Fix symbol values and relocation addends for relocatable links.

The fix for PR 19291 broke some other cases where -r is used with scripts,
as reported in PR 22266. The original fix for PR 22266 ended up breaking
many cases for REL targets, where the addends are stored in the section data,
and are not being adjusted properly.

The problem was basically that in a relocatable output file (ET_REL),
symbol values are supposed to be relative to the start address of their
section. Usually in a relocatable file, all sections start at 0, so the
failure to get this right is often irrelevant, but with a linker script,
we occasionally see an output section whose starting address is not 0,
and gold would occasionally write a symbol with its relocated value instead
of its section-relative value.

This patch reverts the recent fix for PR 22266 as well as my original fix
for PR 19291. The original fix moved the symbol value adjustment to
write_local_symbols, but neglected to undo a few places where the adjustment
was also being applied, resulting in an occasional double adjustment. The
more recent fix removed those other adjustments, but then failed to
re-account for the adjustment when rewriting the relocations on REL targets.

With the old attempts reverted, we now apply the symbol value adjustment to
the one case that had been missed (non-section symbols in merge sections).
But now we also need to account for the adjustment when rewriting the addends
for RELA relocations.

gold/
	PR gold/19291
	PR gold/22266
	* object.cc (Sized_relobj_file::compute_final_local_value_internal):
	Revert changes from 2017-11-08 patch.  Adjust symbol value in
	relocatable links for non-section symbols.
	(Sized_relobj_file::compute_final_local_value): Revert changes from
	2017-11-08 patch.
	(Sized_relobj_file::do_finalize_local_symbols): Likewise.
	(Sized_relobj_file::write_local_symbols): Revert changes from
	2015-11-25 patch.
	* object.h (Sized_relobj_file::compute_final_local_value_internal):
	Revert changes from 2017-11-08 patch.
	* powerpc.cc (Target_powerpc::relocate_relocs): Adjust addend for
	relocatable links.
	* target-reloc.h (relocate_relocs): Adjust addend for relocatable links.
	* testsuite/pr22266_a.c (hello): New function.
	* testsuite/pr22266_main.c (main): Add test for merge sections.
	* testsuite/pr22266_script.t: Add rule for .rodata.

8 files changed, 92 insertions, 28 deletions

diff --git a/gold/ChangeLog b/gold/ChangeLog
index 4c631ca..c3c7481 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,24 @@
+2017-11-27  Cary Coutant  <ccoutant@gmail.com>
+
+	PR gold/19291
+	PR gold/22266
+	* object.cc (Sized_relobj_file::compute_final_local_value_internal):
+	Revert changes from 2017-11-08 patch.  Adjust symbol value in
+	relocatable links for non-section symbols.
+	(Sized_relobj_file::compute_final_local_value): Revert changes from
+	2017-11-08 patch.
+	(Sized_relobj_file::do_finalize_local_symbols): Likewise.
+	(Sized_relobj_file::write_local_symbols): Revert changes from
+	2015-11-25 patch.
+	* object.h (Sized_relobj_file::compute_final_local_value_internal):
+	Revert changes from 2017-11-08 patch.
+	* powerpc.cc (Target_powerpc::relocate_relocs): Adjust addend for
+	relocatable links.
+	* target-reloc.h (relocate_relocs): Adjust addend for relocatable links.
+	* testsuite/pr22266_a.c (hello): New function.
+	* testsuite/pr22266_main.c (main): Add test for merge sections.
+	* testsuite/pr22266_script.t: Add rule for .rodata.
+
 2017-11-19  Ian Lance Taylor  <iant@google.com>
 	    Cary Coutant  <ccoutant@gmail.com>
 
diff --git a/gold/object.cc b/gold/object.cc
index 2e975bb..f7fe088 100644
--- a/gold/object.cc
+++ b/gold/object.cc
@@ -2318,6 +2318,7 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
     unsigned int r_sym,
     const Symbol_value<size>* lv_in,
     Symbol_value<size>* lv_out,
+    bool relocatable,
     const Output_sections& out_sections,
     const std::vector<Address>& out_offsets,
     const Symbol_table* symtab)
@@ -2404,8 +2405,11 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
 	    {
 	      // This is not a section symbol.  We can determine
 	      // the final value now.
-	      lv_out->set_output_value(
-		  os->output_address(this, shndx, lv_in->input_value()));
+	      uint64_t value =
+		os->output_address(this, shndx, lv_in->input_value());
+	      if (relocatable)
+		value -= os->address();
+	      lv_out->set_output_value(value);
 	    }
 	  else if (!os->find_starting_output_address(this, shndx, &start))
 	    {
@@ -2419,7 +2423,10 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
 		os->find_relaxed_input_section(this, shndx);
 	      if (posd != NULL)
 		{
-		  lv_out->set_output_value(posd->address());
+		  uint64_t value = posd->address();
+		  if (relocatable)
+		    value -= os->address();
+		  lv_out->set_output_value(value);
 		}
 	      else
 		lv_out->set_output_value(os->address());
@@ -2428,10 +2435,14 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
 	    {
 	      // We have to consider the addend to determine the
 	      // value to use in a relocation.  START is the start
-	      // of this input section.
+	      // of this input section.  If we are doing a relocatable
+	      // link, use offset from start output section instead of
+	      // address.
+	      Address adjusted_start =
+		relocatable ? start - os->address() : start;
 	      Merged_symbol_value<size>* msv =
 		new Merged_symbol_value<size>(lv_in->input_value(),
-					      start);
+					      adjusted_start);
 	      lv_out->set_merged_symbol_value(msv);
 	    }
 	}
@@ -2442,7 +2453,7 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
 				 + secoffset
 				 + lv_in->input_value());
       else
-	lv_out->set_output_value(os->address()
+	lv_out->set_output_value((relocatable ? 0 : os->address())
 				 + secoffset
 				 + lv_in->input_value());
     }
@@ -2468,11 +2479,12 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value(
     const Symbol_table* symtab)
 {
   // This is just a wrapper of compute_final_local_value_internal.
+  const bool relocatable = parameters->options().relocatable();
   const Output_sections& out_sections(this->output_sections());
   const std::vector<Address>& out_offsets(this->section_offsets());
   return this->compute_final_local_value_internal(r_sym, lv_in, lv_out,
-						  out_sections, out_offsets,
-						  symtab);
+						  relocatable, out_sections,
+						  out_offsets, symtab);
 }
 
 // Finalize the local symbols.  Here we set the final value in
@@ -2492,6 +2504,7 @@ Sized_relobj_file<size, big_endian>::do_finalize_local_symbols(
   const unsigned int loccount = this->local_symbol_count_;
   this->local_symbol_offset_ = off;
 
+  const bool relocatable = parameters->options().relocatable();
   const Output_sections& out_sections(this->output_sections());
   const std::vector<Address>& out_offsets(this->section_offsets());
 
@@ -2500,8 +2513,9 @@ Sized_relobj_file<size, big_endian>::do_finalize_local_symbols(
       Symbol_value<size>* lv = &this->local_values_[i];
 
       Compute_final_local_value_status cflv_status =
-	this->compute_final_local_value_internal(i, lv, lv, out_sections,
-						 out_offsets, symtab);
+	this->compute_final_local_value_internal(i, lv, lv, relocatable,
+						 out_sections, out_offsets,
+						 symtab);
       switch (cflv_status)
 	{
 	case CFLV_OK:
@@ -2666,7 +2680,6 @@ Sized_relobj_file<size, big_endian>::write_local_symbols(
       elfcpp::Sym<size, big_endian> isym(psyms);
 
       Symbol_value<size>& lv(this->local_values_[i]);
-      typename elfcpp::Elf_types<size>::Elf_Addr sym_value = lv.value(this, 0);
 
       bool is_ordinary;
       unsigned int st_shndx = this->adjust_sym_shndx(i, isym.get_st_shndx(),
@@ -2676,9 +2689,6 @@ Sized_relobj_file<size, big_endian>::write_local_symbols(
 	  gold_assert(st_shndx < out_sections.size());
 	  if (out_sections[st_shndx] == NULL)
 	    continue;
-	  // In relocatable object files symbol values are section relative.
-	  if (parameters->options().relocatable())
-	    sym_value -= out_sections[st_shndx]->address();
 	  st_shndx = out_sections[st_shndx]->out_shndx();
 	  if (st_shndx >= elfcpp::SHN_LORESERVE)
 	    {
@@ -2698,7 +2708,7 @@ Sized_relobj_file<size, big_endian>::write_local_symbols(
 	  gold_assert(isym.get_st_name() < strtab_size);
 	  const char* name = pnames + isym.get_st_name();
 	  osym.put_st_name(sympool->get_offset(name));
-	  osym.put_st_value(sym_value);
+	  osym.put_st_value(lv.value(this, 0));
 	  osym.put_st_size(isym.get_st_size());
 	  osym.put_st_info(isym.get_st_info());
 	  osym.put_st_other(isym.get_st_other());
@@ -2716,7 +2726,7 @@ Sized_relobj_file<size, big_endian>::write_local_symbols(
 	  gold_assert(isym.get_st_name() < strtab_size);
 	  const char* name = pnames + isym.get_st_name();
 	  osym.put_st_name(dynpool->get_offset(name));
-	  osym.put_st_value(sym_value);
+	  osym.put_st_value(lv.value(this, 0));
 	  osym.put_st_size(isym.get_st_size());
 	  osym.put_st_info(isym.get_st_info());
 	  osym.put_st_other(isym.get_st_other());
diff --git a/gold/object.h b/gold/object.h
index c6c4927..508e79c 100644
--- a/gold/object.h
+++ b/gold/object.h
@@ -2772,7 +2772,8 @@ class Sized_relobj_file : public Sized_relobj<size, big_endian>
   // LV_IN points to a local symbol value containing the input value.
   // LV_OUT points to a local symbol value storing the final output value,
   // which must not be a merged symbol value since before calling this
-  // method to avoid memory leak.  OUT_SECTIONS is an array of output
+  // method to avoid memory leak.  RELOCATABLE indicates whether we are
+  // linking a relocatable output.  OUT_SECTIONS is an array of output
   // sections.  OUT_OFFSETS is an array of offsets of the sections.  SYMTAB
   // points to a symbol table.
   //
@@ -2784,6 +2785,7 @@ class Sized_relobj_file : public Sized_relobj<size, big_endian>
   compute_final_local_value_internal(unsigned int r_sym,
 				     const Symbol_value<size>* lv_in,
 				     Symbol_value<size>* lv_out,
+				     bool relocatable,
 				     const Output_sections& out_sections,
 				     const std::vector<Address>& out_offsets,
 				     const Symbol_table* symtab);
diff --git a/gold/powerpc.cc b/gold/powerpc.cc
index 244c221..d529519 100644
--- a/gold/powerpc.cc
+++ b/gold/powerpc.cc
@@ -9734,6 +9734,8 @@ Target_powerpc<size, big_endian>::relocate_relocs(
       gold_assert(got2_addend != invalid_address);
     }
 
+  const bool relocatable = parameters->options().relocatable();
+
   unsigned char* pwrite = reloc_view;
   bool zap_next = false;
   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
@@ -9829,7 +9831,7 @@ Target_powerpc<size, big_endian>::relocate_relocs(
       // In an object file, r_offset is an offset within the section.
       // In an executable or dynamic object, generated by
       // --emit-relocs, r_offset is an absolute address.
-      if (!parameters->options().relocatable())
+      if (!relocatable)
 	{
 	  offset += view_address;
 	  if (static_cast<Address>(offset_in_output_section) != invalid_address)
@@ -9842,8 +9844,15 @@ Target_powerpc<size, big_endian>::relocate_relocs(
       else if (strategy == Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA)
 	{
 	  const Symbol_value<size>* psymval = object->local_symbol(orig_r_sym);
-	  gold_assert(os != NULL);
-	  addend = psymval->value(object, addend) - os->address();
+	  addend = psymval->value(object, addend);
+	  // In a relocatable link, the symbol value is relative to
+	  // the start of the output section. For a non-relocatable
+	  // link, we need to adjust the addend.
+	  if (!relocatable)
+	    {
+	      gold_assert(os != NULL);
+	      addend -= os->address();
+	    }
 	}
       else if (strategy == Relocatable_relocs::RELOC_SPECIAL)
 	{
@@ -9866,7 +9875,7 @@ Target_powerpc<size, big_endian>::relocate_relocs(
       else
 	gold_unreachable();
 
-      if (!parameters->options().relocatable())
+      if (!relocatable)
 	{
 	  if (r_type == elfcpp::R_POWERPC_GOT_TLSGD16
 	      || r_type == elfcpp::R_POWERPC_GOT_TLSGD16_LO
diff --git a/gold/target-reloc.h b/gold/target-reloc.h
index c8b86c6..79ed1d3 100644
--- a/gold/target-reloc.h
+++ b/gold/target-reloc.h
@@ -755,6 +755,8 @@ relocate_relocs(
 
   unsigned char* pwrite = reloc_view;
 
+  const bool relocatable = parameters->options().relocatable();
+
   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
     {
       Relocatable_relocs::Reloc_strategy strategy = relinfo->rr->strategy(i);
@@ -857,7 +859,7 @@ relocate_relocs(
       // In an object file, r_offset is an offset within the section.
       // In an executable or dynamic object, generated by
       // --emit-relocs, r_offset is an absolute address.
-      if (!parameters->options().relocatable())
+      if (!relocatable)
 	{
 	  new_offset += view_address;
 	  if (offset_in_output_section != invalid_address)
@@ -892,10 +894,17 @@ relocate_relocs(
 	    {
 	    case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA:
 	      {
-		typename elfcpp::Elf_types<size>::Elf_Swxword addend;
-		addend = Classify_reloc::get_r_addend(&reloc);
-		gold_assert(os != NULL);
-		addend = psymval->value(object, addend) - os->address();
+		typename elfcpp::Elf_types<size>::Elf_Swxword addend
+		    = Classify_reloc::get_r_addend(&reloc);
+		addend = psymval->value(object, addend);
+		// In a relocatable link, the symbol value is relative to
+		// the start of the output section. For a non-relocatable
+		// link, we need to adjust the addend.
+		if (!relocatable)
+		  {
+		    gold_assert(os != NULL);
+		    addend -= os->address();
+		  }
 		Classify_reloc::put_r_addend(&reloc_write, addend);
 	      }
 	      break;
diff --git a/gold/testsuite/pr22266_a.c b/gold/testsuite/pr22266_a.c
index b58254c..bdc09d4 100644
--- a/gold/testsuite/pr22266_a.c
+++ b/gold/testsuite/pr22266_a.c
@@ -3,3 +3,11 @@ static int int_from_a_1 = 0x11223344;
 
 __attribute__((section(".data.rel.ro.a")))
 int *p_int_from_a_2 = &int_from_a_1;
+
+const char *hello (void);
+
+const char *
+hello (void)
+{
+  return "XXXHello, world!" + 3;
+}
\ No newline at end of file
diff --git a/gold/testsuite/pr22266_main.c b/gold/testsuite/pr22266_main.c
index 1f3476e..b49b5e1 100644
--- a/gold/testsuite/pr22266_main.c
+++ b/gold/testsuite/pr22266_main.c
@@ -1,9 +1,13 @@
 #include <stdlib.h>
+#include <string.h>
 
 extern int *p_int_from_a_2;
+extern const char *hello (void);
 
 int main (void) {
   if (*p_int_from_a_2 != 0x11223344)
     abort ();
+  if (strcmp(hello(), "Hello, world!") != 0)
+    abort ();
   return 0;
 }
diff --git a/gold/testsuite/pr22266_script.t b/gold/testsuite/pr22266_script.t
index a9bc364..7b49988 100644
--- a/gold/testsuite/pr22266_script.t
+++ b/gold/testsuite/pr22266_script.t
@@ -8,8 +8,9 @@ SECTIONS
     .text : {
         *(.text*)
     }
-    .rodata.cst16 : {
-        *(.rodata.cst16*)
+    .rodata :
+    {
+        *(.rodata .rodata.* .gnu.linkonce.r.*)
     }
     .data.rel.ro : {
         *(.data.rel.ro*)