Re: [PATCH 0/2] Support compiling out the prctl syscall

On Wed, Nov 09, 2016 at 01:26:53AM +0100, Arnd Bergmann wrote:

On Tuesday, November 8, 2016 4:17:47 PM CET Josh Triplett wrote:

quoted

Some embedded systems can do without the prctl syscall, saving some space.

This also avoids regular increases in tinyconfig size as people add more
non-optional functionality to prctl (observed via the 0-day kernel
infrastructure).

The first patch moves prctl and all its helpers into a separate source file,
kernel/prctl.c, to allow making it optional via the Makefile without any
ifdefs.  The second patch adds the Kconfig option to make prctl optional.

Josh Triplett (2):
  kernel: Move prctl and helpers from kernel/sys.c to new kernel/prctl.c
  kernel: Support compiling out the prctl syscall

Both of these look really nice to me. Another syscall that comes to
mind as a candidate to be made optional is ptrace, and I've added
Nicolas Pitre to Cc here, as he has looked into this before.

I've looked at that as well; it's a rather more complex patch, as
several other bits of the kernel hook into ptrace or otherwise depend on
ptrace.  (And ptrace_may_access will need to stick around even when
ptrace doesn't.)

- Josh Triplett