[PATCH] Allow main to come from a shared library for PIE [BZ #262]

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

2004-07-15  Jakub Jelinek  <jakub@redhat.com>

	[BZ #262]
	* sysdeps/i386/elf/start.S (_start): Use @GOT instead of @GOTOFF
	for main.  Patch by Solar Designer <solar@openwall.com>.
	* elf/Makefile: Add rules to build and run tst-pie1.
	* elf/tst-pie1.c: New test.
	* elf/tst-piemod1.c: New file.

--- libc/sysdeps/i386/elf/start.S.jj	2004-07-15 14:41:46.000000000 +0200
+++ libc/sysdeps/i386/elf/start.S	2004-07-15 14:42:37.000000000 +0200
@@ -1,5 +1,6 @@
 /* Startup code compliant to the ELF i386 ABI.
-   Copyright (C) 1995-1998,2000,2001,2002,2003 Free Software Foundation, Inc.
+   Copyright (C) 1995, 1996, 1997, 1998, 2000, 2001, 2002, 2003, 2004
+   Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -81,8 +82,7 @@ _start:
 	pushl %ecx		/* Push second argument: argv.  */
 	pushl %esi		/* Push first argument: argc.  */
 
-	leal BP_SYM (main)@GOTOFF(%ebx), %eax
-	pushl %eax
+	pushl BP_SYM (main)@GOT(%ebx)
 
 	/* Call the user's main function, and exit with its value.
 	   But let the libc call main.    */
--- libc/elf/tst-pie1.c.jj	2004-07-15 14:37:41.000000000 +0200
+++ libc/elf/tst-pie1.c	2004-07-15 14:37:41.000000000 +0200
@@ -0,0 +1,5 @@
+int
+foo (void)
+{
+  return 34;
+}
--- libc/elf/Makefile.jj	2004-06-17 17:08:46.000000000 +0200
+++ libc/elf/Makefile	2004-07-15 14:47:43.000000000 +0200
@@ -80,7 +80,7 @@ distribute	:= rtld-Rules \
 		   nodel2mod1.c nodel2mod2.c nodel2mod3.c \
 		   reldep9.c reldep9mod1.c reldep9mod2.c reldep9mod3.c \
 		   tst-array1.exp tst-array2.exp tst-array4.exp \
-		   tst-array2dep.c \
+		   tst-array2dep.c tst-piemod1.c \
 		   tst-execstack-mod.c tst-dlmodcount.c \
 		   check-textrel.c dl-sysdep.h
 
@@ -160,6 +160,9 @@ tests-nodelete-yes = nodelete nodelete2
 tests-nodlopen-yes = nodlopen nodlopen2
 tests-execstack-yes = tst-execstack tst-execstack-needed tst-execstack-prog
 endif
+ifeq (yesyes,$(have-fpie)$(build-shared))
+tests: $(objpfx)tst-pie1.out
+endif
 modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		testobj1_1 failobj constload2 constload3 unloadmod \
 		dep1 dep2 dep3 dep4 $(modules-vis-$(have-protected)) \
@@ -185,6 +188,9 @@ modules-names = testobj1 testobj2 testob
 ifeq (yes,$(have-initfini-array))
 modules-names += tst-array2dep
 endif
+ifeq (yesyes,$(have-fpie)$(build-shared))
+modules-names += tst-piemod1
+endif
 modules-vis-yes = vismod1 vismod2 vismod3
 modules-nodelete-yes = nodelmod1 nodelmod2 nodelmod3 nodelmod4 \
 		       nodel2mod1 nodel2mod2 nodel2mod3
@@ -705,6 +711,25 @@ $(objpfx)tst-array4.out: $(objpfx)tst-ar
 	  $< > $@
 	cmp $@ tst-array4.exp > /dev/null
 
+ifeq (yesyes,$(have-fpie)$(build-shared))
+CFLAGS-tst-pie1.c += -fpie
+
+$(objpfx)tst-pie1.out: $(objpfx)tst-pie1
+	$(elf-objpfx)$(rtld-installed-name) \
+	  --library-path $(rpath-link)$(patsubst %,:%,$(sysdep-library-path)) \
+	  $< > $@
+
+$(objpfx)tst-pie1: $(objpfx)tst-pie1.o $(objpfx)tst-piemod1.so
+	$(LINK.o) -pie -Wl,-O1 \
+	  $(sysdep-LDFLAGS) $(config-LDFLAGS) \
+	  $(extra-B-$(@F:lib%.so=%).so) -B$(csu-objpfx) \
+	  $(extra-B-$(@F:lib%.so=%).so) $(load-map-file) \
+	  $(LDFLAGS) $(LDFLAGS-$(@F)) \
+	  -L$(subst :, -L,$(rpath-link)) -Wl,-rpath-link=$(rpath-link) \
+	  -o $@ $(objpfx)tst-pie1.o $(objpfx)tst-piemod1.so \
+	  $(common-objpfx)libc_nonshared.a
+endif
+
 check-textrel-CFLAGS = -O -Wall -D_XOPEN_SOURCE=600 -D_BSD_SOURCE
 $(objpfx)check-textrel: check-textrel.c
 	$(native-compile)
--- libc/elf/tst-piemod1.c.jj	2004-07-15 14:37:41.000000000 +0200
+++ libc/elf/tst-piemod1.c	2004-07-15 14:37:41.000000000 +0200
@@ -0,0 +1,20 @@
+#include <stdio.h>
+
+int
+foo (void)
+{
+  return 21;
+}
+
+int
+main (void)
+{
+  int val = foo ();
+  if (val != 34)
+    {
+      printf ("foo () returned %d\n", val);
+      return 1;
+    }
+
+  return 0;
+}

	Jakub