Messages in this thread | | | From | Masami Hiramatsu <> | Subject | [RFC PATCH 0/4] perf probe: Introduce remote cross-arch probes | Date | Wed, 24 Aug 2016 14:57:35 +0900 |
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Hi,
Here is an RFC series for remote cross-arch probe support on perf-probe.
I've made a perf-probe for remote arch (currently arm on x86-64) for helping debugging and performance analysis.
Currently perf-probe doesn't supoort cross/remote target. This means we have to cross-build the perf-tools including libraries (elfutils, libelf etc.), and to prepare vmlinux with debuginfo which can be accessed from the target machine. This requires too much resource for a small embededd device.
If we can analyze the debuginfo by perf-probe on host machine, we do not need to cross-build perf-tools, nor copy vmlinux on the device. :)
This series introduces such features on perf-probe.
To use this, on host machine (with cross build kernel image), below command outputs the target-machine's kprobe-events definition in <output-directory>/kprobe_events.
perf probe -k <cross-vmlinux> --outdir=<output-directory> \ <probe-point> <arguments>
Perf analyzes the given vmlinux and get the architecture and switch the dwarf-register mappings.
Here is an example: ----- $ mkdir tracing $ sudo perf probe --outdir=./tracing --vmlinux=./vmlinux-arm \ do_sys_open '$vars' Added new event: probe:do_sys_open (on do_sys_open with $vars)
You can now use it in all perf tools, such as:
perf record -e probe:do_sys_open -aR sleep 1
$ cat tracing/kprobe_events p:probe/do_sys_open _text+1282292 dfd=%r5:s32 filename=%r1:u32 flags=%r6:s32 mode=%r3:u16 op=-60(%sp) fd=%r4:s32 tmp=%r7:u32 ----- Here, we can get probe/do_sys_open event by "copy & paste" the definition to target-machine's debugfs/tracing/kprobe_events.
To make sure it is correct: ----- $ nm vmlinux-arm | grep "T _text" 80008000 T _text $ nm vmlinux-arm | grep "T do_sys_open" 801410f4 T do_sys_open $ expr `printf "%d + %d" 0x80008000 1282292` 2148798708 $ printf "%x\n" 2148798708 801410f4 ----- So "_text+12882292" indicates do_sys_open on the target binary correctly.
Thanks, ---
Masami Hiramatsu (4): perf-probe: Remove unused tracing_dir variable perf-probe: Add offline output directory option perf-probe: Ignore vmlinux buildid if offline kernel is given perf-probe: Support probing on offline cross-arch binary
tools/perf/arch/arm/include/dwarf-regs-table.h | 9 +++ tools/perf/arch/arm64/include/dwarf-regs-table.h | 13 +++++ tools/perf/arch/powerpc/include/dwarf-regs-table.h | 27 ++++++++++ tools/perf/arch/s390/include/dwarf-regs-table.h | 8 +++ tools/perf/arch/sh/include/dwarf-regs-table.h | 25 +++++++++ tools/perf/arch/sparc/include/dwarf-regs-table.h | 18 +++++++ tools/perf/arch/x86/include/dwarf-regs-table.h | 14 +++++ tools/perf/arch/xtensa/include/dwarf-regs-table.h | 8 +++ tools/perf/builtin-probe.c | 8 +++ tools/perf/util/Build | 1 tools/perf/util/dwarf-regs.c | 55 ++++++++++++++++++++ tools/perf/util/include/dwarf-regs.h | 6 ++ tools/perf/util/probe-event.h | 1 tools/perf/util/probe-file.c | 22 ++++++-- tools/perf/util/probe-finder.c | 27 ++++++---- tools/perf/util/probe-finder.h | 1 tools/perf/util/symbol-elf.c | 2 - 17 files changed, 228 insertions(+), 17 deletions(-) create mode 100644 tools/perf/arch/arm/include/dwarf-regs-table.h create mode 100644 tools/perf/arch/arm64/include/dwarf-regs-table.h create mode 100644 tools/perf/arch/powerpc/include/dwarf-regs-table.h create mode 100644 tools/perf/arch/s390/include/dwarf-regs-table.h create mode 100644 tools/perf/arch/sh/include/dwarf-regs-table.h create mode 100644 tools/perf/arch/sparc/include/dwarf-regs-table.h create mode 100644 tools/perf/arch/x86/include/dwarf-regs-table.h create mode 100644 tools/perf/arch/xtensa/include/dwarf-regs-table.h create mode 100644 tools/perf/util/dwarf-regs.c
-- Masami Hiramatsu (Linaro Ltd.) <mhiramat@kernel.org>
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