tracing/probes: Add $arg* meta argument for all function args
Add the '$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. Link: https://lore.kernel.org/all/168507475126.913472.18329684401466211816.stgit@mhiramat.roam.corp.google.com/ Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
This commit is contained in:
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b576e09701
commit
18b1e870a4
@ -925,14 +925,16 @@ static int __trace_fprobe_create(int argc, const char *argv[])
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* FETCHARG:TYPE : use TYPE instead of unsigned long.
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*/
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struct trace_fprobe *tf = NULL;
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int i, len, ret = 0;
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int i, len, new_argc = 0, ret = 0;
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bool is_return = false;
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char *symbol = NULL, *tmp = NULL;
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const char *event = NULL, *group = FPROBE_EVENT_SYSTEM;
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const char **new_argv = NULL;
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int maxactive = 0;
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char buf[MAX_EVENT_NAME_LEN];
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char gbuf[MAX_EVENT_NAME_LEN];
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char sbuf[KSYM_NAME_LEN];
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char abuf[MAX_BTF_ARGS_LEN];
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bool is_tracepoint = false;
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struct tracepoint *tpoint = NULL;
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struct traceprobe_parse_context ctx = {
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@ -1040,9 +1042,22 @@ static int __trace_fprobe_create(int argc, const char *argv[])
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} else
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ctx.funcname = symbol;
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argc -= 2; argv += 2;
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new_argv = traceprobe_expand_meta_args(argc, argv, &new_argc,
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abuf, MAX_BTF_ARGS_LEN, &ctx);
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if (IS_ERR(new_argv)) {
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ret = PTR_ERR(new_argv);
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new_argv = NULL;
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goto out;
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}
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if (new_argv) {
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argc = new_argc;
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argv = new_argv;
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}
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/* setup a probe */
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tf = alloc_trace_fprobe(group, event, symbol, tpoint, maxactive,
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argc - 2, is_return);
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argc, is_return);
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if (IS_ERR(tf)) {
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ret = PTR_ERR(tf);
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/* This must return -ENOMEM, else there is a bug */
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@ -1054,7 +1069,6 @@ static int __trace_fprobe_create(int argc, const char *argv[])
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tf->mod = __module_text_address(
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(unsigned long)tf->tpoint->probestub);
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argc -= 2; argv += 2;
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/* parse arguments */
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for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
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trace_probe_log_set_index(i + 2);
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@ -1083,6 +1097,7 @@ static int __trace_fprobe_create(int argc, const char *argv[])
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out:
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trace_probe_log_clear();
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kfree(new_argv);
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kfree(symbol);
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return ret;
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@ -732,9 +732,10 @@ static int __trace_kprobe_create(int argc, const char *argv[])
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* FETCHARG:TYPE : use TYPE instead of unsigned long.
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*/
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struct trace_kprobe *tk = NULL;
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int i, len, ret = 0;
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int i, len, new_argc = 0, ret = 0;
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bool is_return = false;
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char *symbol = NULL, *tmp = NULL;
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const char **new_argv = NULL;
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const char *event = NULL, *group = KPROBE_EVENT_SYSTEM;
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enum probe_print_type ptype;
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int maxactive = 0;
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@ -742,6 +743,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
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void *addr = NULL;
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char buf[MAX_EVENT_NAME_LEN];
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char gbuf[MAX_EVENT_NAME_LEN];
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char abuf[MAX_BTF_ARGS_LEN];
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struct traceprobe_parse_context ctx = { .flags = TPARG_FL_KERNEL };
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switch (argv[0][0]) {
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@ -854,19 +856,31 @@ static int __trace_kprobe_create(int argc, const char *argv[])
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event = buf;
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}
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argc -= 2; argv += 2;
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ctx.funcname = symbol;
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new_argv = traceprobe_expand_meta_args(argc, argv, &new_argc,
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abuf, MAX_BTF_ARGS_LEN, &ctx);
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if (IS_ERR(new_argv)) {
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ret = PTR_ERR(new_argv);
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new_argv = NULL;
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goto out;
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}
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if (new_argv) {
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argc = new_argc;
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argv = new_argv;
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}
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/* setup a probe */
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tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
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argc - 2, is_return);
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argc, is_return);
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if (IS_ERR(tk)) {
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ret = PTR_ERR(tk);
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/* This must return -ENOMEM, else there is a bug */
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WARN_ON_ONCE(ret != -ENOMEM);
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goto out; /* We know tk is not allocated */
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}
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argc -= 2; argv += 2;
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/* parse arguments */
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ctx.funcname = symbol;
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for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
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trace_probe_log_set_index(i + 2);
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ctx.offset = 0;
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@ -894,6 +908,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
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out:
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trace_probe_log_clear();
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kfree(new_argv);
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kfree(symbol);
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return ret;
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@ -371,9 +371,11 @@ static const char *type_from_btf_id(struct btf *btf, s32 id)
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return NULL;
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}
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static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr)
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static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr,
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bool tracepoint)
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{
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struct btf *btf = traceprobe_get_btf();
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const struct btf_param *param;
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const struct btf_type *t;
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s32 id;
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@ -395,9 +397,16 @@ static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr
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return ERR_PTR(-ENOENT);
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*nr = btf_type_vlen(t);
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param = (const struct btf_param *)(t + 1);
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if (*nr)
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return (const struct btf_param *)(t + 1);
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/* Hide the first 'data' argument of tracepoint */
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if (tracepoint) {
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(*nr)--;
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param++;
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}
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if (*nr > 0)
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return param;
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else
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return NULL;
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}
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@ -418,7 +427,8 @@ static int parse_btf_arg(const char *varname, struct fetch_insn *code,
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return -EINVAL;
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if (!ctx->params) {
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params = find_btf_func_param(ctx->funcname, &ctx->nr_params);
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params = find_btf_func_param(ctx->funcname, &ctx->nr_params,
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ctx->flags & TPARG_FL_TPOINT);
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if (IS_ERR(params)) {
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trace_probe_log_err(ctx->offset, NO_BTF_ENTRY);
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return PTR_ERR(params);
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@ -451,12 +461,19 @@ static const struct fetch_type *parse_btf_arg_type(int arg_idx,
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return find_fetch_type(typestr, ctx->flags);
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}
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#else
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static struct btf *traceprobe_get_btf(void)
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{
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return NULL;
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}
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static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr,
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bool tracepoint)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static int parse_btf_arg(const char *varname, struct fetch_insn *code,
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struct traceprobe_parse_context *ctx)
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{
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@ -1114,6 +1131,150 @@ void traceprobe_free_probe_arg(struct probe_arg *arg)
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kfree(arg->fmt);
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}
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static int argv_has_var_arg(int argc, const char *argv[], int *args_idx,
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struct traceprobe_parse_context *ctx)
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{
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int i, found = 0;
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for (i = 0; i < argc; i++)
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if (str_has_prefix(argv[i], "$arg")) {
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trace_probe_log_set_index(i + 2);
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if (!tparg_is_function_entry(ctx->flags)) {
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trace_probe_log_err(0, NOFENTRY_ARGS);
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return -EINVAL;
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}
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if (isdigit(argv[i][4])) {
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found = 1;
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continue;
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}
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if (argv[i][4] != '*') {
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trace_probe_log_err(0, BAD_VAR);
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return -EINVAL;
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}
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if (*args_idx >= 0 && *args_idx < argc) {
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trace_probe_log_err(0, DOUBLE_ARGS);
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return -EINVAL;
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}
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found = 1;
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*args_idx = i;
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}
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return found;
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}
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static int sprint_nth_btf_arg(int idx, const char *type,
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char *buf, int bufsize,
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struct traceprobe_parse_context *ctx)
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{
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struct btf *btf = traceprobe_get_btf();
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const char *name;
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int ret;
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if (idx >= ctx->nr_params) {
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trace_probe_log_err(0, NO_BTFARG);
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return -ENOENT;
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}
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name = btf_name_by_offset(btf, ctx->params[idx].name_off);
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if (!name) {
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trace_probe_log_err(0, NO_BTF_ENTRY);
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return -ENOENT;
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}
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ret = snprintf(buf, bufsize, "%s%s", name, type);
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if (ret >= bufsize) {
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trace_probe_log_err(0, ARGS_2LONG);
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return -E2BIG;
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}
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return ret;
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}
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/* Return new_argv which must be freed after use */
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const char **traceprobe_expand_meta_args(int argc, const char *argv[],
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int *new_argc, char *buf, int bufsize,
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struct traceprobe_parse_context *ctx)
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{
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const struct btf_param *params = NULL;
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int i, j, n, used, ret, args_idx = -1;
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const char **new_argv = NULL;
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int nr_params;
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ret = argv_has_var_arg(argc, argv, &args_idx, ctx);
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if (ret < 0)
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return ERR_PTR(ret);
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if (!ret) {
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*new_argc = argc;
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return NULL;
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}
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params = find_btf_func_param(ctx->funcname, &nr_params,
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ctx->flags & TPARG_FL_TPOINT);
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if (IS_ERR(params)) {
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if (args_idx != -1) {
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/* $arg* requires BTF info */
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trace_probe_log_err(0, NOSUP_BTFARG);
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return (const char **)params;
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}
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return 0;
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}
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ctx->params = params;
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ctx->nr_params = nr_params;
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if (args_idx >= 0)
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*new_argc = argc + ctx->nr_params - 1;
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else
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*new_argc = argc;
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new_argv = kcalloc(*new_argc, sizeof(char *), GFP_KERNEL);
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if (!new_argv)
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return ERR_PTR(-ENOMEM);
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used = 0;
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for (i = 0, j = 0; i < argc; i++) {
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trace_probe_log_set_index(i + 2);
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if (i == args_idx) {
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for (n = 0; n < nr_params; n++) {
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ret = sprint_nth_btf_arg(n, "", buf + used,
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bufsize - used, ctx);
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if (ret < 0)
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goto error;
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new_argv[j++] = buf + used;
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used += ret + 1;
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}
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continue;
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}
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if (str_has_prefix(argv[i], "$arg")) {
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char *type = NULL;
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n = simple_strtoul(argv[i] + 4, &type, 10);
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if (type && !(*type == ':' || *type == '\0')) {
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trace_probe_log_err(0, BAD_VAR);
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ret = -ENOENT;
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goto error;
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}
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/* Note: $argN starts from $arg1 */
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ret = sprint_nth_btf_arg(n - 1, type, buf + used,
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bufsize - used, ctx);
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if (ret < 0)
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goto error;
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new_argv[j++] = buf + used;
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used += ret + 1;
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} else
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new_argv[j++] = argv[i];
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}
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return new_argv;
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error:
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kfree(new_argv);
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return ERR_PTR(ret);
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}
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int traceprobe_update_arg(struct probe_arg *arg)
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{
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struct fetch_insn *code = arg->code;
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@ -33,7 +33,9 @@
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#define MAX_ARGSTR_LEN 63
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#define MAX_ARRAY_LEN 64
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#define MAX_ARG_NAME_LEN 32
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#define MAX_BTF_ARGS_LEN 128
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#define MAX_STRING_SIZE PATH_MAX
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#define MAX_ARG_BUF_LEN (MAX_TRACE_ARGS * MAX_ARG_NAME_LEN)
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/* Reserved field names */
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#define FIELD_STRING_IP "__probe_ip"
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@ -391,6 +393,9 @@ struct traceprobe_parse_context {
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extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i,
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const char *argv,
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struct traceprobe_parse_context *ctx);
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const char **traceprobe_expand_meta_args(int argc, const char *argv[],
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int *new_argc, char *buf, int bufsize,
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struct traceprobe_parse_context *ctx);
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extern int traceprobe_update_arg(struct probe_arg *arg);
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extern void traceprobe_free_probe_arg(struct probe_arg *arg);
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@ -485,7 +490,11 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
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C(NO_EP_FILTER, "No filter rule after 'if'"), \
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C(NOSUP_BTFARG, "BTF is not available or not supported"), \
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C(NO_BTFARG, "This variable is not found at this probe point"),\
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C(NO_BTF_ENTRY, "No BTF entry for this probe point"),
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C(NO_BTF_ENTRY, "No BTF entry for this probe point"), \
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C(BAD_VAR_ARGS, "$arg* must be an independent parameter without name etc."),\
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C(NOFENTRY_ARGS, "$arg* can be used only on function entry"), \
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C(DOUBLE_ARGS, "$arg* can be used only once in the parameters"), \
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C(ARGS_2LONG, "$arg* failed because the argument list is too long"),
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#undef C
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#define C(a, b) TP_ERR_##a
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