Without this change, DTrace will refuse to load a DOF section if the
function component of any of its probes exceeds DTRACE_FUNCNAMELEN (128).
Probes in C++ programs can have very long function components. Rather than
rejecting all probes if a single probe exceeds the limit, simply skip the
invalid probe and emit a warning. This ensures that valid probes are
instantiated.
PR: 207735
MFC after: 2 weeks
This allows one to enable DTrace probes relatively early during boot,
during SI_SUB_DTRACE_ANON, before dtrace(1) can invoked. The desired
enabling is created using dtrace -A, which writes a /boot/dtrace.dof
file and uses nextboot(8) to ensure that DTrace kernel modules are loaded
and that the DOF file describing the enabling is loaded by loader(8)
during the subsequent boot. The trace output can then be fetched with
dtrace -a.
With this commit, boot-time DTrace is only functional on i386 and amd64: on
other architectures, the high-resolution timer frequency is initialized
during SI_SUB_CLOCKS and is thus not available when the anonymous
tracing state is initialized. On x86, the TSC is used and is thus available
earlier.
MFC after: 1 month
Relnotes: yes
Upstream, tracepoints are protected by per-CPU mutexes. An unlinked
tracepoint may be freed once all the tracepoint mutexes have been acquired
and released - this is done in fasttrap_mod_barrier(). This mechanism was
not properly ported: in some places, the proc lock is used in place of a
tracepoint lock, and in others the locking is omitted entirely. This change
implements tracepoint locking with an rmlock, where the read lock is used
in fasttrap probe context. As a side effect, this fixes a recursion on the
proc lock when the raise action is used from a userland probe.
MFC after: 1 month
r281257 added support for lazyload mode by allowing dtrace(1) to register
a DOF section on behalf of a traced process. This was implemented by
having libdtrace copy the DOF section into a heap-allocated buffer and
passing its address to the ioctl handler. However, DTrace uses the DOF
section address as a lookup key in certain cases, so the ioctl handler
should be given the target process' DOF section address instead. This
change modifies the ADDDOF handler to copy the DOF section in from the
target process, rather than from dtrace(1).
tunable via sysctl or kernel tunables.
Illumos allows this parameters to be changed via the fasttrap.conf configuration
file, but FreeBSD code hardcoded the parameters. Expose them under
the kern.dtrace.fasttrap sysctl tree.
MFC after: 2 weeks
5930 fasttrap_pid_enable() panics when prfind() fails in forking process
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Gordon Ross <gordon.ross@nexenta.com>
Approved by: Richard Lowe <richlowe@richlowe.net>
Author: Bryan Cantrill <bryan@joyent.com>
illumos/illumos-gate@9df7e4e12e
When a process is exiting, there is a narrow window where p_cred may be
NULL while its threads are still executing. Specifically, the last thread
to exit a process sets the process state to PRS_ZOMBIE with the proc
spinlock held and then calls thread_exit(). thread_exit() drops the spin
lock, permitting the process to be reaped and thus causing its cred struct
to be released. However, the exiting thread may still cause DTrace probes
to fire by calling sched_throw(), resulting in a double fault if such a
probe enabling attempts to access the GID or UID DIF variables.
The thread's cred reference is not susceptible to this race since it is not
released until after the thread has exited.
MFC after: 1 week
years for head. However, it is continuously misused as the mpsafe argument
for callout_init(9). Deprecate the flag and clean up callout_init() calls
to make them more consistent.
Differential Revision: https://reviews.freebsd.org/D2613
Reviewed by: jhb
MFC after: 2 weeks
It would previously call into some unfinished Solaris compatibility code and
return without actually calling panic(9). The compatibility code is
unneeded, however, so just remove it and have dtrace_panic() call vpanic(9)
directly.
Differential Revision: https://reviews.freebsd.org/D2349
Reviewed by: avg
MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division
Passing "-x lazyload" to dtrace -G during compilation causes dtrace(1) to
not link drti.o into the output object file, so the USDT probes are not created
during process startup. Instead, dtrace(1) will automatically discover and
create probes on the process' behalf when attaching.
Differential Revision: https://reviews.freebsd.org/D2203
Reviewed by: rpaulo
MFC after: 1 month
cannot happen on FreeBSD. r278136 overlooked the fact that a destructor
registered with devfs_set_cdevpriv(9) is invoked even in the case of an
error.
X-MFC-With: r278136
Since the upstream for cddl code is now illumos not sun, mechanically
convert all sun #ifdef's to illumos #ifdef's which have been used in all
newer code for some time.
Also do a manual pass to correct the use if #ifdef comments as per style(9)
as well as few uses of #if defined(__FreeBSD__) vs #ifndef illumos.
MFC after: 1 month
Sponsored by: Multiplay
In the old days callout(9) had 1 tick precision and that was inadequate
for some uses, e.g. DTrace profile module, so we had to emulate cyclic
API and behavior. Now we can directly use callout(9) in the very few
places where cyclic was used.
Differential Revision: https://reviews.freebsd.org/D1161
Reviewed by: gnn, jhb, markj
MFC after: 2 weeks
in userland rename in-kernel getenv()/setenv() to kern_setenv()/kern_getenv().
This fixes a namespace collision with libc symbols.
Submitted by: kmacy
Tested by: make universe
6679140 asymmetric alloc/dealloc activity can induce dynamic variable drops
6679193 dtrace_dynvar walker produces flood of dtrace_dynhash_sink
This finishes a set of merges from the older OpenSolaris releases.
Still the FreeBSD port has many differences that are difficult to
account for but that seems normal given that the kernels are different.
MFC after: 1 week
6851093 system drops to kmdb with anonymous dtrace probes + kmdb
This has no effect on FreeBSD (code is ifdef'ed) but is useful as
reference for future merges.
MFC after: 1 week
These have no effect on FreeBSD, in fact they are ifdef'ed,
but make easier future merges:
6699767 panic in spec_open()
6718877 crgetzoneid() use can cause problems when forking processes with
USDT providers in a non global zone
MFC after: 3 days
MFV r260708
4427 pid provider rejects probes with valid UTF-8 names
Use of u8_textprep.c broke the build on powerpc.
Reported by: bz, rpaulo and tinderbox.
Pointyhat: me
2915 DTrace in a zone should see "cpu", "curpsinfo", et al
2916 DTrace in a zone should be able to access fds[]
2917 DTrace in a zone should have limited provider access
MFC after: 2 weeks
4427 pid provider rejects probes with valid UTF-8 names
This make use of Solaris' u8_validate() which we happen to
use since r185029 for ZFS.
Illumos Revision: 1444d846b126463eb1059a572ff114d51f7562e5
Reference:
https://www.illumos.org/issues/4427
Obtained from: Illumos
MFC after: 2 weeks
usage from dtrace. The dtrace code already uses cdevpriv(9) since FreeBSD
8, so this change should be quite harmless.
Reviewed by: markj
Approved by: markj
MFC after: never
sites and installing a hook at the kernel's trap handler. The fasttrap code
will emulate the overwritten instruction in some common cases, but otherwise
copies it out into some scratch space in the traced process' address space
and ensures that it's executed after returning from the trap.
In Solaris and illumos, this (per-thread) scratch space comes from some
reserved space in TLS, accessible via the fs segment register. This
approach is somewhat unappealing on FreeBSD since it would require some
modifications to rtld and jemalloc (for static TLS) to ensure that TLS is
executable, and would thus introduce dependencies on their implementation
details. I think it would also be impossible to safely trace static binaries
compiled without these modifications.
This change implements the functionality in a different way, by having
fasttrap map pages into the target process' address space on demand. Each
page is divided into 64-byte chunks for use by individual threads, and
fasttrap's process descriptor struct has been extended to keep track of
any scratch space allocated for the corresponding process.
With this change it's possible to trace all libc functions in a program,
e.g. with
pid$target:libc.so.*::entry {@[probefunc] = count();}
Previously this would generally cause the victim process to crash, as
tracing memcpy on amd64 requires the functionality described above.
Tested by: Prashanth Kumar <pra_udupi@yahoo.co.in> (earlier version)
MFC after: 6 weeks
4248 dtrace(1M) should never create DOF with empty probes section
4249 Only probes from the first DTrace object file will be included
Illumos Revision: 4a20ab41aadcb81c53e72fc65886e964e9add59
Reference:
https://www.illumos.org/issues/4248https://www.illumos.org/issues/4249
Obtained from: Illumos
MFC after: 1 month
