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    Subject[PATCH v2 0/11] Uprobes patches.
    Uprobes Patches

    Changelog:
    - Added trace_event interface for uprobes.
    - Addressed comments from Andrew Morton and Randy Dunlap.

    For previous posting: please refer: http://lkml.org/lkml/2010/3/20/107

    This patchset implements Uprobes which enables you to dynamically break
    into any routine in a user space application and collect information
    non-disruptively.

    This patchset is a rework based on suggestions from discussions on lkml
    in January this year (http://lkml.org/lkml/2010/1/11/92 and
    http://lkml.org/lkml/2010/1/27/19). This implementation of uprobes
    doesnt depend on utrace.

    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-process "execution out of line (XOL) area". Currently XOL area is
    allocated as one page vma.

    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.

    Here is the list of TODO Items.

    - Provide a perf interface to uprobes.
    - Allowing probes across fork/exec.
    - Allowing probes on per-executable/per dso.
    - Allow multiple probes to share a probepoint.
    - Merge user_bkpt into uprobes.
    - Merge uprobes and kprobes trace_event.
    - replace macro with bits in inat table.
    - Support for other architectures.
    - Return probes.
    - Uprobes booster.

    This patchset is based on 2.6.34-rc3.

    Please do provide your valuable comments.

    Thanks in advance.
    Srikar


    Srikar Dronamraju (10):
    1. X86 instruction analysis: Move Macro W to insn.h
    2. mm: Move replace_page() to mm/memory.c
    3. mm: Enhance replace_page() to support pagecache
    4. user_bkpt: User Space Breakpoint Assistance Layer
    5. user_bkpt: X86 details for User space breakpoint assistance
    6. user_bkpt: Slot allocation for Execution out of line
    7. uprobes: Uprobes Implementation
    8. uprobes: X86 details for Uprobes
    9. uprobes: Uprobes Documentation patch
    10. samples: Uprobes samples
    11. trace: uprobes trace_event interface

    Documentation/uprobes.txt | 244 ++++++++++
    arch/Kconfig | 31 ++
    arch/x86/Kconfig | 2 +
    arch/x86/include/asm/insn.h | 7 +
    arch/x86/include/asm/user_bkpt.h | 43 ++
    arch/x86/kernel/Makefile | 3 +
    arch/x86/kernel/kprobes.c | 7 -
    arch/x86/kernel/uprobes.c | 87 ++++
    arch/x86/kernel/user_bkpt.c | 572 +++++++++++++++++++++++
    include/linux/mm.h | 2 +
    include/linux/sched.h | 3 +
    include/linux/tracehook.h | 18 +
    include/linux/uprobes.h | 187 ++++++++
    include/linux/user_bkpt.h | 305 +++++++++++++
    include/linux/user_bkpt_xol.h | 61 +++
    kernel/Makefile | 3 +
    kernel/fork.c | 3 +
    kernel/trace/Kconfig | 8 +
    kernel/trace/Makefile | 1 +
    kernel/trace/trace.h | 12 +
    kernel/trace/trace_uprobe.c | 926 ++++++++++++++++++++++++++++++++++++++
    kernel/uprobes.c | 803 +++++++++++++++++++++++++++++++++
    kernel/user_bkpt.c | 598 ++++++++++++++++++++++++
    kernel/user_bkpt_xol.c | 289 ++++++++++++
    mm/ksm.c | 59 ---
    mm/memory.c | 62 +++
    samples/Kconfig | 7 +
    samples/uprobes/Makefile | 17 +
    samples/uprobes/uprobe_example.c | 83 ++++
    ---

    0 files changed, 0 insertions(+), 0 deletions(-)




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