Commit 970988e1 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)

tracing/kprobe: Add kprobe_event= boot parameter

Add kprobe_event= boot parameter to define kprobe events
at boot time.
The definition syntax is similar to tracefs/kprobe_events
interface, but use ',' and ';' instead of ' ' and '\n'
respectively. e.g.

  kprobe_event=p,vfs_read,$arg1,$arg2

This puts a probe on vfs_read with argument1 and 2, and
enable the new event.

Link: http://lkml.kernel.org/r/155851395498.15728.830529496248543583.stgit@devnote2Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent b5f8b32c
......@@ -2007,6 +2007,19 @@
Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
the default is off.
kprobe_event=[probe-list]
[FTRACE] Add kprobe events and enable at boot time.
The probe-list is a semicolon delimited list of probe
definitions. Each definition is same as kprobe_events
interface, but the parameters are comma delimited.
For example, to add a kprobe event on vfs_read with
arg1 and arg2, add to the command line;
kprobe_event=p,vfs_read,$arg1,$arg2
See also Documentation/trace/kprobetrace.rst "Kernel
Boot Parameter" section.
kpti= [ARM64] Control page table isolation of user
and kernel address spaces.
Default: enabled on cores which need mitigation.
......
......@@ -146,6 +146,20 @@ You can check the total number of probe hits and probe miss-hits via
The first column is event name, the second is the number of probe hits,
the third is the number of probe miss-hits.
Kernel Boot Parameter
---------------------
You can add and enable new kprobe events when booting up the kernel by
"kprobe_event=" parameter. The parameter accepts a semicolon-delimited
kprobe events, which format is similar to the kprobe_events.
The difference is that the probe definition parameters are comma-delimited
instead of space. For example, adding myprobe event on do_sys_open like below
p:myprobe do_sys_open dfd=%ax filename=%dx flags=%cx mode=+4($stack)
should be below for kernel boot parameter (just replace spaces with comma)
p:myprobe,do_sys_open,dfd=%ax,filename=%dx,flags=%cx,mode=+4($stack)
Usage examples
--------------
......
......@@ -12,6 +12,8 @@
#include <linux/rculist.h>
#include <linux/error-injection.h>
#include <asm/setup.h> /* for COMMAND_LINE_SIZE */
#include "trace_dynevent.h"
#include "trace_kprobe_selftest.h"
#include "trace_probe.h"
......@@ -19,6 +21,17 @@
#define KPROBE_EVENT_SYSTEM "kprobes"
#define KRETPROBE_MAXACTIVE_MAX 4096
#define MAX_KPROBE_CMDLINE_SIZE 1024
/* Kprobe early definition from command line */
static char kprobe_boot_events_buf[COMMAND_LINE_SIZE] __initdata;
static int __init set_kprobe_boot_events(char *str)
{
strlcpy(kprobe_boot_events_buf, str, COMMAND_LINE_SIZE);
return 0;
}
__setup("kprobe_event=", set_kprobe_boot_events);
static int trace_kprobe_create(int argc, const char **argv);
static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev);
......@@ -1494,6 +1507,44 @@ void destroy_local_trace_kprobe(struct trace_event_call *event_call)
}
#endif /* CONFIG_PERF_EVENTS */
static __init void enable_boot_kprobe_events(void)
{
struct trace_array *tr = top_trace_array();
struct trace_event_file *file;
struct trace_kprobe *tk;
struct dyn_event *pos;
mutex_lock(&event_mutex);
for_each_trace_kprobe(tk, pos) {
list_for_each_entry(file, &tr->events, list)
if (file->event_call == &tk->tp.call)
trace_event_enable_disable(file, 1, 0);
}
mutex_unlock(&event_mutex);
}
static __init void setup_boot_kprobe_events(void)
{
char *p, *cmd = kprobe_boot_events_buf;
int ret;
strreplace(kprobe_boot_events_buf, ',', ' ');
while (cmd && *cmd != '\0') {
p = strchr(cmd, ';');
if (p)
*p++ = '\0';
ret = trace_run_command(cmd, create_or_delete_trace_kprobe);
if (ret)
pr_warn("Failed to add event(%d): %s\n", ret, cmd);
cmd = p;
}
enable_boot_kprobe_events();
}
/* Make a tracefs interface for controlling probe points */
static __init int init_kprobe_trace(void)
{
......@@ -1525,6 +1576,9 @@ static __init int init_kprobe_trace(void)
if (!entry)
pr_warn("Could not create tracefs 'kprobe_profile' entry\n");
setup_boot_kprobe_events();
return 0;
}
fs_initcall(init_kprobe_trace);
......
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