[PATCH v9 1/9] tracing/probes: Allow eprobe to use variable without $ prefix
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: 2026-06-25 01:26:03
Also in:
linux-doc, linux-kselftest, lkml
Subsystem:
kernel selftest framework, the rest, tracing · Maintainers:
Shuah Khan, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
The commit 69efd863a785 ("tracing/eprobes: Allow use of BTF names
to dereference pointers") allows eprobe to use event field without
"$" prefix when it is used with typecast, it is natual to allow it
without typecast.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v8:
- Newly added.
---
kernel/trace/trace_probe.c | 12 +++++++++++-
kernel/trace/trace_probe.h | 1 +
.../test.d/dynevent/eprobes_syntax_errors.tc | 3 +--
3 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 0da7c0b53ba7..2ce7d62471cb 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c@@ -1341,7 +1341,17 @@ parse_probe_arg(char *arg, const struct fetch_type *type, ret = handle_typecast(arg, pcode, end, ctx); break; default: - if (isalpha(arg[0]) || arg[0] == '_') { /* BTF variable */ + if (isalpha(arg[0]) || arg[0] == '_') { + /* BTF variable or event field*/ + if (ctx->flags & TPARG_FL_TEVENT) { + ret = parse_trace_event(arg, *pcode, ctx); + if (ret < 0) { + trace_probe_log_err(ctx->offset, + NO_EVENT_FIELD); + return -EINVAL; + } + break; + } if (!tparg_is_function_entry(ctx->flags) && !tparg_is_function_return(ctx->flags)) { trace_probe_log_err(ctx->offset, NOSUP_BTFARG);
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 40b53b5b58a9..2e0d8384ee5c 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h@@ -559,6 +559,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call, C(NO_PTR_STRCT, "This is not a pointer to union/structure."), \ C(NOSUP_DAT_ARG, "Non pointer structure/union argument is not supported."),\ C(BAD_HYPHEN, "Failed to parse single hyphen. Forgot '>'?"), \ + C(NO_EVENT_FIELD, "This event field is not found."), \ C(NO_BTF_FIELD, "This field is not found."), \ C(BAD_BTF_TID, "Failed to get BTF type info."),\ C(BAD_TYPE4STR, "This type does not fit for string."),\
diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/eprobes_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/dynevent/eprobes_syntax_errors.tc
index 2a680c086047..0e65e787e426 100644
--- a/tools/testing/selftests/ftrace/test.d/dynevent/eprobes_syntax_errors.tc
+++ b/tools/testing/selftests/ftrace/test.d/dynevent/eprobes_syntax_errors.tc@@ -10,7 +10,7 @@ check_error() { # command-with-error-pos-by-^ check_error 'e ^a.' # NO_EVENT_INFO check_error 'e ^.b' # NO_EVENT_INFO check_error 'e ^a.b' # BAD_ATTACH_EVENT -check_error 'e syscalls/sys_enter_openat ^foo' # BAD_ATTACH_ARG +check_error 'e syscalls/sys_enter_openat ^foo' # NO_EVENT_FIELD check_error 'e:^/bar syscalls/sys_enter_openat' # NO_GROUP_NAME check_error 'e:^12345678901234567890123456789012345678901234567890123456789012345/bar syscalls/sys_enter_openat' # GROUP_TOO_LONG
@@ -19,7 +19,6 @@ check_error 'e:^ syscalls/sys_enter_openat' # NO_EVENT_NAME check_error 'e:foo/^12345678901234567890123456789012345678901234567890123456789012345 syscalls/sys_enter_openat' # EVENT_TOO_LONG check_error 'e:foo/^bar.1 syscalls/sys_enter_openat' # BAD_EVENT_NAME -check_error 'e:foo/bar syscalls/sys_enter_openat arg=^dfd' # BAD_FETCH_ARG check_error 'e:foo/bar syscalls/sys_enter_openat arg=^$foo' # BAD_ATTACH_ARG if grep -q '<attached-group>\.<attached-event>.*\[if <filter>\]' README; then