[src/trunk]: src/sys/kern Allow ELF objects with more than two PT_LOAD sectio...

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

details:   https://anonhg.NetBSD.org/src/rev/5e46cb183e73
branches:  trunk
changeset: 757224:5e46cb183e73
user:      joerg <joerg%NetBSD.org@localhost>
date:      Fri Aug 20 14:59:53 2010 +0000

description:
Allow ELF objects with more than two PT_LOAD sections. Go creates such
binaries by default with separate sections for executable, writeable
data and constants. Use the same heuristic as FreeBSD to match up the
text and data segment assumptions.

diffstat:

 sys/kern/exec_elf.c |  37 ++++++++++++++++++-------------------
 1 files changed, 18 insertions(+), 19 deletions(-)

diffs (70 lines):

diff -r 77f6df75826b -r 5e46cb183e73 sys/kern/exec_elf.c
--- a/sys/kern/exec_elf.c       Fri Aug 20 12:20:23 2010 +0000
+++ b/sys/kern/exec_elf.c       Fri Aug 20 14:59:53 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: exec_elf.c,v 1.23 2010/06/24 13:03:11 hannken Exp $    */
+/*     $NetBSD: exec_elf.c,v 1.24 2010/08/20 14:59:53 joerg 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 1.23 2010/06/24 13:03:11 hannken Exp $");
+__KERNEL_RCSID(1, "$NetBSD: exec_elf.c,v 1.24 2010/08/20 14:59:53 joerg Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_pax.h"
@@ -730,28 +730,22 @@
 
                switch (ph[i].p_type) {
                case PT_LOAD:
-                       /*
-                        * XXX
-                        * Can handle only 2 sections: text and data
-                        */
-                       if (nload++ == 2) {
-                               error = ENOEXEC;
-                               goto bad;
-                       }
                        elf_load_psection(&epp->ep_vmcmds, epp->ep_vp,
                            &ph[i], &addr, &size, &prot, VMCMD_FIXED);
 
                        /*
-                        * Decide whether it's text or data by looking
-                        * at the entry point.
+                        * Consider this as text segment, if it is executable.
+                        * If there is more than one text segment, pick the
+                        * largest.
+                        *
+                        * If it is not executable, use the last section
+                        * as data segment to make break() happy.
                         */
-                       if (eh->e_entry >= addr &&
-                           eh->e_entry < (addr + size)) {
-                               epp->ep_taddr = addr;
-                               epp->ep_tsize = size;
-                               if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) {
-                                       epp->ep_daddr = addr;
-                                       epp->ep_dsize = size;
+                       if (ph[i].p_flags & PF_X) {
+                               if (epp->ep_taddr == ELFDEFNNAME(NO_ADDR) ||
+                                   size > epp->ep_tsize) {
+                                       epp->ep_taddr = addr;
+                                       epp->ep_tsize = size;
                                }
                        } else {
                                epp->ep_daddr = addr;
@@ -780,6 +774,11 @@
                }
        }
 
+       if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) {
+               epp->ep_daddr = epp->ep_taddr;
+               epp->ep_dsize = epp->ep_tsize;
+       }
+
        /*
         * Check if we found a dynamically linked binary and arrange to load
         * its interpreter