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    Subject[PATCH v9 3.2 7/9] tracing: uprobes trace_event interface

    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

    TODO: Connect a filter to a consumer.

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

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

    Documentation/trace/uprobetracer.txt | 93 ++++
    arch/Kconfig | 10
    kernel/trace/Kconfig | 16 +
    kernel/trace/Makefile | 1
    kernel/trace/trace.h | 5
    kernel/trace/trace_kprobe.c | 4
    kernel/trace/trace_probe.c | 14 -
    kernel/trace/trace_probe.h | 3
    kernel/trace/trace_uprobe.c | 768 ++++++++++++++++++++++++++++++++++
    9 files changed, 898 insertions(+), 16 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..457932f
    --- /dev/null
    +++ b/Documentation/trace/uprobetracer.txt
    @@ -0,0 +1,93 @@
    + Uprobe-tracer: Uprobe-based Event Tracing
    + =========================================
    + Documentation is written by Srikar Dronamraju
    +
    +Overview
    +--------
    +These events are similar to kprobe based 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.
    +
    +
    +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
    +
    +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.
    diff --git a/arch/Kconfig b/arch/Kconfig
    index 6328b49..6c6df9f 100644
    --- a/arch/Kconfig
    +++ b/arch/Kconfig
    @@ -62,15 +62,7 @@ config OPTPROBES
    depends on !PREEMPT

    config UPROBES
    - bool "User-space probes (EXPERIMENTAL)"
    - depends on ARCH_SUPPORTS_UPROBES
    - default n
    - help
    - Uprobes enables kernel subsystems to establish probepoints
    - in user applications and execute handler functions when
    - the probepoints are hit.
    -
    - If in doubt, say "N".
    + def_bool n

    config HAVE_EFFICIENT_UNALIGNED_ACCESS
    bool
    diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
    index 520106a..b001fb1 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 traceevents 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 092e1f8..f5f7bb3 100644
    --- a/kernel/trace/trace.h
    +++ b/kernel/trace/trace.h
    @@ -97,6 +97,11 @@ 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 967e634..60384df 100644
    --- a/kernel/trace/trace_kprobe.c
    +++ b/kernel/trace/trace_kprobe.c
    @@ -524,8 +524,8 @@ 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);
    + ret = traceprobe_parse_probe_arg(arg, &tp->size,
    + &tp->args[i], 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 e79a9e5..c0a98e6 100644
    --- a/kernel/trace/trace_probe.c
    +++ b/kernel/trace/trace_probe.c
    @@ -529,13 +529,17 @@ 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)
    {
    int ret = 0;
    unsigned long param;
    long offset;
    char *tmp;

    + /* 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);
    @@ -585,7 +589,8 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
    if (!dprm)
    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 {
    @@ -640,7 +645,7 @@ 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;
    @@ -666,7 +671,8 @@ 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);
    if (ret >= 0) {
    diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
    index 84eef0a..31e635e 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 */
    @@ -144,7 +145,7 @@ 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..af29368
    --- /dev/null
    +++ b/kernel/trace/trace_uprobe.c
    @@ -0,0 +1,768 @@
    +/*
    + * 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/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 *tp;
    +};
    +
    +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 *tp);
    +static void unregister_uprobe_event(struct trace_uprobe *tp);
    +
    +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 *tp;
    +
    + if (!event || !is_good_name(event))
    + return ERR_PTR(-EINVAL);
    +
    + if (!group || !is_good_name(group))
    + return ERR_PTR(-EINVAL);
    +
    + tp = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
    + if (!tp)
    + return ERR_PTR(-ENOMEM);
    +
    + tp->call.class = &tp->class;
    + tp->call.name = kstrdup(event, GFP_KERNEL);
    + if (!tp->call.name)
    + goto error;
    +
    + tp->class.system = kstrdup(group, GFP_KERNEL);
    + if (!tp->class.system)
    + goto error;
    +
    + INIT_LIST_HEAD(&tp->list);
    + return tp;
    +error:
    + kfree(tp->call.name);
    + kfree(tp);
    + return ERR_PTR(-ENOMEM);
    +}
    +
    +static void free_trace_uprobe(struct trace_uprobe *tp)
    +{
    + int i;
    +
    + for (i = 0; i < tp->nr_args; i++)
    + traceprobe_free_probe_arg(&tp->args[i]);
    +
    + iput(tp->inode);
    + kfree(tp->call.class->system);
    + kfree(tp->call.name);
    + kfree(tp->filename);
    + 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.class->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)
    +{
    + list_del(&tp->list);
    + unregister_uprobe_event(tp);
    + free_trace_uprobe(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.class->system);
    + if (old_tp)
    + /* delete old event */
    + unregister_trace_uprobe(old_tp);
    +
    + ret = register_uprobe_event(tp);
    + if (ret) {
    + pr_warning("Failed to register probe event(%d)\n", ret);
    + goto end;
    + }
    +
    + list_add_tail(&tp->list, &uprobe_list);
    +end:
    + mutex_unlock(&uprobe_lock);
    + return ret;
    +}
    +
    +static int create_trace_uprobe(int argc, char **argv)
    +{
    + /*
    + * Argument syntax:
    + * - Add uprobe: p[:[GRP/]EVENT] VADDR@PID [%REG]
    + *
    + * - Remove uprobe: -:[GRP/]EVENT
    + */
    + struct path path;
    + struct inode *inode = NULL;
    + struct trace_uprobe *tp;
    + int i, ret = 0;
    + int is_delete = 0;
    + char *arg = NULL, *event = NULL, *group = NULL;
    + unsigned long offset;
    + char buf[MAX_EVENT_NAME_LEN];
    + char *filename;
    +
    + /* 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;
    + }
    + mutex_lock(&uprobe_lock);
    + tp = find_probe_event(event, group);
    + if (!tp) {
    + mutex_unlock(&uprobe_lock);
    + pr_info("Event %s/%s doesn't exist.\n", group, event);
    + return -ENOENT;
    + }
    + /* delete an event */
    + unregister_trace_uprobe(tp);
    + 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;
    +
    + inode = igrab(path.dentry->d_inode);
    +
    + ret = strict_strtoul(arg, 0, &offset);
    + if (ret)
    + goto fail_address_parse;
    +
    + 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);
    + }
    + tp = alloc_trace_uprobe(group, event, argc);
    + if (IS_ERR(tp)) {
    + pr_info("Failed to allocate trace_uprobe.(%d)\n",
    + (int)PTR_ERR(tp));
    + iput(inode);
    + return PTR_ERR(tp);
    + }
    + tp->offset = offset;
    + tp->inode = inode;
    + tp->filename = kstrdup(filename, GFP_KERNEL);
    + if (!tp->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 */
    + tp->nr_args++;
    +
    + /* Parse argument name */
    + arg = strchr(argv[i], '=');
    + if (arg) {
    + *arg++ = '\0';
    + tp->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);
    + tp->args[i].name = kstrdup(buf, GFP_KERNEL);
    + }
    +
    + if (!tp->args[i].name) {
    + pr_info("Failed to allocate argument[%d] name.\n", i);
    + ret = -ENOMEM;
    + goto error;
    + }
    +
    + if (!is_good_name(tp->args[i].name)) {
    + pr_info("Invalid argument[%d] name: %s\n",
    + i, tp->args[i].name);
    + ret = -EINVAL;
    + goto error;
    + }
    +
    + if (traceprobe_conflict_field_name(tp->args[i].name,
    + tp->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, &tp->size, &tp->args[i],
    + false, false);
    + if (ret) {
    + pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
    + goto error;
    + }
    + }
    +
    + ret = register_trace_uprobe(tp);
    + if (ret)
    + goto error;
    + return 0;
    +
    +error:
    + free_trace_uprobe(tp);
    + 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 *tp;
    +
    + mutex_lock(&uprobe_lock);
    + while (!list_empty(&uprobe_list)) {
    + tp = list_entry(uprobe_list.next, struct trace_uprobe, list);
    + unregister_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;
    +
    + seq_printf(m, "p:%s/%s", tp->call.class->system, tp->call.name);
    + seq_printf(m, " %s:0x%p", tp->filename, (void *)tp->offset);
    +
    + for (i = 0; i < tp->nr_args; i++)
    + seq_printf(m, " %s=%s", tp->args[i].name, tp->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 *tp = v;
    +
    + seq_printf(m, " %s %-44s %15lu\n", tp->filename, 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 trace_uprobe *tp, 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 = &tp->call;
    +
    + tp->nhit++;
    +
    + local_save_flags(irq_flags);
    + pc = preempt_count();
    +
    + size = sizeof(*entry) + tp->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 = get_uprobe_bkpt_addr(task_pt_regs(current));
    + data = (u8 *)&entry[1];
    + for (i = 0; i < tp->nr_args; i++)
    + call_fetch(&tp->args[i].fetch, regs,
    + data + tp->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 *tp;
    + u8 *data;
    + int i;
    +
    + field = (struct uprobe_trace_entry_head *)iter->ent;
    + tp = container_of(event, struct trace_uprobe, call.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;
    +
    + data = (u8 *)&field[1];
    + for (i = 0; i < tp->nr_args; i++)
    + if (!tp->args[i].type->print(s, tp->args[i].name,
    + data + tp->args[i].offset, field))
    + 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 trace_uprobe *tp, int flag)
    +{
    + struct uprobe_trace_consumer *utc;
    + int ret = 0;
    +
    + if (!tp->inode || tp->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 = register_uprobe(tp->inode, tp->offset, &utc->cons);
    + if (ret) {
    + kfree(utc);
    + return ret;
    + }
    +
    + tp->flags |= flag;
    + utc->tp = tp;
    + tp->consumer = utc;
    + return 0;
    +}
    +
    +static void probe_event_disable(struct trace_uprobe *tp, int flag)
    +{
    + if (!tp->inode || !tp->consumer)
    + return;
    +
    + unregister_uprobe(tp->inode, tp->offset, &tp->consumer->cons);
    + tp->flags &= ~flag;
    + kfree(tp->consumer);
    + tp->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 *tp = (struct trace_uprobe *)event_call->data;
    +
    + DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
    + /* Set argument names as fields */
    + for (i = 0; i < tp->nr_args; i++) {
    + ret = trace_define_field(event_call, tp->args[i].type->fmttype,
    + tp->args[i].name,
    + sizeof(field) + tp->args[i].offset,
    + tp->args[i].type->size,
    + tp->args[i].type->is_signed,
    + FILTER_OTHER);
    + if (ret)
    + return ret;
    + }
    + 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=%s",
    + tp->args[i].name, tp->args[i].type->fmt);
    + }
    +
    + 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 trace_uprobe *tp, struct pt_regs *regs)
    +{
    + struct ftrace_event_call *call = &tp->call;
    + struct uprobe_trace_entry_head *entry;
    + struct hlist_head *head;
    + u8 *data;
    + int size, __size, i;
    + int rctx;
    +
    + __size = sizeof(*entry) + tp->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;
    +
    + entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
    + if (!entry)
    + return;
    +
    + entry->ip = get_uprobe_bkpt_addr(task_pt_regs(current));
    + data = (u8 *)&entry[1];
    + for (i = 0; i < tp->nr_args; i++)
    + call_fetch(&tp->args[i].fetch, regs,
    + data + tp->args[i].offset);
    +
    + head = this_cpu_ptr(call->perf_events);
    + perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head);
    +}
    +#endif /* CONFIG_PERF_EVENTS */
    +
    +static
    +int uprobe_register(struct ftrace_event_call *event, enum trace_reg type)
    +{
    + switch (type) {
    + case TRACE_REG_REGISTER:
    + return probe_event_enable(event->data, TP_FLAG_TRACE);
    + case TRACE_REG_UNREGISTER:
    + probe_event_disable(event->data, TP_FLAG_TRACE);
    + return 0;
    +
    +#ifdef CONFIG_PERF_EVENTS
    + case TRACE_REG_PERF_REGISTER:
    + return probe_event_enable(event->data, TP_FLAG_PROFILE);
    + case TRACE_REG_PERF_UNREGISTER:
    + probe_event_disable(event->data, TP_FLAG_PROFILE);
    + return 0;
    +#endif
    + }
    + return 0;
    +}
    +
    +static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
    +{
    + struct uprobe_trace_consumer *utc;
    + struct trace_uprobe *tp;
    +
    + utc = container_of(con, struct uprobe_trace_consumer, cons);
    + tp = utc->tp;
    + if (!tp || tp->consumer != utc)
    + return 0;
    +
    + if (tp->flags & TP_FLAG_TRACE)
    + uprobe_trace_func(tp, regs);
    +#ifdef CONFIG_PERF_EVENTS
    + if (tp->flags & TP_FLAG_PROFILE)
    + uprobe_perf_func(tp, regs);
    +#endif
    + return 0;
    +}
    +
    +static struct trace_event_functions uprobe_funcs = {
    + .trace = print_uprobe_event
    +};
    +
    +static int register_uprobe_event(struct trace_uprobe *tp)
    +{
    + struct ftrace_event_call *call = &tp->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(tp) < 0)
    + return -ENOMEM;
    + ret = register_ftrace_event(&call->event);
    + if (!ret) {
    + kfree(call->print_fmt);
    + return -ENODEV;
    + }
    + call->flags = 0;
    + call->class->reg = uprobe_register;
    + 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(&call->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);
    + tp->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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      Last update: 2012-01-10 12:59    [W:0.082 / U:0.332 seconds]
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