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Subject[PATCH v2 11/11] Uprobes traceevents patch.
Uprobes Trace_events interface 

The following patch implements trace_event support for uprobes. In its
current form it can be used to put probes at a specified text address
in a process and dump the required registers when the code flow reaches
the probed address.

This is based on trace_events for kprobes to the extent that it may
resemble that file on 2.6.34-rc3.

The following example shows how to dump the instruction pointer and %ax a
register at the probed text address.

Start a process to trace. Get the address to trace.
[Here pid is asssumed as 3548]
[Address to trace is 0x0000000000446420]
[Registers to be dumped are %ip and %ax]

# cd /sys/kernel/debug/tracing/
# echo 'p 3548:0x0000000000446420 %ip %ax' > uprobe_events
# cat uprobe_events
p:uprobes/p_3548_0x0000000000446420 3548:0x0000000000446420 %ip=%ip %ax=%ax
# cat events/uprobes/p_3548_0x0000000000446420/enable
0
[enable the event]
# echo 1 > events/uprobes/p_3548_0x0000000000446420/enable
# cat events/uprobes/p_3548_0x0000000000446420/enable
1
# #### do some activity on the program so that it hits the breakpoint
# cat uprobe_profile
3548 p_3548_0x0000000000446420 234
# head trace
# tracer: nop
#
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
zsh-3548 [001] 294.285812: p_3548_0x0000000000446420: (0x446420) %ip=446421 %ax=1
zsh-3548 [001] 294.285884: p_3548_0x0000000000446420: (0x446420) %ip=446421 %ax=1
zsh-3548 [001] 294.285894: p_3548_0x0000000000446420: (0x446420) %ip=446421 %ax=1
zsh-3548 [001] 294.285903: p_3548_0x0000000000446420: (0x446420) %ip=446421 %ax=1
zsh-3548 [001] 294.285912: p_3548_0x0000000000446420: (0x446420) %ip=446421 %ax=1
zsh-3548 [001] 294.285922: p_3548_0x0000000000446420: (0x446420) %ip=446421 %ax=1

TODO: Documentation/trace/uprobetrace.txt

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

kernel/trace/Kconfig | 8
kernel/trace/Makefile | 1
kernel/trace/trace.h | 12 +
kernel/trace/trace_uprobe.c | 926 +++++++++++++++++++++++++++++++++++++++++++
4 files changed, 947 insertions(+), 0 deletions(-)
create mode 100644 kernel/trace/trace_uprobe.c


diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 13e13d4..1435e09 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -557,6 +557,14 @@ config RING_BUFFER_BENCHMARK

If unsure, say N.

+config UPROBE_EVENT
+ depends on UPROBES
+ bool "Enable uprobes-based dynamic events"
+ select TRACING
+ default y
+ help
+ This allows the user to add tracing events (similar to tracepoints)
+ on the fly via the traceevents interface.
endif # FTRACE

endif # TRACING_SUPPORT
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 78edc64..8911959 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -58,5 +58,6 @@ obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
obj-$(CONFIG_KSYM_TRACER) += trace_ksym.o
obj-$(CONFIG_EVENT_TRACING) += power-traces.o
+obj-$(CONFIG_UPROBE_EVENT) += trace_uprobe.o

libftrace-y := ftrace.o
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2825ef2..9fe02ab 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -126,6 +126,18 @@ struct kretprobe_trace_entry {
(offsetof(struct kretprobe_trace_entry, args) + \
(sizeof(unsigned long) * (n)))

+struct uprobe_trace_entry {
+ struct trace_entry ent;
+ pid_t pid;
+ unsigned long ip;
+ int nargs;
+ unsigned long args[];
+};
+
+#define SIZEOF_UPROBE_TRACE_ENTRY(n) \
+ (offsetof(struct uprobe_trace_entry, args) + \
+ (sizeof(unsigned long) * (n)))
+
/*
* trace_flag_type is an enumeration that holds different
* states when a trace occurs. These are:
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
new file mode 100644
index 0000000..3e146ef
--- /dev/null
+++ b/kernel/trace/trace_uprobe.c
@@ -0,0 +1,926 @@
+/*
+ * Uprobes-based tracing events
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (C) IBM Corporation, 2010
+ * Author: Srikar Dronamraju
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/uprobes.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/ptrace.h>
+#include <linux/perf_event.h>
+
+#include "trace.h"
+#include "trace_output.h"
+
+#define MAX_TRACE_ARGS 128
+#define MAX_ARGSTR_LEN 63
+#define MAX_EVENT_NAME_LEN 64
+#define UPROBE_EVENT_SYSTEM "uprobes"
+
+/* Reserved field names */
+#define FIELD_STRING_IP "__probe_ip"
+#define FIELD_STRING_NARGS "__probe_nargs"
+#define FIELD_STRING_PID "__probe_pid"
+
+const char *ureserved_field_names[] = {
+ "common_type",
+ "common_flags",
+ "common_preempt_count",
+ "common_pid",
+ "common_tgid",
+ "common_lock_depth",
+ FIELD_STRING_IP,
+ FIELD_STRING_NARGS,
+ FIELD_STRING_PID,
+};
+
+struct fetch_func {
+ unsigned long (*func)(struct pt_regs *, void *);
+ void *data;
+};
+
+static unsigned long call_fetch(struct fetch_func *f,
+ struct pt_regs *regs)
+{
+ return f->func(regs, f->data);
+}
+
+/* fetch handlers */
+static unsigned long fetch_register(struct pt_regs *regs,
+ void *offset)
+{
+ return regs_get_register(regs, (unsigned int)((unsigned long)offset));
+}
+
+/**
+ * Uprobe event core functions
+ */
+
+/* Flags for trace_probe */
+#define TP_FLAG_TRACE 1
+#define TP_FLAG_PROFILE 2
+#define UPROBE_ENABLED 4
+
+struct probe_arg {
+ struct fetch_func fetch;
+ const char *name;
+};
+
+struct trace_uprobe {
+ struct list_head list;
+ struct uprobe up;
+ unsigned long nhit;
+ unsigned int flags; /* For TP_FLAG_* */
+ struct ftrace_event_call call;
+ struct trace_event event;
+ unsigned int nr_args;
+ struct probe_arg args[];
+};
+
+#define SIZEOF_TRACE_UPROBE(n) \
+ (offsetof(struct trace_uprobe, args) + \
+ (sizeof(struct probe_arg) * (n)))
+
+static int probe_arg_string(char *buf, size_t n, struct fetch_func *ff)
+{
+ int ret = -EINVAL;
+
+ if (ff->func == fetch_register) {
+ const char *name;
+ name = regs_query_register_name((unsigned int)((long)ff->data));
+ ret = snprintf(buf, n, "%%%s", name);
+ }
+ if (ret >= n)
+ return -ENOSPC;
+ return ret;
+}
+
+static int register_uprobe_event(struct trace_uprobe *tp);
+static void unregister_uprobe_event(struct trace_uprobe *tp);
+
+static DEFINE_MUTEX(uprobe_lock);
+static LIST_HEAD(uprobe_list);
+
+static void uprobe_dispatcher(struct uprobe *up, struct pt_regs *regs);
+
+/* Check the name is good for event/group */
+static int check_event_name(const char *name)
+{
+ if (!isalpha(*name) && *name != '_')
+ return 0;
+ while (*++name != '\0') {
+ if (!isalpha(*name) && !isdigit(*name) && *name != '_')
+ return 0;
+ }
+ return 1;
+}
+
+/*
+ * Allocate new trace_uprobe and initialize it (including uprobes).
+ */
+static struct trace_uprobe *alloc_trace_uprobe(const char * group,
+ const char *event,
+ void *addr,
+ pid_t pid, int nargs)
+{
+ struct trace_uprobe *tp;
+ int ret = -ENOMEM;
+
+ if (!event || !check_event_name(event))
+ return ERR_PTR(-EINVAL);
+
+ if (!group || !check_event_name(group))
+ return ERR_PTR(-EINVAL);
+
+ tp = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
+ if (!tp)
+ return ERR_PTR(ret);
+
+ tp->up.vaddr = (unsigned long)addr;
+ tp->up.pid = pid;
+ tp->up.handler = uprobe_dispatcher;
+
+ tp->call.name = kstrdup(event, GFP_KERNEL);
+ if (!tp->call.name)
+ goto error;
+
+ tp->call.system = kstrdup(group, GFP_KERNEL);
+ if (!tp->call.system)
+ goto error;
+
+ INIT_LIST_HEAD(&tp->list);
+ return tp;
+error:
+ kfree(tp->call.name);
+ kfree(tp);
+ return ERR_PTR(ret);
+}
+
+static void free_probe_arg(struct probe_arg *arg)
+{
+ kfree(arg->name);
+}
+
+static void free_trace_uprobe(struct trace_uprobe *tp)
+{
+ int i;
+
+ for (i = 0; i < tp->nr_args; i++)
+ free_probe_arg(&tp->args[i]);
+
+ kfree(tp->call.system);
+ kfree(tp->call.name);
+ kfree(tp);
+}
+
+static struct trace_uprobe *find_probe_event(const char *event,
+ const char *group)
+{
+ struct trace_uprobe *tp;
+
+ list_for_each_entry(tp, &uprobe_list, list)
+ if (strcmp(tp->call.name, event) == 0 &&
+ strcmp(tp->call.system, group) == 0)
+ return tp;
+ return NULL;
+}
+
+/* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
+static void unregister_trace_uprobe(struct trace_uprobe *tp)
+{
+ if (tp->flags & UPROBE_ENABLED)
+ unregister_uprobe(&tp->up);
+ list_del(&tp->list);
+ unregister_uprobe_event(tp);
+}
+
+/* Register a trace_uprobe and probe_event */
+static int register_trace_uprobe(struct trace_uprobe *tp)
+{
+ struct trace_uprobe *old_tp;
+ int ret;
+
+ mutex_lock(&uprobe_lock);
+
+ /* register as an event */
+ old_tp = find_probe_event(tp->call.name, tp->call.system);
+ if (old_tp) {
+ /* delete old event */
+ unregister_trace_uprobe(old_tp);
+ free_trace_uprobe(old_tp);
+ }
+ ret = register_uprobe_event(tp);
+ if (ret) {
+ pr_warning("Faild to register probe event(%d)\n", ret);
+ goto end;
+ }
+
+ list_add_tail(&tp->list, &uprobe_list);
+end:
+ mutex_unlock(&uprobe_lock);
+ return ret;
+}
+
+#define PARAM_MAX_ARGS 16
+#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
+
+/* Recursive argument parser */
+static int __parse_probe_arg(char *arg, struct fetch_func *ff)
+{
+ int ret = 0;
+
+ switch (arg[0]) {
+ case '%': /* named register */
+ ret = regs_query_register_offset(arg + 1);
+ if (ret >= 0) {
+ ff->func = fetch_register;
+ ff->data = (void *)(unsigned long)ret;
+ ret = 0;
+ }
+ break;
+ default:
+ /* TODO: support custom handler */
+ ret = -EINVAL;
+ }
+ return ret;
+}
+
+/* String length checking wrapper */
+static int parse_probe_arg(char *arg, struct fetch_func *ff)
+{
+ if (strlen(arg) > MAX_ARGSTR_LEN) {
+ pr_info("Argument is too long.: %s\n", arg);
+ return -ENOSPC;
+ }
+ return __parse_probe_arg(arg, ff);
+}
+
+/* Return 1 if name is reserved or already used by another argument */
+static int conflict_field_name(const char *name,
+ struct probe_arg *args, int narg)
+{
+ int i;
+ for (i = 0; i < ARRAY_SIZE(ureserved_field_names); i++)
+ if (strcmp(ureserved_field_names[i], name) == 0)
+ return 1;
+ for (i = 0; i < narg; i++)
+ if (strcmp(args[i].name, name) == 0)
+ return 1;
+ return 0;
+}
+
+static int create_trace_uprobe(int argc, char **argv)
+{
+ /*
+ * Argument syntax:
+ * - Add uprobe: p[:[GRP/]EVENT] VADDR@PID [%REG]
+ *
+ * - Remove uprobe: -:[GRP/]EVENT
+ */
+ struct trace_uprobe *tp;
+ int i, ret = 0;
+ int is_delete = 0;
+ char *arg = NULL, *event = NULL, *group = NULL;
+ void *addr = NULL;
+ pid_t pid = 0;
+ char buf[MAX_EVENT_NAME_LEN];
+
+ /* argc must be >= 1 */
+ if (argv[0][0] == '-')
+ is_delete = 1;
+ else if (argv[0][0] != 'p') {
+ pr_info("Probe definition must be started with 'p', 'r' or"
+ " '-'.\n");
+ return -EINVAL;
+ }
+
+ if (argv[0][1] == ':') {
+ event = &argv[0][2];
+ if (strchr(event, '/')) {
+ group = event;
+ event = strchr(group, '/') + 1;
+ event[-1] = '\0';
+ if (strlen(group) == 0) {
+ pr_info("Group name is not specified\n");
+ return -EINVAL;
+ }
+ }
+ if (strlen(event) == 0) {
+ pr_info("Event name is not specified\n");
+ return -EINVAL;
+ }
+ }
+ if (!group)
+ group = UPROBE_EVENT_SYSTEM;
+
+ if (is_delete) {
+ if (!event) {
+ pr_info("Delete command needs an event name.\n");
+ return -EINVAL;
+ }
+ tp = find_probe_event(event, group);
+ if (!tp) {
+ pr_info("Event %s/%s doesn't exist.\n", group, event);
+ return -ENOENT;
+ }
+ /* delete an event */
+ unregister_trace_uprobe(tp);
+ free_trace_uprobe(tp);
+ return 0;
+ }
+
+ if (argc < 2) {
+ pr_info("Probe point is not specified.\n");
+ return -EINVAL;
+ }
+ if (isdigit(argv[1][0])) {
+ /* an address specified */
+ arg = strchr(argv[1], ':');
+ if (!arg)
+ goto fail_address_parse;
+
+ *arg++ = '\0';
+ ret = strict_strtoul(&argv[1][0], 0, (unsigned long *)&pid);
+ if (ret)
+ goto fail_address_parse;
+
+ ret = strict_strtoul(arg, 0, (unsigned long *)&addr);
+ if (ret)
+ goto fail_address_parse;
+ }
+ argc -= 2; argv += 2;
+
+ /* setup a probe */
+ if (!event) {
+ snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%d_0x%p", 'p',
+ pid, addr);
+ event = buf;
+ }
+ tp = alloc_trace_uprobe(group, event, addr, pid, argc);
+ if (IS_ERR(tp)) {
+ pr_info("Failed to allocate trace_uprobe.(%d)\n",
+ (int)PTR_ERR(tp));
+ return PTR_ERR(tp);
+ }
+
+ /* parse arguments */
+ ret = 0;
+ for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+ /* Parse argument name */
+ arg = strchr(argv[i], '=');
+ if (arg)
+ *arg++ = '\0';
+ else
+ arg = argv[i];
+
+ if (conflict_field_name(argv[i], tp->args, i)) {
+ pr_info("Argument%d name '%s' conflicts with "
+ "another field.\n", i, argv[i]);
+ ret = -EINVAL;
+ goto error;
+ }
+
+ tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
+ if (!tp->args[i].name) {
+ pr_info("Failed to allocate argument%d name '%s'.\n",
+ i, argv[i]);
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ /* Parse fetch argument */
+ ret = parse_probe_arg(arg, &tp->args[i].fetch);
+ if (ret) {
+ pr_info("Parse error at argument%d. (%d)\n", i, ret);
+ kfree(tp->args[i].name);
+ goto error;
+ }
+
+ tp->nr_args++;
+ }
+
+ ret = register_trace_uprobe(tp);
+ if (ret)
+ goto error;
+ return 0;
+
+error:
+ free_trace_uprobe(tp);
+ return ret;
+
+fail_address_parse:
+ pr_info("Failed to parse address.\n");
+ return ret;
+}
+
+static void cleanup_all_probes(void)
+{
+ struct trace_uprobe *tp;
+
+ mutex_lock(&uprobe_lock);
+ /* TODO: Use batch unregistration */
+ while (!list_empty(&uprobe_list)) {
+ tp = list_entry(uprobe_list.next, struct trace_uprobe, list);
+ unregister_trace_uprobe(tp);
+ free_trace_uprobe(tp);
+ }
+ mutex_unlock(&uprobe_lock);
+}
+
+
+/* Probes listing interfaces */
+static void *probes_seq_start(struct seq_file *m, loff_t *pos)
+{
+ mutex_lock(&uprobe_lock);
+ return seq_list_start(&uprobe_list, *pos);
+}
+
+static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ return seq_list_next(v, &uprobe_list, pos);
+}
+
+static void probes_seq_stop(struct seq_file *m, void *v)
+{
+ mutex_unlock(&uprobe_lock);
+}
+
+static int probes_seq_show(struct seq_file *m, void *v)
+{
+ struct trace_uprobe *tp = v;
+ int i, ret;
+ char buf[MAX_ARGSTR_LEN + 1];
+
+ seq_printf(m, "%c", 'p');
+ seq_printf(m, ":%s/%s", tp->call.system, tp->call.name);
+
+ seq_printf(m, " %d:0x%p", tp->up.pid, (void *)tp->up.vaddr);
+
+ for (i = 0; i < tp->nr_args; i++) {
+ ret = probe_arg_string(buf, MAX_ARGSTR_LEN, &tp->args[i].fetch);
+ if (ret < 0) {
+ pr_warning("Argument%d decoding error(%d).\n", i, ret);
+ return ret;
+ }
+ seq_printf(m, " %s=%s", tp->args[i].name, buf);
+ }
+ seq_printf(m, "\n");
+ return 0;
+}
+
+static const struct seq_operations probes_seq_op = {
+ .start = probes_seq_start,
+ .next = probes_seq_next,
+ .stop = probes_seq_stop,
+ .show = probes_seq_show
+};
+
+static int probes_open(struct inode *inode, struct file *file)
+{
+ if ((file->f_mode & FMODE_WRITE) &&
+ (file->f_flags & O_TRUNC))
+ cleanup_all_probes();
+
+ return seq_open(file, &probes_seq_op);
+}
+
+static int command_trace_uprobe(const char *buf)
+{
+ char **argv;
+ int argc = 0, ret = 0;
+
+ argv = argv_split(GFP_KERNEL, buf, &argc);
+ if (!argv)
+ return -ENOMEM;
+
+ if (argc)
+ ret = create_trace_uprobe(argc, argv);
+
+ argv_free(argv);
+ return ret;
+}
+
+#define WRITE_BUFSIZE 128
+
+static ssize_t probes_write(struct file *file, const char __user *buffer,
+ size_t count, loff_t *ppos)
+{
+ char *kbuf, *tmp;
+ int ret;
+ size_t done;
+ size_t size;
+
+ kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+
+ ret = done = 0;
+ while (done < count) {
+ size = count - done;
+ if (size >= WRITE_BUFSIZE)
+ size = WRITE_BUFSIZE - 1;
+ if (copy_from_user(kbuf, buffer + done, size)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ kbuf[size] = '\0';
+ tmp = strchr(kbuf, '\n');
+ if (tmp) {
+ *tmp = '\0';
+ size = tmp - kbuf + 1;
+ } else if (done + size < count) {
+ pr_warning("Line length is too long: "
+ "Should be less than %d.", WRITE_BUFSIZE);
+ ret = -EINVAL;
+ goto out;
+ }
+ done += size;
+ /* Remove comments */
+ tmp = strchr(kbuf, '#');
+ if (tmp)
+ *tmp = '\0';
+
+ ret = command_trace_uprobe(kbuf);
+ if (ret)
+ goto out;
+ }
+ ret = done;
+out:
+ kfree(kbuf);
+ return ret;
+}
+
+static const struct file_operations uprobe_events_ops = {
+ .owner = THIS_MODULE,
+ .open = probes_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+ .write = probes_write,
+};
+
+/* Probes profiling interfaces */
+static int probes_profile_seq_show(struct seq_file *m, void *v)
+{
+ struct trace_uprobe *tp = v;
+
+ seq_printf(m, " %d %-44s %15lu\n",tp->up.pid, tp->call.name, tp->nhit);
+ return 0;
+}
+
+static const struct seq_operations profile_seq_op = {
+ .start = probes_seq_start,
+ .next = probes_seq_next,
+ .stop = probes_seq_stop,
+ .show = probes_profile_seq_show
+};
+
+static int profile_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &profile_seq_op);
+}
+
+static const struct file_operations uprobe_profile_ops = {
+ .owner = THIS_MODULE,
+ .open = profile_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
+/* Uprobe handler */
+static void uprobe_trace_func(struct uprobe *up, struct pt_regs *regs)
+{
+ struct trace_uprobe *tp = container_of(up, struct trace_uprobe, up);
+ struct uprobe_trace_entry *entry;
+ struct ring_buffer_event *event;
+ struct ring_buffer *buffer;
+ int size, i, pc;
+ unsigned long irq_flags;
+ struct ftrace_event_call *call = &tp->call;
+
+ tp->nhit++;
+
+ local_save_flags(irq_flags);
+ pc = preempt_count();
+
+ size = SIZEOF_UPROBE_TRACE_ENTRY(tp->nr_args);
+
+ event = trace_current_buffer_lock_reserve(&buffer, call->id, size,
+ irq_flags, pc);
+ if (!event)
+ return;
+
+ entry = ring_buffer_event_data(event);
+ entry->nargs = tp->nr_args;
+ entry->ip = (unsigned long)up->vaddr;
+ for (i = 0; i < tp->nr_args; i++)
+ entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
+
+ if (!filter_current_check_discard(buffer, call, entry, event))
+ trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
+}
+
+/* Event entry printers */
+enum print_line_t
+print_uprobe_event(struct trace_iterator *iter, int flags)
+{
+ struct uprobe_trace_entry *field;
+ struct trace_seq *s = &iter->seq;
+ struct trace_event *event;
+ struct trace_uprobe *tp;
+ int i;
+
+ field = (struct uprobe_trace_entry *)iter->ent;
+ event = ftrace_find_event(field->ent.type);
+ tp = container_of(event, struct trace_uprobe, event);
+
+ if (!trace_seq_printf(s, "%s: (", tp->call.name))
+ goto partial;
+
+ if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
+ goto partial;
+
+ if (!trace_seq_puts(s, ")"))
+ goto partial;
+
+ for (i = 0; i < field->nargs; i++)
+ if (!trace_seq_printf(s, " %s=%lx",
+ tp->args[i].name, field->args[i]))
+ goto partial;
+
+ if (!trace_seq_puts(s, "\n"))
+ goto partial;
+
+ return TRACE_TYPE_HANDLED;
+partial:
+ return TRACE_TYPE_PARTIAL_LINE;
+}
+
+
+static int probe_event_enable(struct ftrace_event_call *call)
+{
+ int ret = 0;
+ struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+ if (!(tp->flags & UPROBE_ENABLED)) {
+ ret = register_uprobe(&tp->up);
+ if (!ret)
+ tp->flags |= (UPROBE_ENABLED | TP_FLAG_TRACE);
+ }
+ return ret;
+}
+
+static void probe_event_disable(struct ftrace_event_call *call)
+{
+ struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+ if (tp->flags & UPROBE_ENABLED) {
+ unregister_uprobe(&tp->up);
+ tp->flags &= ~(UPROBE_ENABLED | TP_FLAG_TRACE);
+ }
+}
+
+static int probe_event_raw_init(struct ftrace_event_call *event_call)
+{
+ INIT_LIST_HEAD(&event_call->fields);
+
+ return 0;
+}
+
+#undef DEFINE_FIELD
+#define DEFINE_FIELD(type, item, name, is_signed) \
+ do { \
+ ret = trace_define_field(event_call, #type, name, \
+ offsetof(typeof(field), item), \
+ sizeof(field.item), is_signed, \
+ FILTER_OTHER); \
+ if (ret) \
+ return ret; \
+ } while (0)
+
+static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
+{
+ int ret, i;
+ struct uprobe_trace_entry field;
+ struct trace_uprobe *tp = (struct trace_uprobe *)event_call->data;
+
+ DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+ DEFINE_FIELD(int, nargs, FIELD_STRING_NARGS, 1);
+ DEFINE_FIELD(pid_t, pid, FIELD_STRING_PID, 2);
+ /* Set argument names as fields */
+ for (i = 0; i < tp->nr_args; i++)
+ DEFINE_FIELD(unsigned long, args[i], tp->args[i].name, 0);
+ return 0;
+}
+
+static int __set_print_fmt(struct trace_uprobe *tp, char *buf, int len)
+{
+ int i;
+ int pos = 0;
+
+ const char *fmt, *arg;
+
+ fmt = "(%lx)";
+ arg = "REC->" FIELD_STRING_IP;
+
+ /* When len=0, we just calculate the needed length */
+#define LEN_OR_ZERO (len ? len - pos : 0)
+
+ pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
+ for (i = 0; i < tp->nr_args; i++)
+ pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%%lx",
+ tp->args[i].name);
+
+ pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
+ for (i = 0; i < tp->nr_args; i++)
+ pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
+ tp->args[i].name);
+
+#undef LEN_OR_ZERO
+
+ /* return the length of print_fmt */
+ return pos;
+}
+
+static int set_print_fmt(struct trace_uprobe *tp)
+{
+ int len;
+ char *print_fmt;
+
+ /* First: called with 0 length to calculate the needed length */
+ len = __set_print_fmt(tp, NULL, 0);
+ print_fmt = kmalloc(len + 1, GFP_KERNEL);
+ if (!print_fmt)
+ return -ENOMEM;
+
+ /* Second: actually write the @print_fmt */
+ __set_print_fmt(tp, print_fmt, len + 1);
+ tp->call.print_fmt = print_fmt;
+
+ return 0;
+}
+
+#ifdef CONFIG_PERF_EVENTS
+
+/* Uprobe profile handler */
+static void uprobe_perf_func(struct uprobe *up,
+ struct pt_regs *regs)
+{
+ struct trace_uprobe *tp = container_of(up, struct trace_uprobe, up);
+ struct ftrace_event_call *call = &tp->call;
+ struct uprobe_trace_entry *entry;
+ int size, __size, i;
+ unsigned long irq_flags;
+ int rctx;
+
+ __size = SIZEOF_UPROBE_TRACE_ENTRY(tp->nr_args);
+ size = ALIGN(__size + sizeof(u32), sizeof(u64));
+ size -= sizeof(u32);
+ if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
+ "profile buffer not large enough"))
+ return;
+
+ entry = perf_trace_buf_prepare(size, call->id, &rctx, &irq_flags);
+ if (!entry)
+ return;
+
+ entry->nargs = tp->nr_args;
+ entry->ip = (unsigned long)up->vaddr;
+ for (i = 0; i < tp->nr_args; i++)
+ entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
+
+ perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, irq_flags, regs);
+}
+
+static int probe_perf_enable(struct ftrace_event_call *call)
+{
+ int ret = 0;
+ struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+ if (!(tp->flags & UPROBE_ENABLED)) {
+ ret = register_uprobe(&tp->up);
+ if (!ret)
+ tp->flags |= (UPROBE_ENABLED | TP_FLAG_PROFILE);
+ }
+ return ret;
+}
+
+static void probe_perf_disable(struct ftrace_event_call *call)
+{
+ struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+ if (tp->flags & UPROBE_ENABLED) {
+ unregister_uprobe(&tp->up);
+ tp->flags &= ~(UPROBE_ENABLED | TP_FLAG_PROFILE);
+ }
+}
+#endif /* CONFIG_PERF_EVENTS */
+
+
+static
+void uprobe_dispatcher(struct uprobe *up, struct pt_regs *regs)
+{
+ struct trace_uprobe *tp = container_of(up, struct trace_uprobe, up);
+
+ if (tp->flags & TP_FLAG_TRACE)
+ uprobe_trace_func(up, regs);
+#ifdef CONFIG_PERF_EVENTS
+ if (tp->flags & TP_FLAG_PROFILE)
+ uprobe_perf_func(up, regs);
+#endif
+}
+
+
+static int register_uprobe_event(struct trace_uprobe *tp)
+{
+ struct ftrace_event_call *call = &tp->call;
+ int ret;
+
+ /* Initialize ftrace_event_call */
+ tp->event.trace = print_uprobe_event;
+ call->raw_init = probe_event_raw_init;
+ call->define_fields = uprobe_event_define_fields;
+ if (set_print_fmt(tp) < 0)
+ return -ENOMEM;
+
+ call->event = &tp->event;
+ call->id = register_ftrace_event(&tp->event);
+ if (!call->id) {
+ kfree(call->print_fmt);
+ return -ENODEV;
+ }
+
+ call->enabled = 0;
+ call->regfunc = probe_event_enable;
+ call->unregfunc = probe_event_disable;
+
+#ifdef CONFIG_PERF_EVENTS
+ call->perf_event_enable = probe_perf_enable;
+ call->perf_event_disable = probe_perf_disable;
+#endif
+ call->data = tp;
+ ret = trace_add_event_call(call);
+ if (ret) {
+ pr_info("Failed to register uprobe event: %s\n", call->name);
+ kfree(call->print_fmt);
+ unregister_ftrace_event(&tp->event);
+ }
+ return ret;
+}
+
+static void unregister_uprobe_event(struct trace_uprobe *tp)
+{
+ /* tp->event is unregistered in trace_remove_event_call() */
+ trace_remove_event_call(&tp->call);
+ kfree(tp->call.print_fmt);
+}
+
+/* Make a debugfs interface for controling probe points */
+static __init int init_uprobe_trace(void)
+{
+ struct dentry *d_tracer;
+ struct dentry *entry;
+
+ d_tracer = tracing_init_dentry();
+ if (!d_tracer)
+ return 0;
+
+ entry = debugfs_create_file("uprobe_events", 0644, d_tracer,
+ NULL, &uprobe_events_ops);
+
+ /* Event list interface */
+ if (!entry)
+ pr_warning("Could not create debugfs "
+ "'uprobe_events' entry\n");
+
+ /* Profile interface */
+ entry = debugfs_create_file("uprobe_profile", 0444, d_tracer,
+ NULL, &uprobe_profile_ops);
+
+ if (!entry)
+ pr_warning("Could not create debugfs "
+ "'uprobe_profile' entry\n");
+ return 0;
+}
+fs_initcall(init_uprobe_trace);

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