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systemtap 2.9 release
- From: "Frank Ch. Eigler" <fche at redhat dot com>
- To: systemtap at sourceware dot org
- Cc: lwn at lwn dot net, linux-kernel at vger dot kernel dot org
- Date: Thu, 8 Oct 2015 22:33:44 -0400
- Subject: systemtap 2.9 release
- Authentication-results: sourceware.org; auth=none
The SystemTap team announces release 2.9!
More compiler optimizations, prologue-searching option, backtracing
with kernel symbols without debuginfo, callee probe extensions,
STAP_PRINTF embedded-C macro, improved debuginfo-related
diagnostics, and more tapset functions, reduced translator memory
= Where to get it
https://sourceware.org/systemtap/ - our project page
git tag release-2.9 (commit 7009f2f782e5)
There have been over 232.66 commits since the last release.
There have been between 50 and 500 bugs fixed / features added
since the last release. Closer to 50.
= How to build it
See the README and NEWS files at
Further information at https://sourceware.org/systemtap/wiki/
= SystemTap frontend (stap) changes
- New --prologue-searching[=WHEN] option has been added to stap with '-P' being
its short counterpart. Using --prologue-searching=never turns prologue
searching deliberately off working around issue of int_arg() returning wrong
value when a 32-bit userspace binary having debug info is being probed with
active prologue searching.
- Callee probe points now support '.return' and '.call' suffix.
will fire upon returning from bar when called by foo.
will only fire for non-inlined callees.
- SystemTap has reduced its memory consumption by using interned_strings (a
wrapper for boost::string_ref) in place of std::string instances. The change
is to reduce the number of duplicate strings created by replacing them with
interned_strings which act like pointers to existing strings.
= SystemTap script language changes
- Embedded-C functions may now use the new STAP_PRINTF(fmt, ...)
macro for output.
- Embedded-C functions with parameter arity-0 can now be marked with
the /* stable */ /* pure */ pragmas, if (roughly speaking) the
function is side-effect-free and idempotent. The translator may
execute these speculatively and have their results memoized. This
lets probes with multiple calls to such functions run faster.
Context variable ($foo) getter functions (in non-guru mode), and
numerous tapset functions are now marked as /* stable */ /* pure */.
Several example scripts have been modified to eschew explicit
= SystemTap runtime changes
- SystemTap now uses symbols from /proc/kallsyms when kernel debuginfo is not
- When using the procfs .maxsize() parameter, an error will be generated if the
buffer is too small.
= SystemTap tapset changes
logging.stp new assert() function
many uses of error() in registers.stp
have been replaced in favor of assert()
dentry.stp new functions fullpath_struct_path() and
fullpath_struct_nameidata() resolve full path
names from internal kernel struct pointers,
fullpath_struct_file gets the full path to root
task.stp new function task_fd_lookup gets the file struct
for a task's fd
registers.stp new functions arch_bytes() and uarch_bytes()
to obtain address size of kernel and user space
switchfile.stp new function switch_file() allows control over
rotation of output files
- The [nd_]syscall tapset got autodocumented. Related paragraph got added to PDF
and HTML tapset reference. Also a new tapset::syscall 3stap man page got added.
- The following tapset variables and functions are deprecated in
- The '__int32_compat' library macro got deprecated in favor of
new '__compat_long' library macro.
- The 'uargs' convenience variable of the 'seccomp' syscall probe
got deprecated in favor of new 'uargs_uaddr' variable.
- The powerpc variant of nd_syscall.compat_sysctl got deprecated on favor of
nd_syscall.sysctl32. This aligns the nd_syscall to its respective syscall and
to ia64/s390/x86_64 variants too.
= SystemTap sample scripts
- New samples:
switchfile.stp every second print a log message
and switch log files every 5 seconds.
slowvfs.stp prints a line for every kernel vfs_open
operation that takes longer than a
configurable number of microseconds.
= Examples of tested kernel versions
2.6.18 (RHEL 5 x86 and x86_64)
2.6.32 (RHEL 6 x86 and x86_64)
3.10.0 (RHEL 7 x86_64)
4.1.6 (Fedora 22 x86_64)
4.3.0-rc3 (Fedora rawhide x86_64)
= Known issues with this release
- Some kernel crashes continue to be reported when a script probes
broad kernel function wildcards. (PR2725)
- 32-on-64 bit userspace unwinding is truncated on older kernels, such
as 2.6.32 (PR15757)
- The dyninst backend is still very much a prototype, with a number
of issues, limitations, and general teething woes. For instance:
+ lack of support for multiarch/cross-instrumentation
+ tapset functions are still incomplete relative to what is supported
when the kernel backend is active
+ exception handling becomes completely broken in programs
instrumented by the current version of dyninst (PR14702)
+ not all registers are made available on 32-bit x86 (PR15136)
See dyninst/README and the systemtap/dyninst Bugzilla component
(http://tinyurl.com/stapdyn-PR-list) if you want all the gory
details about the state of the feature.
= Contributors for this release
Abegail Jakop, David Smith, Felix Lu, Frank Ch. Eigler,
Ivan Diorditsa*, Jose Castillo*, Josh Stone, Lukas Berk,
Mark Wielaard, Martin Cermak, Mikhail Kulemin*, Nicolas Brito*
Special thanks to new contributors, marked with '*' above.
Special thanks to Felix Lu for compiling these notes.
= Bugs fixed for this release <https://sourceware.org/PR#####>
909 perf counter events, perfmon? kernel API
2111 document syscalls tapset
10487 flight recorder control from script
10977 Getting the address size used in a module
11263 exposing foo32 syscalls
12151 support /* stable */ embedded-c pragma
13664 support dwarf types for stap variables
15972 core dump with process probes
16493 Improve bkl.stp to add backtrace
16968 bad formatting in many help pages for probes
17831 kprobes_onthefly.exp fails on powerpc
17893 el6: cannot stat `build/en-US/pdf/*SystemTap_Beginners_Guide*.pdf': No such file or directory
17920 File descriptor to pathname function
17921 kernel backtrace missing /proc/kallsyms symbols
18455 const_folder::visit_binary_expression hurting type inference
18462 macro deprecation
18503 procfs .maxsize() overflow should generate error
18555 ppc64le: can't probe demangled C++ function names
18562 the listing_mode.exp test case has lots of errors on systems without uprobes
18563 on ppc64, the mbrwatch.stp example script fails when tested
18571 Tapset support and test coverage for bpf and seccomp syscalls.
18577 on rhel7, listing_mode_sanity.exp always gets a failure when doing 'stap -l **'
18597 long_arg() doesn't correctly handle negative values in 32-on-64 environment
18598 stap_staticmarkers.stp tapset has no test case
18630 dwarfless parameters from a uprobe need test coverage
18634 on rawhide, using timer probes gets a compilation error
18649 int_arg() misbehaves on x86[_64] for 32-bit uprobe in binary having debuginfo
18650 powerpc variant of longlong_arg() for uprobes swaps the high and low half of its 64bit retval
18651 Possible nd_syscall tapset cleanup based on PR18597 fix
18711 Pass 4 failure on RHEL7 for examples netfilter_summary and netfilter_drop
18751 support a STAP_PRINTF(....) macro for use in embedded-C functions
18769 [ppc64BE/--dyninst] unknown operator @__compat_task
18827 consistency check for syscall and nd_syscall tapset
18856 nfsd.close probe alias fails on rawhide
18885 Use /* unmodified-fnargs */ in tapsets
18889 lost ability to probe kernel module initializers
18936 script cache will fail if $jiffies is referenced
18942 any script will include all the globals from tapset/argv.stp
18944 the ioblock.stp tapset fails to compile on RHEL7
18971 process_by_pid.exp issues
18999 error("") stall (causing similar assert() stall)
19000 several task tapset functions can cause kernel crash
19021 the tapset function task_dentry_path() should handle more than just files
19043 __bio_ino(), __rqstp_gid() and __rqstp_uid() can crash the kernel
19045 kernel_string_quoted() can crash the kernel
19057 _is_reset() can crash the rhel6 / s390 kernel
19065 task_fd_lookup() can crash the s390x kernel when invoked with an invalid input
19069 task_euid() doesn't compile on aarch64
19070 Call to __ustack_raw(0) causes 'Unknown symbol in module' on rhel6-