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Re: [PATCH][1-3] New configure option to enable Position independent executable as default.


lördag 16 november 2013 20.37.58 skrev  Ryan Hill:
> On Wed, 13 Nov 2013 23:28:45 +0100
> 
> Magnus Granberg <zorry@gentoo.org> wrote:
> > Hi
> > This patchset will add a new configure options --enable-default-pie.
> > With the new option enable will make it pass -fPIE and -pie from the gcc
> > and g++ frontend. Have only add the support for two targets but should
> > work on more targes. In configure.ac we add the new option. We can't
> > compile the compiler or the crt stuff with -fPIE it will brake the PCH
> > and the crtbegin and crtend files. The disabling is done in the
> > Makefiles. The needed spec is added to DRIVER_SELF_SPECS. We disable all
> > the profiling test for the linking will fail.Tested on x86_64 linux
> > (Gentoo).
> > 
> > /Magnus Granberg
> 
> Hey Magnus.  Some nits:
......
> > +for C, C++, ObjC, ObjC++, if none of @option{-fno-PIE},
> > @option{-fno-pie},
> > +@option{-fPIC}, @option{-fpic}, @option{-fno-PIC}, @option{-fno-pic},
> > +@option{-nostdlib}, @option{-nostartfiles}, @option{-shared},
> > +@option{-nodefaultlibs}, nor @option{static} are found.
> 
> Looks like nodefaultlibs is missing from PIE_DRIVER_SELF_SPECS or this needs
> to be updated.
> 
> Thanks!

Thankyou for the nits. Have updated the patches with the fixes.
The same changlog should work in my first post about this new option.

>Mike Stump wrote
>Ick.  Would be nice to figure out on what systems one can do this and just do 
>it without the configure option.  Is there some reason that we need an option 
>for it?
It would work well on most *-*-linux* targets but i don't have all the 
hardware for testing and I agre with Ian that it should not be default enable.

/Magnus Granberg
--- a/gcc/testsuite/gcc.dg/default-pie.c	2013-11-09 21:07:16.741479728 +0100
+++ b/gcc/testsuite/gcc.dg/default-pie.c	2013-11-09 21:05:07.801479218 +0100
@@ -0,0 +1,12 @@
+/* { dg-do compile { target *-*-linux* *-*-gnu* } } */
+/* { dg-require-effective-target default_pie } */
+/* { dg-options "-O2" } */
+int foo (void);
+
+int
+main (void)
+{
+	return foo ();
+}
+
+/* { dg-final { scan-assembler "foo@PLT" } } */
--- a/gcc/testsuite/g++.dg/other/anon5.C	2012-11-10 15:34:42.000000000 +0100
+++ b/gcc/testsuite/g++.dg/other/anon5.C	2013-11-09 14:49:52.281390127 +0100
@@ -1,5 +1,6 @@
 // PR c++/34094
 // { dg-do link { target { ! { *-*-darwin* *-*-hpux* *-*-solaris2.* } } } }
+// { dg-skip-if "" { default_pie } { "*" } { "" } }
 // { dg-options "-g" }
 // Ignore additional message on powerpc-ibm-aix
 // { dg-prune-output "obtain more information" } */
--- a/gcc/testsuite/lib/target-supports.exp	2013-10-01 11:18:30.000000000 +0200
+++ b/gcc/testsuite/lib/target-supports.exp	2013-10-25 22:01:46.743388469 +0200
@@ -474,6 +474,11 @@ proc check_profiling_available { test_wh
 	}
     }
 
+    # Profiling don't work with default -fPIE -pie.
+    if { [check_effective_target_default_pie] } {
+      return 0
+    }
+
     # Support for -p on solaris2 relies on mcrt1.o which comes with the
     # vendor compiler.  We cannot reliably predict the directory where the
     # vendor compiler (and thus mcrt1.o) is installed so we can't
@@ -839,6 +844,14 @@ proc check_effective_target_pie { } {
     return 0
 }
 
+# Return 1 if -pie, -fPIE are default enable, 0 otherwise.
+
+proc check_effective_target_default_pie { } {
+    global ENABLE_DEFAULT_PIE
+    return [info exists ENABLE_DEFAULT_PIE]
+    return 0
+}
+
 # Return true if the target supports -mpaired-single (as used on MIPS).
 
 proc check_effective_target_mpaired_single { } {
--- a/gcc/config/gnu-user.h	2013-08-20 10:31:40.000000000 +0200
+++ b/gcc/config/gnu-user.h	2013-10-23 22:01:42.337238981 +0200
@@ -134,3 +134,17 @@ see the files COPYING3 and COPYING.RUNTI
 /* Additional libraries needed by -static-libtsan.  */
 #undef STATIC_LIBTSAN_LIBS
 #define STATIC_LIBTSAN_LIBS "-ldl -lpthread"
+
+/* We use this to make the compiler use -fPIE as default and link
+   with -pie.  */
+#ifdef ENABLE_DEFAULT_PIE
+#define PIE_DRIVER_SELF_SPECS \
+"%{pie|fpic|fPIC|fpie|fPIE|fno-pic|fno-PIC|fno-pie|fno-PIE| \
+  shared|static|nostdlib|nodefaultlibs|nostartfiles:;:-fPIE -pie}"
+#else
+#define PIE_DRIVER_SELF_SPECS ""
+#endif
+
+#ifndef GNU_DRIVER_SELF_SPECS
+#define GNU_DRIVER_SELF_SPECS PIE_DRIVER_SELF_SPECS
+#endif
--- a/gcc/config/i386/gnu-user-common.h	2013-01-10 21:38:27.000000000 +0100
+++ b/gcc/config/i386/gnu-user-common.h	2013-10-23 17:37:45.432767049 +0200
@@ -70,3 +70,8 @@ along with GCC; see the file COPYING3.
 
 /* Static stack checking is supported by means of probes.  */
 #define STACK_CHECK_STATIC_BUILTIN 1
+
+/* Use GNU_DRIVER_SELF_SPECS.  */
+#ifndef DRIVER_SELF_SPECS
+#define DRIVER_SELF_SPECS GNU_DRIVER_SELF_SPECS
+#endif
--- a/gcc/configure.ac	2013-09-25 18:10:35.000000000 +0200
+++ b/gcc/configure.ac	2013-10-22 21:26:56.287602139 +0200
@@ -5434,6 +5434,30 @@ if test x"${LINKER_HASH_STYLE}" != x; th
                                          [The linker hash style])
 fi
 
+# Check whether --enable-default-pie was given and target have the support.
+AC_ARG_ENABLE(default-pie,
+[AS_HELP_STRING([--enable-default-pie],
+  [enable Position Independent Executable as default])],
+enable_default_pie=$enableval,
+enable_default_pie=no)
+if test x$enable_default_pie = xyes; then
+  AC_MSG_CHECKING(if $target supports default PIE)
+  enable_default_pie=no
+  case $target in
+    i?86*-*-linux* | x86_64*-*-linux*)
+      enable_default_pie=yes
+      ;;
+    *)
+      ;;
+    esac
+  AC_MSG_RESULT($enable_default_pie)
+fi
+if test x$enable_default_pie == xyes ; then
+  AC_DEFINE(ENABLE_DEFAULT_PIE, 1,
+      [Define if your target supports default PIE and it is enabled.])
+fi
+AC_SUBST([enable_default_pie])
+
 # Configure the subdirectories
 # AC_CONFIG_SUBDIRS($subdirs)
 
--- a/gcc/Makefile.in	2013-10-02 21:52:27.000000000 +0200
+++ b/gcc/Makefile.in	2013-10-24 17:46:22.055357122 +0200
@@ -957,14 +957,23 @@ CONTEXT_H = context.h
 # cross compiler which does not use the native headers and libraries.
 INTERNAL_CFLAGS = -DIN_GCC @CROSS@
 
+# We don't want to compile the compiler with -fPIE, it make PCH fail.
+enable_default_pie = @enable_default_pie@
+ifeq ($(enable_default_pie),yes)
+NOPIE_CFLAGS = -fno-PIE
+else
+NOPIE_CFLAGS=
+endif
+
 # This is the variable actually used when we compile. If you change this,
 # you probably want to update BUILD_CFLAGS in configure.ac
-ALL_CFLAGS = $(T_CFLAGS) $(CFLAGS-$@) \
+ALL_CFLAGS = $(NOPIE_CFLAGS) $(T_CFLAGS) $(CFLAGS-$@) \
   $(CFLAGS) $(INTERNAL_CFLAGS) $(COVERAGE_FLAGS) $(WARN_CFLAGS) @DEFS@
 
 # The C++ version.
-ALL_CXXFLAGS = $(T_CFLAGS) $(CFLAGS-$@) $(CXXFLAGS) $(INTERNAL_CFLAGS) \
-  $(COVERAGE_FLAGS) $(NOEXCEPTION_FLAGS) $(WARN_CXXFLAGS) @DEFS@
+ALL_CXXFLAGS = $(NOPIE_CFLAGS) $(T_CFLAGS) $(CFLAGS-$@) $(CXXFLAGS) \
+  $(INTERNAL_CFLAGS) $(COVERAGE_FLAGS) $(NOEXCEPTION_FLAGS) \
+  $(WARN_CXXFLAGS) @DEFS@
 
 # Likewise.  Put INCLUDES at the beginning: this way, if some autoconf macro
 # puts -I options in CPPFLAGS, our include files in the srcdir will always
@@ -1805,6 +1814,7 @@ libgcc.mvars: config.status Makefile spe
 	echo GCC_CFLAGS = '$(GCC_CFLAGS)' >> tmp-libgcc.mvars
 	echo INHIBIT_LIBC_CFLAGS = '$(INHIBIT_LIBC_CFLAGS)' >> tmp-libgcc.mvars
 	echo TARGET_SYSTEM_ROOT = '$(TARGET_SYSTEM_ROOT)' >> tmp-libgcc.mvars
+	echo enable_default_pie = '$(enable_default_pie)' >> tmp-libgcc.mvars
 
 	mv tmp-libgcc.mvars libgcc.mvars
 
@@ -3460,6 +3470,9 @@ site.exp: ./config.status Makefile
 	@if test "@enable_lto@" = "yes" ; then \
 	  echo "set ENABLE_LTO 1" >> ./site.tmp; \
 	fi
+	@if test "@enable_default_pie@" = "yes" ; then \
+	  echo "set ENABLE_DEFAULT_PIE 1" >> ./site.tmp; \
+	fi
 # If newlib has been configured, we need to pass -B to gcc so it can find
 # newlib's crt0.o if it exists.  This will cause a "path prefix not used"
 # message if it doesn't, but the testsuite is supposed to ignore the message -
--- a/libgcc/Makefile.in	2011-11-22 04:01:02.000000000 +0100
+++ b/libgcc/Makefile.in	2012-06-29 00:15:04.534016511 +0200
@@ -275,11 +275,17 @@ override CFLAGS := $(filter-out -fprofil
 INTERNAL_CFLAGS = $(CFLAGS) $(LIBGCC2_CFLAGS) $(HOST_LIBGCC2_CFLAGS) \
 		  $(INCLUDES) @set_have_cc_tls@ @set_use_emutls@
 
+#Don't use -fPIE when compiling crtbegin/end.
+ifeq ($(enable_default_pie),yes)
+NOPIE_CFLAGS = -fno-PIE
+else
+NOPIE_CFLAGS=
+endif
 # Options to use when compiling crtbegin/end.
 CRTSTUFF_CFLAGS = -O2 $(GCC_CFLAGS) $(INCLUDES) $(MULTILIB_CFLAGS) -g0 \
   -finhibit-size-directive -fno-inline -fno-exceptions \
   -fno-zero-initialized-in-bss -fno-toplevel-reorder -fno-tree-vectorize \
-  -fno-stack-protector \
+  -fno-stack-protector $(NOPIE_CFLAGS) \
   $(INHIBIT_LIBC_CFLAGS)
 
 # Extra flags to use when compiling crt{begin,end}.o.
--- a/gcc/doc/install.texi	2013-10-01 19:29:40.000000000 +0200
+++ b/gcc/doc/install.texi	2013-11-17 16:13:20.474144921 +0100
@@ -1421,6 +1421,10 @@ do a @samp{make -C gcc gnatlib_and_tools
 Specify that the run-time libraries for stack smashing protection
 should not be built.
 
+@item --enable-default-pie
+Turn on @option{-fPIE} and @option{-pie} by default if supported.
+Currently supported targets are i?86-*-linux* and x86-64-*-linux*.
+
 @item --disable-libquadmath
 Specify that the GCC quad-precision math library should not be built.
 On some systems, the library is required to be linkable when building
--- a/gcc/doc/invoke.texi	2013-10-03 19:13:50.000000000 +0200
+++ b/gcc/doc/invoke.texi	2013-11-17 21:30:02.784220111 +0100
@@ -10134,6 +10134,12 @@ For predictable results, you must also s
 used for compilation (@option{-fpie}, @option{-fPIE},
 or model suboptions) when you specify this linker option.
 
+NOTE: With configure --enable-default-pie this option is enabled by default
+for C, C++, ObjC, ObjC++, if none of @option{-fno-PIE}, @option{-fno-pie},
+@option{-fPIC}, @option{-fpic}, @option{-fno-PIC}, @option{-fno-pic},
+@option{-nostdlib}, @option{-nostartfiles}, @option{-shared},
+@option{-nodefaultlibs}, nor @option{static} are found.
+
 @item -rdynamic
 @opindex rdynamic
 Pass the flag @option{-export-dynamic} to the ELF linker, on targets
@@ -21371,6 +21377,12 @@ used during linking.
 @code{__pie__} and @code{__PIE__}.  The macros have the value 1
 for @option{-fpie} and 2 for @option{-fPIE}.
 
+NOTE: With configure --enable-default-pie this option is enabled by default
+for C, C++, ObjC, ObjC++, if none of @option{-fno-PIE}, @option{-fno-pie},
+@option{-fPIC}, @option{-fpic}, @option{-fno-PIC}, @option{-fno-pic},
+@option{-nostdlib}, @option{-nostartfiles}, @option{-shared},
+@option{-nodefaultlibs}, nor @option{static} are found.
+
 @item -fno-jump-tables
 @opindex fno-jump-tables
 Do not use jump tables for switch statements even where it would be

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