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Re: PING^3: [PATCH]: New configure options that make the compiler use -fPIE and -pie as default option


"H.J. Lu" <hjl.tools@gmail.com> writes:

> Here is the complete patch.  Tested on Linux/x86-64.  It is also
> available on hjl/pie/master branch in git mirror.

As always, please keep generated files like configure and config.in out
of the submission: it simplifies review.

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index ab9b637..e429274 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -253,6 +253,12 @@ LINKER = $(CC)
 LINKER_FLAGS = $(CFLAGS)
 endif
 
+# We don't want to compile the compiler with -fPIE, it make PCH fail.
                                                            ^s
+COMPILER += @NO_PIE_CFLAGS@

@@ -750,6 +756,8 @@ CC_FOR_BUILD = @CC_FOR_BUILD@
 CXX_FOR_BUILD = @CXX_FOR_BUILD@
 BUILD_CFLAGS= @BUILD_CFLAGS@ -DGENERATOR_FILE
 BUILD_CXXFLAGS = @BUILD_CXXFLAGS@ -DGENERATOR_FILE
+BUILD_CFLAGS += @NO_PIE_CFLAGS@
+BUILD_CXXFLAGS += @NO_PIE_CFLAGS@
 
Here and in several other places, you use += instead of just adding
@NO_PIE_CFLAGS@ to the existing BUILD_CFLAGS variable.  Please lets
keep to the existing idiom instead of randomly introducing another.

@@ -761,6 +769,7 @@ BUILD_LINKERFLAGS = $(BUILD_CXXFLAGS)
 
 # Native linker and preprocessor flags.  For x-fragment overrides.
 BUILD_LDFLAGS=@BUILD_LDFLAGS@
+BUILD_LDFLAGS += @NO_PIE_FLAG@

Likewise.

 BUILD_CPPFLAGS= -I. -I$(@D) -I$(srcdir) -I$(srcdir)/$(@D) \
 		-I$(srcdir)/../include @INCINTL@ $(CPPINC) $(CPPFLAGS)
 
@@ -1864,6 +1873,12 @@ libgcc.mvars: config.status Makefile specs xgcc$(exeext)
 	echo GCC_CFLAGS = '$(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
+	if test @enable_default_pie@ = yes; then \
+	  NO_PIE_CFLAGS="-fno-PIE"; \

Why literal -fno-PIE instead of @NO_PIE_CFLAGS@?

+	else \
+	  NO_PIE_CFLAGS=; \
+	fi; \
+	echo NO_PIE_CFLAGS = "$$NO_PIE_CFLAGS" >> tmp-libgcc.mvars
 
 	mv tmp-libgcc.mvars libgcc.mvars
 
Besides, we're trying to get away from libgcc.mvars, moving the
detection to libgcc proper.  It would be nice to do so here.

diff --git a/gcc/ada/gcc-interface/Makefile.in b/gcc/ada/gcc-interface/Makefile.in
index ecc443e..90aedb5 100644
--- a/gcc/ada/gcc-interface/Makefile.in
+++ b/gcc/ada/gcc-interface/Makefile.in
@@ -267,6 +267,9 @@ TOOLS_LIBS = ../link.o ../targext.o ../../ggc-none.o ../../libcommon-target.a \
   ../../libcommon.a ../../../libcpp/libcpp.a $(LIBGNAT) $(LIBINTL) $(LIBICONV) \
   ../$(LIBBACKTRACE) ../$(LIBIBERTY) $(SYSLIBS) $(TGT_LIB)
 
+# Add -no-pie to TOOLS_LIBS since some of them are compiled with -fno-PIE.
+TOOLS_LIBS += @NO_PIE_FLAG@

Again, avoid +=

diff --git a/gcc/config/sol2.h b/gcc/config/sol2.h
index 4dceb16..adf6f3b 100644
--- a/gcc/config/sol2.h
+++ b/gcc/config/sol2.h
@@ -127,7 +127,7 @@ along with GCC; see the file COPYING3.  If not see
 #define ASM_SPEC_BASE \
 "%{v:-V} %{Qy:} %{!Qn:-Qy} %{Ym,*} -s %(asm_cpu)"
 
-#define ASM_PIC_SPEC " %{fpic|fpie|fPIC|fPIE:-K PIC}"
+#define ASM_PIC_SPEC " %{" FPIE_OR_FPIC_SPEC ":-K PIC}"
 
 #undef ASM_CPU_DEFAULT_SPEC
 #define ASM_CPU_DEFAULT_SPEC \

This is ok once the rest goes in.  I haven't reviewed the other
target-specific parts, though.

diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 04332c1..437a534 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -1585,6 +1585,9 @@ not be built.
 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.
+
 @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

This option was added in a seemingly completely random place, between
options to enable/disable runtime libs.  Please find a better place.

diff --git a/gcc/opts.c b/gcc/opts.c
index 9deb8df..4b6d978 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -739,8 +739,22 @@ finish_options (struct gcc_options *opts, struct gcc_options *opts_set,
       opts->x_flag_section_anchors = 0;
     }
 
+#ifndef ENABLE_DEFAULT_PIE
+#undef DEFAULT_FLAG_PIE
+#define DEFAULT_FLAG_PIE 0
+#endif
+

Couldn't this be done in defaults.h, too?  It seems confusing to provide
DEFAULT_FLAG_PIE defaults both here and in defaults.h.

	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University


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