Re: [PATCH v8 2/5] tracing: Add a probe that attaches to trace events
From: Masami Hiramatsu
Date: Thu Aug 19 2021 - 20:10:34 EST
On Thu, 19 Aug 2021 11:26:06 -0400
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx>
>
> A new dynamic event is introduced: event probe. The event is attached
> to an existing tracepoint and uses its fields as arguments. The user
> can specify custom format string of the new event, select what tracepoint
> arguments will be printed and how to print them.
> An event probe is created by writing configuration string in
> 'dynamic_events' ftrace file:
> e[:[SNAME/]ENAME] SYSTEM/EVENT [FETCHARGS] - Set an event probe
> -:SNAME/ENAME - Delete an event probe
>
> Where:
> SNAME - System name, if omitted 'eprobes' is used.
> ENAME - Name of the new event in SNAME, if omitted the SYSTEM_EVENT is used.
> SYSTEM - Name of the system, where the tracepoint is defined, mandatory.
> EVENT - Name of the tracepoint event in SYSTEM, mandatory.
> FETCHARGS - Arguments:
> <name>=$<field>[:TYPE] - Fetch given filed of the tracepoint and print
> it as given TYPE with given name. Supported
> types are:
> (u8/u16/u32/u64/s8/s16/s32/s64), basic type
> (x8/x16/x32/x64), hexadecimal types
> "string", "ustring" and bitfield.
>
> Example, attach an event probe on openat system call and print name of the
> file that will be opened:
> echo "e:esys/eopen syscalls/sys_enter_openat file=\$filename:string" >> dynamic_events
> A new dynamic event is created in events/esys/eopen/ directory. It
> can be deleted with:
> echo "-:esys/eopen" >> dynamic_events
>
> Filters, triggers and histograms can be attached to the new event, it can
> be matched in synthetic events. There is one limitation - an event probe
> can not be attached to kprobe, uprobe or another event probe.
>
> Link: https://lkml.kernel.org/r/20210812145805.2292326-1-tz.stoyanov@xxxxxxxxx
> Link: https://lkml.kernel.org/r/20210819041842.485382601@xxxxxxxxxxx
>
This looks good to me.
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Thank you!
> Co-developed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> ---
> include/linux/trace_events.h | 4 +
> kernel/trace/Makefile | 1 +
> kernel/trace/trace.c | 5 +-
> kernel/trace/trace.h | 18 +
> kernel/trace/trace_eprobe.c | 903 ++++++++++++++++++++++++++++
> kernel/trace/trace_events_trigger.c | 14 +-
> kernel/trace/trace_kprobe.c | 8 -
> kernel/trace/trace_probe.c | 16 +-
> kernel/trace/trace_probe.h | 6 +-
> 9 files changed, 962 insertions(+), 13 deletions(-)
> create mode 100644 kernel/trace/trace_eprobe.c
>
> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> index 9564c4d9a3b6..0a0144580bbd 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -313,6 +313,7 @@ enum {
> TRACE_EVENT_FL_DYNAMIC_BIT,
> TRACE_EVENT_FL_KPROBE_BIT,
> TRACE_EVENT_FL_UPROBE_BIT,
> + TRACE_EVENT_FL_EPROBE_BIT,
> };
>
> /*
> @@ -325,6 +326,7 @@ enum {
> * DYNAMIC - Event is a dynamic event (created at run time)
> * KPROBE - Event is a kprobe
> * UPROBE - Event is a uprobe
> + * EPROBE - Event is an event probe
> */
> enum {
> TRACE_EVENT_FL_FILTERED = (1 << TRACE_EVENT_FL_FILTERED_BIT),
> @@ -335,6 +337,7 @@ enum {
> TRACE_EVENT_FL_DYNAMIC = (1 << TRACE_EVENT_FL_DYNAMIC_BIT),
> TRACE_EVENT_FL_KPROBE = (1 << TRACE_EVENT_FL_KPROBE_BIT),
> TRACE_EVENT_FL_UPROBE = (1 << TRACE_EVENT_FL_UPROBE_BIT),
> + TRACE_EVENT_FL_EPROBE = (1 << TRACE_EVENT_FL_EPROBE_BIT),
> };
>
> #define TRACE_EVENT_FL_UKPROBE (TRACE_EVENT_FL_KPROBE | TRACE_EVENT_FL_UPROBE)
> @@ -680,6 +683,7 @@ enum event_trigger_type {
> ETT_EVENT_ENABLE = (1 << 3),
> ETT_EVENT_HIST = (1 << 4),
> ETT_HIST_ENABLE = (1 << 5),
> + ETT_EVENT_EPROBE = (1 << 6),
> };
>
> extern int filter_match_preds(struct event_filter *filter, void *rec);
> diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> index b1c47ccf4f73..6de5d4d63165 100644
> --- a/kernel/trace/Makefile
> +++ b/kernel/trace/Makefile
> @@ -77,6 +77,7 @@ obj-$(CONFIG_EVENT_TRACING) += trace_event_perf.o
> endif
> obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
> obj-$(CONFIG_EVENT_TRACING) += trace_events_trigger.o
> +obj-$(CONFIG_PROBE_EVENTS) += trace_eprobe.o
> obj-$(CONFIG_TRACE_EVENT_INJECT) += trace_events_inject.o
> obj-$(CONFIG_SYNTH_EVENTS) += trace_events_synth.o
> obj-$(CONFIG_HIST_TRIGGERS) += trace_events_hist.o
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 8425c3d70895..489924cde4f8 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -5543,6 +5543,7 @@ static const char readme_msg[] =
> #ifdef CONFIG_HIST_TRIGGERS
> "\t s:[synthetic/]<event> <field> [<field>]\n"
> #endif
> + "\t e[:[<group>/]<event>] <attached-group>.<attached-event> [<args>]\n"
> "\t -:[<group>/]<event>\n"
> #ifdef CONFIG_KPROBE_EVENTS
> "\t place: [<module>:]<symbol>[+<offset>]|<memaddr>\n"
> @@ -5552,7 +5553,7 @@ static const char readme_msg[] =
> " place (uprobe): <path>:<offset>[%return][(ref_ctr_offset)]\n"
> #endif
> "\t args: <name>=fetcharg[:type]\n"
> - "\t fetcharg: %<register>, @<address>, @<symbol>[+|-<offset>],\n"
> + "\t fetcharg: (%<register>|$<efield>), @<address>, @<symbol>[+|-<offset>],\n"
> #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
> "\t $stack<index>, $stack, $retval, $comm, $arg<N>,\n"
> #else
> @@ -5567,6 +5568,8 @@ static const char readme_msg[] =
> "\t stype: u8/u16/u32/u64, s8/s16/s32/s64, pid_t,\n"
> "\t [unsigned] char/int/long\n"
> #endif
> + "\t efield: For event probes ('e' types), the field is on of the fields\n"
> + "\t of the <attached-group>/<attached-event>.\n"
> #endif
> " events/\t\t- Directory containing all trace event subsystems:\n"
> " enable\t\t- Write 0/1 to enable/disable tracing of all events\n"
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 4a0e693000c6..b7c0f8e160fb 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -126,6 +126,11 @@ struct kprobe_trace_entry_head {
> unsigned long ip;
> };
>
> +struct eprobe_trace_entry_head {
> + struct trace_entry ent;
> + unsigned int type;
> +};
> +
> struct kretprobe_trace_entry_head {
> struct trace_entry ent;
> unsigned long func;
> @@ -1508,9 +1513,14 @@ static inline int register_trigger_hist_enable_disable_cmds(void) { return 0; }
> extern int register_trigger_cmds(void);
> extern void clear_event_triggers(struct trace_array *tr);
>
> +enum {
> + EVENT_TRIGGER_FL_PROBE = BIT(0),
> +};
> +
> struct event_trigger_data {
> unsigned long count;
> int ref;
> + int flags;
> struct event_trigger_ops *ops;
> struct event_command *cmd_ops;
> struct event_filter __rcu *filter;
> @@ -1918,6 +1928,14 @@ static inline bool is_good_name(const char *name)
> return true;
> }
>
> +/* Convert certain expected symbols into '_' when generating event names */
> +static inline void sanitize_event_name(char *name)
> +{
> + while (*name++ != '\0')
> + if (*name == ':' || *name == '.')
> + *name = '_';
> +}
> +
> /*
> * This is a generic way to read and write a u64 value from a file in tracefs.
> *
> diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
> new file mode 100644
> index 000000000000..56a96e9750cf
> --- /dev/null
> +++ b/kernel/trace/trace_eprobe.c
> @@ -0,0 +1,903 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * event probes
> + *
> + * Part of this code was copied from kernel/trace/trace_kprobe.c written by
> + * Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> + *
> + * Copyright (C) 2021, VMware Inc, Steven Rostedt <rostedt@xxxxxxxxxxx>
> + * Copyright (C) 2021, VMware Inc, Tzvetomir Stoyanov tz.stoyanov@xxxxxxxxx>
> + *
> + */
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/ftrace.h>
> +
> +#include "trace_dynevent.h"
> +#include "trace_probe.h"
> +#include "trace_probe_tmpl.h"
> +
> +#define EPROBE_EVENT_SYSTEM "eprobes"
> +
> +struct trace_eprobe {
> + /* tracepoint system */
> + const char *event_system;
> +
> + /* tracepoint event */
> + const char *event_name;
> +
> + struct trace_event_call *event;
> +
> + struct dyn_event devent;
> + struct trace_probe tp;
> +};
> +
> +struct eprobe_data {
> + struct trace_event_file *file;
> + struct trace_eprobe *ep;
> +};
> +
> +static int __trace_eprobe_create(int argc, const char *argv[]);
> +
> +static void trace_event_probe_cleanup(struct trace_eprobe *ep)
> +{
> + if (!ep)
> + return;
> + trace_probe_cleanup(&ep->tp);
> + kfree(ep->event_name);
> + kfree(ep->event_system);
> + if (ep->event)
> + trace_event_put_ref(ep->event);
> + kfree(ep);
> +}
> +
> +static struct trace_eprobe *to_trace_eprobe(struct dyn_event *ev)
> +{
> + return container_of(ev, struct trace_eprobe, devent);
> +}
> +
> +static int eprobe_dyn_event_create(const char *raw_command)
> +{
> + return trace_probe_create(raw_command, __trace_eprobe_create);
> +}
> +
> +static int eprobe_dyn_event_show(struct seq_file *m, struct dyn_event *ev)
> +{
> + struct trace_eprobe *ep = to_trace_eprobe(ev);
> + int i;
> +
> + seq_printf(m, "e:%s/%s", trace_probe_group_name(&ep->tp),
> + trace_probe_name(&ep->tp));
> + seq_printf(m, " %s.%s", ep->event_system, ep->event_name);
> +
> + for (i = 0; i < ep->tp.nr_args; i++)
> + seq_printf(m, " %s=%s", ep->tp.args[i].name, ep->tp.args[i].comm);
> + seq_putc(m, '\n');
> +
> + return 0;
> +}
> +
> +static int unregister_trace_eprobe(struct trace_eprobe *ep)
> +{
> + /* If other probes are on the event, just unregister eprobe */
> + if (trace_probe_has_sibling(&ep->tp))
> + goto unreg;
> +
> + /* Enabled event can not be unregistered */
> + if (trace_probe_is_enabled(&ep->tp))
> + return -EBUSY;
> +
> + /* Will fail if probe is being used by ftrace or perf */
> + if (trace_probe_unregister_event_call(&ep->tp))
> + return -EBUSY;
> +
> +unreg:
> + dyn_event_remove(&ep->devent);
> + trace_probe_unlink(&ep->tp);
> +
> + return 0;
> +}
> +
> +static int eprobe_dyn_event_release(struct dyn_event *ev)
> +{
> + struct trace_eprobe *ep = to_trace_eprobe(ev);
> + int ret = unregister_trace_eprobe(ep);
> +
> + if (!ret)
> + trace_event_probe_cleanup(ep);
> + return ret;
> +}
> +
> +static bool eprobe_dyn_event_is_busy(struct dyn_event *ev)
> +{
> + struct trace_eprobe *ep = to_trace_eprobe(ev);
> +
> + return trace_probe_is_enabled(&ep->tp);
> +}
> +
> +static bool eprobe_dyn_event_match(const char *system, const char *event,
> + int argc, const char **argv, struct dyn_event *ev)
> +{
> + struct trace_eprobe *ep = to_trace_eprobe(ev);
> +
> + return strcmp(trace_probe_name(&ep->tp), event) == 0 &&
> + (!system || strcmp(trace_probe_group_name(&ep->tp), system) == 0) &&
> + trace_probe_match_command_args(&ep->tp, argc, argv);
> +}
> +
> +static struct dyn_event_operations eprobe_dyn_event_ops = {
> + .create = eprobe_dyn_event_create,
> + .show = eprobe_dyn_event_show,
> + .is_busy = eprobe_dyn_event_is_busy,
> + .free = eprobe_dyn_event_release,
> + .match = eprobe_dyn_event_match,
> +};
> +
> +static struct trace_eprobe *alloc_event_probe(const char *group,
> + const char *this_event,
> + struct trace_event_call *event,
> + int nargs)
> +{
> + struct trace_eprobe *ep;
> + const char *event_name;
> + const char *sys_name;
> + int ret = -ENOMEM;
> +
> + if (!event)
> + return ERR_PTR(-ENODEV);
> +
> + sys_name = event->class->system;
> + event_name = trace_event_name(event);
> +
> + ep = kzalloc(struct_size(ep, tp.args, nargs), GFP_KERNEL);
> + if (!ep) {
> + trace_event_put_ref(ep->event);
> + goto error;
> + }
> + ep->event = event;
> + ep->event_name = kstrdup(event_name, GFP_KERNEL);
> + if (!ep->event_name)
> + goto error;
> + ep->event_system = kstrdup(sys_name, GFP_KERNEL);
> + if (!ep->event_system)
> + goto error;
> +
> + ret = trace_probe_init(&ep->tp, this_event, group, false);
> + if (ret < 0)
> + goto error;
> +
> + dyn_event_init(&ep->devent, &eprobe_dyn_event_ops);
> + return ep;
> +error:
> + trace_event_probe_cleanup(ep);
> + return ERR_PTR(ret);
> +}
> +
> +static int trace_eprobe_tp_arg_update(struct trace_eprobe *ep, int i)
> +{
> + struct probe_arg *parg = &ep->tp.args[i];
> + struct ftrace_event_field *field;
> + struct list_head *head;
> +
> + head = trace_get_fields(ep->event);
> + list_for_each_entry(field, head, link) {
> + if (!strcmp(parg->code->data, field->name)) {
> + kfree(parg->code->data);
> + parg->code->data = field;
> + return 0;
> + }
> + }
> + kfree(parg->code->data);
> + parg->code->data = NULL;
> + return -ENOENT;
> +}
> +
> +static int eprobe_event_define_fields(struct trace_event_call *event_call)
> +{
> + int ret;
> + struct eprobe_trace_entry_head field;
> + struct trace_probe *tp;
> +
> + tp = trace_probe_primary_from_call(event_call);
> + if (WARN_ON_ONCE(!tp))
> + return -ENOENT;
> +
> + DEFINE_FIELD(unsigned int, type, FIELD_STRING_TYPE, 0);
> +
> + return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
> +}
> +
> +static struct trace_event_fields eprobe_fields_array[] = {
> + { .type = TRACE_FUNCTION_TYPE,
> + .define_fields = eprobe_event_define_fields },
> + {}
> +};
> +
> +/* Event entry printers */
> +static enum print_line_t
> +print_eprobe_event(struct trace_iterator *iter, int flags,
> + struct trace_event *event)
> +{
> + struct eprobe_trace_entry_head *field;
> + struct trace_event_call *pevent;
> + struct trace_event *probed_event;
> + struct trace_seq *s = &iter->seq;
> + struct trace_probe *tp;
> +
> + field = (struct eprobe_trace_entry_head *)iter->ent;
> + tp = trace_probe_primary_from_call(
> + container_of(event, struct trace_event_call, event));
> + if (WARN_ON_ONCE(!tp))
> + goto out;
> +
> + trace_seq_printf(s, "%s: (", trace_probe_name(tp));
> +
> + probed_event = ftrace_find_event(field->type);
> + if (probed_event) {
> + pevent = container_of(probed_event, struct trace_event_call, event);
> + trace_seq_printf(s, "%s.%s", pevent->class->system,
> + trace_event_name(pevent));
> + } else {
> + trace_seq_printf(s, "%u", field->type);
> + }
> +
> + trace_seq_putc(s, ')');
> +
> + if (print_probe_args(s, tp->args, tp->nr_args,
> + (u8 *)&field[1], field) < 0)
> + goto out;
> +
> + trace_seq_putc(s, '\n');
> + out:
> + return trace_handle_return(s);
> +}
> +
> +static unsigned long get_event_field(struct fetch_insn *code, void *rec)
> +{
> + struct ftrace_event_field *field = code->data;
> + unsigned long val;
> + void *addr;
> +
> + addr = rec + field->offset;
> +
> + switch (field->size) {
> + case 1:
> + if (field->is_signed)
> + val = *(char *)addr;
> + else
> + val = *(unsigned char *)addr;
> + break;
> + case 2:
> + if (field->is_signed)
> + val = *(short *)addr;
> + else
> + val = *(unsigned short *)addr;
> + break;
> + case 4:
> + if (field->is_signed)
> + val = *(int *)addr;
> + else
> + val = *(unsigned int *)addr;
> + break;
> + default:
> + if (field->is_signed)
> + val = *(long *)addr;
> + else
> + val = *(unsigned long *)addr;
> + break;
> + }
> + return val;
> +}
> +
> +static int get_eprobe_size(struct trace_probe *tp, void *rec)
> +{
> + struct probe_arg *arg;
> + int i, len, ret = 0;
> +
> + for (i = 0; i < tp->nr_args; i++) {
> + arg = tp->args + i;
> + if (unlikely(arg->dynamic)) {
> + unsigned long val;
> +
> + val = get_event_field(arg->code, rec);
> + len = process_fetch_insn_bottom(arg->code + 1, val, NULL, NULL);
> + if (len > 0)
> + ret += len;
> + }
> + }
> +
> + return ret;
> +}
> +
> +/* Kprobe specific fetch functions */
> +
> +/* Note that we don't verify it, since the code does not come from user space */
> +static int
> +process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
> + void *base)
> +{
> + unsigned long val;
> +
> + val = get_event_field(code, rec);
> + return process_fetch_insn_bottom(code + 1, val, dest, base);
> +}
> +NOKPROBE_SYMBOL(process_fetch_insn)
> +
> +/* Return the length of string -- including null terminal byte */
> +static nokprobe_inline int
> +fetch_store_strlen_user(unsigned long addr)
> +{
> + const void __user *uaddr = (__force const void __user *)addr;
> +
> + return strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
> +}
> +
> +/* Return the length of string -- including null terminal byte */
> +static nokprobe_inline int
> +fetch_store_strlen(unsigned long addr)
> +{
> + int ret, len = 0;
> + u8 c;
> +
> +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
> + if (addr < TASK_SIZE)
> + return fetch_store_strlen_user(addr);
> +#endif
> +
> + do {
> + ret = copy_from_kernel_nofault(&c, (u8 *)addr + len, 1);
> + len++;
> + } while (c && ret == 0 && len < MAX_STRING_SIZE);
> +
> + return (ret < 0) ? ret : len;
> +}
> +
> +/*
> + * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
> + * with max length and relative data location.
> + */
> +static nokprobe_inline int
> +fetch_store_string_user(unsigned long addr, void *dest, void *base)
> +{
> + const void __user *uaddr = (__force const void __user *)addr;
> + int maxlen = get_loc_len(*(u32 *)dest);
> + void *__dest;
> + long ret;
> +
> + if (unlikely(!maxlen))
> + return -ENOMEM;
> +
> + __dest = get_loc_data(dest, base);
> +
> + ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);
> + if (ret >= 0)
> + *(u32 *)dest = make_data_loc(ret, __dest - base);
> +
> + return ret;
> +}
> +
> +/*
> + * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
> + * length and relative data location.
> + */
> +static nokprobe_inline int
> +fetch_store_string(unsigned long addr, void *dest, void *base)
> +{
> + int maxlen = get_loc_len(*(u32 *)dest);
> + void *__dest;
> + long ret;
> +
> +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
> + if ((unsigned long)addr < TASK_SIZE)
> + return fetch_store_string_user(addr, dest, base);
> +#endif
> +
> + if (unlikely(!maxlen))
> + return -ENOMEM;
> +
> + __dest = get_loc_data(dest, base);
> +
> + /*
> + * Try to get string again, since the string can be changed while
> + * probing.
> + */
> + ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
> + if (ret >= 0)
> + *(u32 *)dest = make_data_loc(ret, __dest - base);
> +
> + return ret;
> +}
> +
> +static nokprobe_inline int
> +probe_mem_read_user(void *dest, void *src, size_t size)
> +{
> + const void __user *uaddr = (__force const void __user *)src;
> +
> + return copy_from_user_nofault(dest, uaddr, size);
> +}
> +
> +static nokprobe_inline int
> +probe_mem_read(void *dest, void *src, size_t size)
> +{
> +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
> + if ((unsigned long)src < TASK_SIZE)
> + return probe_mem_read_user(dest, src, size);
> +#endif
> + return copy_from_kernel_nofault(dest, src, size);
> +}
> +
> +/* eprobe handler */
> +static inline void
> +__eprobe_trace_func(struct eprobe_data *edata, void *rec)
> +{
> + struct eprobe_trace_entry_head *entry;
> + struct trace_event_call *call = trace_probe_event_call(&edata->ep->tp);
> + struct trace_event_buffer fbuffer;
> + int dsize;
> +
> + if (WARN_ON_ONCE(call != edata->file->event_call))
> + return;
> +
> + if (trace_trigger_soft_disabled(edata->file))
> + return;
> +
> + fbuffer.trace_ctx = tracing_gen_ctx();
> + fbuffer.trace_file = edata->file;
> +
> + dsize = get_eprobe_size(&edata->ep->tp, rec);
> + fbuffer.regs = NULL;
> +
> + fbuffer.event =
> + trace_event_buffer_lock_reserve(&fbuffer.buffer, edata->file,
> + call->event.type,
> + sizeof(*entry) + edata->ep->tp.size + dsize,
> + fbuffer.trace_ctx);
> + if (!fbuffer.event)
> + return;
> +
> + entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
> + if (edata->ep->event)
> + entry->type = edata->ep->event->event.type;
> + else
> + entry->type = 0;
> + store_trace_args(&entry[1], &edata->ep->tp, rec, sizeof(*entry), dsize);
> +
> + trace_event_buffer_commit(&fbuffer);
> +}
> +
> +/*
> + * The event probe implementation uses event triggers to get access to
> + * the event it is attached to, but is not an actual trigger. The below
> + * functions are just stubs to fulfill what is needed to use the trigger
> + * infrastructure.
> + */
> +static int eprobe_trigger_init(struct event_trigger_ops *ops,
> + struct event_trigger_data *data)
> +{
> + return 0;
> +}
> +
> +static void eprobe_trigger_free(struct event_trigger_ops *ops,
> + struct event_trigger_data *data)
> +{
> +
> +}
> +
> +static int eprobe_trigger_print(struct seq_file *m,
> + struct event_trigger_ops *ops,
> + struct event_trigger_data *data)
> +{
> + /* Do not print eprobe event triggers */
> + return 0;
> +}
> +
> +static void eprobe_trigger_func(struct event_trigger_data *data,
> + struct trace_buffer *buffer, void *rec,
> + struct ring_buffer_event *rbe)
> +{
> + struct eprobe_data *edata = data->private_data;
> +
> + __eprobe_trace_func(edata, rec);
> +}
> +
> +static struct event_trigger_ops eprobe_trigger_ops = {
> + .func = eprobe_trigger_func,
> + .print = eprobe_trigger_print,
> + .init = eprobe_trigger_init,
> + .free = eprobe_trigger_free,
> +};
> +
> +static int eprobe_trigger_cmd_func(struct event_command *cmd_ops,
> + struct trace_event_file *file,
> + char *glob, char *cmd, char *param)
> +{
> + return -1;
> +}
> +
> +static int eprobe_trigger_reg_func(char *glob, struct event_trigger_ops *ops,
> + struct event_trigger_data *data,
> + struct trace_event_file *file)
> +{
> + return -1;
> +}
> +
> +static void eprobe_trigger_unreg_func(char *glob, struct event_trigger_ops *ops,
> + struct event_trigger_data *data,
> + struct trace_event_file *file)
> +{
> +
> +}
> +
> +static struct event_trigger_ops *eprobe_trigger_get_ops(char *cmd,
> + char *param)
> +{
> + return &eprobe_trigger_ops;
> +}
> +
> +static struct event_command event_trigger_cmd = {
> + .name = "eprobe",
> + .trigger_type = ETT_EVENT_EPROBE,
> + .flags = EVENT_CMD_FL_NEEDS_REC,
> + .func = eprobe_trigger_cmd_func,
> + .reg = eprobe_trigger_reg_func,
> + .unreg = eprobe_trigger_unreg_func,
> + .unreg_all = NULL,
> + .get_trigger_ops = eprobe_trigger_get_ops,
> + .set_filter = NULL,
> +};
> +
> +static struct event_trigger_data *
> +new_eprobe_trigger(struct trace_eprobe *ep, struct trace_event_file *file)
> +{
> + struct event_trigger_data *trigger;
> + struct eprobe_data *edata;
> +
> + edata = kzalloc(sizeof(*edata), GFP_KERNEL);
> + trigger = kzalloc(sizeof(*trigger), GFP_KERNEL);
> + if (!trigger || !edata) {
> + kfree(edata);
> + kfree(trigger);
> + return ERR_PTR(-ENOMEM);
> + }
> +
> + trigger->flags = EVENT_TRIGGER_FL_PROBE;
> + trigger->count = -1;
> + trigger->ops = &eprobe_trigger_ops;
> +
> + /*
> + * EVENT PROBE triggers are not registered as commands with
> + * register_event_command(), as they are not controlled by the user
> + * from the trigger file
> + */
> + trigger->cmd_ops = &event_trigger_cmd;
> +
> + INIT_LIST_HEAD(&trigger->list);
> + RCU_INIT_POINTER(trigger->filter, NULL);
> +
> + edata->file = file;
> + edata->ep = ep;
> + trigger->private_data = edata;
> +
> + return trigger;
> +}
> +
> +static int enable_eprobe(struct trace_eprobe *ep,
> + struct trace_event_file *eprobe_file)
> +{
> + struct event_trigger_data *trigger;
> + struct trace_event_file *file;
> + struct trace_array *tr = eprobe_file->tr;
> +
> + file = find_event_file(tr, ep->event_system, ep->event_name);
> + if (!file)
> + return -ENOENT;
> + trigger = new_eprobe_trigger(ep, eprobe_file);
> + if (IS_ERR(trigger))
> + return PTR_ERR(trigger);
> +
> + list_add_tail_rcu(&trigger->list, &file->triggers);
> +
> + trace_event_trigger_enable_disable(file, 1);
> + update_cond_flag(file);
> +
> + return 0;
> +}
> +
> +static struct trace_event_functions eprobe_funcs = {
> + .trace = print_eprobe_event
> +};
> +
> +static int disable_eprobe(struct trace_eprobe *ep,
> + struct trace_array *tr)
> +{
> + struct event_trigger_data *trigger;
> + struct trace_event_file *file;
> + struct eprobe_data *edata;
> +
> + file = find_event_file(tr, ep->event_system, ep->event_name);
> + if (!file)
> + return -ENOENT;
> +
> + list_for_each_entry(trigger, &file->triggers, list) {
> + if (!(trigger->flags & EVENT_TRIGGER_FL_PROBE))
> + continue;
> + edata = trigger->private_data;
> + if (edata->ep == ep)
> + break;
> + }
> + if (list_entry_is_head(trigger, &file->triggers, list))
> + return -ENODEV;
> +
> + list_del_rcu(&trigger->list);
> +
> + trace_event_trigger_enable_disable(file, 0);
> + update_cond_flag(file);
> + return 0;
> +}
> +
> +static int enable_trace_eprobe(struct trace_event_call *call,
> + struct trace_event_file *file)
> +{
> + struct trace_probe *pos, *tp;
> + struct trace_eprobe *ep;
> + bool enabled;
> + int ret = 0;
> +
> + tp = trace_probe_primary_from_call(call);
> + if (WARN_ON_ONCE(!tp))
> + return -ENODEV;
> + enabled = trace_probe_is_enabled(tp);
> +
> + /* This also changes "enabled" state */
> + if (file) {
> + ret = trace_probe_add_file(tp, file);
> + if (ret)
> + return ret;
> + } else
> + trace_probe_set_flag(tp, TP_FLAG_PROFILE);
> +
> + if (enabled)
> + return 0;
> +
> + list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> + ep = container_of(pos, struct trace_eprobe, tp);
> + ret = enable_eprobe(ep, file);
> + if (ret)
> + break;
> + enabled = true;
> + }
> +
> + if (ret) {
> + /* Failed to enable one of them. Roll back all */
> + if (enabled)
> + disable_eprobe(ep, file->tr);
> + if (file)
> + trace_probe_remove_file(tp, file);
> + else
> + trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
> + }
> +
> + return ret;
> +}
> +
> +static int disable_trace_eprobe(struct trace_event_call *call,
> + struct trace_event_file *file)
> +{
> + struct trace_probe *pos, *tp;
> + struct trace_eprobe *ep;
> +
> + tp = trace_probe_primary_from_call(call);
> + if (WARN_ON_ONCE(!tp))
> + return -ENODEV;
> +
> + if (file) {
> + if (!trace_probe_get_file_link(tp, file))
> + return -ENOENT;
> + if (!trace_probe_has_single_file(tp))
> + goto out;
> + trace_probe_clear_flag(tp, TP_FLAG_TRACE);
> + } else
> + trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
> +
> + if (!trace_probe_is_enabled(tp)) {
> + list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
> + ep = container_of(pos, struct trace_eprobe, tp);
> + disable_eprobe(ep, file->tr);
> + }
> + }
> +
> + out:
> + if (file)
> + /*
> + * Synchronization is done in below function. For perf event,
> + * file == NULL and perf_trace_event_unreg() calls
> + * tracepoint_synchronize_unregister() to ensure synchronize
> + * event. We don't need to care about it.
> + */
> + trace_probe_remove_file(tp, file);
> +
> + return 0;
> +}
> +
> +static int eprobe_register(struct trace_event_call *event,
> + enum trace_reg type, void *data)
> +{
> + struct trace_event_file *file = data;
> +
> + switch (type) {
> + case TRACE_REG_REGISTER:
> + return enable_trace_eprobe(event, file);
> + case TRACE_REG_UNREGISTER:
> + return disable_trace_eprobe(event, file);
> +#ifdef CONFIG_PERF_EVENTS
> + case TRACE_REG_PERF_REGISTER:
> + case TRACE_REG_PERF_UNREGISTER:
> + case TRACE_REG_PERF_OPEN:
> + case TRACE_REG_PERF_CLOSE:
> + case TRACE_REG_PERF_ADD:
> + case TRACE_REG_PERF_DEL:
> + return 0;
> +#endif
> + }
> + return 0;
> +}
> +
> +static inline void init_trace_eprobe_call(struct trace_eprobe *ep)
> +{
> + struct trace_event_call *call = trace_probe_event_call(&ep->tp);
> +
> + call->flags = TRACE_EVENT_FL_EPROBE;
> + call->event.funcs = &eprobe_funcs;
> + call->class->fields_array = eprobe_fields_array;
> + call->class->reg = eprobe_register;
> +}
> +
> +static struct trace_event_call *
> +find_and_get_event(const char *system, const char *event_name)
> +{
> + struct trace_event_call *tp_event;
> + const char *name;
> +
> + list_for_each_entry(tp_event, &ftrace_events, list) {
> + /* Skip other probes and ftrace events */
> + if (tp_event->flags &
> + (TRACE_EVENT_FL_IGNORE_ENABLE |
> + TRACE_EVENT_FL_KPROBE |
> + TRACE_EVENT_FL_UPROBE |
> + TRACE_EVENT_FL_EPROBE))
> + continue;
> + if (!tp_event->class->system ||
> + strcmp(system, tp_event->class->system))
> + continue;
> + name = trace_event_name(tp_event);
> + if (!name || strcmp(event_name, name))
> + continue;
> + if (!trace_event_try_get_ref(tp_event)) {
> + return NULL;
> + break;
> + }
> + return tp_event;
> + break;
> + }
> + return NULL;
> +}
> +
> +static int trace_eprobe_tp_update_arg(struct trace_eprobe *ep, const char *argv[], int i)
> +{
> + unsigned int flags = TPARG_FL_KERNEL | TPARG_FL_TPOINT;
> + int ret;
> +
> + ret = traceprobe_parse_probe_arg(&ep->tp, i, argv[i], flags);
> + if (ret)
> + return ret;
> +
> + if (ep->tp.args[i].code->op == FETCH_OP_TP_ARG)
> + ret = trace_eprobe_tp_arg_update(ep, i);
> +
> + return ret;
> +}
> +
> +static int __trace_eprobe_create(int argc, const char *argv[])
> +{
> + /*
> + * Argument syntax:
> + * e[:[GRP/]ENAME] SYSTEM.EVENT [FETCHARGS]
> + * Fetch args:
> + * <name>=$<field>[:TYPE]
> + */
> + const char *event = NULL, *group = EPROBE_EVENT_SYSTEM;
> + const char *sys_event = NULL, *sys_name = NULL;
> + struct trace_event_call *event_call;
> + struct trace_eprobe *ep = NULL;
> + char buf1[MAX_EVENT_NAME_LEN];
> + char buf2[MAX_EVENT_NAME_LEN];
> + int ret = 0;
> + int i;
> +
> + if (argc < 2 || argv[0][0] != 'e')
> + return -ECANCELED;
> +
> + trace_probe_log_init("event_probe", argc, argv);
> +
> + event = strchr(&argv[0][1], ':');
> + if (event) {
> + event++;
> + ret = traceprobe_parse_event_name(&event, &group, buf1,
> + event - argv[0]);
> + if (ret)
> + goto parse_error;
> + } else {
> + strscpy(buf1, argv[1], MAX_EVENT_NAME_LEN);
> + sanitize_event_name(buf1);
> + event = buf1;
> + }
> + if (!is_good_name(event) || !is_good_name(group))
> + goto parse_error;
> +
> + sys_event = argv[1];
> + ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2,
> + sys_event - argv[1]);
> + if (ret || !sys_name)
> + goto parse_error;
> + if (!is_good_name(sys_event) || !is_good_name(sys_name))
> + goto parse_error;
> +
> + mutex_lock(&event_mutex);
> + event_call = find_and_get_event(sys_name, sys_event);
> + ep = alloc_event_probe(group, event, event_call, argc - 2);
> + mutex_unlock(&event_mutex);
> +
> + if (IS_ERR(ep)) {
> + ret = PTR_ERR(ep);
> + /* This must return -ENOMEM, else there is a bug */
> + WARN_ON_ONCE(ret != -ENOMEM);
> + goto error; /* We know ep is not allocated */
> + }
> +
> + argc -= 2; argv += 2;
> + /* parse arguments */
> + for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
> + trace_probe_log_set_index(i + 2);
> + ret = trace_eprobe_tp_update_arg(ep, argv, i);
> + if (ret)
> + goto error;
> + }
> + ret = traceprobe_set_print_fmt(&ep->tp, PROBE_PRINT_EVENT);
> + if (ret < 0)
> + goto error;
> + init_trace_eprobe_call(ep);
> + mutex_lock(&event_mutex);
> + ret = trace_probe_register_event_call(&ep->tp);
> + if (ret) {
> + if (ret == -EEXIST) {
> + trace_probe_log_set_index(0);
> + trace_probe_log_err(0, EVENT_EXIST);
> + }
> + mutex_unlock(&event_mutex);
> + goto error;
> + }
> + ret = dyn_event_add(&ep->devent, &ep->tp.event->call);
> + mutex_unlock(&event_mutex);
> + return ret;
> +parse_error:
> + ret = -EINVAL;
> +error:
> + trace_event_probe_cleanup(ep);
> + return ret;
> +}
> +
> +/*
> + * Register dynevent at core_initcall. This allows kernel to setup eprobe
> + * events in postcore_initcall without tracefs.
> + */
> +static __init int trace_events_eprobe_init_early(void)
> +{
> + int err = 0;
> +
> + err = dyn_event_register(&eprobe_dyn_event_ops);
> + if (err)
> + pr_warn("Could not register eprobe_dyn_event_ops\n");
> +
> + return err;
> +}
> +core_initcall(trace_events_eprobe_init_early);
> diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
> index 6b11e335a62e..3d5c07239a2a 100644
> --- a/kernel/trace/trace_events_trigger.c
> +++ b/kernel/trace/trace_events_trigger.c
> @@ -124,6 +124,18 @@ static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
> return seq_list_next(t, &event_file->triggers, pos);
> }
>
> +static bool check_user_trigger(struct trace_event_file *file)
> +{
> + struct event_trigger_data *data;
> +
> + list_for_each_entry_rcu(data, &file->triggers, list) {
> + if (data->flags & EVENT_TRIGGER_FL_PROBE)
> + continue;
> + return true;
> + }
> + return false;
> +}
> +
> static void *trigger_start(struct seq_file *m, loff_t *pos)
> {
> struct trace_event_file *event_file;
> @@ -134,7 +146,7 @@ static void *trigger_start(struct seq_file *m, loff_t *pos)
> if (unlikely(!event_file))
> return ERR_PTR(-ENODEV);
>
> - if (list_empty(&event_file->triggers))
> + if (list_empty(&event_file->triggers) || !check_user_trigger(event_file))
> return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;
>
> return seq_list_start(&event_file->triggers, *pos);
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 882c27044029..3a64ba4bbad6 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -707,14 +707,6 @@ static struct notifier_block trace_kprobe_module_nb = {
> .priority = 1 /* Invoked after kprobe module callback */
> };
>
> -/* Convert certain expected symbols into '_' when generating event names */
> -static inline void sanitize_event_name(char *name)
> -{
> - while (*name++ != '\0')
> - if (*name == ':' || *name == '.')
> - *name = '_';
> -}
> -
> static int __trace_kprobe_create(int argc, const char *argv[])
> {
> /*
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index 782c00eb6859..3ed2a3f37297 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -319,6 +319,13 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
> code->op = FETCH_OP_ARG;
> code->param = (unsigned int)param - 1;
> #endif
> + } else if (flags & TPARG_FL_TPOINT) {
> + if (code->data)
> + return -EFAULT;
> + code->data = kstrdup(arg, GFP_KERNEL);
> + if (!code->data)
> + return -ENOMEM;
> + code->op = FETCH_OP_TP_ARG;
> } else
> goto inval_var;
>
> @@ -646,13 +653,14 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
> !strcmp(parg->type->name, "ustring")) {
> if (code->op != FETCH_OP_DEREF && code->op != FETCH_OP_UDEREF &&
> code->op != FETCH_OP_IMM && code->op != FETCH_OP_COMM &&
> - code->op != FETCH_OP_DATA) {
> + code->op != FETCH_OP_DATA && code->op != FETCH_OP_TP_ARG) {
> trace_probe_log_err(offset + (t ? (t - arg) : 0),
> BAD_STRING);
> goto fail;
> }
> if ((code->op == FETCH_OP_IMM || code->op == FETCH_OP_COMM ||
> - code->op == FETCH_OP_DATA) || parg->count) {
> + code->op == FETCH_OP_DATA) || code->op == FETCH_OP_TP_ARG ||
> + parg->count) {
> /*
> * IMM, DATA and COMM is pointing actual address, those
> * must be kept, and if parg->count != 0, this is an
> @@ -867,6 +875,10 @@ static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
> fmt = "(%lx <- %lx)";
> arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
> break;
> + case PROBE_PRINT_EVENT:
> + fmt = "(%u)";
> + arg = "REC->" FIELD_STRING_TYPE;
> + break;
> default:
> WARN_ON_ONCE(1);
> return 0;
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 66701a92d186..99e7a5df025e 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -38,6 +38,7 @@
> #define FIELD_STRING_IP "__probe_ip"
> #define FIELD_STRING_RETIP "__probe_ret_ip"
> #define FIELD_STRING_FUNC "__probe_func"
> +#define FIELD_STRING_TYPE "__probe_type"
>
> #undef DEFINE_FIELD
> #define DEFINE_FIELD(type, item, name, is_signed) \
> @@ -102,6 +103,7 @@ enum fetch_op {
> FETCH_OP_MOD_BF, /* Bitfield: .basesize, .lshift, .rshift */
> // Stage 5 (loop) op
> FETCH_OP_LP_ARRAY, /* Array: .param = loop count */
> + FETCH_OP_TP_ARG, /* Trace Point argument */
> FETCH_OP_END,
> FETCH_NOP_SYMBOL, /* Unresolved Symbol holder */
> };
> @@ -351,7 +353,8 @@ int trace_probe_create(const char *raw_command, int (*createfn)(int, const char
> #define TPARG_FL_RETURN BIT(0)
> #define TPARG_FL_KERNEL BIT(1)
> #define TPARG_FL_FENTRY BIT(2)
> -#define TPARG_FL_MASK GENMASK(2, 0)
> +#define TPARG_FL_TPOINT BIT(3)
> +#define TPARG_FL_MASK GENMASK(3, 0)
>
> extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i,
> const char *argv, unsigned int flags);
> @@ -366,6 +369,7 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
> enum probe_print_type {
> PROBE_PRINT_NORMAL,
> PROBE_PRINT_RETURN,
> + PROBE_PRINT_EVENT,
> };
>
> extern int traceprobe_set_print_fmt(struct trace_probe *tp, enum probe_print_type ptype);
> --
> 2.30.2
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>