On 01/17, Masami Hiramatsu wrote:

On Tue, 14 Jan 2025 15:21:29 +0100
Jiri Olsa [off-list ref] wrote:

quoted

On Tue, Jan 14, 2025 at 12:21:07PM +0100, Oleg Nesterov wrote:

quoted

But please not that the uretprobed function can return any value
including -ENOSYS, and this is what sys_uretprobe() has to return.

right, uretprobe syscall returns value of the uretprobed function,
so we can't use any reserved value

We can make uretprobe (entry) fail if the return value is one of
errno or NULL, because it *knows* what the return value here.

I fail to understand... Could you spell please?

But whatever you meant, I don't think it is right, sorry.. please
correct me.

"it *knows*". Who it? How can it know??? I'd say "it" can't know,
but probably I missed your point.

Not to mention it doesn't really matter. It is not safe to even try
to do

	movq $__NR_uretprobe, %rax
	syscall

if the probed task has seccomp filters.

Oleg.