[PATCH v4 1/2] ptrace: save the type of syscall-stop in ptrace_message
Oleg Nesterov
oleg at redhat.com
Thu Nov 29 15:03:28 UTC 2018
On 11/28, Andy Lutomirski wrote:
>
> I don't like any of this at all. Can we please choose a sensible API
> design and let the API drive the implementation instead of vice versa?
I too do not understand your concerns...
> ISTM the correct solution is to add some new state to task_struct for
> this.
Sure we can do this. I have argued with the previous version not because
the new member blows the task_struct. Although I think it is better to avoid
this if possible.
But this doesn't affect the API.
Yes, this version uses ->ptrace_message but I think this is _good_ exactly
because it is already visible to userspace, so if debugger only needs to
distinguish syscall entry/exit it can simply use PTRACE_GETEVENTMSG without
PTRACE_GET_SYSCALL_INFO.
> If we're concerned about making task_struct bigger, I have a
> half-finished patch to factor all the ptrace tracee state into a
> separate struct.
I even sent the patch(es) which does this several years ago ;)
Oleg.
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