Re: Request for implementation of KERN_PROC_SIGTRAMP sysctl

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

On Fri, Oct 15, 2021 at 23:14:39 +0300, Valery Ushakov wrote:

> On Fri, Oct 15, 2021 at 14:44:16 -0500, John Marino (NetBSD) wrote:
> 
> > Is it possible for NetBSD to implement KERN_PROC_SIGTRAMP sysctl?
> 
> It's been ages since I touched this area, but don't we have
> per-sigaction trampolines?  I mean, in practice they all use the same
> __sigtramp_siginfo_$version trampoline, that sigaction passes to the
> actual syscall, but in principle the process can have different
> trampolines for different signals, can't it?
> 
> struct sys___sigaction_sigtramp_args {
> 	syscallarg(int) signum;
> 	syscallarg(const struct sigaction *) nsa;
> 	syscallarg(struct sigaction *) osa;
> 	syscallarg(const void *) tramp; // <-
> 	syscallarg(int) vers;
> };

PS: We used to have a trampoline that the kernel copied out into the
process address space (bottom of the stack, iirc) - and that would be
something for KERN_PROC_SIGTRAMP to return indeed.  But that was like
before netbsd 2.0, iirc.

-uwe