This patchset implements Uprobes which enables you to dynamically probe any routine in a user space application and collect information non-disruptively. This patchset resolves most of the comments on the previous posting (https://lkml.org/lkml/2011/11/10/408) patchset applies on top of commit cfcfc9eca2b This patchset depends on bulkref patch from Paul McKenney https://lkml.org/lkml/2011/11/2/365 and enable interrupts before calling do_notify_resume on i686 patch https://lkml.org/lkml/2011/10/25/265. uprobes git is hosted at git://github.com/srikard/linux.git with branch inode_uprobes_v32rc2. (The previous patchset posted to lkml has been rebased to 3.2-rc2 is also available at branch inode_uprobes_v32rc2_prev. This is to help the reviewers of the previous patchsets to quickly identify the changes.) Uprobes Patches This patchset implements inode based uprobes which are specified as <file>:<offset> where offset is the offset from start of the map. When a uprobe is registered, Uprobes makes a copy of the probed instruction, replaces the first byte(s) of the probed instruction with a breakpoint instruction. (Uprobes uses background page replacement mechanism and ensures that the breakpoint affects only that process.) When a CPU hits the breakpoint instruction, Uprobes gets notified of trap and finds the associated uprobe. It then executes the associated handler. Uprobes single-steps its copy of the probed instruction and resumes execution of the probed process at the instruction following the probepoint. Instruction copies to be single-stepped are stored in a per-mm "execution out of line (XOL) area". Currently XOL area is allocated as one page vma. For previous postings: please refer: https://lkml.org/lkml/2011/9/20/123 https://lkml.org/lkml/2011/6/7/232 https://lkml.org/lkml/2011/4/1/176 http://lkml.org/lkml/2011/3/14/171/ http://lkml.org/lkml/2010/12/16/65 http://lkml.org/lkml/2010/8/25/165 http://lkml.org/lkml/2010/7/27/121 http://lkml.org/lkml/2010/7/12/67 http://lkml.org/lkml/2010/7/8/239 http://lkml.org/lkml/2010/6/29/299 http://lkml.org/lkml/2010/6/14/41 http://lkml.org/lkml/2010/3/20/107 and http://lkml.org/lkml/2010/5/18/307 This patchset is a rework based on suggestions from discussions on lkml in September, March and January 2010 (http://lkml.org/lkml/2010/1/11/92, http://lkml.org/lkml/2010/1/27/19, http://lkml.org/lkml/2010/3/20/107 and http://lkml.org/lkml/2010/3/31/199 ). This implementation of uprobes doesnt depend on utrace. Advantages of uprobes over conventional debugging include: 1. Non-disruptive. Unlike current ptrace based mechanisms, uprobes tracing wouldnt involve signals, stopping threads and context switching between the tracer and tracee. 2. Much better handling of multithreaded programs because of XOL. Current ptrace based mechanisms use single stepping inline, i.e they copy back the original instruction on hitting a breakpoint. In such mechanisms tracers have to stop all the threads on a breakpoint hit or tracers will not be able to handle all hits to the location of interest. Uprobes uses execution out of line, where the instruction to be traced is analysed at the time of breakpoint insertion and a copy of instruction is stored at a different location. On breakpoint hit, uprobes jumps to that copied location and singlesteps the same instruction and does the necessary fixups post singlestepping. 3. Multiple tracers for an application. Multiple uprobes based tracer could work in unison to trace an application. There could one tracer that could be interested in generic events for a particular set of process. While there could be another tracer that is just interested in one specific event of a particular process thats part of the previous set of process. 4. Corelating events from kernels and userspace. Uprobes could be used with other tools like kprobes, tracepoints or as part of higher level tools like perf to give a consolidated set of events from kernel and userspace. In future we could look at a single backtrace showing application, library and kernel calls. Changes from last patchset: - Rebased to Linus's 3.2-rc2 (cfcfc9eca2b) - abort_xol does arch specific cleanups. - added nop optimization. Here is the list of TODO Items. - Prefiltering (i.e filtering at the time of probe insertion) - Return probes. - Support for other architectures. - Uprobes booster. - replace macro W with bits in inat table. Please refer "[PATCH 3.2-rc2 21/30] tracing: uprobes trace_event interface". Please refer "[PATCH 3.2-rc2 23/30] perf: perf interface for uprobes". Please do provide your valuable comments. Thanks in advance. Srikar Srikar Dronamraju (30) 0: Uprobes patchset with perf probe support 1: uprobes: Auxillary routines to insert, find, delete uprobes 2: Uprobes: Allow multiple consumers for an uprobe. 3: Uprobes: register/unregister probes. 4: uprobes: Define hooks for mmap/munmap. 5: Uprobes: copy of the original instruction. 6: Uprobes: define fixups. 7: Uprobes: uprobes arch info 8: x86: analyze instruction and determine fixups. 9: Uprobes: Background page replacement. 10: x86: Set instruction pointer. 11: x86: Introduce TIF_UPROBE FLAG. 12: Uprobes: Handle breakpoint and Singlestep 13: x86: define a x86 specific exception notifier. 14: uprobe: register exception notifier 15: x86: Define x86_64 specific uprobe_task_arch_info structure 16: uprobes: Introduce uprobe_task_arch_info structure. 17: x86: arch specific hooks for pre/post singlestep handling. 18: uprobes: slot allocation. 19: tracing: modify is_delete, is_return from ints to bool. 20: tracing: Extract out common code for kprobes/uprobes traceevents. 21: tracing: uprobes trace_event interface 22: perf: rename target_module to target 23: perf: perf interface for uprobes 24: perf: show possible probes in a given executable file or library. 25: uprobes: call post_xol() unconditionally 26: uprobes: introduce uprobe_deny_signal() 27: uprobes: x86: introduce xol_was_trapped() 28: uprobes: introduce UTASK_SSTEP_TRAPPED logic 29: uprobes: Introduce uprobe flags 30: x86: skip singlestep where possible Documentation/trace/uprobetracer.txt | 93 ++ arch/Kconfig | 3 + arch/x86/Kconfig | 5 +- arch/x86/include/asm/thread_info.h | 2 + arch/x86/include/asm/uprobes.h | 59 ++ arch/x86/kernel/Makefile | 1 + arch/x86/kernel/signal.c | 6 + arch/x86/kernel/uprobes.c | 648 +++++++++++++ include/linux/mm_types.h | 5 + include/linux/sched.h | 4 + include/linux/uprobes.h | 178 ++++ kernel/Makefile | 1 + kernel/fork.c | 15 + kernel/signal.c | 3 + kernel/trace/Kconfig | 20 + kernel/trace/Makefile | 2 + kernel/trace/trace.h | 5 + kernel/trace/trace_kprobe.c | 899 +------------------ kernel/trace/trace_probe.c | 785 ++++++++++++++++ kernel/trace/trace_probe.h | 161 ++++ kernel/trace/trace_uprobe.c | 768 ++++++++++++++++ kernel/uprobes.c | 1500 +++++++++++++++++++++++++++++++ mm/mmap.c | 33 +- tools/perf/Documentation/perf-probe.txt | 14 + tools/perf/builtin-probe.c | 49 +- tools/perf/util/probe-event.c | 411 +++++++-- tools/perf/util/probe-event.h | 12 +- tools/perf/util/symbol.c | 8 + tools/perf/util/symbol.h | 1 + 29 files changed, 4710 insertions(+), 981 deletions(-) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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