This is supposed to be a dtrace_id_t, which is a uint32_t, while id_t is a uint64_t. sdt.h avoids depending on dtrace.h so we can't use dtrace_id_t directly. Bump __FreeBSD_version since the layout of structures in the SDT probe linker set has changed. Sponsored by: NetApp, Inc. Sponsored by: Klara, Inc.
Suppose a kernel module A defines an SDT provider and probes, and kernel linker file B, dependant on A, contains tracepoints for those probes. When sdt.ko is loaded, it iterates over all loaded KLDs to initialize probe structures and register them with dtrace. In particular it uses linker_file_foreach(), which is not sorted; in the above scenario, B may be visited before A. Thus, it's possible for sdt_kld_load_probes() to try to add tracepoints to an uninitialized SDT probe. An example of the above arises when pfsync, pf, and sdt are loaded in that exact order after commit 4bb3b36577645. Fix this by initializing probe structures in the first pass over loaded KLDs. Then, the second pass can safely add tracepoints to any probe structure. Note that the scenario where B and A are loaded after sdt.ko is already handled properly, as there, the kld_load eventhandler is responsible for registering probes with dtrace, and that eventhandler fires for dependencies before it does for the dependent KLD. This presumes, however, that there are no cycles in the dependency graph. Reported by: jenkins MFC after: 2 weeks
Previously only providers in kernel modules were removed leaving dangling pointers to tracepoints, etc. in unloaded kernel modules. PR: 281825 Reported by: Sony Arpita Das <sonyarpitad@chelsio.com> Reviewed by: markj Fixes: ddf0ed09bd8f sdt: Implement SDT probes using hot-patching Sponsored by: Chelsio Communications Differential Revision: https://reviews.freebsd.org/D46890
DTrace probes have an "aframes" attribute, used when unwinding the stack
from dtrace_probe(). It counts the number of leading frames to skip
when returning a stack trace, thus is used to hide internal functions.
Commit ddf0ed09bd8f set the aframes value for SDT probes to 0, which was
correct for an earlier iteration of the patch, but now doesn't take
sdt_probe()/sdt_probe6() into account.
Fix the aframes definition for SDT probes. Also try to improve
lockstat(1) output by adding an additional aframe for lockstat probes,
which otherwise show internal mtx(9), rwlock(9), etc. functions as the
probe "caller". This is not quite correct as the number of frames to
skip may differ depending on the lock type and kernel configuration (see
e.g., the MUTEX_NOINLINE kernel option), but this is not a new problem.
Reported by: mjg
Fixes: ddf0ed09bd8f ("sdt: Implement SDT probes using hot-patching")
SDT calls dtrace_probe() directly, and this can be used to pass up to five probe arguments directly. To pass the sixth argument (SDT currently doesn't support more than this), we use a hack: just add additional parameters to the call and cast dtrace_probe accordingly. This happens to work on amd64, but doesn't work in general. Modify SDT to call dtrace_probe() after storing arguments beyond the first five in thread-local storage. Implement sdt_getargval() to fetch extra argument values this way. An alternative would be to use invop handlers instead and make sdt_probe_func point to a breakpoint instruction, so that one can extract arguments using the breakpoint exception trapframe, but this makes the providers more expensive when enabled and doesn't seem justified. This approach works well unless we want to add more than one or two more parameters to SDT probes, which seems unlikely at present. In particular, this fixes fetching the last argument of most ip and tcp probes on arm64. Reported by: rwatson Reviewed by: Domagoj Stolfa MFC after: 1 month Sponsored by: Innovate UK Differential Revision: https://reviews.freebsd.org/D45648
The idea here is to avoid a memory access and conditional branch per
probe site. Instead, the probe is represented by an "unreachable"
unconditional function call. asm goto is used to store the address of
the probe site (represented by a no-op sled) and the address of the
function call into a tracepoint record. Each SDT probe carries a list
of tracepoints.
When the probe is enabled, the no-op sled corresponding to each
tracepoint is overwritten with a jmp to the corresponding label. The
implementation uses smp_rendezvous() to park all other CPUs while the
instruction is being overwritten, as this can't be done atomically in
general. The compiler moves argument marshalling code and the
sdt_probe() function call out-of-line, i.e., to the end of the function.
Per gallatin@ in D43504, this approach has less overhead when probes are
disabled. To make the implementation a bit simpler, I removed support
for probes with 7 arguments; nothing makes use of this except a
regression test case. It could be re-added later if need be.
The approach taken in this patch enables some more improvements:
1. We can now automatically fill out the "function" field of SDT probe
names. The SDT macros let the programmer specify the function and
module names, but this is really a bug and shouldn't have been
allowed. The intent was to be able to have the same probe in
multiple functions and to let the user restrict which probes actually
get enabled by specifying a function name or glob.
2. We can avoid branching on SDT_PROBES_ENABLED() by adding the ability
to include blocks of code in the out-of-line path. For example:
if (SDT_PROBES_ENABLED()) {
int reason = CLD_EXITED;
if (WCOREDUMP(signo))
reason = CLD_DUMPED;
else if (WIFSIGNALED(signo))
reason = CLD_KILLED;
SDT_PROBE1(proc, , , exit, reason);
}
could be written
SDT_PROBE1_EXT(proc, , , exit, reason,
int reason;
reason = CLD_EXITED;
if (WCOREDUMP(signo))
reason = CLD_DUMPED;
else if (WIFSIGNALED(signo))
reason = CLD_KILLED;
);
In the future I would like to use this mechanism more generally, e.g.,
to remove branches and marshalling code used by hwpmc, and generally to
make it easier to add new tracepoint consumers without having to add
more conditional branches to hot code paths.
Reviewed by: Domagoj Stolfa, avg
MFC after: 2 months
Differential Revision: https://reviews.freebsd.org/D44483
Apply the following automated changes to try to eliminate no-longer-needed sys/cdefs.h includes as well as now-empty blank lines in a row. Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/ Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/ Remove /\n+#if.*\n#endif.*\n+/ Remove /^#if.*\n#endif.*\n/ Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/ Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/ Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/ Sponsored by: Netflix
Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/
The sdt module's load handler iterates over SDT linker sets for the kernel and all loaded modules to create probes and providers defined by SDT(9). Probes in one module may belong to a provider in a different module, but when a probe is created we assume that the provider is already defined. To maintain this invariant, modify the load handler to perform two separate passes over loaded modules: one to define providers and the other to define probes. The problem manifests when loading linux.ko, which depends on linux_common.ko, which defines providers used by probes defined in linux.ko. Reported by: gallatin MFC after: 2 weeks Sponsored by: The FreeBSD Foundation
The primary benefit is maintaining a completely shared code base with the community allowing FreeBSD to receive new features sooner and with less effort. I would advise against doing 'zpool upgrade' or creating indispensable pools using new features until this change has had a month+ to soak. Work on merging FreeBSD support in to what was at the time "ZFS on Linux" began in August 2018. I first publicly proposed transitioning FreeBSD to (new) OpenZFS on December 18th, 2018. FreeBSD support in OpenZFS was finally completed in December 2019. A CFT for downstreaming OpenZFS support in to FreeBSD was first issued on July 8th. All issues that were reported have been addressed or, for a couple of less critical matters there are pull requests in progress with OpenZFS. iXsystems has tested and dogfooded extensively internally. The TrueNAS 12 release is based on OpenZFS with some additional features that have not yet made it upstream. Improvements include: project quotas, encrypted datasets, allocation classes, vectorized raidz, vectorized checksums, various command line improvements, zstd compression. Thanks to those who have helped along the way: Ryan Moeller, Allan Jude, Zack Welch, and many others. Sponsored by: iXsystems, Inc. Differential Revision: https://reviews.freebsd.org/D25872