forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
100 lines
2.2 KiB
100 lines
2.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
/* |
|
* nop tracer |
|
* |
|
* Copyright (C) 2008 Steven Noonan <[email protected]> |
|
* |
|
*/ |
|
|
|
#include <linux/module.h> |
|
#include <linux/ftrace.h> |
|
|
|
#include "trace.h" |
|
|
|
/* Our two options */ |
|
enum { |
|
TRACE_NOP_OPT_ACCEPT = 0x1, |
|
TRACE_NOP_OPT_REFUSE = 0x2 |
|
}; |
|
|
|
/* Options for the tracer (see trace_options file) */ |
|
static struct tracer_opt nop_opts[] = { |
|
/* Option that will be accepted by set_flag callback */ |
|
{ TRACER_OPT(test_nop_accept, TRACE_NOP_OPT_ACCEPT) }, |
|
/* Option that will be refused by set_flag callback */ |
|
{ TRACER_OPT(test_nop_refuse, TRACE_NOP_OPT_REFUSE) }, |
|
{ } /* Always set a last empty entry */ |
|
}; |
|
|
|
static struct tracer_flags nop_flags = { |
|
/* You can check your flags value here when you want. */ |
|
.val = 0, /* By default: all flags disabled */ |
|
.opts = nop_opts |
|
}; |
|
|
|
static struct trace_array *ctx_trace; |
|
|
|
static void start_nop_trace(struct trace_array *tr) |
|
{ |
|
/* Nothing to do! */ |
|
} |
|
|
|
static void stop_nop_trace(struct trace_array *tr) |
|
{ |
|
/* Nothing to do! */ |
|
} |
|
|
|
static int nop_trace_init(struct trace_array *tr) |
|
{ |
|
ctx_trace = tr; |
|
start_nop_trace(tr); |
|
return 0; |
|
} |
|
|
|
static void nop_trace_reset(struct trace_array *tr) |
|
{ |
|
stop_nop_trace(tr); |
|
} |
|
|
|
/* It only serves as a signal handler and a callback to |
|
* accept or refuse the setting of a flag. |
|
* If you don't implement it, then the flag setting will be |
|
* automatically accepted. |
|
*/ |
|
static int nop_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) |
|
{ |
|
/* |
|
* Note that you don't need to update nop_flags.val yourself. |
|
* The tracing Api will do it automatically if you return 0 |
|
*/ |
|
if (bit == TRACE_NOP_OPT_ACCEPT) { |
|
printk(KERN_DEBUG "nop_test_accept flag set to %d: we accept." |
|
" Now cat trace_options to see the result\n", |
|
set); |
|
return 0; |
|
} |
|
|
|
if (bit == TRACE_NOP_OPT_REFUSE) { |
|
printk(KERN_DEBUG "nop_test_refuse flag set to %d: we refuse." |
|
" Now cat trace_options to see the result\n", |
|
set); |
|
return -EINVAL; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
|
|
struct tracer nop_trace __read_mostly = |
|
{ |
|
.name = "nop", |
|
.init = nop_trace_init, |
|
.reset = nop_trace_reset, |
|
#ifdef CONFIG_FTRACE_SELFTEST |
|
.selftest = trace_selftest_startup_nop, |
|
#endif |
|
.flags = &nop_flags, |
|
.set_flag = nop_set_flag, |
|
.allow_instances = true, |
|
}; |
|
|
|
|