[gold][aarch64] Fix internal error while fixing 843419

[Han Shen <shenhan at google dot com>]

Hi Cary, here is the patch for gold internal error while fixing
erratum 843419 (reported by Android NDK).

The crash reason is that the insn to be moved to stub may be a
relocation spot, so instead of placing the origin insn (that is insn
before-relocation) to the stub, I have to place the relocated one.
Note the relocation involved is non-pc-relative, so it is safe to move
the relocated insn.

Testing - Build the problematic android component, assembly examined
(also add this to local aarch64 test set). And passed all previous
tests.

Ok for trunk?

gold/ChangeLog:
        * AArch64.cc (Erratum_stub::Insn_utilities): New typedef.
        (Erratum_stub::update_erratum_insn): New method.
        (Stub_table::relocate_stubs): Modified to place relocated insn.
        (AArch64_relobj::fix_errata): Modified gold_assert.

diff --git a/gold/aarch64.cc b/gold/aarch64.cc
index 72a65db..acdc0e8 100644
--- a/gold/aarch64.cc
+++ b/gold/aarch64.cc
@@ -892,10 +892,11 @@ template<int size, bool big_endian>
 class Erratum_stub : public Stub_base<size, big_endian>
 {
 public:
   typedef AArch64_relobj<size, big_endian> The_aarch64_relobj;
   typedef typename elfcpp::Elf_types<size>::Elf_Addr AArch64_address;
+  typedef AArch64_insn_utilities<big_endian> Insn_utilities;
   typedef typename AArch64_insn_utilities<big_endian>::Insntype Insntype;
 
   static const int STUB_ADDR_ALIGN;
 
   static const Insntype invalid_insn = static_cast<Insntype>(-1);
@@ -936,10 +937,43 @@ public:
   // Set the insn that the erratum happens to.
   void
   set_erratum_insn(Insntype insn)
   { this->erratum_insn_ = insn; }
 
+  // For 843419, the erratum insn is ld/st xt, [xn, #uimm], which may
+  // be a relocation spot, in this case, the erratum_insn_ recorded at
+  // scanning phase is no long the one we want to write out to the
+  // stub, update erratum_insn_ with relocated version. Also note that
+  // in this case xn must not be "PC", so it is safe to move the
+  // erratum insn from the origin place to the stub. For 835769, the
+  // erratum insn is multiply-accumulate insn, which could not be a
+  // relocation spot (assertion added though).
+  void
+  update_erratum_insn(Insntype insn)
+  {
+    gold_assert(this->erratum_insn_ != this->invalid_insn);
+    switch (this->type())
+      {
+      case ST_E_843419:
+	gold_assert(Insn_utilities::aarch64_ldst_uimm(insn));
+	gold_assert(Insn_utilities::aarch64_ldst_uimm(this->erratum_insn()));
+	gold_assert(Insn_utilities::aarch64_rd(insn) ==
+		    Insn_utilities::aarch64_rd(this->erratum_insn()));
+	gold_assert(Insn_utilities::aarch64_rn(insn) ==
+		    Insn_utilities::aarch64_rn(this->erratum_insn()));
+	// Update plain ld/st insn with relocated insn.
+	this->erratum_insn_ = insn;
+	break;
+      case ST_E_835769:
+	gold_assert(insn == this->erratum_insn());
+	break;
+      default:
+	gold_unreachable();
+      }
+  }
+
+
   // Return the address where an erratum must be done.
   AArch64_address
   erratum_address() const
   {
     gold_assert(this->erratum_address_ != this->invalid_address);
@@ -1415,11 +1449,11 @@ Stub_table<size, big_endian>::add_erratum_stub(The_erratum_stub* stub)
   stub->set_offset(this->erratum_stubs_size_);
   this->erratum_stubs_size_ += stub->stub_size();
 }
 
 
-// Find if such erratum exists for givein (obj, shndx, sh_offset).
+// Find if such erratum exists for given (obj, shndx, sh_offset).
 
 template<int size, bool big_endian>
 Erratum_stub<size, big_endian>*
 Stub_table<size, big_endian>::find_erratum_stub(
     The_aarch64_relobj* a64relobj, unsigned int shndx, unsigned int sh_offset)
@@ -1502,10 +1536,11 @@ relocate_stubs(const The_relocate_info* relinfo,
     relocate_stub(p->second, relinfo, target_aarch64, output_section,
 		  view, address, view_size);
 
   // Just for convenience.
   const int BPI = AArch64_insn_utilities<big_endian>::BYTES_PER_INSN;
+  typedef typename elfcpp::Swap<32, big_endian>::Valtype Insntype;
 
   // Now 'relocate' erratum stubs.
   for(Erratum_stub_set_iter i = this->erratum_stubs_.begin();
       i != this->erratum_stubs_.end(); ++i)
     {
@@ -1516,10 +1551,17 @@ relocate_stubs(const The_relocate_info* relinfo,
       int b_offset = 0;
       switch ((*i)->type())
 	{
 	case ST_E_843419:
 	case ST_E_835769:
+	  // The 1st insn of the erratum could be a relocation spot,
+	  // in this case we need to fix it with
+	  // "(*i)->erratum_insn()".
+	  elfcpp::Swap<32, big_endian>::writeval(
+	      reinterpret_cast<Insntype*>(
+		  view + (stub_address - this->address())),
+	      (*i)->erratum_insn());
 	  // For the erratum, the 2nd insn is a b-insn to be patched
 	  // (relocated).
 	  stub_b_insn_address = stub_address + 1 * BPI;
 	  b_offset = (*i)->destination_address() - stub_b_insn_address;
 	  AArch64_relocate_functions<size, big_endian>::construct_b(
@@ -1833,17 +1875,21 @@ AArch64_relobj<size, big_endian>::fix_errata(
 	  The_erratum_stub* stub = *p;
 	  typename Sized_relobj_file<size, big_endian>::View_size&
 	    pview((*pviews)[i]);
 
 	  // Double check data before fix.
+	  gold_assert(pview.address + stub->sh_offset()
+		      == stub->erratum_address());
+
+	  // Update previously recorded erratum insn with relocated
+	  // version.
 	  Insntype* ip =
 	    reinterpret_cast<Insntype*>(pview.view + stub->sh_offset());
 	  Insntype insn_to_fix = ip[0];
-	  gold_assert(insn_to_fix == stub->erratum_insn());
-	  gold_assert(pview.address + stub->sh_offset()
-		      == stub->erratum_address());
+	  stub->update_erratum_insn(insn_to_fix);
 
+	  // Replace the erratum insn with a branch-to-stub.
 	  AArch64_address stub_address =
 	    stub_table->erratum_stub_address(stub);
 	  unsigned int b_offset = stub_address - stub->erratum_address();
 	  AArch64_relocate_functions<size, big_endian>::construct_b(
 	    pview.view + stub->sh_offset(), b_offset & 0xfffffff);