Fix overflow checking for 32-bit pc-relative relocations on x32.

The problem here is that x32 is really using 64-bit addressing,
while pretending to be 32-bit. Even though the object file format
is 32-bit, we need to do the overflow checking with 64-bit
arithmetic (because that's what the hardware will be using).
This patch overrides the pcrela32_check functions in reloc.h
with target-specific versions that do 64-bit checking.

I've also updated the test case to use -Tdata instead of adding
a huge .space directive, to reduce the size of the .o files.

gold/
	PR gold/19567
	* reloc.h (Relocate_functions::Overflow_check): Add comments.
	* x86_64.cc (X86_64_relocate_functions): New class.
	(Target_x86_64::Relocate::relocate): Use the new class.
	* testsuite/Makefile.am (x86_64_overflow_pc32): Add -Tdata option.
	(x32_overflow_pc32): New test case.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/x32_overflow_pc32.sh: New script.
	* testsuite/x86_64_overflow_pc32.s: Remove .space directive.

gold/ChangeLog

@@ -1,3 +1,15 @@
+2016-02-06  Cary Coutant  <ccoutant@gmail.com>
+
+	PR gold/19567
+	* reloc.h (Relocate_functions::Overflow_check): Add comments.
+	* x86_64.cc (X86_64_relocate_functions): New class.
+	(Target_x86_64::Relocate::relocate): Use the new class.
+	* testsuite/Makefile.am (x86_64_overflow_pc32): Add -Tdata option.
+	(x32_overflow_pc32): New test case.
+	* testsuite/Makefile.in: Regenerate.
+	* testsuite/x32_overflow_pc32.sh: New script.
+	* testsuite/x86_64_overflow_pc32.s: Remove .space directive.
+
 2016-02-06  Cary Coutant  <ccoutant@gmail.com>
 
 	PR gold/19577

gold/reloc.h

@@ -336,9 +336,14 @@ class Relocate_functions
 
   enum Overflow_check
   {
+    // No overflow checking.
     CHECK_NONE,
+    // Check for overflow of a signed value.
     CHECK_SIGNED,
+    // Check for overflow of an unsigned value.
     CHECK_UNSIGNED,
+    // Check for overflow of a signed or unsigned value.
+    // (i.e., no error if either signed or unsigned fits.)
     CHECK_SIGNED_OR_UNSIGNED
   };
 

gold/testsuite/Makefile.am

@@ -1080,14 +1080,30 @@ MOSTLYCLEANFILES += x86_64_overflow_pc32.err
 x86_64_overflow_pc32.o: x86_64_overflow_pc32.s
 	$(TEST_AS) -o $@ $<
 x86_64_overflow_pc32.err: x86_64_overflow_pc32.o gcctestdir/ld
-	@echo $(CXXLINK) -Bgcctestdir/ -shared -o x86_64_overflow_pc32 x86_64_overflow_pc32.o "2>$@"
+	@echo gcctestdir/ld -e bar -Tdata=0x81000000 -o x86_64_overflow_pc32 x86_64_overflow_pc32.o "2>$@"
-	@if $(CXXLINK) -Bgcctestdir/ -shared -o x86_64_overflow_pc32 x86_64_overflow_pc32.o 2>$@; \
+	@if gcctestdir/ld -e bar -Tdata=0x81000000 -o x86_64_overflow_pc32 x86_64_overflow_pc32.o 2>$@; \
 	then \
 	  echo 1>&2 "Link of x86_64_overflow_pc32 should have failed"; \
 	  rm -f $@; \
 	  exit 1; \
 	fi
 
+check_SCRIPTS += x32_overflow_pc32.sh
+check_DATA += x32_overflow_pc32.err
+MOSTLYCLEANFILES += x32_overflow_pc32.err
+x86_64_overflow_pc32.o: x86_64_overflow_pc32.s
+	$(TEST_AS) -o $@ $<
+x32_overflow_pc32.o: x86_64_overflow_pc32.s
+	$(TEST_AS) --x32 -o $@ $<
+x32_overflow_pc32.err: x32_overflow_pc32.o gcctestdir/ld
+	@echo gcctestdir/ld -e bar -Tdata=0x81000000 -o x32_overflow_pc32 x32_overflow_pc32.o "2>$@"
+	@if gcctestdir/ld -e bar -Tdata=0x81000000 -o x32_overflow_pc32 x32_overflow_pc32.o 2>$@; \
+	then \
+	  echo 1>&2 "Link of x32_overflow_pc32 should have failed"; \
+	  rm -f $@; \
+	  exit 1; \
+	fi
+
 endif DEFAULT_TARGET_X86_64
 
 if DEFAULT_TARGET_I386

gold/testsuite/Makefile.in

@@ -200,7 +200,8 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
 @GCC_TRUE@@HAVE_STATIC_TRUE@@NATIVE_LINKER_TRUE@@STATIC_TLS_TRUE@@TLS_TRUE@	tls_static_pic_test
 @FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@@TLS_TRUE@am__append_25 = tls_shared_nonpic_test
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_26 = x86_64_mov_to_lea.sh \
-@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_overflow_pc32.sh
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_overflow_pc32.sh \
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x32_overflow_pc32.sh
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_27 = x86_64_mov_to_lea1.stdout \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_mov_to_lea2.stdout \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_mov_to_lea3.stdout \
@@ -215,7 +216,8 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_mov_to_lea12.stdout \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_mov_to_lea13.stdout \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_mov_to_lea14.stdout \
-@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_overflow_pc32.err
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_overflow_pc32.err \
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x32_overflow_pc32.err
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_28 = x86_64_mov_to_lea1 \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_mov_to_lea2 \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_mov_to_lea3 \
@@ -230,7 +232,8 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_mov_to_lea12 \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_mov_to_lea13 \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_mov_to_lea14 \
-@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_overflow_pc32.err
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x86_64_overflow_pc32.err \
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	x32_overflow_pc32.err
 @DEFAULT_TARGET_I386_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_29 = i386_mov_to_lea.sh
 @DEFAULT_TARGET_I386_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_30 = i386_mov_to_lea1.stdout  i386_mov_to_lea2.stdout \
 @DEFAULT_TARGET_I386_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	i386_mov_to_lea3.stdout  i386_mov_to_lea4.stdout \
@@ -4445,6 +4448,8 @@ x86_64_mov_to_lea.sh.log: x86_64_mov_to_lea.sh
 	@p='x86_64_mov_to_lea.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
 x86_64_overflow_pc32.sh.log: x86_64_overflow_pc32.sh
 	@p='x86_64_overflow_pc32.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
+x32_overflow_pc32.sh.log: x32_overflow_pc32.sh
+	@p='x32_overflow_pc32.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
 i386_mov_to_lea.sh.log: i386_mov_to_lea.sh
 	@p='i386_mov_to_lea.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
 debug_msg.sh.log: debug_msg.sh
@@ -5491,13 +5496,25 @@ uninstall-am:
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@x86_64_overflow_pc32.o: x86_64_overflow_pc32.s
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(TEST_AS) -o $@ $<
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@x86_64_overflow_pc32.err: x86_64_overflow_pc32.o gcctestdir/ld
-@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	@echo $(CXXLINK) -Bgcctestdir/ -shared -o x86_64_overflow_pc32 x86_64_overflow_pc32.o "2>$@"
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	@echo gcctestdir/ld -e bar -Tdata=0x81000000 -o x86_64_overflow_pc32 x86_64_overflow_pc32.o "2>$@"
-@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	@if $(CXXLINK) -Bgcctestdir/ -shared -o x86_64_overflow_pc32 x86_64_overflow_pc32.o 2>$@; \
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	@if gcctestdir/ld -e bar -Tdata=0x81000000 -o x86_64_overflow_pc32 x86_64_overflow_pc32.o 2>$@; \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	then \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	  echo 1>&2 "Link of x86_64_overflow_pc32 should have failed"; \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	  rm -f $@; \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	  exit 1; \
 @DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	fi
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@x86_64_overflow_pc32.o: x86_64_overflow_pc32.s
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(TEST_AS) -o $@ $<
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@x32_overflow_pc32.o: x86_64_overflow_pc32.s
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(TEST_AS) --x32 -o $@ $<
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@x32_overflow_pc32.err: x32_overflow_pc32.o gcctestdir/ld
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	@echo gcctestdir/ld -e bar -Tdata=0x81000000 -o x32_overflow_pc32 x32_overflow_pc32.o "2>$@"
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	@if gcctestdir/ld -e bar -Tdata=0x81000000 -o x32_overflow_pc32 x32_overflow_pc32.o 2>$@; \
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	then \
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	  echo 1>&2 "Link of x32_overflow_pc32 should have failed"; \
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	  rm -f $@; \
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	  exit 1; \
+@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	fi
 
 @DEFAULT_TARGET_I386_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@i386_mov_to_lea1.o: i386_mov_to_lea1.s
 @DEFAULT_TARGET_I386_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(TEST_AS) --32 -o $@ $<

gold/testsuite/x32_overflow_pc32.sh

@@ -0,0 +1,42 @@
+#!/bin/sh
+
+# x86_64_overflow_pc32.sh -- a test case for overflow checking.
+
+# Copyright (C) 2016 Free Software Foundation, Inc.
+# Written by Cary Coutant <ccoutant@gmail.com>.
+
+# This file is part of gold.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+check()
+{
+    if ! grep -q "$2" "$1"
+    then
+	echo "Did not find expected error in $1:"
+	echo "   $2"
+	echo ""
+	echo "Actual error output below:"
+	cat "$1"
+	exit 1
+    fi
+}
+
+# We don't know how the compiler might order these variables, so we
+# can't test for the actual offset from .data, hence the regexp.
+check x86_64_overflow_pc32.err "function bar: error: relocation overflow"
+
+exit 0

gold/testsuite/x86_64_overflow_pc32.s

@@ -1,5 +1,4 @@
 	.data
-	.space 0x8ff00000
 	.hidden foo
 	.globl	foo
 foo:

gold/x86_64.cc

@@ -3347,6 +3347,52 @@ Target_x86_64<size>::do_finalize_sections(
     }
 }
 
+// For x32, we need to handle PC-relative relocations using full 64-bit
+// arithmetic, so that we can detect relocation overflows properly.
+// This class overrides the pcrela32_check methods from the defaults in
+// Relocate_functions in reloc.h.
+
+template<int size>
+class X86_64_relocate_functions : public Relocate_functions<size, false>
+{
+ public:
+  typedef Relocate_functions<size, false> Base;
+
+  // Do a simple PC relative relocation with the addend in the
+  // relocation.
+  static inline typename Base::Reloc_status
+  pcrela32_check(unsigned char* view,
+		 typename elfcpp::Elf_types<64>::Elf_Addr value,
+		 typename elfcpp::Elf_types<64>::Elf_Swxword addend,
+		 typename elfcpp::Elf_types<64>::Elf_Addr address)
+  {
+    typedef typename elfcpp::Swap<32, false>::Valtype Valtype;
+    Valtype* wv = reinterpret_cast<Valtype*>(view);
+    value = value + addend - address;
+    elfcpp::Swap<32, false>::writeval(wv, value);
+    return (Bits<32>::has_overflow(value)
+	    ? Base::RELOC_OVERFLOW : Base::RELOC_OK);
+  }
+
+  // Do a simple PC relative relocation with a Symbol_value with the
+  // addend in the relocation.
+  static inline typename Base::Reloc_status
+  pcrela32_check(unsigned char* view,
+		 const Sized_relobj_file<size, false>* object,
+		 const Symbol_value<size>* psymval,
+		 typename elfcpp::Elf_types<64>::Elf_Swxword addend,
+		 typename elfcpp::Elf_types<64>::Elf_Addr address)
+  {
+    typedef typename elfcpp::Swap<32, false>::Valtype Valtype;
+    Valtype* wv = reinterpret_cast<Valtype*>(view);
+    typename elfcpp::Elf_types<64>::Elf_Addr value =
+	psymval->value(object, addend) - address;
+    elfcpp::Swap<32, false>::writeval(wv, value);
+    return (Bits<32>::has_overflow(value)
+	    ? Base::RELOC_OVERFLOW : Base::RELOC_OK);
+  }
+};
+
 // Perform a relocation.
 
 template<int size>
@@ -3364,7 +3410,7 @@ Target_x86_64<size>::Relocate::relocate(
     typename elfcpp::Elf_types<size>::Elf_Addr address,
     section_size_type view_size)
 {
-  typedef Relocate_functions<size, false> Reloc_funcs;
+  typedef X86_64_relocate_functions<size> Reloc_funcs;
   const elfcpp::Rela<size, false> rela(preloc);
   unsigned int r_type = elfcpp::elf_r_type<size>(rela.get_r_info());
 
@@ -3476,7 +3522,7 @@ Target_x86_64<size>::Relocate::relocate(
     case elfcpp::R_X86_64_PC32:
     case elfcpp::R_X86_64_PC32_BND:
       rstatus = Reloc_funcs::pcrela32_check(view, object, psymval, addend,
-					    address, Reloc_funcs::CHECK_SIGNED);
+					    address);
       break;
 
     case elfcpp::R_X86_64_16:
@@ -3507,7 +3553,7 @@ Target_x86_64<size>::Relocate::relocate(
       // behaves differently because psymval was set to point to
       // the PLT entry, rather than the symbol, in Scan::global().
       rstatus = Reloc_funcs::pcrela32_check(view, object, psymval, addend,
-					    address, Reloc_funcs::CHECK_SIGNED);
+					    address);
       break;
 
     case elfcpp::R_X86_64_PLTOFF64:
@@ -3532,7 +3578,7 @@ Target_x86_64<size>::Relocate::relocate(
 	gold_assert(gsym);
 	typename elfcpp::Elf_types<size>::Elf_Addr value;
 	value = target->got_plt_section()->address();
-	Reloc_funcs::pcrela32(view, value, addend, address);
+	Reloc_funcs::pcrela32_check(view, value, addend, address);
       }
       break;
 
@@ -3577,8 +3623,7 @@ Target_x86_64<size>::Relocate::relocate(
 		  && Target_x86_64<size>::can_convert_mov_to_lea(gsym))))
 	{
 	  view[-2] = 0x8d;
-	  Reloc_funcs::pcrela32(view, object, psymval, addend,
+	  Reloc_funcs::pcrela32(view, object, psymval, addend, address);
-						    address);
 	}
       else
 	{
@@ -3596,7 +3641,7 @@ Target_x86_64<size>::Relocate::relocate(
 	    }
 	  typename elfcpp::Elf_types<size>::Elf_Addr value;
 	  value = target->got_plt_section()->address() + got_offset;
-	  Reloc_funcs::pcrela32(view, value, addend, address);
+	  Reloc_funcs::pcrela32_check(view, value, addend, address);
 	}
       }
       break;