Skip PLT for function pointer initialization

[external/binutils.git] / bfd / elf64-x86-64.c

diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index f15d33e..f753c7a 100644 (file)
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -767,6 +767,10 @@ struct elf_x86_64_link_hash_entry
   /* TRUE if symbol has at least one BND relocation.  */
   unsigned int has_bnd_reloc : 1;
 
+  /* Reference count of C/C++ function pointer relocations in read-write
+     section which can be resolved at run-time.  */
+  bfd_signed_vma func_pointer_refcount;
+
   /* Information about the GOT PLT entry. Filled when there are both
      GOT and PLT relocations against the same function.  */
   union gotplt_union plt_got;
@@ -906,6 +910,7 @@ elf_x86_64_link_hash_newfunc (struct bfd_hash_entry *entry,
       eh->tls_type = GOT_UNKNOWN;
       eh->needs_copy = 0;
       eh->has_bnd_reloc = 0;
+      eh->func_pointer_refcount = 0;
       eh->plt_bnd.offset = (bfd_vma) -1;
       eh->plt_got.offset = (bfd_vma) -1;
       eh->tlsdesc_got = (bfd_vma) -1;
@@ -976,6 +981,7 @@ elf_x86_64_get_local_sym_hash (struct elf_x86_64_link_hash_table *htab,
       ret->elf.indx = sec->id;
       ret->elf.dynstr_index = htab->r_sym (rel->r_info);
       ret->elf.dynindx = -1;
+      ret->func_pointer_refcount = 0;
       ret->plt_got.offset = (bfd_vma) -1;
       *slot = ret;
     }
@@ -1173,7 +1179,15 @@ elf_x86_64_copy_indirect_symbol (struct bfd_link_info *info,
       dir->pointer_equality_needed |= ind->pointer_equality_needed;
     }
   else
-    _bfd_elf_link_hash_copy_indirect (info, dir, ind);
+    {
+      if (eind->func_pointer_refcount > 0)
+       {
+         edir->func_pointer_refcount += eind->func_pointer_refcount;
+         eind->func_pointer_refcount = 0;
+       }
+
+      _bfd_elf_link_hash_copy_indirect (info, dir, ind);
+    }
 }
 
 static bfd_boolean
@@ -1950,7 +1964,22 @@ pointer:
              if (r_type != R_X86_64_PC32
                  && r_type != R_X86_64_PC32_BND
                  && r_type != R_X86_64_PC64)
-               h->pointer_equality_needed = 1;
+               {
+                 h->pointer_equality_needed = 1;
+                 /* At run-time, R_X86_64_64 can be resolved for both
+                    x86-64 and x32. But R_X86_64_32 and R_X86_64_32S
+                    can only be resolved for x32.  */
+                 if ((sec->flags & SEC_READONLY) == 0
+                     && (r_type == R_X86_64_64
+                         || (!ABI_64_P (abfd)
+                             && (r_type == R_X86_64_32
+                                 || r_type == R_X86_64_32S))))
+                   {
+                     struct elf_x86_64_link_hash_entry *eh
+                       = (struct elf_x86_64_link_hash_entry *) h;
+                     eh->func_pointer_refcount += 1;
+                   }
+               }
            }
 
          size_reloc = FALSE;
@@ -2177,6 +2206,7 @@ elf_x86_64_gc_sweep_hook (bfd *abfd, struct bfd_link_info *info,
       unsigned long r_symndx;
       unsigned int r_type;
       struct elf_link_hash_entry *h = NULL;
+      bfd_boolean pointer_reloc;
 
       r_symndx = htab->r_sym (rel->r_info);
       if (r_symndx >= symtab_hdr->sh_info)
@@ -2228,6 +2258,7 @@ elf_x86_64_gc_sweep_hook (bfd *abfd, struct bfd_link_info *info,
                                       rel, relend, h, r_symndx))
        return FALSE;
 
+      pointer_reloc = FALSE;
       switch (r_type)
        {
        case R_X86_64_TLSLD:
@@ -2261,11 +2292,15 @@ elf_x86_64_gc_sweep_hook (bfd *abfd, struct bfd_link_info *info,
            }
          break;
 
-       case R_X86_64_8:
-       case R_X86_64_16:
        case R_X86_64_32:
-       case R_X86_64_64:
        case R_X86_64_32S:
+         pointer_reloc = !ABI_64_P (abfd);
+         goto pointer;
+
+       case R_X86_64_64:
+         pointer_reloc = TRUE;
+       case R_X86_64_8:
+       case R_X86_64_16:
        case R_X86_64_PC8:
        case R_X86_64_PC16:
        case R_X86_64_PC32:
@@ -2273,6 +2308,7 @@ elf_x86_64_gc_sweep_hook (bfd *abfd, struct bfd_link_info *info,
        case R_X86_64_PC64:
        case R_X86_64_SIZE32:
        case R_X86_64_SIZE64:
+pointer:
          if (bfd_link_pic (info)
              && (h == NULL || h->type != STT_GNU_IFUNC))
            break;
@@ -2285,6 +2321,13 @@ elf_x86_64_gc_sweep_hook (bfd *abfd, struct bfd_link_info *info,
            {
              if (h->plt.refcount > 0)
                h->plt.refcount -= 1;
+             if (pointer_reloc && (sec->flags & SEC_READONLY) == 0)
+               {
+                 struct elf_x86_64_link_hash_entry *eh
+                   = (struct elf_x86_64_link_hash_entry *) h;
+                 if (eh->func_pointer_refcount > 0)
+                   eh->func_pointer_refcount -= 1;
+               }
            }
          break;
 
@@ -2516,6 +2559,11 @@ elf_x86_64_allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf)
       eh->plt_got.refcount = 1;
     }
 
+  /* Clear the reference count of function pointer relocations if
+     symbol isn't a normal function.  */
+  if (h->type != STT_FUNC)
+    eh->func_pointer_refcount = 0;
+
   /* Since STT_GNU_IFUNC symbol must go through PLT, we handle it
      here if it is defined and referenced in a non-shared object.  */
   if (h->type == STT_GNU_IFUNC
@@ -2542,11 +2590,18 @@ elf_x86_64_allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf)
       else
        return FALSE;
     }
+  /* Don't create the PLT entry if there are only function pointer
+     relocations which can be resolved at run-time.  */
   else if (htab->elf.dynamic_sections_created
-          && (h->plt.refcount > 0 || eh->plt_got.refcount > 0))
+          && (h->plt.refcount > eh->func_pointer_refcount
+              || eh->plt_got.refcount > 0))
     {
       bfd_boolean use_plt_got;
 
+      /* Clear the reference count of function pointer relocations
+        if PLT is used.  */
+      eh->func_pointer_refcount = 0;
+
       if ((info->flags & DF_BIND_NOW) && !h->pointer_equality_needed)
        {
          /* Don't use the regular PLT for DF_BIND_NOW. */
@@ -2791,9 +2846,10 @@ elf_x86_64_allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf)
     {
       /* For the non-shared case, discard space for relocs against
         symbols which turn out to need copy relocs or are not
-        dynamic.  */
+        dynamic.  Keep dynamic relocations for run-time function
+        pointer initialization.  */
 
-      if (!h->non_got_ref
+      if ((!h->non_got_ref || eh->func_pointer_refcount > 0)
          && ((h->def_dynamic
               && !h->def_regular)
              || (htab->elf.dynamic_sections_created
@@ -2814,6 +2870,7 @@ elf_x86_64_allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf)
        }
 
       eh->dyn_relocs = NULL;
+      eh->func_pointer_refcount = 0;
 
     keep: ;
     }
@@ -4346,7 +4403,8 @@ direct:
 
           /* Don't copy a pc-relative relocation into the output file
              if the symbol needs copy reloc or the symbol is undefined
-             when building executable.  */
+             when building executable.  Copy dynamic function pointer
+             relocations.  */
          if ((bfd_link_pic (info)
               && !(bfd_link_executable (info)
                    && h != NULL
@@ -4365,7 +4423,7 @@ direct:
                  && !bfd_link_pic (info)
                  && h != NULL
                  && h->dynindx != -1
-                 && !h->non_got_ref
+                 && (!h->non_got_ref || eh->func_pointer_refcount > 0)
                  && ((h->def_dynamic
                       && !h->def_regular)
                      || h->root.type == bfd_link_hash_undefweak