[src/netbsd-7]: src/sys/kern Apply patch (requested by martin in ticket #1062):

[riz <riz%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/2bd13e84da74
branches:  netbsd-7
changeset: 799759:2bd13e84da74
user:      riz <riz%NetBSD.org@localhost>
date:      Tue Jan 26 01:18:37 2016 +0000

description:
Apply patch (requested by martin in ticket #1062):

sys/kern/exec_elf.c                     patch

        Restore binary compatibility on sparc64 for old binaries.
        [martin, ticket #1062]

diffstat:

 sys/kern/exec_elf.c |  44 +++++++++++++++++++++++++++++++++++---------
 1 files changed, 35 insertions(+), 9 deletions(-)

diffs (89 lines):

diff -r f275763dd4a6 -r 2bd13e84da74 sys/kern/exec_elf.c
--- a/sys/kern/exec_elf.c       Tue Jan 26 01:11:13 2016 +0000
+++ b/sys/kern/exec_elf.c       Tue Jan 26 01:18:37 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: exec_elf.c,v 1.69.2.3 2015/11/08 00:57:09 riz Exp $    */
+/*     $NetBSD: exec_elf.c,v 1.69.2.4 2016/01/26 01:18:37 riz Exp $    */
 
 /*-
  * Copyright (c) 1994, 2000, 2005 The NetBSD Foundation, Inc.
@@ -57,7 +57,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.69.2.3 2015/11/08 00:57:09 riz Exp $");
+__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.69.2.4 2016/01/26 01:18:37 riz Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_pax.h"
@@ -77,6 +77,7 @@
 #include <sys/kauth.h>
 #include <sys/bitops.h>
 #include <sys/cprng.h>
+#include <sys/atomic.h>
 
 #include <sys/cpu.h>
 #include <machine/reg.h>
@@ -409,20 +410,18 @@
        u_long phsize;
        Elf_Addr addr = *last;
        struct proc *p;
-       bool use_topdown;
+       bool use_topdown, restore_topdown;
 
        p = l->l_proc;
 
        KASSERT(p->p_vmspace);
-       if (__predict_true(p->p_vmspace != proc0.p_vmspace)) {
-               use_topdown = p->p_vmspace->vm_map.flags & VM_MAP_TOPDOWN;
-       } else {
+       KASSERT(p->p_vmspace != proc0.p_vmspace);
+       restore_topdown = false;
 #ifdef __USE_TOPDOWN_VM
-               use_topdown = epp->ep_flags & EXEC_TOPDOWN_VM;
+       use_topdown = epp->ep_flags & EXEC_TOPDOWN_VM;
 #else
-               use_topdown = false;
+       use_topdown = false;
 #endif
-       }
 
        /*
         * 1. open file
@@ -537,9 +536,36 @@
                /*
                 * Now compute the size and load address.
                 */
+               if (__predict_false(
+                   /* vmspace is marked as topdown */
+                   (((p->p_vmspace->vm_map.flags & VM_MAP_TOPDOWN) != 0)
+                       !=
+                    /* but this differs from the topdown usage we need */
+                    use_topdown))) {
+                       /*
+                        * The vmmap might be shared, but this flag is
+                        * considered r/o and we will restore it immediately
+                        * after calculating the load address.
+                        */
+                       int flags = p->p_vmspace->vm_map.flags;
+                       int n = use_topdown
+                                   ? (flags | VM_MAP_TOPDOWN)
+                                   : (flags & ~VM_MAP_TOPDOWN);
+
+                       restore_topdown = true;
+                       atomic_swap_32(&p->p_vmspace->vm_map.flags, n);
+               }
                addr = (*epp->ep_esch->es_emul->e_vm_default_addr)(p,
                    epp->ep_daddr,
                    round_page(limit) - trunc_page(base_ph->p_vaddr));
+               if (__predict_false(restore_topdown)) {
+                       int flags = p->p_vmspace->vm_map.flags;
+                       int n = !use_topdown
+                                   ? (flags | VM_MAP_TOPDOWN)
+                                   : (flags & ~VM_MAP_TOPDOWN);
+
+                       atomic_swap_32(&p->p_vmspace->vm_map.flags, n);
+               }
        } else
                addr = *last; /* may be ELF_LINK_ADDR */