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Message-Id: <20111216122756.2085.95791.sendpatchset@srdronam.in.ibm.com> Date: Fri, 16 Dec 2011 17:57:56 +0530 From: Srikar Dronamraju <srikar@...ux.vnet.ibm.com> To: Peter Zijlstra <peterz@...radead.org>, Linus Torvalds <torvalds@...ux-foundation.org> Cc: Oleg Nesterov <oleg@...hat.com>, Ingo Molnar <mingo@...e.hu>, Andrew Morton <akpm@...ux-foundation.org>, LKML <linux-kernel@...r.kernel.org>, Linux-mm <linux-mm@...ck.org>, Andi Kleen <andi@...stfloor.org>, Christoph Hellwig <hch@...radead.org>, Steven Rostedt <rostedt@...dmis.org>, Roland McGrath <roland@...k.frob.com>, Thomas Gleixner <tglx@...utronix.de>, Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>, Arnaldo Carvalho de Melo <acme@...radead.org>, Anton Arapov <anton@...hat.com>, Ananth N Mavinakayanahalli <ananth@...ibm.com>, Jim Keniston <jkenisto@...ux.vnet.ibm.com>, Stephen Rothwell <sfr@...b.auug.org.au> Subject: [PATCH v8 3.2.0-rc5 0/9] uprobes patchset 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/2011/11/18/149) patchset applies on top of commit (dc47ce9 Linux 3.2-rc5) This patchset depends on Paul McKenney's "rcu: Introduce raw SRCU read-side primitives" - 0c53dd8b3; and my patches "x86: Clean up and extend do_int3()" - cc3a1bf52; "x86: Call do_notify_resume() with interrupts enabled" - 3596ff4e6b All three commits in -tip tree. uprobes git is hosted at git://github.com/srikard/linux.git with branch inode_uprobes_v32rc5. Branch for-next is also updated with these 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/2011/11/10/408 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 dc47ce9 Linux 3.2-rc5 - Re-split the patches including separating the probe hit optimization. - Fixes for build failures as reported on linux-next. - Handled comments from Peter. Here is the list of TODO Items. - worker thread if unregister_uprobe were to fail. - 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-rc5 7/9] tracing: uprobes trace_event interface". Please refer "[PATCH 3.2-rc5 9/9] perf: perf interface for uprobes". Please do provide your valuable comments. Thanks in advance. Srikar Srikar Dronamraju (9) 0: Uprobes patchset with perf probe support 1: uprobes: Install and remove breakpoints. 2: uprobes: handle breakpoint and signal step exception. 3: uprobes: slot allocation. 4: uprobes: counter to optimize probe hits. 5: tracing: modify is_delete, is_return from ints to bool. 6: tracing: Extract out common code for kprobes/uprobes traceevents. 7: tracing: uprobes trace_event interface 8: perf: rename target_module to target 9: perf: perf interface for uprobes 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 | 675 ++++++++++++++ include/linux/mm_types.h | 5 + include/linux/sched.h | 4 + include/linux/uprobes.h | 171 ++++ 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 | 786 ++++++++++++++++ kernel/trace/trace_probe.h | 162 ++++ kernel/trace/trace_uprobe.c | 768 +++++++++++++++ kernel/uprobes.c | 1547 +++++++++++++++++++++++++++++++ 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, 4779 insertions(+), 981 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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