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tracing/function: Introduce persistent trace option

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This patch introduces 'func_ptrace' option, now available in
/sys/kernel/debug/tracing/options when function tracer
is selected.

The patch also adds some tiny code that calls back to pstore
to record the trace. The callback is no-op when PSTORE=n.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Anton Vorontsov 2012-07-09 17:10:42 -07:00 committed by Greg Kroah-Hartman
parent 060287b8c4
commit 21f679404a
1 changed files with 20 additions and 5 deletions
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25
kernel/trace/trace_functions.c
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@ -13,6 +13,7 @@
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/pstore.h>
#include <linux/fs.h>
#include "trace.h"
@ -74,6 +75,14 @@ function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
preempt_enable_notrace();
}
/* Our two options */
enum {
TRACE_FUNC_OPT_STACK = 0x1,
TRACE_FUNC_OPT_PSTORE = 0x2,
};
static struct tracer_flags func_flags;
static void
function_trace_call(unsigned long ip, unsigned long parent_ip)
{
@ -97,6 +106,12 @@ function_trace_call(unsigned long ip, unsigned long parent_ip)
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1)) {
/*
* So far tracing doesn't support multiple buffers, so
* we make an explicit call for now.
*/
if (unlikely(func_flags.val & TRACE_FUNC_OPT_PSTORE))
pstore_ftrace_call(ip, parent_ip);
pc = preempt_count();
trace_function(tr, ip, parent_ip, flags, pc);
}
@ -158,14 +173,12 @@ static struct ftrace_ops trace_stack_ops __read_mostly =
.flags = FTRACE_OPS_FL_GLOBAL,
};
/* Our two options */
enum {
TRACE_FUNC_OPT_STACK = 0x1,
};
static struct tracer_opt func_opts[] = {
#ifdef CONFIG_STACKTRACE
{ TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
#endif
#ifdef CONFIG_PSTORE_FTRACE
{ TRACER_OPT(func_pstore, TRACE_FUNC_OPT_PSTORE) },
#endif
{ } /* Always set a last empty entry */
};
@ -217,6 +230,8 @@ static int func_set_flag(u32 old_flags, u32 bit, int set)
register_ftrace_function(&trace_ops);
}
return 0;
} else if (bit == TRACE_FUNC_OPT_PSTORE) {
return 0;
}