Call kthread_exit() rather than kproc_exit() for a premature kthread exit.

Kernel threads (and processes) are supposed to call kthread_exit() (or
kproc_exit()) to terminate. However, the kernel inc

Call kthread_exit() rather than kproc_exit() for a premature kthread exit.

Kernel threads (and processes) are supposed to call kthread_exit() (or
kproc_exit()) to terminate. However, the kernel includes a fallback in
fork_exit() to force a kthread exit if a kernel thread's "main" routine
returns. This fallback was added back when the kernel only had processes
and was not updated to call kthread_exit() instead of kproc_exit() when
threads were added to the kernel.

This mistake was particular exciting when the errant thread belonged to
proc0. Due to the missing P_KTHREAD flag the fallback did not kick in
and instead tried to return to userland via whatever garbage was in the
trapframe. With P_KTHREAD set it tried to terminate proc0 resulting in
other amusements.

PR: 204999
MFC after: 1 week

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MFH

Sponsored by: The FreeBSD Foundation

Merge ^/head r294961 through r295350.

fork: ansify sys_pdfork

No functional changes.

Guard against runnable td2 exiting and than being reused for unrelated
process when the parent sleeps waiting for the debugger attach on
fork.

Diagnosed and reviewed by: mjg
Sponsored by: The FreeBS

Guard against runnable td2 exiting and than being reused for unrelated
process when the parent sleeps waiting for the debugger attach on
fork.

Diagnosed and reviewed by: mjg
Sponsored by: The FreeBSD Foundation

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fork: plug a use after free of the returned process

fork1 required its callers to pass a pointer to struct proc * which would
be set to the new process (if any). procdesc and racct manipulation also

fork: plug a use after free of the returned process

fork1 required its callers to pass a pointer to struct proc * which would
be set to the new process (if any). procdesc and racct manipulation also
used said pointer.

However, the process could have exited prior to do_fork return and be
automatically reaped, thus making this a use-after-free.

Fix the problem by letting callers indicate whether they want the pid or
the struct proc, return the process in stopped state for the latter case.

Reviewed by: kib

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fork: pass arguments to fork1 in a dedicated structure

Suggested by: kib

MFH @r294567

MFH r289384-r293170

Sponsored by: The FreeBSD Foundation

Add ptrace(2) reporting for LWP events.

Add two new LWPINFO flags: PL_FLAG_BORN and PL_FLAG_EXITED for reporting
thread creation and destruction. Newly created threads will stop to report
PL_FLAG_BO

Add ptrace(2) reporting for LWP events.

Add two new LWPINFO flags: PL_FLAG_BORN and PL_FLAG_EXITED for reporting
thread creation and destruction. Newly created threads will stop to report
PL_FLAG_BORN before returning to userland and exiting threads will stop to
report PL_FLAG_EXIT before exiting completely. Both of these events are
only enabled and reported if PT_LWP_EVENTS is enabled on a process.

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MFH @r292599

This includes the pluggable TCP framework and other chnages to the
netstack to track for VNET stability.

Security: The FreeBSD Foundation

Fix style issues around existing SDT probes.

- Use SDT_PROBE<N>() instead of SDT_PROBE(). This has no functional effect
at the moment, but will be needed for some future changes.
- Don't hardcode

Fix style issues around existing SDT probes.

- Use SDT_PROBE<N>() instead of SDT_PROBE(). This has no functional effect
at the moment, but will be needed for some future changes.
- Don't hardcode the module component of the probe identifier. This is
set automatically by the SDT framework.

MFC after: 1 week

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Catch up with head (r291075).

Merge from head

Merge from head

Sponsored by: Gandi.net

Add a way to distinguish between forking and thread creation in schedtail.

For CloudABI we need to initialize the registers of new threads
differently based on whether the thread got created through

Add a way to distinguish between forking and thread creation in schedtail.

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

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Merge from head

If falloc_caps() failed, cleanup needs to be performed. This is a bug
in r289026.

Sponsored by: The FreeBSD Foundation

Merge from head

Sync up with head up to r289211.

Merge from head

Enforce the maxproc limitation before allocating struct proc, initial
struct thread and kernel stack for the thread. Otherwise, a load
similar to a fork bomb would exhaust KVA and possibly kmem, mos

Enforce the maxproc limitation before allocating struct proc, initial
struct thread and kernel stack for the thread. Otherwise, a load
similar to a fork bomb would exhaust KVA and possibly kmem, mostly due
to the struct proc being type-stable.

The nprocs counter is changed from being protected by allproc_lock sx
to be an atomic variable. Note that ddb/db_ps.c:db_ps() use of nprocs
was unsafe before, and is still unsafe, but it seems that the only
possible undesired consequence is the harmless warning printed when
allproc linked list length does not match nprocs.

Diagnosed by: Svatopluk Kraus <onwahe@gmail.com>
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

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Fix various edge cases related to system call tracing.
- 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 th

Fix various edge cases related to system call tracing.
- 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

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Merge ^/head r288197 through r288456.

Merge from head