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Commit 19007a67 authored by Frederic Weisbecker's avatar Frederic Weisbecker
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tracing: Support for syscall events raw records in perfcounters 



This bring the support for raw syscall events in perfcounters.
The arguments or exit value are saved as a raw sample using
the PERF_SAMPLE_RAW attribute in a perf counter.

Example (for now you must explicitly set the PERF_SAMPLE_RAW flag
in perf record):

perf record -e syscalls:sys_enter_open -f -F 1 -a
perf report -D

	0x2cbb8 [0x50]: event: 9
	.
	. ... raw event: size 80 bytes
	.  0000:  09 00 00 00 02 00 50 00 20 e9 39 ab 0a 7f 00 00  ......P. .9....
	.  0010:  bc 14 00 00 bc 14 00 00 01 00 00 00 00 00 00 00  ...............
	.  0020:  2c 00 00 00 15 01 01 00 bc 14 00 00 bc 14 00 00  ,..............
                  ^  ^  ^  ^  ^  ^  ^  ..........................
                  Event Size  struct trace_entry

	.  0030:  00 00 00 00 46 98 43 02 00 00 00 00 80 08 00 00  ....F.C........
                  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^
                  ptr to file name        open flags

	.  0040:  00 00 00 00 02 00 00 00 00 00 00 00 00 00 00 00  ...............
                  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^  ^
	.         open mode               padding

	0x2cbb8 [0x50]: PERF_EVENT_SAMPLE (IP, 2): 5308: 0x7f0aab39e920 period: 1

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
parent dc4ddb4c

kernel/trace/trace_syscalls.c

+37 −2
Original line number Diff line number Diff line
@@ -301,6 +301,17 @@ struct trace_event event_syscall_exit = { 
};



#ifdef CONFIG_EVENT_PROFILE



struct syscall_enter_record {

	struct trace_entry	entry;

	unsigned long		args[0];

};



struct syscall_exit_record {

	struct trace_entry	entry;

	unsigned long		ret;

};



static DECLARE_BITMAP(enabled_prof_enter_syscalls, FTRACE_SYSCALL_MAX);

static DECLARE_BITMAP(enabled_prof_exit_syscalls, FTRACE_SYSCALL_MAX);

static int sys_prof_refcount_enter;
@@ -308,8 +319,10 @@ static int sys_prof_refcount_exit; 


static void prof_syscall_enter(struct pt_regs *regs, long id)

{

	struct syscall_enter_record *rec;

	struct syscall_metadata *sys_data;

	int syscall_nr;

	int size;



	syscall_nr = syscall_get_nr(current, regs);

	if (!test_bit(syscall_nr, enabled_prof_enter_syscalls))
@@ -319,7 +332,24 @@ static void prof_syscall_enter(struct pt_regs *regs, long id) 
	if (!sys_data)

		return;



	perf_tpcounter_event(sys_data->enter_id, 0, 1, NULL, 0);

	/* get the size after alignment with the u32 buffer size field */

	size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);

	size = ALIGN(size + sizeof(u32), sizeof(u64));

	size -= sizeof(u32);



	do {

		char raw_data[size];



		/* zero the dead bytes from align to not leak stack to user */

		*(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;



		rec = (struct syscall_enter_record *) raw_data;

		tracing_generic_entry_update(&rec->entry, 0, 0);

		rec->entry.type = sys_data->enter_id;

		syscall_get_arguments(current, regs, 0, sys_data->nb_args,

				       (unsigned long *)&rec->args);

		perf_tpcounter_event(sys_data->enter_id, 0, 1, rec, size);

	} while(0);

}



int reg_prof_syscall_enter(char *name)
@@ -364,6 +394,7 @@ void unreg_prof_syscall_enter(char *name) 
static void prof_syscall_exit(struct pt_regs *regs, long ret)

{

	struct syscall_metadata *sys_data;

	struct syscall_exit_record rec;

	int syscall_nr;



	syscall_nr = syscall_get_nr(current, regs);
@@ -374,7 +405,11 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret) 
	if (!sys_data)

		return;



	perf_tpcounter_event(sys_data->exit_id, 0, 1, NULL, 0);

	tracing_generic_entry_update(&rec.entry, 0, 0);

	rec.entry.type = sys_data->exit_id;

	rec.ret = syscall_get_return_value(current, regs);



	perf_tpcounter_event(sys_data->exit_id, 0, 1, &rec, sizeof(rec));

}



int reg_prof_syscall_exit(char *name)