[PATCH v6 00/21] tracing: probeevent: Improve fetcharg features

Masami Hiramatsu
2018-03-17T12:38:10Z

Hi,

This is the 6th version of the fetch-arg improvement series.
This includes variable changes on fetcharg framework like,

- Add fetcharg testcases (syntax, argN, symbol, string and array)
and probepoint testcase.
- Rewrite fetcharg framework with fetch_insn, switch-case based
instead of function pointer.
- Add "symbol" type support, which shows symbol+offset instead of
address value.
- Add "$argN" fetcharg, which fetches function parameters.
(currently only for x86-64)
- Add array type support (including string arrary :) ) ,
which enables to get fixed length array from probe-events.
- Add array type support for perf-probe, so that user can
dump partial array entries.

V5 is here:
https://lkml.org/lkml/2018/3/12/558

Changes from the v5 is here:

- [16/21] Fix README to add backslash escapes to "[]"
- [20/21] Add a bugfix patch for perf-probe.
- [21/21] Add array type support for perf-probe.

Note that [20/21] is same as https://lkml.org/lkml/2018/3/16/108
I have to add this because the last patch depends on it.
Anyway, [20/21] and [21/21] is only for showing how perf-probe
will enhanced by this series. So those are extra work.
I will resend thodr again after [01/21]-[19/21] are merged.

Here are examples:

o 'symbol' type

# echo 'p vfs_read $stack0:symbol' > kprobe_events
# echo 1 > events/kprobes/p_vfs_read_0/enable
# tail -n 3 trace
sh-729 [007] ...2 105.753637: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=SyS_read+0x42/0x90
tail-736 [000] ...2 105.754904: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=kernel_read+0x2c/0x40
tail-736 [000] ...2 105.754929: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=kernel_read+0x2c/0x40

o $argN

# echo 'p vfs_read $arg0 $arg1 $arg2' > kprobe_events
# echo 1 > events/kprobes/p_vfs_read_0/enable
# tail -n 3 trace
sh-726 [007] ...2 134.288973: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffff88001d98ec00 arg2=0x7ffeb4330f79 arg3=0x1
tail-731 [000] ...2 134.289987: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffff88001d9dd200 arg2=0xffff88001d8a0a00 arg3=0x80
tail-731 [000] ...2 134.290016: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffff88001d9dd200 arg2=0xffff88001faf4a00 arg3=0x150

o Array type

# echo 'p vfs_read +0($stack):x64 +0($stack):x8[8]' > kprobe_events
# echo 1 > events/kprobes/p_vfs_read_0/enable
# tail -n 3 trace
sh-729 [007] ...2 91.701664: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffffffff811b1252 arg2={0x52,0x12,0x1b,0x81,0xff,0xff,0xff,0xff}
tail-734 [000] ...2 91.702366: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffffffff811b0dec arg2={0xec,0xd,0x1b,0x81,0xff,0xff,0xff,0xff}
tail-734 [000] ...2 91.702386: p_vfs_read_0: (vfs_read+0x0/0x130) arg1=0xffffffff811b0dec arg2={0xec,0xd,0x1b,0x81,0xff,0xff,0xff,0xff}
#
# cat events/kprobes/p_vfs_read_0/format
name: p_vfs_read_0
ID: 1069
format:
field:unsigned short common_type; offset:0; size:2; signed:0;
field:unsigned char common_flags; offset:2; size:1; signed:0;
field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
field:int common_pid; offset:4; size:4; signed:1;

field:unsigned long __probe_ip; offset:8; size:8; signed:0;
field:u64 arg1; offset:16; size:0; signed:0;
field:u8 arg2[8]; offset:24; size:8; signed:0;

print fmt: "(%lx) arg1=0x%Lx arg2={0x%x,0x%x,0x%x,0x%x,0x%x,0x%x,0x%x,0x%x}", REC->__probe_ip, REC->arg1, REC->arg2[0], REC->arg2[1], REC->arg2[2], REC->arg2[3], REC->arg2[4], REC->arg2[5], REC->arg2[6], REC->arg2[7]

o String Array type

# echo "p create_trace_kprobe arg1=+0(%si):string[3]" > kprobe_events
# echo test1 test2 test3 >> kprobe_events
sh: write error: Invalid argument
# echo 'p vfs_read $stack' >> kprobe_events
# tail -n 2 trace
sh-744 [007] ...1 183.382407: p_create_trace_kprobe_0: (create_trace_kprobe+0x0/0x890) arg1={"test1","test2","test3"}
sh-744 [007] ...1 230.487809: p_create_trace_kprobe_0: (create_trace_kprobe+0x0/0x890) arg1={"p","vfs_read","$stack"}

Thank you,

---

Masami Hiramatsu (21):
[BUGFIX] tracing: probeevent: Fix to support minus offset from symbol
selftests: ftrace: Add probe event argument syntax testcase
selftests: ftrace: Add a testcase for string type with kprobe_event
selftests: ftrace: Add a testcase for probepoint
tracing: probeevent: Cleanup print argument functions
tracing: probeevent: Cleanup argument field definition
tracing: probeevent: Remove NOKPROBE_SYMBOL from print functions
tracing: probeevent: Introduce new argument fetching code
tracing: probeevent: Unify fetch type tables
tracing: probeevent: Return consumed bytes of dynamic area
tracing: probeevent: Append traceprobe_ for exported function
tracing: probeevent: Unify fetch_insn processing common part
tracing: probeevent: Add symbol type
x86: ptrace: Add function argument access API
tracing: probeevent: Add $argN for accessing function args
tracing: probeevent: Add array type support
selftests: ftrace: Add a testcase for symbol type
selftests: ftrace: Add a testcase for $argN with kprobe_event
selftests: ftrace: Add a testcase for array type with kprobe_event
[RESEND] perf-probe: Fix to convert array type collectly
perf-probe: Add array argument support

Documentation/trace/kprobetrace.txt | 26 +
arch/Kconfig | 7
arch/x86/Kconfig | 1
arch/x86/include/asm/ptrace.h | 38 +
kernel/trace/trace.c | 9
kernel/trace/trace_kprobe.c | 366 ++++--------
kernel/trace/trace_probe.c | 628 +++++++++-----------
kernel/trace/trace_probe.h | 284 +++------
kernel/trace/trace_probe_tmpl.h | 214 +++++++
kernel/trace/trace_uprobe.c | 168 ++---
tools/perf/Documentation/perf-probe.txt | 2
tools/perf/util/probe-event.c | 20 +
tools/perf/util/probe-event.h | 2
tools/perf/util/probe-file.c | 5
tools/perf/util/probe-file.h | 1
tools/perf/util/probe-finder.c | 108 ++-
.../ftrace/test.d/kprobe/kprobe_args_argN.tc | 25 +
.../ftrace/test.d/kprobe/kprobe_args_array.tc | 92 +++
.../ftrace/test.d/kprobe/kprobe_args_string.tc | 46 +
.../ftrace/test.d/kprobe/kprobe_args_symbol.tc | 77 ++
.../ftrace/test.d/kprobe/kprobe_args_syntax.tc | 97 +++
.../selftests/ftrace/test.d/kprobe/probepoint.tc | 43 +
22 files changed, 1319 insertions(+), 940 deletions(-)
create mode 100644 kernel/trace/trace_probe_tmpl.h
create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_argN.tc
create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_array.tc
create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_string.tc
create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_symbol.tc
create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_syntax.tc
create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/probepoint.tc

--
Masami Hiramatsu (Linaro) <mhiramat@kernel.org>