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tracing: Provide trace events interface for uprobes

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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:0x0000000000046420
 # 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@linux.vnet.ibm.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com>
Cc: Linux-mm <linux-mm@kvack.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Anton Arapov <anton@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120411103043.GB29437@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Srikar Dronamraju 2012-04-11 16:00:43 +05:30 committed by Ingo Molnar
parent 8ab83f5647
commit f3f096cfed
9 changed files with 919 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
Documentation/trace/uprobetracer.txt Normal file
View File

@ -0,0 +1,95 @@
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:0x0000000000046420
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.

2
arch/Kconfig
View File

@ -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

16
kernel/trace/Kconfig
View File

@ -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

1
kernel/trace/Makefile
View File

@ -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

5
kernel/trace/trace.h
View File

@ -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:

2
kernel/trace/trace_kprobe.c
View File

@ -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;

14
kernel/trace/trace_probe.c
View File

@ -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);

3
kernel/trace/trace_probe.h
View File

@ -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);

788
kernel/trace/trace_uprobe.c Normal file
View File

@ -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@linux.vnet.ibm.com>
*/
#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);