From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Add the '$arg*' meta fetch argument for function-entry probe events. This
will be expanded to the all arguments of the function and the tracepoint
using BTF function argument information.
e.g.
# echo 'p vfs_read $arg*' >> dynamic_events
# echo 'f vfs_write $arg*' >> dynamic_events
# echo 't sched_overutilized_tp $arg*' >> dynamic_events
# cat dynamic_events
p:kprobes/p_vfs_read_0 vfs_read file=file buf=buf count=count pos=pos
f:fprobes/vfs_write__entry vfs_write file=file buf=buf count=count pos=pos
t:tracepoints/sched_overutilized_tp sched_overutilized_tp rd=rd overutilized=overutilized
Also, single '$arg[0-9]*' will be converted to the BTF function argument.
NOTE: This seems like a wildcard, but a fake one at this moment. This
is just for telling user that this can be expanded to several arguments.
And it is not like other $-vars, you can not use this $arg* as a part of
fetch args, e.g. specifying name "foo=$arg*" and using it in dereferences
"+0($arg*)" will lead a parse error.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
---
Changes in v13:
- Ignore BTF error if '$arg*' is not there.
- Fix to remove meaningless $argN format check.
- Fix kernel crash when only pass the $argN without '$arg*'.
- Fix to show $argN instead of $argN+1
Changes in v11:
- Change $args to $arg*.
- Convert single '$arg[0-9]*' to BTF function argument.
- Cleanup code.
Changes in v10:
- Change $$args to $args so that user can use $$ for current task's pid.
Changes in v6:
- update patch description.
---
kernel/trace/trace_fprobe.c | 21 +++++
kernel/trace/trace_kprobe.c | 23 +++++-
kernel/trace/trace_probe.c | 169 ++++++++++++++++++++++++++++++++++++++++++-
kernel/trace/trace_probe.h | 11 +++
4 files changed, 212 insertions(+), 12 deletions(-)
diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index 2dd884609321..dfe2e546acdc 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -925,14 +925,16 @@ static int __trace_fprobe_create(int argc, const char *argv[])
* FETCHARG:TYPE : use TYPE instead of unsigned long.
*/
struct trace_fprobe *tf = NULL;
- int i, len, ret = 0;
+ int i, len, new_argc = 0, ret = 0;
bool is_return = false;
char *symbol = NULL, *tmp = NULL;
const char *event = NULL, *group = FPROBE_EVENT_SYSTEM;
+ const char **new_argv = NULL;
int maxactive = 0;
char buf[MAX_EVENT_NAME_LEN];
char gbuf[MAX_EVENT_NAME_LEN];
char sbuf[KSYM_NAME_LEN];
+ char abuf[MAX_BTF_ARGS_LEN];
bool is_tracepoint = false;
struct tracepoint *tpoint = NULL;
struct traceprobe_parse_context ctx = {
@@ -1040,9 +1042,22 @@ static int __trace_fprobe_create(int argc, const char *argv[])
} else
ctx.funcname = symbol;
+ argc -= 2; argv += 2;
+ new_argv = traceprobe_expand_meta_args(argc, argv, &new_argc,
+ abuf, MAX_BTF_ARGS_LEN, &ctx);
+ if (IS_ERR(new_argv)) {
+ ret = PTR_ERR(new_argv);
+ new_argv = NULL;
+ goto out;
+ }
+ if (new_argv) {
+ argc = new_argc;
+ argv = new_argv;
+ }
+
/* setup a probe */
tf = alloc_trace_fprobe(group, event, symbol, tpoint, maxactive,
- argc - 2, is_return);
+ argc, is_return);
if (IS_ERR(tf)) {
ret = PTR_ERR(tf);
/* This must return -ENOMEM, else there is a bug */
@@ -1054,7 +1069,6 @@ static int __trace_fprobe_create(int argc, const char *argv[])
tf->mod = __module_text_address(
(unsigned long)tf->tpoint->probestub);
- argc -= 2; argv += 2;
/* parse arguments */
for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
trace_probe_log_set_index(i + 2);
@@ -1083,6 +1097,7 @@ static int __trace_fprobe_create(int argc, const char *argv[])
out:
trace_probe_log_clear();
+ kfree(new_argv);
kfree(symbol);
return ret;
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 7cc32da3e8e8..74adb82331dd 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -732,9 +732,10 @@ static int __trace_kprobe_create(int argc, const char *argv[])
* FETCHARG:TYPE : use TYPE instead of unsigned long.
*/
struct trace_kprobe *tk = NULL;
- int i, len, ret = 0;
+ int i, len, new_argc = 0, ret = 0;
bool is_return = false;
char *symbol = NULL, *tmp = NULL;
+ const char **new_argv = NULL;
const char *event = NULL, *group = KPROBE_EVENT_SYSTEM;
enum probe_print_type ptype;
int maxactive = 0;
@@ -742,6 +743,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
void *addr = NULL;
char buf[MAX_EVENT_NAME_LEN];
char gbuf[MAX_EVENT_NAME_LEN];
+ char abuf[MAX_BTF_ARGS_LEN];
struct traceprobe_parse_context ctx = { .flags = TPARG_FL_KERNEL };
switch (argv[0][0]) {
@@ -854,19 +856,31 @@ static int __trace_kprobe_create(int argc, const char *argv[])
event = buf;
}
+ argc -= 2; argv += 2;
+ ctx.funcname = symbol;
+ new_argv = traceprobe_expand_meta_args(argc, argv, &new_argc,
+ abuf, MAX_BTF_ARGS_LEN, &ctx);
+ if (IS_ERR(new_argv)) {
+ ret = PTR_ERR(new_argv);
+ new_argv = NULL;
+ goto out;
+ }
+ if (new_argv) {
+ argc = new_argc;
+ argv = new_argv;
+ }
+
/* setup a probe */
tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
- argc - 2, is_return);
+ argc, is_return);
if (IS_ERR(tk)) {
ret = PTR_ERR(tk);
/* This must return -ENOMEM, else there is a bug */
WARN_ON_ONCE(ret != -ENOMEM);
goto out; /* We know tk is not allocated */
}
- argc -= 2; argv += 2;
/* parse arguments */
- ctx.funcname = symbol;
for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
trace_probe_log_set_index(i + 2);
ctx.offset = 0;
@@ -894,6 +908,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
out:
trace_probe_log_clear();
+ kfree(new_argv);
kfree(symbol);
return ret;
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 2a169ea2ada1..7318642aceb3 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -371,9 +371,11 @@ static const char *type_from_btf_id(struct btf *btf, s32 id)
return NULL;
}
-static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr)
+static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr,
+ bool tracepoint)
{
struct btf *btf = traceprobe_get_btf();
+ const struct btf_param *param;
const struct btf_type *t;
s32 id;
@@ -395,9 +397,16 @@ static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr
return ERR_PTR(-ENOENT);
*nr = btf_type_vlen(t);
+ param = (const struct btf_param *)(t + 1);
- if (*nr)
- return (const struct btf_param *)(t + 1);
+ /* Hide the first 'data' argument of tracepoint */
+ if (tracepoint) {
+ (*nr)--;
+ param++;
+ }
+
+ if (*nr > 0)
+ return param;
else
return NULL;
}
@@ -418,7 +427,8 @@ static int parse_btf_arg(const char *varname, struct fetch_insn *code,
return -EINVAL;
if (!ctx->params) {
- params = find_btf_func_param(ctx->funcname, &ctx->nr_params);
+ params = find_btf_func_param(ctx->funcname, &ctx->nr_params,
+ ctx->flags & TPARG_FL_TPOINT);
if (IS_ERR(params)) {
trace_probe_log_err(ctx->offset, NO_BTF_ENTRY);
return PTR_ERR(params);
@@ -451,12 +461,19 @@ static const struct fetch_type *parse_btf_arg_type(int arg_idx,
return find_fetch_type(typestr, ctx->flags);
}
+
#else
static struct btf *traceprobe_get_btf(void)
{
return NULL;
}
+static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr,
+ bool tracepoint)
+{
+ return ERR_PTR(-EOPNOTSUPP);
+}
+
static int parse_btf_arg(const char *varname, struct fetch_insn *code,
struct traceprobe_parse_context *ctx)
{
@@ -1114,6 +1131,150 @@ void traceprobe_free_probe_arg(struct probe_arg *arg)
kfree(arg->fmt);
}
+static int argv_has_var_arg(int argc, const char *argv[], int *args_idx,
+ struct traceprobe_parse_context *ctx)
+{
+ int i, found = 0;
+
+ for (i = 0; i < argc; i++)
+ if (str_has_prefix(argv[i], "$arg")) {
+ trace_probe_log_set_index(i + 2);
+
+ if (!tparg_is_function_entry(ctx->flags)) {
+ trace_probe_log_err(0, NOFENTRY_ARGS);
+ return -EINVAL;
+ }
+
+ if (isdigit(argv[i][4])) {
+ found = 1;
+ continue;
+ }
+
+ if (argv[i][4] != '*') {
+ trace_probe_log_err(0, BAD_VAR);
+ return -EINVAL;
+ }
+
+ if (*args_idx >= 0 && *args_idx < argc) {
+ trace_probe_log_err(0, DOUBLE_ARGS);
+ return -EINVAL;
+ }
+ found = 1;
+ *args_idx = i;
+ }
+
+ return found;
+}
+
+static int sprint_nth_btf_arg(int idx, const char *type,
+ char *buf, int bufsize,
+ struct traceprobe_parse_context *ctx)
+{
+ struct btf *btf = traceprobe_get_btf();
+ const char *name;
+ int ret;
+
+ if (idx >= ctx->nr_params) {
+ trace_probe_log_err(0, NO_BTFARG);
+ return -ENOENT;
+ }
+ name = btf_name_by_offset(btf, ctx->params[idx].name_off);
+ if (!name) {
+ trace_probe_log_err(0, NO_BTF_ENTRY);
+ return -ENOENT;
+ }
+ ret = snprintf(buf, bufsize, "%s%s", name, type);
+ if (ret >= bufsize) {
+ trace_probe_log_err(0, ARGS_2LONG);
+ return -E2BIG;
+ }
+ return ret;
+}
+
+/* Return new_argv which must be freed after use */
+const char **traceprobe_expand_meta_args(int argc, const char *argv[],
+ int *new_argc, char *buf, int bufsize,
+ struct traceprobe_parse_context *ctx)
+{
+ const struct btf_param *params = NULL;
+ int i, j, n, used, ret, args_idx = -1;
+ const char **new_argv = NULL;
+ int nr_params;
+
+ ret = argv_has_var_arg(argc, argv, &args_idx, ctx);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ if (!ret) {
+ *new_argc = argc;
+ return NULL;
+ }
+
+ params = find_btf_func_param(ctx->funcname, &nr_params,
+ ctx->flags & TPARG_FL_TPOINT);
+ if (IS_ERR(params)) {
+ if (args_idx != -1) {
+ /* $arg* requires BTF info */
+ trace_probe_log_err(0, NOSUP_BTFARG);
+ return (const char **)params;
+ }
+ return 0;
+ }
+ ctx->params = params;
+ ctx->nr_params = nr_params;
+
+ if (args_idx >= 0)
+ *new_argc = argc + ctx->nr_params - 1;
+ else
+ *new_argc = argc;
+
+ new_argv = kcalloc(*new_argc, sizeof(char *), GFP_KERNEL);
+ if (!new_argv)
+ return ERR_PTR(-ENOMEM);
+
+ used = 0;
+ for (i = 0, j = 0; i < argc; i++) {
+ trace_probe_log_set_index(i + 2);
+ if (i == args_idx) {
+ for (n = 0; n < nr_params; n++) {
+ ret = sprint_nth_btf_arg(n, "", buf + used,
+ bufsize - used, ctx);
+ if (ret < 0)
+ goto error;
+
+ new_argv[j++] = buf + used;
+ used += ret + 1;
+ }
+ continue;
+ }
+
+ if (str_has_prefix(argv[i], "$arg")) {
+ char *type = NULL;
+
+ n = simple_strtoul(argv[i] + 4, &type, 10);
+ if (type && !(*type == ':' || *type == '\0')) {
+ trace_probe_log_err(0, BAD_VAR);
+ ret = -ENOENT;
+ goto error;
+ }
+ /* Note: $argN starts from $arg1 */
+ ret = sprint_nth_btf_arg(n - 1, type, buf + used,
+ bufsize - used, ctx);
+ if (ret < 0)
+ goto error;
+ new_argv[j++] = buf + used;
+ used += ret + 1;
+ } else
+ new_argv[j++] = argv[i];
+ }
+
+ return new_argv;
+
+error:
+ kfree(new_argv);
+ return ERR_PTR(ret);
+}
+
int traceprobe_update_arg(struct probe_arg *arg)
{
struct fetch_insn *code = arg->code;
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 2c7e7e9e9ce7..c864e6dea10f 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -33,7 +33,9 @@
#define MAX_ARGSTR_LEN 63
#define MAX_ARRAY_LEN 64
#define MAX_ARG_NAME_LEN 32
+#define MAX_BTF_ARGS_LEN 128
#define MAX_STRING_SIZE PATH_MAX
+#define MAX_ARG_BUF_LEN (MAX_TRACE_ARGS * MAX_ARG_NAME_LEN)
/* Reserved field names */
#define FIELD_STRING_IP "__probe_ip"
@@ -391,6 +393,9 @@ struct traceprobe_parse_context {
extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i,
const char *argv,
struct traceprobe_parse_context *ctx);
+const char **traceprobe_expand_meta_args(int argc, const char *argv[],
+ int *new_argc, char *buf, int bufsize,
+ struct traceprobe_parse_context *ctx);
extern int traceprobe_update_arg(struct probe_arg *arg);
extern void traceprobe_free_probe_arg(struct probe_arg *arg);
@@ -485,7 +490,11 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
C(NO_EP_FILTER, "No filter rule after 'if'"), \
C(NOSUP_BTFARG, "BTF is not available or not supported"), \
C(NO_BTFARG, "This variable is not found at this probe point"),\
- C(NO_BTF_ENTRY, "No BTF entry for this probe point"),
+ C(NO_BTF_ENTRY, "No BTF entry for this probe point"), \
+ C(BAD_VAR_ARGS, "$arg* must be an independent parameter without name etc."),\
+ C(NOFENTRY_ARGS, "$arg* can be used only on function entry"), \
+ C(DOUBLE_ARGS, "$arg* can be used only once in the parameters"), \
+ C(ARGS_2LONG, "$arg* failed because the argument list is too long"),
#undef C
#define C(a, b) TP_ERR_##a
