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tracing: add trace_bprintk()

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Impact: add a generic printk() for tracing, like trace_printk()

trace_bprintk() uses the infrastructure to record events on ring_buffer.

[ fweisbec@gmail.com: ported to latest -tip, made it work if
  !CONFIG_MODULES, never free the format strings from modules
  because we can't keep track of them and conditionnaly create
  the ftrace format strings section (reported by Steven Rostedt) ]

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Lai Jiangshan 2009-03-06 17:21:48 +01:00 committed by Ingo Molnar
parent 1427cdf059
commit 1ba28e02a1
6 changed files with 133 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/asm-generic/vmlinux.lds.h
View File

@ -69,6 +69,14 @@
#define FTRACE_EVENTS()
#endif
#ifdef CONFIG_TRACING
#define TRACE_PRINTKS() VMLINUX_SYMBOL(__start___trace_bprintk_fmt) = .; \
*(__trace_printk_fmt) /* Trace_printk fmt' pointer */ \
VMLINUX_SYMBOL(__stop___trace_bprintk_fmt) = .;
#else
#define TRACE_PRINTKS()
#endif
/* .data section */
#define DATA_DATA \
*(.data) \
@ -100,6 +108,7 @@
*(__vermagic) /* Kernel version magic */ \
*(__markers_strings) /* Markers: strings */ \
*(__tracepoints_strings)/* Tracepoints: strings */ \
TRACE_PRINTKS() \
} \
\
.rodata1 : AT(ADDR(.rodata1) - LOAD_OFFSET) { \

21
include/linux/ftrace.h
View File

@ -225,6 +225,27 @@ extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
#ifdef CONFIG_TRACE_BPRINTK
extern int trace_vbprintk(unsigned long ip, const char *fmt, va_list args);
extern int __trace_bprintk(unsigned long ip, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
static inline void ____trace_bprintk_check_format(const char *fmt, ...)
__attribute__ ((format (printf, 1, 2)));
static inline void ____trace_bprintk_check_format(const char *fmt, ...) {}
#define __trace_bprintk_check_format(fmt, args...) \
do { \
if (0) \
____trace_bprintk_check_format(fmt, ##args); \
} while (0)
#define trace_bprintk(fmt, args...) \
do { \
static char *__attribute__((section("__trace_bprintk_fmt"))) \
trace_bprintk_fmt = fmt; \
__trace_bprintk_check_format(fmt, ##args); \
__trace_bprintk(_THIS_IP_, trace_bprintk_fmt, ##args); \
} while (0)
#else
#define trace_bprintk trace_printk
#endif
/* May be defined in arch */

5
include/linux/module.h
View File

@ -329,6 +329,11 @@ struct module
unsigned int num_tracepoints;
#endif
#ifdef CONFIG_TRACE_BPRINTK
const char **trace_bprintk_fmt_start;
unsigned int num_trace_bprintk_fmt;
#endif
#ifdef CONFIG_MODULE_UNLOAD
/* What modules depend on me? */
struct list_head modules_which_use_me;

6
kernel/module.c
View File

@ -2158,6 +2158,12 @@ static noinline struct module *load_module(void __user *umod,
&mod->num_tracepoints);
#endif
#ifdef CONFIG_TRACE_BPRINTK
mod->trace_bprintk_fmt_start = section_objs(hdr, sechdrs, secstrings,
"__trace_bprintk_fmt", sizeof(char *),
&mod->num_trace_bprintk_fmt);
#endif
#ifdef CONFIG_MODVERSIONS
if ((mod->num_syms && !mod->crcs)
|| (mod->num_gpl_syms && !mod->gpl_crcs)

15
kernel/trace/trace.c
View File

@ -3848,6 +3848,21 @@ out:
}
EXPORT_SYMBOL_GPL(trace_vbprintk);
int __trace_bprintk(unsigned long ip, const char *fmt, ...)
{
int ret;
va_list ap;
if (!fmt)
return 0;
va_start(ap, fmt);
ret = trace_vbprintk(ip, fmt, ap);
va_end(ap);
return ret;
}
EXPORT_SYMBOL_GPL(__trace_bprintk);
static int trace_panic_handler(struct notifier_block *this,
unsigned long event, void *unused)
{

87
kernel/trace/trace_bprintk.c
View File

@ -19,9 +19,21 @@
#include "trace.h"
#ifdef CONFIG_MODULES
/* binary printk basic */
static DEFINE_MUTEX(btrace_mutex);
static int btrace_metadata_count;
/*
* modules trace_bprintk()'s formats are autosaved in struct trace_bprintk_fmt
* which are queued on trace_bprintk_fmt_list.
*/
static LIST_HEAD(trace_bprintk_fmt_list);
struct trace_bprintk_fmt {
struct list_head list;
char fmt[0];
};
static inline void lock_btrace(void)
{
@ -33,26 +45,75 @@ static inline void unlock_btrace(void)
mutex_unlock(&btrace_mutex);
}
static void get_btrace_metadata(void)
static inline struct trace_bprintk_fmt *lookup_format(const char *fmt)
{
struct trace_bprintk_fmt *pos;
list_for_each_entry(pos, &trace_bprintk_fmt_list, list) {
if (!strcmp(pos->fmt, fmt))
return pos;
}
return NULL;
}
static
void hold_module_trace_bprintk_format(const char **start, const char **end)
{
const char **iter;
lock_btrace();
btrace_metadata_count++;
for (iter = start; iter < end; iter++) {
struct trace_bprintk_fmt *tb_fmt = lookup_format(*iter);
if (tb_fmt) {
*iter = tb_fmt->fmt;
continue;
}
tb_fmt = kmalloc(offsetof(struct trace_bprintk_fmt, fmt)
+ strlen(*iter) + 1, GFP_KERNEL);
if (tb_fmt) {
list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list);
strcpy(tb_fmt->fmt, *iter);
*iter = tb_fmt->fmt;
} else
*iter = NULL;
}
unlock_btrace();
}
static void put_btrace_metadata(void)
static int module_trace_bprintk_format_notify(struct notifier_block *self,
unsigned long val, void *data)
{
lock_btrace();
btrace_metadata_count--;
unlock_btrace();
struct module *mod = data;
if (mod->num_trace_bprintk_fmt) {
const char **start = mod->trace_bprintk_fmt_start;
const char **end = start + mod->num_trace_bprintk_fmt;
if (val == MODULE_STATE_COMING)
hold_module_trace_bprintk_format(start, end);
}
return 0;
}
#else /* !CONFIG_MODULES */
__init static int
module_trace_bprintk_format_notify(struct notifier_block *self,
unsigned long val, void *data)
{
return 0;
}
#endif /* CONFIG_MODULES */
__initdata_or_module static
struct notifier_block module_trace_bprintk_format_nb = {
.notifier_call = module_trace_bprintk_format_notify,
};
/* events tracer */
int trace_bprintk_enable;
static void start_bprintk_trace(struct trace_array *tr)
{
get_btrace_metadata();
tracing_reset_online_cpus(tr);
trace_bprintk_enable = 1;
}
@ -61,7 +122,6 @@ static void stop_bprintk_trace(struct trace_array *tr)
{
trace_bprintk_enable = 0;
tracing_reset_online_cpus(tr);
put_btrace_metadata();
}
static int init_bprintk_trace(struct trace_array *tr)
@ -81,7 +141,14 @@ static struct tracer bprintk_trace __read_mostly =
static __init int init_bprintk(void)
{
return register_tracer(&bprintk_trace);
int ret = register_module_notifier(&module_trace_bprintk_format_nb);
if (ret)
return ret;
ret = register_tracer(&bprintk_trace);
if (ret)
unregister_module_notifier(&module_trace_bprintk_format_nb);
return ret;
}
device_initcall(init_bprintk);