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    Subject[PATCHv8 2.6.35-rc4-tip 9/12] trace: uprobes trace_event interface

    trace: uprobes trace_event interface

    Changelog from v5: Addressed comments from Masami Hiramatsu and Steven
    Rostedt. Some changes because of changes in common probe events.

    Changelog from v4: (Merged to 2.6.35-rc3-tip)

    Changelog from v2/v3: (Addressing comments from Steven Rostedt
    and Frederic Weisbecker)
    * removed pit field from uprobe_trace_entry.
    * share common parts with kprobe trace events.
    * use trace_create_file instead of debugfs_create_file.

    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.

    TODO: Documentation/trace/uprobetrace.txt

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

    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 6016]
    [Address to trace is 0x0000000000446420]
    [Registers to be dumped are %ip and %ax]

    # cd /sys/kernel/debug/tracing/
    # echo 'p 6016:0x0000000000446420 %ip %ax' > uprobe_events
    # cat uprobe_events
    p:uprobes/p_6016_0x0000000000446420 6016:0x0000000000446420 %ip=%ip %ax=%ax
    # cat events/uprobes/p_6016_0x0000000000446420/enable
    0
    [enable the event]
    # echo 1 > events/uprobes/p_6016_0x0000000000446420/enable
    # cat events/uprobes/p_6016_0x0000000000446420/enable
    1
    # #### do some activity on the program so that it hits the breakpoint
    # cat uprobe_profile
    6016 p_6016_0x0000000000446420 234
    # tracer: nop
    #
    # TASK-PID CPU# TIMESTAMP FUNCTION
    # | | | | |
    zsh-6016 [004] 227931.093579: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
    zsh-6016 [005] 227931.097541: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
    zsh-6016 [000] 227931.124909: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
    zsh-6016 [001] 227933.128565: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
    zsh-6016 [004] 227933.132756: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
    zsh-6016 [000] 227933.158802: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
    zsh-6016 [001] 227935.161602: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
    zsh-6016 [004] 227935.165229: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79

    arch/Kconfig | 11 -
    kernel/trace/Kconfig | 16 +
    kernel/trace/Makefile | 1
    kernel/trace/trace.h | 5
    kernel/trace/trace_probe.h | 2
    kernel/trace/trace_uprobe.c | 739 +++++++++++++++++++++++++++++++++++++++++++
    6 files changed, 764 insertions(+), 10 deletions(-)
    create mode 100644 kernel/trace/trace_uprobe.c


    diff --git a/arch/Kconfig b/arch/Kconfig
    index c8c8e3f..af167f8 100644
    --- a/arch/Kconfig
    +++ b/arch/Kconfig
    @@ -48,16 +48,7 @@ config OPTPROBES
    select KALLSYMS_ALL

    config UPROBES
    - bool "User-space probes (EXPERIMENTAL)"
    - default n
    - depends on ARCH_SUPPORTS_UPROBES
    - depends on MMU
    - help
    - Uprobes enables kernel subsystems to establish probepoints
    - in user applications and execute handler functions when
    - the probepoints are hit. For more information, refer to
    - Documentation/uprobes.txt.
    - 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 ab62d9a..2f46188 100644
    --- a/kernel/trace/Kconfig
    +++ b/kernel/trace/Kconfig
    @@ -513,6 +513,22 @@ config RING_BUFFER_BENCHMARK

    If unsure, say N.

    +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.
    +
    endif # FTRACE

    endif # TRACING_SUPPORT
    diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
    index 5a45910..a386d12 100644
    --- a/kernel/trace/Makefile
    +++ b/kernel/trace/Makefile
    @@ -56,5 +56,6 @@ obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
    obj-$(CONFIG_KSYM_TRACER) += trace_ksym.o
    obj-$(CONFIG_EVENT_TRACING) += power-traces.o
    obj-$(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 cc90ccd..8ef185f 100644
    --- a/kernel/trace/trace.h
    +++ b/kernel/trace/trace.h
    @@ -99,6 +99,11 @@ 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_probe.h b/kernel/trace/trace_probe.h
    index ad783a5..b52d527 100644
    --- a/kernel/trace/trace_probe.h
    +++ b/kernel/trace/trace_probe.h
    @@ -44,6 +44,7 @@
    #define FIELD_STRING_IP "__probe_ip"
    #define FIELD_STRING_RETIP "__probe_ret_ip"
    #define FIELD_STRING_FUNC "__probe_func"
    +#define FIELD_STRING_PID "__probe_pid"

    #undef DEFINE_FIELD
    #define DEFINE_FIELD(type, item, name, is_signed) \
    @@ -60,6 +61,7 @@
    /* Flags for trace_probe */
    #define TP_FLAG_TRACE 1
    #define TP_FLAG_PROFILE 2
    +#define TP_FLAG_UPROBE 4


    /* data_rloc: data relative location, compatible with u32 */
    diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
    new file mode 100644
    index 0000000..3aadac7
    --- /dev/null
    +++ b/kernel/trace/trace_uprobe.c
    @@ -0,0 +1,739 @@
    +/*
    + * 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 "trace_probe.h"
    +
    +#define UPROBE_EVENT_SYSTEM "uprobes"
    +
    +/**
    + * uprobe event core functions
    + */
    +
    +struct trace_uprobe {
    + struct list_head list;
    + struct uprobe up;
    + unsigned long nhit;
    + unsigned int flags; /* For TP_FLAG_* */
    + struct ftrace_event_class class;
    + struct ftrace_event_call call;
    + 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 void uprobe_dispatcher(struct uprobe *up, 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,
    + void *addr,
    + pid_t pid, int nargs)
    +{
    + struct trace_uprobe *tp;
    +
    + 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(-ENOMEM);
    +
    + tp->up.vaddr = (unsigned long)addr;
    + tp->up.pid = pid;
    + tp->up.handler = uprobe_dispatcher;
    +
    + 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]);
    +
    + kfree(tp->call.class->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.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)
    +{
    + if (tp->flags & TP_FLAG_UPROBE)
    + 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.class->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("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 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];
    + char *tmp;
    +
    + /* 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);
    + free_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])) {
    + /* 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];
    +
    + 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;
    + }
    + tmp = strchr(tp->args[i].name, ':');
    + if (tmp)
    + *tmp = '_'; /* convert : to _ */
    +
    + 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);
    + 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;
    +
    + seq_printf(m, "%c", 'p');
    + seq_printf(m, ":%s/%s", tp->call.class->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++)
    + 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, " %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_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 = (unsigned long)up->vaddr;
    + 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 */
    +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 ftrace_event_call *call)
    +{
    + int ret = 0;
    + struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
    +
    + if (!(tp->flags & TP_FLAG_UPROBE)) {
    + ret = register_uprobe(&tp->up);
    + if (!ret)
    + tp->flags |= (TP_FLAG_UPROBE | 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 & TP_FLAG_UPROBE) {
    + unregister_uprobe(&tp->up);
    + tp->flags &= ~(TP_FLAG_UPROBE | TP_FLAG_TRACE);
    + }
    +}
    +
    +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 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_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 = (unsigned long)up->vaddr;
    + 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);
    +}
    +
    +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 & TP_FLAG_UPROBE)) {
    + ret = register_uprobe(&tp->up);
    + if (!ret)
    + tp->flags |= (TP_FLAG_UPROBE | 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 & TP_FLAG_UPROBE) {
    + unregister_uprobe(&tp->up);
    + tp->flags &= ~(TP_FLAG_UPROBE | TP_FLAG_PROFILE);
    + }
    +}
    +#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);
    + case TRACE_REG_UNREGISTER:
    + probe_event_disable(event);
    + return 0;
    +
    +#ifdef CONFIG_PERF_EVENTS
    + case TRACE_REG_PERF_REGISTER:
    + return probe_perf_enable(event);
    + case TRACE_REG_PERF_UNREGISTER:
    + probe_perf_disable(event);
    + return 0;
    +#endif
    + }
    + return 0;
    +}
    +
    +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 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);
    +}
    +
    +/* Make a trace 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 = trace_create_file("uprobe_events", 0644, d_tracer,
    + NULL, &uprobe_events_ops);
    + /* Profile interface */
    + entry = 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: 2010-07-08 19:27    [W:0.066 / U:0.684 seconds]
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