Port to glibc 2.24 (pre-release) + ppc64

Inspired by a suggestion by Florian Weimer in:
https://sourceware.org/ml/libc-alpha/2016-07/msg00425.html
* configure.ac (HAVE_PERSONALITY_ADDR_NO_RANDOMIZE):
Rename from HAVE_PERSONALITY_LINUX32, and check for
ADDR_NO_RANDOMIZE (the crucial thing) instead of for LINUX32.
All uses changed.
* src/emacs.c (main) [HAVE_PERSONALITY_ADDR_NO_RANDOMIZE]:
Use ADDR_NO_RANDOMIZE from personality.h rather than inventing the
flag ourselves.  Just set that flag, rather than also setting the
persona.  When doing it, avoid functions like putenv that may
allocate memory.

diff --git a/admin/CPP-DEFINES b/admin/CPP-DEFINES
index c7ec8ce6fed80eb2768ee4ad5d78c5251462f6a8..5e6146b33d82fcf1cad4ff0c64537010c0fc4332 100644 (file)
--- a/admin/CPP-DEFINES
+++ b/admin/CPP-DEFINES
@@ -233,7 +233,7 @@ HAVE_NET_IF_DL_H
 HAVE_NET_IF_H
 HAVE_NLIST_H
 HAVE_OTF_GET_VARIATION_GLYPHS
-HAVE_PERSONALITY_LINUX32
+HAVE_PERSONALITY_ADDR_NO_RANDOMIZE
 HAVE_PNG
 HAVE_PNG_H
 HAVE_POSIX_MEMALIGN

diff --git a/configure.ac b/configure.ac
index dd1af5b435b33ca38130ace37a28375f9e884b70..c94ecb629efac57c6a65c2f6db3ff42624abe8b4 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1643,15 +1643,17 @@ AC_CHECK_HEADERS_ONCE(
   sys/resource.h
   sys/utsname.h pwd.h utmp.h util.h)
 
-AC_MSG_CHECKING(if personality LINUX32 can be set)
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/personality.h>]], [[personality (PER_LINUX32)]])],
-               emacs_cv_personality_linux32=yes,
-              emacs_cv_personality_linux32=no)
-AC_MSG_RESULT($emacs_cv_personality_linux32)
-
-if test $emacs_cv_personality_linux32 = yes; then
-  AC_DEFINE(HAVE_PERSONALITY_LINUX32, 1,
-            [Define to 1 if personality LINUX32 can be set.])
+AC_CACHE_CHECK([for ADDR_NO_RANDOMIZE],
+  [emacs_cv_personality_addr_no_randomize],
+  [AC_COMPILE_IFELSE(
+     [AC_LANG_PROGRAM([[#include <sys/personality.h>]],
+                     [[personality (personality (0xffffffff)
+                                    | ADDR_NO_RANDOMIZE)]])],
+     [emacs_cv_personality_addr_no_randomize=yes],
+     [emacs_cv_personality_addr_no_randomize=no])])
+if test $emacs_cv_personality_addr_no_randomize = yes; then
+  AC_DEFINE([HAVE_PERSONALITY_ADDR_NO_RANDOMIZE], [1],
+            [Define to 1 if personality flag ADDR_NO_RANDOMIZE exists.])
 fi
 
 # Note that Solaris has sys/sysinfo.h which defines struct

diff --git a/src/emacs.c b/src/emacs.c
index bb85733a1f20d3933b1a50475e63b672e50fb202..b2219844ca09b196a481bf5420d77d5dfc75dcf4 100644 (file)
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -112,7 +112,7 @@ extern void moncontrol (int mode);
 #include <sys/resource.h>
 #endif
 
-#ifdef HAVE_PERSONALITY_LINUX32
+#ifdef HAVE_PERSONALITY_ADDR_NO_RANDOMIZE
 #include <sys/personality.h>
 #endif
 
@@ -796,24 +796,22 @@ main (int argc, char **argv)
   dumping = !initialized && (strcmp (argv[argc - 1], "dump") == 0
                             || strcmp (argv[argc - 1], "bootstrap") == 0);
 
-#ifdef HAVE_PERSONALITY_LINUX32
-  if (dumping && ! getenv ("EMACS_HEAP_EXEC"))
+#ifdef HAVE_PERSONALITY_ADDR_NO_RANDOMIZE
+  if (dumping)
     {
-      /* Set this so we only do this once.  */
-      xputenv ("EMACS_HEAP_EXEC=true");
-
-      /* A flag to turn off address randomization which is introduced
-         in linux kernel shipped with fedora core 4 */
-#define ADD_NO_RANDOMIZE 0x0040000
-      personality (PER_LINUX32 | ADD_NO_RANDOMIZE);
-#undef  ADD_NO_RANDOMIZE
-
-      execvp (argv[0], argv);
+      int pers = personality (0xffffffff);
+      if (! (pers & ADDR_NO_RANDOMIZE)
+         && 0 <= personality (pers | ADDR_NO_RANDOMIZE))
+       {
+         /* Address randomization was enabled, but is now disabled.
+            Re-execute Emacs to get a clean slate.  */
+         execvp (argv[0], argv);
 
-      /* If the exec fails, try to dump anyway.  */
-      emacs_perror (argv[0]);
+         /* If the exec fails, warn and then try without a clean slate.  */
+         perror (argv[0]);
+       }
     }
-#endif /* HAVE_PERSONALITY_LINUX32 */
+#endif
 
 #if defined (HAVE_SETRLIMIT) && defined (RLIMIT_STACK) && !defined (CYGWIN)
   /* Extend the stack space available.  Don't do that if dumping,