From 25f00e40ce7953db197af3a59233711d154c9d80 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Mon, 4 Mar 2024 12:40:55 +0900 Subject: tracing/probes: Support $argN in return probe (kprobe and fprobe) Support accessing $argN in the return probe events. This will help users to record entry data in function return (exit) event for simplfing the function entry/exit information in one event, and record the result values (e.g. allocated object/initialized object) at function exit. For example, if we have a function `int init_foo(struct foo *obj, int param)` sometimes we want to check how `obj` is initialized. In such case, we can define a new return event like below; # echo 'r init_foo retval=$retval param=$arg2 field1=+0($arg1)' >> kprobe_events Thus it records the function parameter `param` and its result `obj->field1` (the dereference will be done in the function exit timing) value at once. This also support fprobe, BTF args and'$arg*'. So if CONFIG_DEBUG_INFO_BTF is enabled, we can trace both function parameters and the return value by following command. # echo 'f target_function%return $arg* $retval' >> dynamic_events Link: https://lore.kernel.org/all/170952365552.229804.224112990211602895.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google) --- .../testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc | 4 ++++ tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc | 2 ++ 2 files changed, 6 insertions(+) (limited to 'tools/testing/selftests/ftrace') diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc index 20e42c030095..61877d166451 100644 --- a/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc +++ b/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc @@ -34,7 +34,9 @@ check_error 'f vfs_read ^$stack10000' # BAD_STACK_NUM check_error 'f vfs_read ^$arg10000' # BAD_ARG_NUM +if !grep -q 'kernel return probes support:' README; then check_error 'f vfs_read $retval ^$arg1' # BAD_VAR +fi check_error 'f vfs_read ^$none_var' # BAD_VAR check_error 'f vfs_read ^'$REG # BAD_VAR @@ -99,7 +101,9 @@ if grep -q "" README; then check_error 'f vfs_read args=^$arg*' # BAD_VAR_ARGS check_error 'f vfs_read +0(^$arg*)' # BAD_VAR_ARGS check_error 'f vfs_read $arg* ^$arg*' # DOUBLE_ARGS +if !grep -q 'kernel return probes support:' README; then check_error 'f vfs_read%return ^$arg*' # NOFENTRY_ARGS +fi check_error 'f vfs_read ^hoge' # NO_BTFARG check_error 'f kfree ^$arg10' # NO_BTFARG (exceed the number of parameters) check_error 'f kfree%return ^$retval' # NO_RETVAL diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc index 65fbb26fd58c..a16c6a6f6055 100644 --- a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc @@ -108,7 +108,9 @@ if grep -q "" README; then check_error 'p vfs_read args=^$arg*' # BAD_VAR_ARGS check_error 'p vfs_read +0(^$arg*)' # BAD_VAR_ARGS check_error 'p vfs_read $arg* ^$arg*' # DOUBLE_ARGS +if !grep -q 'kernel return probes support:' README; then check_error 'r vfs_read ^$arg*' # NOFENTRY_ARGS +fi check_error 'p vfs_read+8 ^$arg*' # NOFENTRY_ARGS check_error 'p vfs_read ^hoge' # NO_BTFARG check_error 'p kfree ^$arg10' # NO_BTFARG (exceed the number of parameters) -- cgit v1.2.3-59-g8ed1b From f6e2253a617c4030b807a18383101b59d6f0f536 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Mon, 4 Mar 2024 12:41:05 +0900 Subject: selftests/ftrace: Add test cases for entry args at function exit Add kretprobe and function exit probe test cases for checking whether those can access entry arguments at function exit correctly. Link: https://lore.kernel.org/all/170952366504.229804.11605173085475141091.stgit@devnote2/ Signed-off-by: Masami Hiramatsu (Google) --- .../ftrace/test.d/dynevent/fprobe_entry_arg.tc | 18 ++++++++++++++++++ .../ftrace/test.d/kprobe/kretprobe_entry_arg.tc | 18 ++++++++++++++++++ 2 files changed, 36 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/fprobe_entry_arg.tc create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/kretprobe_entry_arg.tc (limited to 'tools/testing/selftests/ftrace') diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_entry_arg.tc b/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_entry_arg.tc new file mode 100644 index 000000000000..d183b8a8ecf8 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_entry_arg.tc @@ -0,0 +1,18 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Function return probe entry argument access +# requires: dynamic_events 'f[:[/][]] ':README 'kernel return probes support:':README + +echo 'f:tests/myevent1 vfs_open arg=$arg1' >> dynamic_events +echo 'f:tests/myevent2 vfs_open%return arg=$arg1' >> dynamic_events + +echo 1 > events/tests/enable + +echo > trace +cat trace > /dev/null + +function streq() { + test $1 = $2 +} + +streq `grep -A 1 -m 1 myevent1 trace | sed -r 's/^.*(arg=.*)/\1/' ` diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kretprobe_entry_arg.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kretprobe_entry_arg.tc new file mode 100644 index 000000000000..53b82f36a1d0 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kretprobe_entry_arg.tc @@ -0,0 +1,18 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Kretprobe entry argument access +# requires: kprobe_events 'kernel return probes support:':README + +echo 'p:myevent1 vfs_open arg=$arg1' >> kprobe_events +echo 'r:myevent2 vfs_open arg=$arg1' >> kprobe_events + +echo 1 > events/kprobes/enable + +echo > trace +cat trace > /dev/null + +function streq() { + test $1 = $2 +} + +streq `grep -A 1 -m 1 myevent1 trace | sed -r 's/^.*(arg=.*)/\1/' ` -- cgit v1.2.3-59-g8ed1b