1 files changed, 1131 insertions, 0 deletions

diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
new file mode 100644
index 000000000..d2b98d644
--- /dev/null
+++ b/tools/perf/util/probe-file.c
@@ -0,0 +1,1131 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * probe-file.c : operate ftrace k/uprobe events files
+ *
+ * Written by Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
+ */
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <unistd.h>
+#include <linux/zalloc.h>
+#include "namespaces.h"
+#include "event.h"
+#include "strlist.h"
+#include "strfilter.h"
+#include "debug.h"
+#include "build-id.h"
+#include "dso.h"
+#include "color.h"
+#include "symbol.h"
+#include "strbuf.h"
+#include <api/fs/tracing_path.h>
+#include "probe-event.h"
+#include "probe-file.h"
+#include "session.h"
+#include "perf_regs.h"
+#include "string2.h"
+
+/* 4096 - 2 ('\n' + '\0') */
+#define MAX_CMDLEN 4094
+
+static void print_open_warning(int err, bool uprobe)
+{
+	char sbuf[STRERR_BUFSIZE];
+
+	if (err == -ENOENT) {
+		const char *config;
+
+		if (uprobe)
+			config = "CONFIG_UPROBE_EVENTS";
+		else
+			config = "CONFIG_KPROBE_EVENTS";
+
+		pr_warning("%cprobe_events file does not exist"
+			   " - please rebuild kernel with %s.\n",
+			   uprobe ? 'u' : 'k', config);
+	} else if (err == -ENOTSUP)
+		pr_warning("Tracefs or debugfs is not mounted.\n");
+	else
+		pr_warning("Failed to open %cprobe_events: %s\n",
+			   uprobe ? 'u' : 'k',
+			   str_error_r(-err, sbuf, sizeof(sbuf)));
+}
+
+static void print_both_open_warning(int kerr, int uerr)
+{
+	/* Both kprobes and uprobes are disabled, warn it. */
+	if (kerr == -ENOTSUP && uerr == -ENOTSUP)
+		pr_warning("Tracefs or debugfs is not mounted.\n");
+	else if (kerr == -ENOENT && uerr == -ENOENT)
+		pr_warning("Please rebuild kernel with CONFIG_KPROBE_EVENTS "
+			   "or/and CONFIG_UPROBE_EVENTS.\n");
+	else {
+		char sbuf[STRERR_BUFSIZE];
+		pr_warning("Failed to open kprobe events: %s.\n",
+			   str_error_r(-kerr, sbuf, sizeof(sbuf)));
+		pr_warning("Failed to open uprobe events: %s.\n",
+			   str_error_r(-uerr, sbuf, sizeof(sbuf)));
+	}
+}
+
+int open_trace_file(const char *trace_file, bool readwrite)
+{
+	char buf[PATH_MAX];
+	int ret;
+
+	ret = e_snprintf(buf, PATH_MAX, "%s/%s", tracing_path_mount(), trace_file);
+	if (ret >= 0) {
+		pr_debug("Opening %s write=%d\n", buf, readwrite);
+		if (readwrite && !probe_event_dry_run)
+			ret = open(buf, O_RDWR | O_APPEND, 0);
+		else
+			ret = open(buf, O_RDONLY, 0);
+
+		if (ret < 0)
+			ret = -errno;
+	}
+	return ret;
+}
+
+static int open_kprobe_events(bool readwrite)
+{
+	return open_trace_file("kprobe_events", readwrite);
+}
+
+static int open_uprobe_events(bool readwrite)
+{
+	return open_trace_file("uprobe_events", readwrite);
+}
+
+int probe_file__open(int flag)
+{
+	int fd;
+
+	if (flag & PF_FL_UPROBE)
+		fd = open_uprobe_events(flag & PF_FL_RW);
+	else
+		fd = open_kprobe_events(flag & PF_FL_RW);
+	if (fd < 0)
+		print_open_warning(fd, flag & PF_FL_UPROBE);
+
+	return fd;
+}
+
+int probe_file__open_both(int *kfd, int *ufd, int flag)
+{
+	if (!kfd || !ufd)
+		return -EINVAL;
+
+	*kfd = open_kprobe_events(flag & PF_FL_RW);
+	*ufd = open_uprobe_events(flag & PF_FL_RW);
+	if (*kfd < 0 && *ufd < 0) {
+		print_both_open_warning(*kfd, *ufd);
+		return *kfd;
+	}
+
+	return 0;
+}
+
+/* Get raw string list of current kprobe_events  or uprobe_events */
+struct strlist *probe_file__get_rawlist(int fd)
+{
+	int ret, idx, fddup;
+	FILE *fp;
+	char buf[MAX_CMDLEN];
+	char *p;
+	struct strlist *sl;
+
+	if (fd < 0)
+		return NULL;
+
+	sl = strlist__new(NULL, NULL);
+	if (sl == NULL)
+		return NULL;
+
+	fddup = dup(fd);
+	if (fddup < 0)
+		goto out_free_sl;
+
+	fp = fdopen(fddup, "r");
+	if (!fp)
+		goto out_close_fddup;
+
+	while (!feof(fp)) {
+		p = fgets(buf, MAX_CMDLEN, fp);
+		if (!p)
+			break;
+
+		idx = strlen(p) - 1;
+		if (p[idx] == '\n')
+			p[idx] = '\0';
+		ret = strlist__add(sl, buf);
+		if (ret < 0) {
+			pr_debug("strlist__add failed (%d)\n", ret);
+			goto out_close_fp;
+		}
+	}
+	fclose(fp);
+
+	return sl;
+
+out_close_fp:
+	fclose(fp);
+	goto out_free_sl;
+out_close_fddup:
+	close(fddup);
+out_free_sl:
+	strlist__delete(sl);
+	return NULL;
+}
+
+static struct strlist *__probe_file__get_namelist(int fd, bool include_group)
+{
+	char buf[128];
+	struct strlist *sl, *rawlist;
+	struct str_node *ent;
+	struct probe_trace_event tev;
+	int ret = 0;
+
+	memset(&tev, 0, sizeof(tev));
+	rawlist = probe_file__get_rawlist(fd);
+	if (!rawlist)
+		return NULL;
+	sl = strlist__new(NULL, NULL);
+	strlist__for_each_entry(ent, rawlist) {
+		ret = parse_probe_trace_command(ent->s, &tev);
+		if (ret < 0)
+			break;
+		if (include_group) {
+			ret = e_snprintf(buf, 128, "%s:%s", tev.group,
+					tev.event);
+			if (ret >= 0)
+				ret = strlist__add(sl, buf);
+		} else
+			ret = strlist__add(sl, tev.event);
+		clear_probe_trace_event(&tev);
+		/* Skip if there is same name multi-probe event in the list */
+		if (ret == -EEXIST)
+			ret = 0;
+		if (ret < 0)
+			break;
+	}
+	strlist__delete(rawlist);
+
+	if (ret < 0) {
+		strlist__delete(sl);
+		return NULL;
+	}
+	return sl;
+}
+
+/* Get current perf-probe event names */
+struct strlist *probe_file__get_namelist(int fd)
+{
+	return __probe_file__get_namelist(fd, false);
+}
+
+int probe_file__add_event(int fd, struct probe_trace_event *tev)
+{
+	int ret = 0;
+	char *buf = synthesize_probe_trace_command(tev);
+	char sbuf[STRERR_BUFSIZE];
+
+	if (!buf) {
+		pr_debug("Failed to synthesize probe trace event.\n");
+		return -EINVAL;
+	}
+
+	pr_debug("Writing event: %s\n", buf);
+	if (!probe_event_dry_run) {
+		if (write(fd, buf, strlen(buf)) < (int)strlen(buf)) {
+			ret = -errno;
+			pr_warning("Failed to write event: %s\n",
+				   str_error_r(errno, sbuf, sizeof(sbuf)));
+		}
+	}
+	free(buf);
+
+	return ret;
+}
+
+static int __del_trace_probe_event(int fd, struct str_node *ent)
+{
+	char *p;
+	char buf[128];
+	int ret;
+
+	/* Convert from perf-probe event to trace-probe event */
+	ret = e_snprintf(buf, 128, "-:%s", ent->s);
+	if (ret < 0)
+		goto error;
+
+	p = strchr(buf + 2, ':');
+	if (!p) {
+		pr_debug("Internal error: %s should have ':' but not.\n",
+			 ent->s);
+		ret = -ENOTSUP;
+		goto error;
+	}
+	*p = '/';
+
+	pr_debug("Writing event: %s\n", buf);
+	ret = write(fd, buf, strlen(buf));
+	if (ret < 0) {
+		ret = -errno;
+		goto error;
+	}
+
+	return 0;
+error:
+	pr_warning("Failed to delete event: %s\n",
+		   str_error_r(-ret, buf, sizeof(buf)));
+	return ret;
+}
+
+int probe_file__get_events(int fd, struct strfilter *filter,
+			   struct strlist *plist)
+{
+	struct strlist *namelist;
+	struct str_node *ent;
+	const char *p;
+	int ret = -ENOENT;
+
+	if (!plist)
+		return -EINVAL;
+
+	namelist = __probe_file__get_namelist(fd, true);
+	if (!namelist)
+		return -ENOENT;
+
+	strlist__for_each_entry(ent, namelist) {
+		p = strchr(ent->s, ':');
+		if ((p && strfilter__compare(filter, p + 1)) ||
+		    strfilter__compare(filter, ent->s)) {
+			ret = strlist__add(plist, ent->s);
+			if (ret == -ENOMEM) {
+				pr_err("strlist__add failed with -ENOMEM\n");
+				goto out;
+			}
+			ret = 0;
+		}
+	}
+out:
+	strlist__delete(namelist);
+
+	return ret;
+}
+
+int probe_file__del_strlist(int fd, struct strlist *namelist)
+{
+	int ret = 0;
+	struct str_node *ent;
+
+	strlist__for_each_entry(ent, namelist) {
+		ret = __del_trace_probe_event(fd, ent);
+		if (ret < 0)
+			break;
+	}
+	return ret;
+}
+
+int probe_file__del_events(int fd, struct strfilter *filter)
+{
+	struct strlist *namelist;
+	int ret;
+
+	namelist = strlist__new(NULL, NULL);
+	if (!namelist)
+		return -ENOMEM;
+
+	ret = probe_file__get_events(fd, filter, namelist);
+	if (ret < 0)
+		goto out;
+
+	ret = probe_file__del_strlist(fd, namelist);
+out:
+	strlist__delete(namelist);
+	return ret;
+}
+
+/* Caller must ensure to remove this entry from list */
+static void probe_cache_entry__delete(struct probe_cache_entry *entry)
+{
+	if (entry) {
+		BUG_ON(!list_empty(&entry->node));
+
+		strlist__delete(entry->tevlist);
+		clear_perf_probe_event(&entry->pev);
+		zfree(&entry->spev);
+		free(entry);
+	}
+}
+
+static struct probe_cache_entry *
+probe_cache_entry__new(struct perf_probe_event *pev)
+{
+	struct probe_cache_entry *entry = zalloc(sizeof(*entry));
+
+	if (entry) {
+		INIT_LIST_HEAD(&entry->node);
+		entry->tevlist = strlist__new(NULL, NULL);
+		if (!entry->tevlist)
+			zfree(&entry);
+		else if (pev) {
+			entry->spev = synthesize_perf_probe_command(pev);
+			if (!entry->spev ||
+			    perf_probe_event__copy(&entry->pev, pev) < 0) {
+				probe_cache_entry__delete(entry);
+				return NULL;
+			}
+		}
+	}
+
+	return entry;
+}
+
+int probe_cache_entry__get_event(struct probe_cache_entry *entry,
+				 struct probe_trace_event **tevs)
+{
+	struct probe_trace_event *tev;
+	struct str_node *node;
+	int ret, i;
+
+	ret = strlist__nr_entries(entry->tevlist);
+	if (ret > probe_conf.max_probes)
+		return -E2BIG;
+
+	*tevs = zalloc(ret * sizeof(*tev));
+	if (!*tevs)
+		return -ENOMEM;
+
+	i = 0;
+	strlist__for_each_entry(node, entry->tevlist) {
+		tev = &(*tevs)[i++];
+		ret = parse_probe_trace_command(node->s, tev);
+		if (ret < 0)
+			break;
+	}
+	return i;
+}
+
+/* For the kernel probe caches, pass target = NULL or DSO__NAME_KALLSYMS */
+static int probe_cache__open(struct probe_cache *pcache, const char *target,
+			     struct nsinfo *nsi)
+{
+	char cpath[PATH_MAX];
+	char sbuildid[SBUILD_ID_SIZE];
+	char *dir_name = NULL;
+	bool is_kallsyms = false;
+	int ret, fd;
+	struct nscookie nsc;
+
+	if (target && build_id_cache__cached(target)) {
+		/* This is a cached buildid */
+		strlcpy(sbuildid, target, SBUILD_ID_SIZE);
+		dir_name = build_id_cache__linkname(sbuildid, NULL, 0);
+		goto found;
+	}
+
+	if (!target || !strcmp(target, DSO__NAME_KALLSYMS)) {
+		target = DSO__NAME_KALLSYMS;
+		is_kallsyms = true;
+		ret = sysfs__sprintf_build_id("/", sbuildid);
+	} else {
+		nsinfo__mountns_enter(nsi, &nsc);
+		ret = filename__sprintf_build_id(target, sbuildid);
+		nsinfo__mountns_exit(&nsc);
+	}
+
+	if (ret < 0) {
+		pr_debug("Failed to get build-id from %s.\n", target);
+		return ret;
+	}
+
+	/* If we have no buildid cache, make it */
+	if (!build_id_cache__cached(sbuildid)) {
+		ret = build_id_cache__add_s(sbuildid, target, nsi,
+					    is_kallsyms, NULL);
+		if (ret < 0) {
+			pr_debug("Failed to add build-id cache: %s\n", target);
+			return ret;
+		}
+	}
+
+	dir_name = build_id_cache__cachedir(sbuildid, target, nsi, is_kallsyms,
+					    false);
+found:
+	if (!dir_name) {
+		pr_debug("Failed to get cache from %s\n", target);
+		return -ENOMEM;
+	}
+
+	snprintf(cpath, PATH_MAX, "%s/probes", dir_name);
+	fd = open(cpath, O_CREAT | O_RDWR, 0644);
+	if (fd < 0)
+		pr_debug("Failed to open cache(%d): %s\n", fd, cpath);
+	free(dir_name);
+	pcache->fd = fd;
+
+	return fd;
+}
+
+static int probe_cache__load(struct probe_cache *pcache)
+{
+	struct probe_cache_entry *entry = NULL;
+	char buf[MAX_CMDLEN], *p;
+	int ret = 0, fddup;
+	FILE *fp;
+
+	fddup = dup(pcache->fd);
+	if (fddup < 0)
+		return -errno;
+	fp = fdopen(fddup, "r");
+	if (!fp) {
+		close(fddup);
+		return -EINVAL;
+	}
+
+	while (!feof(fp)) {
+		if (!fgets(buf, MAX_CMDLEN, fp))
+			break;
+		p = strchr(buf, '\n');
+		if (p)
+			*p = '\0';
+		/* #perf_probe_event or %sdt_event */
+		if (buf[0] == '#' || buf[0] == '%') {
+			entry = probe_cache_entry__new(NULL);
+			if (!entry) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			if (buf[0] == '%')
+				entry->sdt = true;
+			entry->spev = strdup(buf + 1);
+			if (entry->spev)
+				ret = parse_perf_probe_command(buf + 1,
+								&entry->pev);
+			else
+				ret = -ENOMEM;
+			if (ret < 0) {
+				probe_cache_entry__delete(entry);
+				goto out;
+			}
+			list_add_tail(&entry->node, &pcache->entries);
+		} else {	/* trace_probe_event */
+			if (!entry) {
+				ret = -EINVAL;
+				goto out;
+			}
+			ret = strlist__add(entry->tevlist, buf);
+			if (ret == -ENOMEM) {
+				pr_err("strlist__add failed with -ENOMEM\n");
+				goto out;
+			}
+		}
+	}
+out:
+	fclose(fp);
+	return ret;
+}
+
+static struct probe_cache *probe_cache__alloc(void)
+{
+	struct probe_cache *pcache = zalloc(sizeof(*pcache));
+
+	if (pcache) {
+		INIT_LIST_HEAD(&pcache->entries);
+		pcache->fd = -EINVAL;
+	}
+	return pcache;
+}
+
+void probe_cache__purge(struct probe_cache *pcache)
+{
+	struct probe_cache_entry *entry, *n;
+
+	list_for_each_entry_safe(entry, n, &pcache->entries, node) {
+		list_del_init(&entry->node);
+		probe_cache_entry__delete(entry);
+	}
+}
+
+void probe_cache__delete(struct probe_cache *pcache)
+{
+	if (!pcache)
+		return;
+
+	probe_cache__purge(pcache);
+	if (pcache->fd > 0)
+		close(pcache->fd);
+	free(pcache);
+}
+
+struct probe_cache *probe_cache__new(const char *target, struct nsinfo *nsi)
+{
+	struct probe_cache *pcache = probe_cache__alloc();
+	int ret;
+
+	if (!pcache)
+		return NULL;
+
+	ret = probe_cache__open(pcache, target, nsi);
+	if (ret < 0) {
+		pr_debug("Cache open error: %d\n", ret);
+		goto out_err;
+	}
+
+	ret = probe_cache__load(pcache);
+	if (ret < 0) {
+		pr_debug("Cache read error: %d\n", ret);
+		goto out_err;
+	}
+
+	return pcache;
+
+out_err:
+	probe_cache__delete(pcache);
+	return NULL;
+}
+
+static bool streql(const char *a, const char *b)
+{
+	if (a == b)
+		return true;
+
+	if (!a || !b)
+		return false;
+
+	return !strcmp(a, b);
+}
+
+struct probe_cache_entry *
+probe_cache__find(struct probe_cache *pcache, struct perf_probe_event *pev)
+{
+	struct probe_cache_entry *entry = NULL;
+	char *cmd = synthesize_perf_probe_command(pev);
+
+	if (!cmd)
+		return NULL;
+
+	for_each_probe_cache_entry(entry, pcache) {
+		if (pev->sdt) {
+			if (entry->pev.event &&
+			    streql(entry->pev.event, pev->event) &&
+			    (!pev->group ||
+			     streql(entry->pev.group, pev->group)))
+				goto found;
+
+			continue;
+		}
+		/* Hit if same event name or same command-string */
+		if ((pev->event &&
+		     (streql(entry->pev.group, pev->group) &&
+		      streql(entry->pev.event, pev->event))) ||
+		    (!strcmp(entry->spev, cmd)))
+			goto found;
+	}
+	entry = NULL;
+
+found:
+	free(cmd);
+	return entry;
+}
+
+struct probe_cache_entry *
+probe_cache__find_by_name(struct probe_cache *pcache,
+			  const char *group, const char *event)
+{
+	struct probe_cache_entry *entry = NULL;
+
+	for_each_probe_cache_entry(entry, pcache) {
+		/* Hit if same event name or same command-string */
+		if (streql(entry->pev.group, group) &&
+		    streql(entry->pev.event, event))
+			goto found;
+	}
+	entry = NULL;
+
+found:
+	return entry;
+}
+
+int probe_cache__add_entry(struct probe_cache *pcache,
+			   struct perf_probe_event *pev,
+			   struct probe_trace_event *tevs, int ntevs)
+{
+	struct probe_cache_entry *entry = NULL;
+	char *command;
+	int i, ret = 0;
+
+	if (!pcache || !pev || !tevs || ntevs <= 0) {
+		ret = -EINVAL;
+		goto out_err;
+	}
+
+	/* Remove old cache entry */
+	entry = probe_cache__find(pcache, pev);
+	if (entry) {
+		list_del_init(&entry->node);
+		probe_cache_entry__delete(entry);
+	}
+
+	ret = -ENOMEM;
+	entry = probe_cache_entry__new(pev);
+	if (!entry)
+		goto out_err;
+
+	for (i = 0; i < ntevs; i++) {
+		if (!tevs[i].point.symbol)
+			continue;
+
+		command = synthesize_probe_trace_command(&tevs[i]);
+		if (!command)
+			goto out_err;
+		ret = strlist__add(entry->tevlist, command);
+		if (ret == -ENOMEM) {
+			pr_err("strlist__add failed with -ENOMEM\n");
+			goto out_err;
+		}
+
+		free(command);
+	}
+	list_add_tail(&entry->node, &pcache->entries);
+	pr_debug("Added probe cache: %d\n", ntevs);
+	return 0;
+
+out_err:
+	pr_debug("Failed to add probe caches\n");
+	probe_cache_entry__delete(entry);
+	return ret;
+}
+
+#ifdef HAVE_GELF_GETNOTE_SUPPORT
+static unsigned long long sdt_note__get_addr(struct sdt_note *note)
+{
+	return note->bit32 ?
+		(unsigned long long)note->addr.a32[SDT_NOTE_IDX_LOC] :
+		(unsigned long long)note->addr.a64[SDT_NOTE_IDX_LOC];
+}
+
+static unsigned long long sdt_note__get_ref_ctr_offset(struct sdt_note *note)
+{
+	return note->bit32 ?
+		(unsigned long long)note->addr.a32[SDT_NOTE_IDX_REFCTR] :
+		(unsigned long long)note->addr.a64[SDT_NOTE_IDX_REFCTR];
+}
+
+static const char * const type_to_suffix[] = {
+	":s64", "", "", "", ":s32", "", ":s16", ":s8",
+	"", ":u8", ":u16", "", ":u32", "", "", "", ":u64"
+};
+
+/*
+ * Isolate the string number and convert it into a decimal value;
+ * this will be an index to get suffix of the uprobe name (defining
+ * the type)
+ */
+static int sdt_arg_parse_size(char *n_ptr, const char **suffix)
+{
+	long type_idx;
+
+	type_idx = strtol(n_ptr, NULL, 10);
+	if (type_idx < -8 || type_idx > 8) {
+		pr_debug4("Failed to get a valid sdt type\n");
+		return -1;
+	}
+
+	*suffix = type_to_suffix[type_idx + 8];
+	return 0;
+}
+
+static int synthesize_sdt_probe_arg(struct strbuf *buf, int i, const char *arg)
+{
+	char *op, *desc = strdup(arg), *new_op = NULL;
+	const char *suffix = "";
+	int ret = -1;
+
+	if (desc == NULL) {
+		pr_debug4("Allocation error\n");
+		return ret;
+	}
+
+	/*
+	 * Argument is in N@OP format. N is size of the argument and OP is
+	 * the actual assembly operand. N can be omitted; in that case
+	 * argument is just OP(without @).
+	 */
+	op = strchr(desc, '@');
+	if (op) {
+		op[0] = '\0';
+		op++;
+
+		if (sdt_arg_parse_size(desc, &suffix))
+			goto error;
+	} else {
+		op = desc;
+	}
+
+	ret = arch_sdt_arg_parse_op(op, &new_op);
+
+	if (ret < 0)
+		goto error;
+
+	if (ret == SDT_ARG_VALID) {
+		ret = strbuf_addf(buf, " arg%d=%s%s", i + 1, new_op, suffix);
+		if (ret < 0)
+			goto error;
+	}
+
+	ret = 0;
+error:
+	free(desc);
+	free(new_op);
+	return ret;
+}
+
+static char *synthesize_sdt_probe_command(struct sdt_note *note,
+					const char *pathname,
+					const char *sdtgrp)
+{
+	struct strbuf buf;
+	char *ret = NULL;
+	int i, args_count, err;
+	unsigned long long ref_ctr_offset;
+
+	if (strbuf_init(&buf, 32) < 0)
+		return NULL;
+
+	err = strbuf_addf(&buf, "p:%s/%s %s:0x%llx",
+			sdtgrp, note->name, pathname,
+			sdt_note__get_addr(note));
+
+	ref_ctr_offset = sdt_note__get_ref_ctr_offset(note);
+	if (ref_ctr_offset && err >= 0)
+		err = strbuf_addf(&buf, "(0x%llx)", ref_ctr_offset);
+
+	if (err < 0)
+		goto error;
+
+	if (!note->args)
+		goto out;
+
+	if (note->args) {
+		char **args = argv_split(note->args, &args_count);
+
+		if (args == NULL)
+			goto error;
+
+		for (i = 0; i < args_count; ++i) {
+			if (synthesize_sdt_probe_arg(&buf, i, args[i]) < 0) {
+				argv_free(args);
+				goto error;
+			}
+		}
+
+		argv_free(args);
+	}
+
+out:
+	ret = strbuf_detach(&buf, NULL);
+error:
+	strbuf_release(&buf);
+	return ret;
+}
+
+int probe_cache__scan_sdt(struct probe_cache *pcache, const char *pathname)
+{
+	struct probe_cache_entry *entry = NULL;
+	struct list_head sdtlist;
+	struct sdt_note *note;
+	char *buf;
+	char sdtgrp[64];
+	int ret;
+
+	INIT_LIST_HEAD(&sdtlist);
+	ret = get_sdt_note_list(&sdtlist, pathname);
+	if (ret < 0) {
+		pr_debug4("Failed to get sdt note: %d\n", ret);
+		return ret;
+	}
+	list_for_each_entry(note, &sdtlist, note_list) {
+		ret = snprintf(sdtgrp, 64, "sdt_%s", note->provider);
+		if (ret < 0)
+			break;
+		/* Try to find same-name entry */
+		entry = probe_cache__find_by_name(pcache, sdtgrp, note->name);
+		if (!entry) {
+			entry = probe_cache_entry__new(NULL);
+			if (!entry) {
+				ret = -ENOMEM;
+				break;
+			}
+			entry->sdt = true;
+			ret = asprintf(&entry->spev, "%s:%s=%s", sdtgrp,
+					note->name, note->name);
+			if (ret < 0)
+				break;
+			entry->pev.event = strdup(note->name);
+			entry->pev.group = strdup(sdtgrp);
+			list_add_tail(&entry->node, &pcache->entries);
+		}
+		buf = synthesize_sdt_probe_command(note, pathname, sdtgrp);
+		if (!buf) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		ret = strlist__add(entry->tevlist, buf);
+
+		free(buf);
+		entry = NULL;
+
+		if (ret == -ENOMEM) {
+			pr_err("strlist__add failed with -ENOMEM\n");
+			break;
+		}
+	}
+	if (entry) {
+		list_del_init(&entry->node);
+		probe_cache_entry__delete(entry);
+	}
+	cleanup_sdt_note_list(&sdtlist);
+	return ret;
+}
+#endif
+
+static int probe_cache_entry__write(struct probe_cache_entry *entry, int fd)
+{
+	struct str_node *snode;
+	struct stat st;
+	struct iovec iov[3];
+	const char *prefix = entry->sdt ? "%" : "#";
+	int ret;
+	/* Save stat for rollback */
+	ret = fstat(fd, &st);
+	if (ret < 0)
+		return ret;
+
+	pr_debug("Writing cache: %s%s\n", prefix, entry->spev);
+	iov[0].iov_base = (void *)prefix; iov[0].iov_len = 1;
+	iov[1].iov_base = entry->spev; iov[1].iov_len = strlen(entry->spev);
+	iov[2].iov_base = (void *)"\n"; iov[2].iov_len = 1;
+	ret = writev(fd, iov, 3);
+	if (ret < (int)iov[1].iov_len + 2)
+		goto rollback;
+
+	strlist__for_each_entry(snode, entry->tevlist) {
+		iov[0].iov_base = (void *)snode->s;
+		iov[0].iov_len = strlen(snode->s);
+		iov[1].iov_base = (void *)"\n"; iov[1].iov_len = 1;
+		ret = writev(fd, iov, 2);
+		if (ret < (int)iov[0].iov_len + 1)
+			goto rollback;
+	}
+	return 0;
+
+rollback:
+	/* Rollback to avoid cache file corruption */
+	if (ret > 0)
+		ret = -1;
+	if (ftruncate(fd, st.st_size) < 0)
+		ret = -2;
+
+	return ret;
+}
+
+int probe_cache__commit(struct probe_cache *pcache)
+{
+	struct probe_cache_entry *entry;
+	int ret = 0;
+
+	/* TBD: if we do not update existing entries, skip it */
+	ret = lseek(pcache->fd, 0, SEEK_SET);
+	if (ret < 0)
+		goto out;
+
+	ret = ftruncate(pcache->fd, 0);
+	if (ret < 0)
+		goto out;
+
+	for_each_probe_cache_entry(entry, pcache) {
+		ret = probe_cache_entry__write(entry, pcache->fd);
+		pr_debug("Cache committed: %d\n", ret);
+		if (ret < 0)
+			break;
+	}
+out:
+	return ret;
+}
+
+static bool probe_cache_entry__compare(struct probe_cache_entry *entry,
+				       struct strfilter *filter)
+{
+	char buf[128], *ptr = entry->spev;
+
+	if (entry->pev.event) {
+		snprintf(buf, 128, "%s:%s", entry->pev.group, entry->pev.event);
+		ptr = buf;
+	}
+	return strfilter__compare(filter, ptr);
+}
+
+int probe_cache__filter_purge(struct probe_cache *pcache,
+			      struct strfilter *filter)
+{
+	struct probe_cache_entry *entry, *tmp;
+
+	list_for_each_entry_safe(entry, tmp, &pcache->entries, node) {
+		if (probe_cache_entry__compare(entry, filter)) {
+			pr_info("Removed cached event: %s\n", entry->spev);
+			list_del_init(&entry->node);
+			probe_cache_entry__delete(entry);
+		}
+	}
+	return 0;
+}
+
+static int probe_cache__show_entries(struct probe_cache *pcache,
+				     struct strfilter *filter)
+{
+	struct probe_cache_entry *entry;
+
+	for_each_probe_cache_entry(entry, pcache) {
+		if (probe_cache_entry__compare(entry, filter))
+			printf("%s\n", entry->spev);
+	}
+	return 0;
+}
+
+/* Show all cached probes */
+int probe_cache__show_all_caches(struct strfilter *filter)
+{
+	struct probe_cache *pcache;
+	struct strlist *bidlist;
+	struct str_node *nd;
+	char *buf = strfilter__string(filter);
+
+	pr_debug("list cache with filter: %s\n", buf);
+	free(buf);
+
+	bidlist = build_id_cache__list_all(true);
+	if (!bidlist) {
+		pr_debug("Failed to get buildids: %d\n", errno);
+		return -EINVAL;
+	}
+	strlist__for_each_entry(nd, bidlist) {
+		pcache = probe_cache__new(nd->s, NULL);
+		if (!pcache)
+			continue;
+		if (!list_empty(&pcache->entries)) {
+			buf = build_id_cache__origname(nd->s);
+			printf("%s (%s):\n", buf, nd->s);
+			free(buf);
+			probe_cache__show_entries(pcache, filter);
+		}
+		probe_cache__delete(pcache);
+	}
+	strlist__delete(bidlist);
+
+	return 0;
+}
+
+enum ftrace_readme {
+	FTRACE_README_PROBE_TYPE_X = 0,
+	FTRACE_README_KRETPROBE_OFFSET,
+	FTRACE_README_UPROBE_REF_CTR,
+	FTRACE_README_USER_ACCESS,
+	FTRACE_README_MULTIPROBE_EVENT,
+	FTRACE_README_IMMEDIATE_VALUE,
+	FTRACE_README_END,
+};
+
+static struct {
+	const char *pattern;
+	bool avail;
+} ftrace_readme_table[] = {
+#define DEFINE_TYPE(idx, pat)			\
+	[idx] = {.pattern = pat, .avail = false}
+	DEFINE_TYPE(FTRACE_README_PROBE_TYPE_X, "*type: * x8/16/32/64,*"),
+	DEFINE_TYPE(FTRACE_README_KRETPROBE_OFFSET, "*place (kretprobe): *"),
+	DEFINE_TYPE(FTRACE_README_UPROBE_REF_CTR, "*ref_ctr_offset*"),
+	DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*u]<offset>*"),
+	DEFINE_TYPE(FTRACE_README_MULTIPROBE_EVENT, "*Create/append/*"),
+	DEFINE_TYPE(FTRACE_README_IMMEDIATE_VALUE, "*\\imm-value,*"),
+};
+
+static bool scan_ftrace_readme(enum ftrace_readme type)
+{
+	int fd;
+	FILE *fp;
+	char *buf = NULL;
+	size_t len = 0;
+	bool ret = false;
+	static bool scanned = false;
+
+	if (scanned)
+		goto result;
+
+	fd = open_trace_file("README", false);
+	if (fd < 0)
+		return ret;
+
+	fp = fdopen(fd, "r");
+	if (!fp) {
+		close(fd);
+		return ret;
+	}
+
+	while (getline(&buf, &len, fp) > 0)
+		for (enum ftrace_readme i = 0; i < FTRACE_README_END; i++)
+			if (!ftrace_readme_table[i].avail)
+				ftrace_readme_table[i].avail =
+					strglobmatch(buf, ftrace_readme_table[i].pattern);
+	scanned = true;
+
+	fclose(fp);
+	free(buf);
+
+result:
+	if (type >= FTRACE_README_END)
+		return false;
+
+	return ftrace_readme_table[type].avail;
+}
+
+bool probe_type_is_available(enum probe_type type)
+{
+	if (type >= PROBE_TYPE_END)
+		return false;
+	else if (type == PROBE_TYPE_X)
+		return scan_ftrace_readme(FTRACE_README_PROBE_TYPE_X);
+
+	return true;
+}
+
+bool kretprobe_offset_is_supported(void)
+{
+	return scan_ftrace_readme(FTRACE_README_KRETPROBE_OFFSET);
+}
+
+bool uprobe_ref_ctr_is_supported(void)
+{
+	return scan_ftrace_readme(FTRACE_README_UPROBE_REF_CTR);
+}
+
+bool user_access_is_supported(void)
+{
+	return scan_ftrace_readme(FTRACE_README_USER_ACCESS);
+}
+
+bool multiprobe_event_is_supported(void)
+{
+	return scan_ftrace_readme(FTRACE_README_MULTIPROBE_EVENT);
+}
+
+bool immediate_value_is_supported(void)
+{
+	return scan_ftrace_readme(FTRACE_README_IMMEDIATE_VALUE);
+}