Fix a couple of issues with the stack limit for 32-bit processes on 64-bit

kernels exposed by the recent fixes to resource limits for 32-bit processes
on 64-bit kernels:
- Let ABIs expose their maximum stack size via a new pointer in sysentvec
  and use that in preference to maxssiz during exec() rather than always
  using maxssiz for all processses.
- Apply the ABI's limit fixup to the previous stack size when adjusting
  RLIMIT_STACK to determine if the existing mapping for the stack needs to
  be grown or shrunk (as well as how much it should be grown or shrunk).

Approved by:	re (kensmith)

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/sys/sysent.h b/sys/sys/sysent.h
index ba8fc4b..e0ea4b0 100644
--- a/sys/sys/sysent.h
+++ b/sys/sys/sysent.h
@@ -99,6 +99,7 @@ struct sysentvec {
 	register_t	*(*sv_copyout_strings)(struct image_params *);
 	void		(*sv_setregs)(struct thread *, u_long, u_long, u_long);
 	void		(*sv_fixlimit)(struct rlimit *, int);
+	u_long		*sv_maxssiz;
 };
 
 #ifdef _KERNEL