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uprobes/perf: Teach trace_uprobe/perf code to use UPROBE_HANDLER_REMOVE 

Change uprobe_trace_func() and uprobe_perf_func() to return "int". Change
uprobe_dispatcher() to return "trace_ret | perf_ret" although this is not
needed, currently TP_FLAG_TRACE/TP_FLAG_PROFILE are mutually exclusive.

The only functional change is that uprobe_perf_func() checks the filtering
too and returns UPROBE_HANDLER_REMOVE if nobody wants to trace current.

Testing:

	# perf probe -x /lib/libc.so.6 syscall

	# perf record -e probe_libc:syscall -i perl -e 'fork; syscall -1 for 1..10; wait'

	# perf report --show-total-period
		100.00%            10     perl  libc-2.8.so    [.] syscall

Before this patch:

	# cat /sys/kernel/debug/tracing/uprobe_profile
		/lib/libc.so.6 syscall				20

A child process doesn't have a counter, but still it hits this breakoint
"copied" by dup_mmap().

After the patch:

	# cat /sys/kernel/debug/tracing/uprobe_profile
		/lib/libc.so.6 syscall				11

The child process hits this int3 only once and does unapply_uprobe().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
This commit is contained in:
Oleg Nesterov 2013-02-04 17:48:34 +01:00
parent 31ba334836
commit f42d24a1d2
1 changed files with 14 additions and 7 deletions
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21
kernel/trace/trace_uprobe.c
View File

@ -486,7 +486,7 @@ static const struct file_operations uprobe_profile_ops = {
};
/* uprobe handler */
static void uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
{
struct uprobe_trace_entry_head *entry;
struct ring_buffer_event *event;
@ -504,7 +504,7 @@ static void uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
size, irq_flags, pc);
if (!event)
return;
return 0;
entry = ring_buffer_event_data(event);
entry->ip = instruction_pointer(task_pt_regs(current));
@ -514,6 +514,8 @@ static void uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
if (!filter_current_check_discard(buffer, call, entry, event))
trace_buffer_unlock_commit(buffer, event, irq_flags, pc);
return 0;
}
/* Event entry printers */
@ -721,7 +723,7 @@ static bool uprobe_perf_filter(struct uprobe_consumer *uc,
}
/* uprobe profile handler */
static void uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
{
struct ftrace_event_call *call = &tu->call;
struct uprobe_trace_entry_head *entry;
@ -730,11 +732,14 @@ static void uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
int size, __size, i;
int rctx;
if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
return UPROBE_HANDLER_REMOVE;
__size = sizeof(*entry) + tu->size;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
return;
return 0;
preempt_disable();
@ -752,6 +757,7 @@ static void uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
out:
preempt_enable();
return 0;
}
#endif /* CONFIG_PERF_EVENTS */
@ -792,18 +798,19 @@ int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type,
static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
{
struct trace_uprobe *tu;
int ret = 0;
tu = container_of(con, struct trace_uprobe, consumer);
tu->nhit++;
if (tu->flags & TP_FLAG_TRACE)
uprobe_trace_func(tu, regs);
ret |= uprobe_trace_func(tu, regs);
#ifdef CONFIG_PERF_EVENTS
if (tu->flags & TP_FLAG_PROFILE)
uprobe_perf_func(tu, regs);
ret |= uprobe_perf_func(tu, regs);
#endif
return 0;
return ret;
}
static struct trace_event_functions uprobe_funcs = {