The SystemTap team announces release 2.6, "My god. It's full of probes!"
DWARF type support for integer expressions, on-the-fly probe arming/disarming, support for multiple scripts, DWARF process(PID) probes, PLT return probes, .nearest probes, .statement lineno ranges and enumerations, improved listing mode = Where to get it https://sourceware.org/systemtap/ - our project page https://sourceware.org/systemtap/ftp/releases/systemtap-2.6.tar.gz https://koji.fedoraproject.org/koji/packageinfo?packageID=615 git tag release-2.6 (commit 7682e51d2e11) There have been over 465 commits since the last release. There have been over 47 bugs fixed / features added since the last release. = How to build it See the README and NEWS files at https://sourceware.org/git/?p=systemtap.git;a=tree Further information at https://sourceware.org/systemtap/wiki/ = SystemTap frontend (stap) changes - SystemTap now accepts additional scripts through the new -E SCRIPT option. There still needs to be a main script specified through -e or file in order to provide an additional script. This makes it feasible to have scripts in the $HOME/.systemtap/rc file. For example: -E 'probe begin, end, error { log("systemtap script " . pn()) }' -E 'probe timer.s(30) { error ("timeout") } The -E SCRIPT option can also be used in listing mode (-l/-L), such that probe points for the additional scripts will not be listed, but other parts of the script are still available, such as macros or aliases. - DWARF process probes can now be bound to a specific process using the form: process(PID).function("*") - process("PATH").library("PATH").plt("NAME").return probes are now supported. - SystemTap now asserts that the PID provided for a process probe corresponds to a running process. - While in listing mode (-l/-L), probes printed are now more consistent and precise. - Statement probes now support enumerated linenos to probe discontiguous linenos using the form: process.statement("foo@file.c:3,5-7,9") - statement("*@file:NNN").nearest probes are now available to let SystemTap translate the probe to the nearest probe-able line to the given one if necessary. = SystemTap script language changes - Integer expressions which are derived from DWARF values, like context $vars, @cast, and @var, will now carry that type information into subsequent reads. Such expressions can now use "->" and "[]" operators, as can local variables which were assigned such values. Example usage: foo = $param->foo; printf("x:%d y:%d\n", foo->x, foo->y) printf("my value is %d\n", ($type == 42 ? $foo : $bar)->value) printf("my parent pid is %d\n", task_parent(task_current())->tgid) - SystemTap now supports array slicing within foreach loop conditions, delete statements and membership tests. Wildcards are represented by "*". Examples of the expressions are: foreach ([a,b,c] in val[*,2,*]) delete val[*, 2, *] [*, 2, *] in val = SystemTap runtime changes - SystemTap now supports on-the-fly arming/disarming of certain probe types: kprobes, uprobes, and timer.*s(NUM) probes. For example, this probe probe kernel.function("vfs_read") if (i > 4) { ... } will automatically register/unregister the associated kprobe on vfs_read whenever the value of the condition changes (as some probe handler modifies 'i'). This allows us to avoid probe overhead when we're not interested. If the arming capability is not relevant/useful, nest the condition in the normal probe handler: probe kernel.function("vfs_read") { if (i > 4) { ... } } - Statement counting is now suppressed in the generated c code for probes that are non-recursive and loop-free. Statement counting can be turned back on in unoptimize mode (-u). - SystemTap now supports SDT probes with operands that refer to symbols. = SystemTap tapset changes init.stp new tapset with an 'init' probe alias which triggers as early as possible at runtime ia64/registers.stp support for ia64 dwarfless register access linux/context.stp support for kernels without CONFIG_USER_NS linux/conversions.stp new kernel_string_quoted() function analogous to user_string_quoted() linux/dentry.stp fix possible infinite loop in task_dentry_path() linux/nfsd.stp fix build errors on 32-bit platforms linux/syscalls.stp use kernel_string_quoted() in execve syscall for consistency linux/nd_syscalls.stp ditto container_of.stpm new macros container_of() and module_container_of() to retrieve the structure containing a particular element offsetof.stpm new macros offsetof() and module_offset_of() to retrieve the offset of a member in a struct type_defined.stpm new macros type_defined(), type_member_defined(), module_type_defined(), module_type_member_defined() to check if a type/member is defined - Many of the arrays which were previously initialized in a begin(-1) probe now use the new init probe alias instead. - More work was done to improve the types of the parameters in many syscall probe aliases ([nd_|aux_]syscalls[2].stp). - Many tapsets were simplified by using the new autocast feature. = SystemTap sample scripts - Changed samples: eventcount.stp more sorting options inodewatch.stp use ppfunc() rather than probefunc() inodewatch2.stp ditto traceio2.stp ditto mutex-contention.stp ditto fntimes.stp ditto functioncallcount.stp ditto autofs4.stp use new .nearest probe perf.stp ditto ltrace.stp add perf.return functionality using new plt return probe syscalls_by_pid.stp use nd_syscall instead of syscall syscalls_by_proc.stp ditto latencytap.stp more explanations added and code refactored = Examples of tested kernel versions 2.6.9 (RHEL 4 x86) 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) 3.15.10 (Fedora 20 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*, Brian Chrisman*, David Smith, Frank Ch. Eigler, Honggyu Kim*, Jonathan Lebon, Josh Stone, Lukas Berk, Mark Wielaard, Martin Cermak, Stan Cox, Stefan Hajnoczi*, Tetsuo Handa*, William Cohen, Yaakov Selkowitz* Special thanks to new contributors, marked with '*' above. Special thanks to Jonathan and Abegail for compiling these notes. = Bugs fixed for this release <https://sourceware.org/PR#####> 6897 stap should assert valid PIDs for process(PID) probes 6971 nd_syscalls.stp tapset broken on ia64 10603 Probing *@srcfile:line yields strange results 10995 on-the-fly enabled/disabled probes 12333 array slice operations 13296 inaccessible sdt.h operands of the form symbol(%reg) 14509 Reshuffled chain error messages are misleading for DWARF-search-failures 14737 plt.return probes 14825 dtrace .d parser can't handle compact input 15049 stapdyn mishandling interrupts 15942 support abbreviated process.* probes with stap -x PID 16300 suppress statement-counting protections in loop-free non-recursive probe handlers 16443 typos in the beginners guide 16844 Adapt to tracepoint API changes in 3.15 16861 probes aren't re-registered after module reload 16894 SIGSEGV upon using stap -c commands with ||, &&, etc... 16913 systemtap-testsuite.aarch64 requires prelink 16914 probe syscall.* fails with compilation error 16941 fix listing mode inconsistencies 16951 dtrace regression 16955 blacklisting requires better feedback 16956 nd_syscall.* tapset shouldn't rely on @cast() against kernel debuginfo 16960 today's fresh bits do not work correctly on RHEL6 16991 infinite loop in task_dentry_path 17027 pr16806.exp fails on RHEL6 like systems 17041 cast-scope.exp fails on s390x 17052 race between _stp_ctl_work_callback and _stp_runtime_contexts_free 17073 SystemTap doesn't support module given by full path 17101 [rfe] timeout for stap 17120 tcl testsuite error in gtod.exp/prcwildcard.exp 17121 tcl testsuite error in listing_mode.exp 17127 systemtap sometimes fails to hook targets on busy systems 17131 process(PID).{function, plt, mark} does not limit probe to specified process 17155 systemtap.examples/profiling/functioncallcount.stp failures on x86_64 17178 syscall/nd_syscall test failures on f20 17181 systemtap has problems attaching to resumed processes 17182 sdt_misc V3_uprobe --types failure 17191 upstream head systemtap doesn't build on el6 (license issue) 17216 perf.hw counters misbehaviour 17232 runtime control message race condition: STP_EXIT while STP_STARTing 17242 tapsets should avoid delayed-init globals 17249 module-init functions crashable & not probeable past 3.8 17260 stp_print_flush reentrancy deadlock 17274 procfs_write.exp, the beaker killer 17275 on s390x, buildok/memory-all-probes.stp fails 17301 optim_arridx.exp affected by testsuite's timeout feature 17333 userspace probing by pid broken -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
