* Oleg Nesterov <o...@redhat.com> [2013-04-01 18:08:51]:
> Change uprobe_trace_print() and uprobe_perf_print() to check
> is_ret_probe() and fill ring_buffer_event accordingly.
>
> Also change uprobe_trace_func() and uprobe_perf_func() to not
> _print() if is_ret_probe() is true. Note that we keep ->handler()
> nontrivial even for uretprobe, we need this for filtering and for
> other potential extensions.
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
> ---
> kernel/trace/trace_uprobe.c | 42 +++++++++++++++++++++++++++++++++---------
> 1 files changed, 33 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index e91a354..db2718a 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -515,15 +515,26 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
> int size, i;
> struct ftrace_event_call *call = &tu->call;
>
> - size = SIZEOF_TRACE_ENTRY(1) + tu->size;
> + if (is_ret_probe(tu))
One nit:
Here and couple of places below .. we could check for func instead of
is_ret_probe() right?
Or is there an advantage of checking is_ret_probe() over func?
> + size = SIZEOF_TRACE_ENTRY(2);
> + else
> + size = SIZEOF_TRACE_ENTRY(1);
> +
> event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
> - size, 0, 0);
> + size + tu->size, 0, 0);
> if (!event)
> return;
>
> entry = ring_buffer_event_data(event);
> - entry->vaddr[0] = instruction_pointer(regs);
> - data = DATAOF_TRACE_ENTRY(entry, 1);
> + if (is_ret_probe(tu)) {
> + entry->vaddr[0] = func;
> + entry->vaddr[1] = instruction_pointer(regs);
> + data = DATAOF_TRACE_ENTRY(entry, 2);
> + } else {
> + entry->vaddr[0] = instruction_pointer(regs);
> + data = DATAOF_TRACE_ENTRY(entry, 1);
> + }
> +
> for (i = 0; i < tu->nr_args; i++)
> call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
>
> @@ -534,7 +545,8 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
> /* uprobe handler */
> static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
> {
> - uprobe_trace_print(tu, 0, regs);
> + if (!is_ret_probe(tu))
> + uprobe_trace_print(tu, 0, regs);
Should this hunk be in the previous patch?
Also something for the future:
Most times a user uses a return probe, the user probably wants to probe
the function entry too. So should we extend the abi from p+r to
p+r+..<something else> to mean it traces both function entry and return.
Esp given that uretprobe has been elegantly been designed to make this a
possibility.
> return 0;
> }
>
> @@ -783,7 +795,11 @@ static void uprobe_perf_print(struct trace_uprobe *tu,
> void *data;
> int size, rctx, i;
>
> - size = SIZEOF_TRACE_ENTRY(1);
> + if (is_ret_probe(tu))
> + size = SIZEOF_TRACE_ENTRY(2);
> + else
> + size = SIZEOF_TRACE_ENTRY(1);
> +
> size = ALIGN(size + tu->size + sizeof(u32), sizeof(u64)) - sizeof(u32);
> if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large
> enough"))
> return;
> @@ -794,8 +810,15 @@ static void uprobe_perf_print(struct trace_uprobe *tu,
> goto out;
>
> ip = instruction_pointer(regs);
> - entry->vaddr[0] = ip;
> - data = DATAOF_TRACE_ENTRY(entry, 1);
> + if (is_ret_probe(tu)) {
> + entry->vaddr[0] = func;
> + entry->vaddr[1] = ip;
> + data = DATAOF_TRACE_ENTRY(entry, 2);
> + } else {
> + entry->vaddr[0] = ip;
> + data = DATAOF_TRACE_ENTRY(entry, 1);
> + }
> +
> for (i = 0; i < tu->nr_args; i++)
> call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
>
> @@ -811,7 +834,8 @@ static int uprobe_perf_func(struct trace_uprobe *tu,
> struct pt_regs *regs)
> if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
> return UPROBE_HANDLER_REMOVE;
>
> - uprobe_perf_print(tu, 0, regs);
> + if (!is_ret_probe(tu))
> + uprobe_perf_print(tu, 0, regs);
> return 0;
> }
>
> --
> 1.5.5.1
>
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