[GOLD] Power10 segv due to wild r2

Calling non-pcrel functions from pcrel code requires a stub to set up
r2.  Gold created the stub, but an "optimisation" made the stub jump
to the function local entry, ie. r2 was not initialised.

This patch fixes that long branch stub problem, and another that might
occur for plt call stubs to local functions.

bfd/
	* elf64-ppc.c (write_plt_relocs_for_local_syms): Don't do local
	entry offset optimisation.
gold/
	* powerpc.cc (Powerpc_relobj::do_relocate_sections): Don't do
	local entry offset optimisation for lplt_section.
	(Target_powerpc::Branch_info::make_stub): Don't add local
	entry offset to long branch dest passed to
	add_long_branch_entry.  Do pass st_other bits.
	(Stub_table::Branch_stub_ent): Add "other_" field.
	(Stub_table::add_long_branch_entry): Add "other" param, and
	save.
	(Stub_table::branch_stub_size): Adjust long branch offset.
	(Stub_table::do_write): Likewise.
	(Target_powerpc::Relocate::relocate): Likewise.

(cherry picked from commit fa40fbe484954c560ab1c0ff4bc1b2eeb1511344)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index ac66598c2d742c3d93532edb6928508bffaad9fa..2bca0948f6ea09be89dbf34e3f54fb5af5631a49 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,8 @@
+2020-10-09  Alan Modra  <amodra@gmail.com>
+
+       * elf64-ppc.c (write_plt_relocs_for_local_syms): Don't do local
+       entry offset optimisation.
+
 2020-10-07  H.J. Lu  <hongjiu.lu@intel.com>
 
        PR ld/26711

diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index 0aeda47e5722dae3b718a67030be09e008ff8283..ec8c85eba595b81e15edf3b7ce9bb435f23e368b 100644 (file)
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -14255,8 +14255,6 @@ write_plt_relocs_for_local_syms (struct bfd_link_info *info)
                }
 
              val = sym->st_value + ent->addend;
-             if (ELF_ST_TYPE (sym->st_info) != STT_GNU_IFUNC)
-               val += PPC64_LOCAL_ENTRY_OFFSET (sym->st_other);
              if (sym_sec != NULL && sym_sec->output_section != NULL)
                val += sym_sec->output_offset + sym_sec->output_section->vma;
 

diff --git a/gold/ChangeLog b/gold/ChangeLog
index 0d7576bffc667a071a7179c9f03cb617ebb54d73..03d99a52fe8dbb8a66918356e67b0b27c0100b87 100644 (file)
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,17 @@
+2020-10-09  Alan Modra  <amodra@gmail.com>
+
+       * powerpc.cc (Powerpc_relobj::do_relocate_sections): Don't do
+       local entry offset optimisation for lplt_section.
+       (Target_powerpc::Branch_info::make_stub): Don't add local
+       entry offset to long branch dest passed to
+       add_long_branch_entry.  Do pass st_other bits.
+       (Stub_table::Branch_stub_ent): Add "other_" field.
+       (Stub_table::add_long_branch_entry): Add "other" param, and
+       save.
+       (Stub_table::branch_stub_size): Adjust long branch offset.
+       (Stub_table::do_write): Likewise.
+       (Target_powerpc::Relocate::relocate): Likewise.
+
 2020-10-09  Alan Modra  <amodra@gmail.com>
 
        * powerpc.cc (is_got_reloc): New function.

diff --git a/gold/powerpc.cc b/gold/powerpc.cc
index f9eb4f98bdace607373e0ca3ad80f9e9cb5bbf2c..476fb4e588d85f383b4d68bd9746d9ebb6be4bba 100644 (file)
--- a/gold/powerpc.cc
+++ b/gold/powerpc.cc
@@ -2767,8 +2767,6 @@ Powerpc_relobj<size, big_endian>::do_relocate_sections(
            if (this->local_has_plt_offset(i))
              {
                Address value = this->local_symbol_value(i, 0);
-               if (size == 64)
-                 value += ppc64_local_entry_offset(i);
                size_t off = this->local_plt_offset(i);
                elfcpp::Swap<size, big_endian>::writeval(oview + off, value);
                modified = true;
@@ -3539,6 +3537,7 @@ Target_powerpc<size, big_endian>::Branch_info::make_stub(
       from += (this->object_->output_section(this->shndx_)->address()
               + this->offset_);
       Address to;
+      unsigned int other;
       if (gsym != NULL)
        {
          switch (gsym->source())
@@ -3566,8 +3565,7 @@ Target_powerpc<size, big_endian>::Branch_info::make_stub(
          to = symtab->compute_final_value<size>(gsym, &status);
          if (status != Symbol_table::CFVS_OK)
            return true;
-         if (size == 64)
-           to += this->object_->ppc64_local_entry_offset(gsym);
+         other = gsym->nonvis() >> 3;
        }
       else
        {
@@ -3584,8 +3582,7 @@ Target_powerpc<size, big_endian>::Branch_info::make_stub(
              || !symval.has_output_value())
            return true;
          to = symval.value(this->object_, 0);
-         if (size == 64)
-           to += this->object_->ppc64_local_entry_offset(this->r_sym_);
+         other = this->object_->st_other(this->r_sym_) >> 5;
        }
       if (!(size == 32 && this->r_type_ == elfcpp::R_PPC_PLTREL24))
        to += this->addend_;
@@ -3598,7 +3595,11 @@ Target_powerpc<size, big_endian>::Branch_info::make_stub(
                                         &to, &dest_shndx))
            return true;
        }
-      Address delta = to - from;
+      unsigned int local_ent = 0;
+      if (size == 64
+         && this->r_type_ != elfcpp::R_PPC64_REL24_NOTOC)
+       local_ent = elfcpp::ppc64_decode_local_entry(other);
+      Address delta = to + local_ent - from;
       if (delta + max_branch_offset >= 2 * max_branch_offset
          || (size == 64
              && this->r_type_ == elfcpp::R_PPC64_REL24_NOTOC
@@ -3620,7 +3621,7 @@ Target_powerpc<size, big_endian>::Branch_info::make_stub(
                           && gsym->output_data() == target->savres_section());
          ok = stub_table->add_long_branch_entry(this->object_,
                                                 this->r_type_,
-                                                from, to, save_res);
+                                                from, to, other, save_res);
        }
     }
   if (!ok)
@@ -4688,7 +4689,7 @@ class Stub_table : public Output_relaxed_input_section
   {
     Branch_stub_ent(unsigned int off, bool notoc, bool save_res)
       : off_(off), iter_(0), notoc_(notoc), toc_(0), save_res_(save_res),
-       tocoff_(0)
+       other_(0), tocoff_(0)
     { }
 
     unsigned int off_;
@@ -4696,6 +4697,7 @@ class Stub_table : public Output_relaxed_input_section
     unsigned int notoc_ : 1;
     unsigned int toc_ : 1;
     unsigned int save_res_ : 1;
+    unsigned int other_ : 3;
     unsigned int tocoff_ : 8;
   };
   typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
@@ -4762,7 +4764,7 @@ class Stub_table : public Output_relaxed_input_section
   // Add a long branch stub.
   bool
   add_long_branch_entry(const Powerpc_relobj<size, big_endian>*,
-                       unsigned int, Address, Address, bool);
+                       unsigned int, Address, Address, unsigned int, bool);
 
   const Branch_stub_ent*
   find_long_branch_entry(const Powerpc_relobj<size, big_endian>*,
@@ -5282,6 +5284,7 @@ Stub_table<size, big_endian>::add_long_branch_entry(
     unsigned int r_type,
     Address from,
     Address to,
+    unsigned int other,
     bool save_res)
 {
   Branch_stub_key key(object, to);
@@ -5301,6 +5304,8 @@ Stub_table<size, big_endian>::add_long_branch_entry(
        this->need_resize_ = true;
       p.first->second.toc_ = true;
     }
+  if (p.first->second.other_ == 0)
+    p.first->second.other_ = other;
   gold_assert(save_res == p.first->second.save_res_);
   if (p.second || (this->resizing_ && !p.first->second.iter_))
     {
@@ -6198,6 +6203,7 @@ Stub_table<size, big_endian>::branch_stub_size(
        }
     }
 
+  off += elfcpp::ppc64_decode_local_entry(p->second.other_);
   if (off + (1 << 25) < 2 << 25)
     return bytes + 4;
   if (!this->targ_->power10_stubs()
@@ -6377,6 +6383,7 @@ Stub_table<size, big_endian>::do_write(Output_file* of)
                }
              if (bs->second.toc_)
                {
+                 delta += elfcpp::ppc64_decode_local_entry(bs->second.other_);
                  if (delta + (1 << 25) >= 2 << 25)
                    {
                      Address brlt_addr
@@ -6410,6 +6417,8 @@ Stub_table<size, big_endian>::do_write(Output_file* of)
            }
          else
            {
+             if (!bs->second.notoc_)
+               delta += elfcpp::ppc64_decode_local_entry(bs->second.other_);
              if (bs->second.notoc_ || delta + (1 << 25) >= 2 << 25)
                {
                  unsigned char* startp = p;
@@ -6640,6 +6649,8 @@ Stub_table<size, big_endian>::do_write(Output_file* of)
          p = oview + off;
          Address loc = this->stub_address() + off;
          Address delta = bs->first.dest_ - loc;
+         if (!bs->second.notoc_)
+           delta += elfcpp::ppc64_decode_local_entry(bs->second.other_);
          if (bs->second.notoc_)
            {
              unsigned char* startp = p;
@@ -11039,14 +11050,15 @@ Target_powerpc<size, big_endian>::Relocate::relocate(
                || r_type == elfcpp::R_POWERPC_PLT16_HA)))
        addend = rela.get_r_addend();
       value = psymval->value(object, addend);
+      unsigned int local_ent = 0;
       if (size == 64 && is_branch_reloc<size>(r_type))
        {
          if (target->abiversion() >= 2)
            {
              if (gsym != NULL)
-               value += object->ppc64_local_entry_offset(gsym);
+               local_ent = object->ppc64_local_entry_offset(gsym);
              else
-               value += object->ppc64_local_entry_offset(r_sym);
+               local_ent = object->ppc64_local_entry_offset(r_sym);
            }
          else
            {
@@ -11055,9 +11067,9 @@ Target_powerpc<size, big_endian>::Relocate::relocate(
                                        &value, &dest_shndx);
            }
        }
-      Address max_branch_offset = max_branch_delta<size>(r_type);
-      if (max_branch_offset != 0
-         && (value - address + max_branch_offset >= 2 * max_branch_offset
+      Address max_branch = max_branch_delta<size>(r_type);
+      if (max_branch != 0
+         && (value + local_ent - address + max_branch >= 2 * max_branch
              || (size == 64
                  && r_type == elfcpp::R_PPC64_REL24_NOTOC
                  && (gsym != NULL
@@ -11082,12 +11094,15 @@ Target_powerpc<size, big_endian>::Relocate::relocate(
                               + ent->off_);
                      if (size == 64
                          && r_type != elfcpp::R_PPC64_REL24_NOTOC)
-                       value += ent->tocoff_;
+                       value += (elfcpp::ppc64_decode_local_entry(ent->other_)
+                                 + ent->tocoff_);
                    }
                  has_stub_value = true;
                }
            }
        }
+      if (!has_stub_value)
+       value += local_ent;
     }
 
   switch (r_type)