[Updated PATCH 3/3] tracing: Provide trace events interface for uprobes

From: Srikar Dronamraju
Date: Fri Apr 13 2012 - 07:38:10 EST

From: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>

Implements trace_event support for uprobes. In its current form it can
be used to put probes at a specified offset in a file and dump the
required registers when the code flow reaches the probed address.

The following example shows how to dump the instruction pointer and %ax
a register at the probed text address. Here we are trying to probe
zfree in /bin/zsh

# cd /sys/kernel/debug/tracing/
# cat /proc/`pgrep zsh`/maps | grep /bin/zsh | grep r-xp
00400000-0048a000 r-xp 00000000 08:03 130904 /bin/zsh
# objdump -T /bin/zsh | grep -w zfree
0000000000446420 g DF .text 0000000000000012 Base zfree
# echo 'p /bin/zsh:0x46420 %ip %ax' > uprobe_events
# cat uprobe_events
p:uprobes/p_zsh_0x46420 /bin/zsh:0x00046420 arg1=%ip arg2=%ax
# echo 1 > events/uprobes/enable
# sleep 20
# echo 0 > events/uprobes/enable
# cat trace
# tracer: nop
#
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
zsh-24842 [006] 258544.995456: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
zsh-24842 [007] 258545.000270: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
zsh-24842 [002] 258545.043929: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
zsh-24842 [004] 258547.046129: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79

Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
---

Changelog (since v9)
- Updated Documentation as suggested by Masami.
- Handle comments from Steven Rostedt about uprobe tracer documentation.
- Disable preemption while in perf handler as suggested by Jiri Olsa.

Changelog (since v5)
- Added uprobe tracer documentation to this patch.

Documentation/trace/uprobetracer.txt | 113 +++++
arch/Kconfig | 2
kernel/trace/Kconfig | 16 +
kernel/trace/Makefile | 1
kernel/trace/trace.h | 5
kernel/trace/trace_kprobe.c | 2
kernel/trace/trace_probe.c | 14 -
kernel/trace/trace_probe.h | 3
kernel/trace/trace_uprobe.c | 788 ++++++++++++++++++++++++++++++++++
9 files changed, 937 insertions(+), 7 deletions(-)
create mode 100644 Documentation/trace/uprobetracer.txt
create mode 100644 kernel/trace/trace_uprobe.c

diff --git a/Documentation/trace/uprobetracer.txt b/Documentation/trace/uprobetracer.txt
new file mode 100644
index 0000000..61813d1
--- /dev/null
+++ b/Documentation/trace/uprobetracer.txt
@@ -0,0 +1,113 @@
+ Uprobe-tracer: Uprobe-based Event Tracing
+ =========================================
+ Documentation written by Srikar Dronamraju
+
+Overview
+--------
+Uprobe based trace events are similar to kprobe based trace events.
+To enable this feature, build your kernel with CONFIG_UPROBE_EVENTS=y.
+
+Similar to the kprobe-event tracer, this doesn't need to be activated via
+current_tracer. Instead of that, add probe points via
+/sys/kernel/debug/tracing/uprobe_events, and enable it via
+/sys/kernel/debug/tracing/events/uprobes/<EVENT>/enabled.
+
+However unlike kprobe-event tracer, the uprobe event interface expects the
+user to calculate the offset of the probepoint in the object
+
+Synopsis of uprobe_tracer
+-------------------------
+ p[:[GRP/]EVENT] PATH:SYMBOL[+offs] [FETCHARGS] : Set a probe
+
+ GRP : Group name. If omitted, use "uprobes" for it.
+ EVENT : Event name. If omitted, the event name is generated
+ based on SYMBOL+offs.
+ PATH : path to an executable or a library.
+ SYMBOL[+offs] : Symbol+offset where the probe is inserted.
+
+ FETCHARGS : Arguments. Each probe can have up to 128 args.
+ %REG : Fetch register REG
+
+Event Profiling
+---------------
+ You can check the total number of probe hits and probe miss-hits via
+/sys/kernel/debug/tracing/uprobe_profile.
+ The first column is event name, the second is the number of probe hits,
+the third is the number of probe miss-hits.
+
+Usage examples
+--------------
+To add a probe as a new event, write a new definition to uprobe_events
+as below.
+
+ echo 'p: /bin/bash:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events
+
+ This sets a uprobe at an offset of 0x4245c0 in the executable /bin/bash
+
+ echo > /sys/kernel/debug/tracing/uprobe_events
+
+ This clears all probe points.
+
+The following example shows how to dump the instruction pointer and %ax
+a register at the probed text address. Here we are trying to probe
+function zfree in /bin/zsh
+
+ # cd /sys/kernel/debug/tracing/
+ # cat /proc/`pgrep zsh`/maps | grep /bin/zsh | grep r-xp
+ 00400000-0048a000 r-xp 00000000 08:03 130904 /bin/zsh
+ # objdump -T /bin/zsh | grep -w zfree
+ 0000000000446420 g DF .text 0000000000000012 Base zfree
+
+0x46420 is the offset of zfree in object /bin/zsh that is loaded at
+0x00400000. Hence the command to probe would be :
+
+ # echo 'p /bin/zsh:0x46420 %ip %ax' > uprobe_events
+
+Please note: User has to explicitly calculate the offset of the probepoint
+in the object. We can see the events that are registered by looking at the
+uprobe_events file.
+
+ # cat uprobe_events
+ p:uprobes/p_zsh_0x46420 /bin/zsh:0x00046420 arg1=%ip arg2=%ax
+
+The format of events can be seen by viewing the file events/uprobes/p_zsh_0x46420/format
+
+ # cat events/uprobes/p_zsh_0x46420/format
+ name: p_zsh_0x46420
+ ID: 922
+ format:
+ field:unsigned short common_type; offset:0; size:2; signed:0;
+ field:unsigned char common_flags; offset:2; size:1; signed:0;
+ field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
+ field:int common_pid; offset:4; size:4; signed:1;
+ field:int common_padding; offset:8; size:4; signed:1;
+
+ field:unsigned long __probe_ip; offset:12; size:4; signed:0;
+ field:u32 arg1; offset:16; size:4; signed:0;
+ field:u32 arg2; offset:20; size:4; signed:0;
+
+ print fmt: "(%lx) arg1=%lx arg2=%lx", REC->__probe_ip, REC->arg1, REC->arg2
+
+Right after definition, each event is disabled by default. For tracing these
+events, you need to enable it by:
+
+ # echo 1 > events/uprobes/enable
+
+Lets disable the event after sleeping for some time.
+ # sleep 20
+ # echo 0 > events/uprobes/enable
+
+And you can see the traced information via /sys/kernel/debug/tracing/trace.
+
+ # cat trace
+ # tracer: nop
+ #
+ # TASK-PID CPU# TIMESTAMP FUNCTION
+ # | | | | |
+ zsh-24842 [006] 258544.995456: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
+ zsh-24842 [007] 258545.000270: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
+ zsh-24842 [002] 258545.043929: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
+ zsh-24842 [004] 258547.046129: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
+
+Each line shows us probes were triggered for a pid 24842 with ip being
+0x446421 and contents of ax register being 79.
diff --git a/arch/Kconfig b/arch/Kconfig
index e5d3778..0f8f968 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -78,7 +78,7 @@ config OPTPROBES

config UPROBES
bool "Transparent user-space probes (EXPERIMENTAL)"
- depends on ARCH_SUPPORTS_UPROBES && PERF_EVENTS
+ depends on UPROBE_EVENTS && PERF_EVENTS
default n
help
Uprobes is the user-space counterpart to kprobes: they
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index ce5a5c5..ea4bff6 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -386,6 +386,22 @@ config KPROBE_EVENT
This option is also required by perf-probe subcommand of perf tools.
If you want to use perf tools, this option is strongly recommended.

+config UPROBE_EVENT
+ bool "Enable uprobes-based dynamic events"
+ depends on ARCH_SUPPORTS_UPROBES
+ depends on MMU
+ select UPROBES
+ select PROBE_EVENTS
+ select TRACING
+ default n
+ help
+ This allows the user to add tracing events on top of userspace
+ dynamic events (similar to tracepoints) on the fly via the trace
+ events interface. Those events can be inserted wherever uprobes
+ can probe, and record various registers.
+ This option is required if you plan to use perf-probe subcommand
+ of perf tools on user space applications.
+
config PROBE_EVENTS
def_bool n

diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index fa10d5c..1734c03 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -62,5 +62,6 @@ ifeq ($(CONFIG_TRACING),y)
obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
endif
obj-$(CONFIG_PROBE_EVENTS) += trace_probe.o
+obj-$(CONFIG_UPROBE_EVENT) += trace_uprobe.o

libftrace-y := ftrace.o
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 95059f0..1bcdbec 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -103,6 +103,11 @@ struct kretprobe_trace_entry_head {
unsigned long ret_ip;
};

+struct uprobe_trace_entry_head {
+ struct trace_entry ent;
+ unsigned long ip;
+};
+
/*
* trace_flag_type is an enumeration that holds different
* states when a trace occurs. These are:
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index f8b7773..b31d3d5 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -525,7 +525,7 @@ static int create_trace_probe(int argc, char **argv)

/* Parse fetch argument */
ret = traceprobe_parse_probe_arg(arg, &tp->size, &tp->args[i],
- is_return);
+ is_return, true);
if (ret) {
pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
goto error;
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 8e526b9..daa9980 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -550,7 +550,7 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,

/* Recursive argument parser */
static int parse_probe_arg(char *arg, const struct fetch_type *t,
- struct fetch_param *f, bool is_return)
+ struct fetch_param *f, bool is_return, bool is_kprobe)
{
unsigned long param;
long offset;
@@ -558,6 +558,11 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
int ret;

ret = 0;
+
+ /* Until uprobe_events supports only reg arguments */
+ if (!is_kprobe && arg[0] != '%')
+ return -EINVAL;
+
switch (arg[0]) {
case '$':
ret = parse_probe_vars(arg + 1, t, f, is_return);
@@ -619,7 +624,8 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
return -ENOMEM;

dprm->offset = offset;
- ret = parse_probe_arg(arg, t2, &dprm->orig, is_return);
+ ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
+ is_kprobe);
if (ret)
kfree(dprm);
else {
@@ -677,7 +683,7 @@ static int __parse_bitfield_probe_arg(const char *bf,

/* String length checking wrapper */
int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
- struct probe_arg *parg, bool is_return)
+ struct probe_arg *parg, bool is_return, bool is_kprobe)
{
const char *t;
int ret;
@@ -703,7 +709,7 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
}
parg->offset = *size;
*size += parg->type->size;
- ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return);
+ ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return, is_kprobe);

if (ret >= 0 && t != NULL)
ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 2df9a18..9337086 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -66,6 +66,7 @@
#define TP_FLAG_TRACE 1
#define TP_FLAG_PROFILE 2
#define TP_FLAG_REGISTERED 4
+#define TP_FLAG_UPROBE 8


/* data_rloc: data relative location, compatible with u32 */
@@ -143,7 +144,7 @@ static inline int is_good_name(const char *name)
}

extern int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
- struct probe_arg *parg, bool is_return);
+ struct probe_arg *parg, bool is_return, bool is_kprobe);

extern int traceprobe_conflict_field_name(const char *name,
struct probe_arg *args, int narg);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
new file mode 100644
index 0000000..2b36ac6
--- /dev/null
+++ b/kernel/trace/trace_uprobe.c
@@ -0,0 +1,788 @@
+/*
+ * 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, 2010-2012
+ * Author: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/uprobes.h>
+#include <linux/namei.h>
+
+#include "trace_probe.h"
+
+#define UPROBE_EVENT_SYSTEM "uprobes"
+
+/*
+ * uprobe event core functions
+ */
+struct trace_uprobe;
+struct uprobe_trace_consumer {
+ struct uprobe_consumer cons;
+ struct trace_uprobe *tu;
+};
+
+struct trace_uprobe {
+ struct list_head list;
+ struct ftrace_event_class class;
+ struct ftrace_event_call call;
+ struct uprobe_trace_consumer *consumer;
+ struct inode *inode;
+ char *filename;
+ unsigned long offset;
+ unsigned long nhit;
+ unsigned int flags; /* For TP_FLAG_* */
+ ssize_t size; /* trace entry size */
+ 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 register_uprobe_event(struct trace_uprobe *tu);
+static void unregister_uprobe_event(struct trace_uprobe *tu);
+
+static DEFINE_MUTEX(uprobe_lock);
+static LIST_HEAD(uprobe_list);
+
+static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
+
+/*
+ * Allocate new trace_uprobe and initialize it (including uprobes).
+ */
+static struct trace_uprobe *
+alloc_trace_uprobe(const char *group, const char *event, int nargs)
+{
+ struct trace_uprobe *tu;
+
+ if (!event || !is_good_name(event))
+ return ERR_PTR(-EINVAL);
+
+ if (!group || !is_good_name(group))
+ return ERR_PTR(-EINVAL);
+
+ tu = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
+ if (!tu)
+ return ERR_PTR(-ENOMEM);
+
+ tu->call.class = &tu->class;
+ tu->call.name = kstrdup(event, GFP_KERNEL);
+ if (!tu->call.name)
+ goto error;
+
+ tu->class.system = kstrdup(group, GFP_KERNEL);
+ if (!tu->class.system)
+ goto error;
+
+ INIT_LIST_HEAD(&tu->list);
+ return tu;
+
+error:
+ kfree(tu->call.name);
+ kfree(tu);
+
+ return ERR_PTR(-ENOMEM);
+}
+
+static void free_trace_uprobe(struct trace_uprobe *tu)
+{
+ int i;
+
+ for (i = 0; i < tu->nr_args; i++)
+ traceprobe_free_probe_arg(&tu->args[i]);
+
+ iput(tu->inode);
+ kfree(tu->call.class->system);
+ kfree(tu->call.name);
+ kfree(tu->filename);
+ kfree(tu);
+}
+
+static struct trace_uprobe *find_probe_event(const char *event, const char *group)
+{
+ struct trace_uprobe *tu;
+
+ list_for_each_entry(tu, &uprobe_list, list)
+ if (strcmp(tu->call.name, event) == 0 &&
+ strcmp(tu->call.class->system, group) == 0)
+ return tu;
+
+ return NULL;
+}
+
+/* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
+static void unregister_trace_uprobe(struct trace_uprobe *tu)
+{
+ list_del(&tu->list);
+ unregister_uprobe_event(tu);
+ free_trace_uprobe(tu);
+}
+
+/* Register a trace_uprobe and probe_event */
+static int register_trace_uprobe(struct trace_uprobe *tu)
+{
+ struct trace_uprobe *old_tp;
+ int ret;
+
+ mutex_lock(&uprobe_lock);
+
+ /* register as an event */
+ old_tp = find_probe_event(tu->call.name, tu->call.class->system);
+ if (old_tp)
+ /* delete old event */
+ unregister_trace_uprobe(old_tp);
+
+ ret = register_uprobe_event(tu);
+ if (ret) {
+ pr_warning("Failed to register probe event(%d)\n", ret);
+ goto end;
+ }
+
+ list_add_tail(&tu->list, &uprobe_list);
+
+end:
+ mutex_unlock(&uprobe_lock);
+
+ return ret;
+}
+
+/*
+ * Argument syntax:
+ * - Add uprobe: p[:[GRP/]EVENT] PATH:SYMBOL[+offs] [FETCHARGS]
+ *
+ * - Remove uprobe: -:[GRP/]EVENT
+ */
+static int create_trace_uprobe(int argc, char **argv)
+{
+ struct trace_uprobe *tu;
+ struct inode *inode;
+ char *arg, *event, *group, *filename;
+ char buf[MAX_EVENT_NAME_LEN];
+ struct path path;
+ unsigned long offset;
+ bool is_delete;
+ int i, ret;
+
+ inode = NULL;
+ ret = 0;
+ is_delete = false;
+ event = NULL;
+ group = NULL;
+
+ /* argc must be >= 1 */
+ if (argv[0][0] == '-')
+ is_delete = true;
+ 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];
+ arg = strchr(event, '/');
+
+ if (arg) {
+ group = event;
+ event = arg + 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;
+ }
+ mutex_lock(&uprobe_lock);
+ tu = find_probe_event(event, group);
+
+ if (!tu) {
+ mutex_unlock(&uprobe_lock);
+ pr_info("Event %s/%s doesn't exist.\n", group, event);
+ return -ENOENT;
+ }
+ /* delete an event */
+ unregister_trace_uprobe(tu);
+ mutex_unlock(&uprobe_lock);
+ return 0;
+ }
+
+ if (argc < 2) {
+ pr_info("Probe point is not specified.\n");
+ return -EINVAL;
+ }
+ if (isdigit(argv[1][0])) {
+ pr_info("probe point must be have a filename.\n");
+ return -EINVAL;
+ }
+ arg = strchr(argv[1], ':');
+ if (!arg)
+ goto fail_address_parse;
+
+ *arg++ = '\0';
+ filename = argv[1];
+ ret = kern_path(filename, LOOKUP_FOLLOW, &path);
+ if (ret)
+ goto fail_address_parse;
+
+ ret = strict_strtoul(arg, 0, &offset);
+ if (ret)
+ goto fail_address_parse;
+
+ inode = igrab(path.dentry->d_inode);
+
+ argc -= 2;
+ argv += 2;
+
+ /* setup a probe */
+ if (!event) {
+ char *tail = strrchr(filename, '/');
+ char *ptr;
+
+ ptr = kstrdup((tail ? tail + 1 : filename), GFP_KERNEL);
+ if (!ptr) {
+ ret = -ENOMEM;
+ goto fail_address_parse;
+ }
+
+ tail = ptr;
+ ptr = strpbrk(tail, ".-_");
+ if (ptr)
+ *ptr = '\0';
+
+ snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_0x%lx", 'p', tail, offset);
+ event = buf;
+ kfree(tail);
+ }
+
+ tu = alloc_trace_uprobe(group, event, argc);
+ if (IS_ERR(tu)) {
+ pr_info("Failed to allocate trace_uprobe.(%d)\n", (int)PTR_ERR(tu));
+ ret = PTR_ERR(tu);
+ goto fail_address_parse;
+ }
+ tu->offset = offset;
+ tu->inode = inode;
+ tu->filename = kstrdup(filename, GFP_KERNEL);
+
+ if (!tu->filename) {
+ pr_info("Failed to allocate filename.\n");
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ /* parse arguments */
+ ret = 0;
+ for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+ /* Increment count for freeing args in error case */
+ tu->nr_args++;
+
+ /* Parse argument name */
+ arg = strchr(argv[i], '=');
+ if (arg) {
+ *arg++ = '\0';
+ tu->args[i].name = kstrdup(argv[i], GFP_KERNEL);
+ } else {
+ arg = argv[i];
+ /* If argument name is omitted, set "argN" */
+ snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
+ tu->args[i].name = kstrdup(buf, GFP_KERNEL);
+ }
+
+ if (!tu->args[i].name) {
+ pr_info("Failed to allocate argument[%d] name.\n", i);
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ if (!is_good_name(tu->args[i].name)) {
+ pr_info("Invalid argument[%d] name: %s\n", i, tu->args[i].name);
+ ret = -EINVAL;
+ goto error;
+ }
+
+ if (traceprobe_conflict_field_name(tu->args[i].name, tu->args, i)) {
+ pr_info("Argument[%d] name '%s' conflicts with "
+ "another field.\n", i, argv[i]);
+ ret = -EINVAL;
+ goto error;
+ }
+
+ /* Parse fetch argument */
+ ret = traceprobe_parse_probe_arg(arg, &tu->size, &tu->args[i], false, false);
+ if (ret) {
+ pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
+ goto error;
+ }
+ }
+
+ ret = register_trace_uprobe(tu);
+ if (ret)
+ goto error;
+ return 0;
+
+error:
+ free_trace_uprobe(tu);
+ return ret;
+
+fail_address_parse:
+ if (inode)
+ iput(inode);
+
+ pr_info("Failed to parse address.\n");
+
+ return ret;
+}
+
+static void cleanup_all_probes(void)
+{
+ struct trace_uprobe *tu;
+
+ mutex_lock(&uprobe_lock);
+ while (!list_empty(&uprobe_list)) {
+ tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
+ unregister_trace_uprobe(tu);
+ }
+ 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 *tu = v;
+ int i;
+
+ seq_printf(m, "p:%s/%s", tu->call.class->system, tu->call.name);
+ seq_printf(m, " %s:0x%p", tu->filename, (void *)tu->offset);
+
+ for (i = 0; i < tu->nr_args; i++)
+ seq_printf(m, " %s=%s", tu->args[i].name, tu->args[i].comm);
+
+ 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 ssize_t probes_write(struct file *file, const char __user *buffer,
+ size_t count, loff_t *ppos)
+{
+ return traceprobe_probes_write(file, buffer, count, ppos, create_trace_uprobe);
+}
+
+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 *tu = v;
+
+ seq_printf(m, " %s %-44s %15lu\n", tu->filename, tu->call.name, tu->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 trace_uprobe *tu, struct pt_regs *regs)
+{
+ struct uprobe_trace_entry_head *entry;
+ struct ring_buffer_event *event;
+ struct ring_buffer *buffer;
+ u8 *data;
+ int size, i, pc;
+ unsigned long irq_flags;
+ struct ftrace_event_call *call = &tu->call;
+
+ tu->nhit++;
+
+ local_save_flags(irq_flags);
+ pc = preempt_count();
+
+ size = sizeof(*entry) + tu->size;
+
+ event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
+ size, irq_flags, pc);
+ if (!event)
+ return;
+
+ entry = ring_buffer_event_data(event);
+ entry->ip = uprobe_get_swbp_addr(task_pt_regs(current));
+ data = (u8 *)&entry[1];
+ for (i = 0; i < tu->nr_args; i++)
+ call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
+
+ if (!filter_current_check_discard(buffer, call, entry, event))
+ trace_buffer_unlock_commit(buffer, event, irq_flags, pc);
+}
+
+/* Event entry printers */
+static enum print_line_t
+print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *event)
+{
+ struct uprobe_trace_entry_head *field;
+ struct trace_seq *s = &iter->seq;
+ struct trace_uprobe *tu;
+ u8 *data;
+ int i;
+
+ field = (struct uprobe_trace_entry_head *)iter->ent;
+ tu = container_of(event, struct trace_uprobe, call.event);
+
+ if (!trace_seq_printf(s, "%s: (", tu->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;
+
+ data = (u8 *)&field[1];
+ for (i = 0; i < tu->nr_args; i++) {
+ if (!tu->args[i].type->print(s, tu->args[i].name,
+ data + tu->args[i].offset, field))
+ goto partial;
+ }
+
+ if (trace_seq_puts(s, "\n"))
+ return TRACE_TYPE_HANDLED;
+
+partial:
+ return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static int probe_event_enable(struct trace_uprobe *tu, int flag)
+{
+ struct uprobe_trace_consumer *utc;
+ int ret = 0;
+
+ if (!tu->inode || tu->consumer)
+ return -EINTR;
+
+ utc = kzalloc(sizeof(struct uprobe_trace_consumer), GFP_KERNEL);
+ if (!utc)
+ return -EINTR;
+
+ utc->cons.handler = uprobe_dispatcher;
+ utc->cons.filter = NULL;
+ ret = uprobe_register(tu->inode, tu->offset, &utc->cons);
+ if (ret) {
+ kfree(utc);
+ return ret;
+ }
+
+ tu->flags |= flag;
+ utc->tu = tu;
+ tu->consumer = utc;
+
+ return 0;
+}
+
+static void probe_event_disable(struct trace_uprobe *tu, int flag)
+{
+ if (!tu->inode || !tu->consumer)
+ return;
+
+ uprobe_unregister(tu->inode, tu->offset, &tu->consumer->cons);
+ tu->flags &= ~flag;
+ kfree(tu->consumer);
+ tu->consumer = NULL;
+}
+
+static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
+{
+ int ret, i;
+ struct uprobe_trace_entry_head field;
+ struct trace_uprobe *tu = (struct trace_uprobe *)event_call->data;
+
+ DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+ /* Set argument names as fields */
+ for (i = 0; i < tu->nr_args; i++) {
+ ret = trace_define_field(event_call, tu->args[i].type->fmttype,
+ tu->args[i].name,
+ sizeof(field) + tu->args[i].offset,
+ tu->args[i].type->size,
+ tu->args[i].type->is_signed,
+ FILTER_OTHER);
+
+ if (ret)
+ return ret;
+ }
+ return 0;
+}
+
+#define LEN_OR_ZERO (len ? len - pos : 0)
+static int __set_print_fmt(struct trace_uprobe *tu, char *buf, int len)
+{
+ const char *fmt, *arg;
+ int i;
+ int pos = 0;
+
+ fmt = "(%lx)";
+ arg = "REC->" FIELD_STRING_IP;
+
+ /* When len=0, we just calculate the needed length */
+
+ pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
+
+ for (i = 0; i < tu->nr_args; i++) {
+ pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
+ tu->args[i].name, tu->args[i].type->fmt);
+ }
+
+ pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
+
+ for (i = 0; i < tu->nr_args; i++) {
+ pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
+ tu->args[i].name);
+ }
+
+ return pos; /* return the length of print_fmt */
+}
+#undef LEN_OR_ZERO
+
+static int set_print_fmt(struct trace_uprobe *tu)
+{
+ char *print_fmt;
+ int len;
+
+ /* First: called with 0 length to calculate the needed length */
+ len = __set_print_fmt(tu, NULL, 0);
+ print_fmt = kmalloc(len + 1, GFP_KERNEL);
+ if (!print_fmt)
+ return -ENOMEM;
+
+ /* Second: actually write the @print_fmt */
+ __set_print_fmt(tu, print_fmt, len + 1);
+ tu->call.print_fmt = print_fmt;
+
+ return 0;
+}
+
+#ifdef CONFIG_PERF_EVENTS
+/* uprobe profile handler */
+static void uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
+{
+ struct ftrace_event_call *call = &tu->call;
+ struct uprobe_trace_entry_head *entry;
+ struct hlist_head *head;
+ u8 *data;
+ int size, __size, i;
+ int rctx;
+
+ __size = sizeof(*entry) + tu->size;
+ size = ALIGN(__size + sizeof(u32), sizeof(u64));
+ size -= sizeof(u32);
+ if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
+ return;
+
+ preempt_disable();
+
+ entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
+ if (!entry)
+ goto out;
+
+ entry->ip = uprobe_get_swbp_addr(task_pt_regs(current));
+ data = (u8 *)&entry[1];
+ for (i = 0; i < tu->nr_args; i++)
+ call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
+
+ head = this_cpu_ptr(call->perf_events);
+ perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head);
+
+ out:
+ preempt_enable();
+}
+#endif /* CONFIG_PERF_EVENTS */
+
+static
+int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
+{
+ struct trace_uprobe *tu = (struct trace_uprobe *)event->data;
+
+ switch (type) {
+ case TRACE_REG_REGISTER:
+ return probe_event_enable(tu, TP_FLAG_TRACE);
+
+ case TRACE_REG_UNREGISTER:
+ probe_event_disable(tu, TP_FLAG_TRACE);
+ return 0;
+
+#ifdef CONFIG_PERF_EVENTS
+ case TRACE_REG_PERF_REGISTER:
+ return probe_event_enable(tu, TP_FLAG_PROFILE);
+
+ case TRACE_REG_PERF_UNREGISTER:
+ probe_event_disable(tu, TP_FLAG_PROFILE);
+ return 0;
+#endif
+ default:
+ return 0;
+ }
+ return 0;
+}
+
+static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
+{
+ struct uprobe_trace_consumer *utc;
+ struct trace_uprobe *tu;
+
+ utc = container_of(con, struct uprobe_trace_consumer, cons);
+ tu = utc->tu;
+ if (!tu || tu->consumer != utc)
+ return 0;
+
+ if (tu->flags & TP_FLAG_TRACE)
+ uprobe_trace_func(tu, regs);
+
+#ifdef CONFIG_PERF_EVENTS
+ if (tu->flags & TP_FLAG_PROFILE)
+ uprobe_perf_func(tu, regs);
+#endif
+ return 0;
+}
+
+static struct trace_event_functions uprobe_funcs = {
+ .trace = print_uprobe_event
+};
+
+static int register_uprobe_event(struct trace_uprobe *tu)
+{
+ struct ftrace_event_call *call = &tu->call;
+ int ret;
+
+ /* Initialize ftrace_event_call */
+ INIT_LIST_HEAD(&call->class->fields);
+ call->event.funcs = &uprobe_funcs;
+ call->class->define_fields = uprobe_event_define_fields;
+
+ if (set_print_fmt(tu) < 0)
+ return -ENOMEM;
+
+ ret = register_ftrace_event(&call->event);
+ if (!ret) {
+ kfree(call->print_fmt);
+ return -ENODEV;
+ }
+ call->flags = 0;
+ call->class->reg = trace_uprobe_register;
+ call->data = tu;
+ 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(&call->event);
+ }
+
+ return ret;
+}
+
+static void unregister_uprobe_event(struct trace_uprobe *tu)
+{
+ /* tu->event is unregistered in trace_remove_event_call() */
+ trace_remove_event_call(&tu->call);
+ kfree(tu->call.print_fmt);
+ tu->call.print_fmt = NULL;
+}
+
+/* Make a trace interface for controling probe points */
+static __init int init_uprobe_trace(void)
+{
+ struct dentry *d_tracer;
+
+ d_tracer = tracing_init_dentry();
+ if (!d_tracer)
+ return 0;
+
+ trace_create_file("uprobe_events", 0644, d_tracer,
+ NULL, &uprobe_events_ops);
+ /* Profile interface */
+ trace_create_file("uprobe_profile", 0444, d_tracer,
+ NULL, &uprobe_profile_ops);
+ return 0;
+}
+
+fs_initcall(init_uprobe_trace);


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