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Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 127 |
1 files changed, 124 insertions, 3 deletions
@@ -1,9 +1,130 @@ * What's new +- Module signing: If the appropriate nss libraries are available on your system, + stap will sign each compiled module using a self-generated certificate. + This is the first step toward extending authority to load certain modules to + unprivileged users. For now, if the system administrator adds a certificate + to a database of trusted signers (stap-authorize-signing-cert), modules signed + using that certificate will be verified by staprun against tampering. + Otherwise, you should notice no difference in the operation of stap or staprun. + +* What's new in version 0.9.7 + +- @cast can now determine its type information using an explicit header + specification. For example: + @cast(tv, "timeval", "<sys/time.h>")->tv_sec + @cast(task, "task_struct", "kernel<linux/sched.h>")->tgid + +- The overlapping process.* tapsets are now separated. Those probe points + documented in stapprobes(3stap) remain the same. Those that were formerly + in stapprobes.process(3stap) have been renamed to kprocess, to reflect + their kernel perspective on processes. + +- The --skip-badvars option now also suppresses run-time error + messages that would otherwise result from erroneous memory accesses. + Such accesses can originate from $context expressions fueled by + erroneous debug data, or by kernel_{long,string,...}() tapset calls. + +- New probes kprobe.function(FUNCTION) and kprobe.function(FUNCTION).return + for dwarfless probing. These postpone function address resolution to + run-time and use the kprobe symbol-resolution mechanism. + Probing of absolute statements can be done using the + kprobe.statement(ADDRESS).absolute construct. + +- EXPERIMENTAL support for user process unwinding. A new collection of + tapset functions have been added to handle user space backtraces from + probe points that support them (currently process and timer probes - + for timer probes test whether or not in user space first with the + already existing user_mode() function). The new tapset functions are: + uaddr - User space address of current running task. + usymname - Return the symbol of an address in the current task. + usymdata - Return the symbol and module offset of an address. + print_ustack - Print out stack for the current task from string. + print_ubacktrace - Print stack back trace for current task. + ubacktrace - Hex backtrace of current task stack. + Please read http://sourceware.org/ml/systemtap/2009-q2/msg00364.html + on the current restrictions and possible changes in the future and + give feedback if you want to influence future developments. + +* What's new in version 0.9.5 + +- New probes process().insn and process().insn.block that allows + inspection of the process after each instruction or block of + instructions executed. So to count the total number of instructions + a process executes during a run do something like: + $ stap -e 'global steps; probe process("/bin/ls").insn {steps++} + probe end {printf("Total instructions: %d\n", steps);}' \ + -c /bin/ls + This feature can slow down execution of a process somewhat. + +- Systemtap probes and function man pages extracted from the tapsets + are now available under 3stap. To show the page for probe vm.pagefault + or the stap function pexecname do: + $ man 3stap vm.pagefault + $ man 3stap pexecname + +- Kernel tracepoints are now supported for probing predefined kernel + events without any debuginfo. Tracepoints incur less overhead than + kprobes, and context parameters are available with full type + information. Any kernel 2.6.28 and later should have defined + tracepoints. Try the following to see what's available: + $ stap -L 'kernel.trace("*")' + +- Typecasting with @cast now supports modules search paths, which is + useful in case there are multiple places where the type definition + may be found. For example: + @cast(sdev, "scsi_device", "kernel:scsi_mod")->sdev_state + +- On-file flight recorder is supported. It allows stap to record huge + trace log on the disk and to run in background. + Passing -F option with -o option runs stap in background mode. In this + mode, staprun is detached from console, and stap itself shows staprun's + pid and exits. + Specifying the max size and the max number of log files are also available + by passing -S option. This option has one or two arguments seperated by + a comma. The first argument is the max size of a log file in MB. If the + size of a log file exceeds it, stap switches to the next log file + automatically. The second is how many files are kept on the disk. If the + number of log files exceeds it, the oldest log file is removed + automatically. The second argument can be omitted. + + For example, this will record output on log files each of them is smaller + than 1024MB and keep last 3 logs, in background. + % stap -F -o /tmp/staplog -S 1024,3 script.stp + +- In guru mode (-g), the kernel probing blacklist is disabled, leaving + only a subset - the kernel's own internal kprobe blacklist - to attempt + to filter out areas unsafe to probe. The differences may be enough to + probe more interrupt handlers. + - Variables unavailable in current context may be skipped by setting a - session level flag with command line option --skip-badvars now available. - This will simply substitute the otherwise error causing variable with a - literal 0 and print a warning message when the substitution has been made. + session level flag with command line option --skip-badvars now available. + This replaces any dwarf $variable expressions that could not be resolved + with literal numeric zeros, along with a warning message. + +- Both kernel markers and kernel tracepoint support argument listing + through stap -L 'kernel.mark("*")' or stap -L 'kernel.trace("*")' + +- Users can use -DINTERRUPTIBLE=0 to prevent interrupt reentrancy in + their script, at the cost of a bit more overhead to toggle the + interrupt mask. + +- Added reentrancy debugging. If stap is run with the arguments + "-t -DDEBUG_REENTRANCY", additional warnings will be printed for + every reentrancy event, including the probe points of the + resident and interloper probes. + +- Default to --disable-pie for configure. + Use --enable-pie to turn it back on. + +- Improved sdt.h compatibility and test suite for static dtrace + compatible user space markers. + +- Some architectures now use syscall wrappers (HAVE_SYSCALL_WRAPPERS). + The syscall tapset has been enhanced to take care of the syscall + wrappers in this release. + +- Security fix for CVE-2009-0784: stapusr module-path checking race. * What's new in version 0.9 |