored by: EMC / Isilon Storage Division
TDP_NOSLEEPING leaking from syscallret() to userret() so that also
trap handling is covered. Also, the check on td_locks is not duplicated
between the two functions.
Reported by: avg
Reviewed by: kib
MFC after: 1 week
in td_errno. Flag is supposed to be used by syscalls returning
EJUSTRETURN because errno was already placed into the usermode frame
by a call to set_syscall_retval(9). Both ktrace and dtrace get errno
value from td_errno if the flag is set.
Use the flag to fix sigsuspend(2) error return ktrace records.
Requested by: bde
MFC after: 1 week
not get syscall exit notification until the child performed exec of
exit. Swap the order of doing ptracestop() and waiting for P_PPWAIT
clearing, by postponing the wait into syscallret after ptracestop()
notification is done.
Reported, tested and reviewed by: Dmitry Mikulin <dmitrym juniper net>
MFC after: 2 weeks
about new child not only when doing PT_TO_SCX, but also for PT_CONTINUE.
If TDB_FORK flag is set, always issue a stop, the same as is done for
TDB_EXEC.
Reported by: Dmitry Mikulin <dmitrym juniper net>
MFC after: 1 week
syscall exit path. Otherwise, if SIGTRAP is ignored, that tdsendsignal()
do not want to deliver the signal, and debugger never get a notification
of exec.
Found and tested by: Anton Yuzhaninov <citrin citrin ru>
Discussed with: jhb
MFC after: 2 weeks
