svn commit: r354790 - in head/sys: sys vm

[Konstantin Belousov]

Author: kib
Date: Sun Nov 17 14:54:07 2019
New Revision: 354790
URL: https://svnweb.freebsd.org/changeset/base/354790

Log:
  Add elf image flag to disable stack gap.
  
  Reviewed by:	markj
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week
  Differential revision:	https://reviews.freebsd.org/D22379

Modified:
  head/sys/sys/elf_common.h
  head/sys/vm/vm_map.c

Modified: head/sys/sys/elf_common.h
==============================================================================
--- head/sys/sys/elf_common.h	Sun Nov 17 14:52:45 2019	(r354789)
+++ head/sys/sys/elf_common.h	Sun Nov 17 14:54:07 2019	(r354790)
@@ -784,6 +784,7 @@ typedef struct {
 /* NT_FREEBSD_FEATURE_CTL desc[0] bits */
 #define	NT_FREEBSD_FCTL_ASLR_DISABLE	0x00000001
 #define	NT_FREEBSD_FCTL_PROTMAX_DISABLE	0x00000002
+#define	NT_FREEBSD_FCTL_STKGAP_DISABLE	0x00000004
 
 /* Values for n_type.  Used in core files. */
 #define	NT_PRSTATUS	1	/* Process status. */

Modified: head/sys/vm/vm_map.c
==============================================================================
--- head/sys/vm/vm_map.c	Sun Nov 17 14:52:45 2019	(r354789)
+++ head/sys/vm/vm_map.c	Sun Nov 17 14:54:07 2019	(r354790)
@@ -69,6 +69,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/systm.h>
+#include <sys/elf.h>
 #include <sys/kernel.h>
 #include <sys/ktr.h>
 #include <sys/lock.h>
@@ -4136,7 +4137,8 @@ vm_map_stack_locked(vm_map_t map, vm_offset_t addrbos,
 	    addrbos + max_ssize > vm_map_max(map) ||
 	    addrbos + max_ssize <= addrbos)
 		return (KERN_INVALID_ADDRESS);
-	sgp = (curproc->p_flag2 & P2_STKGAP_DISABLE) != 0 ? 0 :
+	sgp = ((curproc->p_flag2 & P2_STKGAP_DISABLE) != 0 ||
+	    (curproc->p_fctl0 & NT_FREEBSD_FCTL_STKGAP_DISABLE) != 0) ? 0 :
 	    (vm_size_t)stack_guard_page * PAGE_SIZE;
 	if (sgp >= max_ssize)
 		return (KERN_INVALID_ARGUMENT);
@@ -4273,7 +4275,8 @@ retry:
 	} else {
 		return (KERN_FAILURE);
 	}
-	guard = (curproc->p_flag2 & P2_STKGAP_DISABLE) != 0 ? 0 :
+	guard = ((curproc->p_flag2 & P2_STKGAP_DISABLE) != 0 ||
+	    (curproc->p_fctl0 & NT_FREEBSD_FCTL_STKGAP_DISABLE) != 0) ? 0 :
 	    gap_entry->next_read;
 	max_grow = gap_entry->end - gap_entry->start;
 	if (guard > max_grow)