elf_backend_section_flags and _bfd_elf_init_private_section_data

I was looking at elf_backend_section_flags as a means of setting
SEC_SMALL_DATA for .sdata, .sbss and the like, and condidered adding
an asection* parameter to access the section name easily before
realising that hdr->bfd_section of course makes the section
available.  So no new parameter needed.  In fact the flagword*
parameter isn't needed either, so out it goes.

The patch also tidies some horrible code in _bfd_elf_new_section_hook
that can change whether known ABI sections have sh_type and sh_flags
set up depending on which of the bfd_make_section functions is used.
(Some of those set section flags before _bfd_elf_new_section_hook is
called, others leave the flags zero.)  The function also had some
hacks for .init_array and .fini_array to affect how
_bfd_elf_init_private_section_data behaved for those sections.  It's
cleaner to do that in _bfd_elf_init_private_section_data.  So that all
goes and we now init sh_type and sh_flags for all known ABI sections
in _bfd_elf_new_section_hook.  _bfd_elf_init_private_section_data is
changed to suit, and now doesn't just single out SHT_INIT_ARRAY and
SHT_FINI_ARRAY but rather any of the special section types.

The _bfd_elf_new_section_hook change resulting in
+FAIL: ld-aarch64/erratum835769-843419
exposing some errors in the aarch64 backend.  elfNN_aarch64_size_stubs
should not be looking at linker created sections in the stub bfd.  Nor
should code like "symtab_hdr = &elf_tdata (input_bfd)->symtab_hdr" be
run without first checking that input_bfd is ELF.

	* elf-bfd.h (elf_backend_section_flags): Remove flagword* param.
	* elf.c (_bfd_elf_make_section_from_shdr): Set section flags before
	calling elf_backend_section_flags with adjusted params.  Use
	newsect->flags past that point.
	(_bfd_elf_new_section_hook): Always set sh_type and sh_flags for
	special sections.
	(_bfd_elf_init_private_section_data): Allow normal sh_type sections
	to have their type overridden, and all sh_flags but processor and
	os specific.
	* elf32-arm.c (elf32_arm_section_flags): Adjust for changed params.
	* elf32-mep.c (mep_elf_section_flags): Likewise.
	* elf32-nios2.c (nios2_elf32_section_flags): Likewise.
	* elf64-alpha.c (elf64_alpha_section_flags): Likewise.
	* elf64-ia64-vms.c (elf64_ia64_section_flags): Likewise.
	* elfnn-ia64.c (elfNN_ia64_section_flags): Likewise.
	* elfnn-aarch64.c (elfNN_aarch64_size_stubs): Exclude the linker
	stub BFD and non-aarch64 input files when scanning for stubs.

bfd/ChangeLog

@@ -1,3 +1,23 @@
+2020-03-02  Alan Modra  <amodra@gmail.com>
+
+	* elf-bfd.h (elf_backend_section_flags): Remove flagword* param.
+	* elf.c (_bfd_elf_make_section_from_shdr): Set section flags before
+	calling elf_backend_section_flags with adjusted params.  Use
+	newsect->flags past that point.
+	(_bfd_elf_new_section_hook): Always set sh_type and sh_flags for
+	special sections.
+	(_bfd_elf_init_private_section_data): Allow normal sh_type sections
+	to have their type overridden, and all sh_flags but processor and
+	os specific.
+	* elf32-arm.c (elf32_arm_section_flags): Adjust for changed params.
+	* elf32-mep.c (mep_elf_section_flags): Likewise.
+	* elf32-nios2.c (nios2_elf32_section_flags): Likewise.
+	* elf64-alpha.c (elf64_alpha_section_flags): Likewise.
+	* elf64-ia64-vms.c (elf64_ia64_section_flags): Likewise.
+	* elfnn-ia64.c (elfNN_ia64_section_flags): Likewise.
+	* elfnn-aarch64.c (elfNN_aarch64_size_stubs): Exclude the linker
+	stub BFD and non-aarch64 input files when scanning for stubs.
+
 2020-03-02  Alan Modra  <amodra@gmail.com>
 
 	* coff-alpha.c (alpha_ecoff_get_elt_at_filepos): Provide an upper

bfd/elf-bfd.h

@@ -955,7 +955,7 @@ struct elf_backend_data
   /* A function to convert machine dependent ELF section header flags to
      BFD internal section header flags.  */
   bfd_boolean (*elf_backend_section_flags)
-    (flagword *, const Elf_Internal_Shdr *);
+    (const Elf_Internal_Shdr *);
 
   /* A function that returns a struct containing ELF section flags and
      type for the given BFD section.   */

bfd/elf.c

@@ -1114,12 +1114,12 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
       && elf_next_in_group (newsect) == NULL)
     flags |= SEC_LINK_ONCE | SEC_LINK_DUPLICATES_DISCARD;
 
-  bed = get_elf_backend_data (abfd);
+  if (!bfd_set_section_flags (newsect, flags))
-  if (bed->elf_backend_section_flags)
-    if (! bed->elf_backend_section_flags (&flags, hdr))
     return FALSE;
 
-  if (!bfd_set_section_flags (newsect, flags))
+  bed = get_elf_backend_data (abfd);
+  if (bed->elf_backend_section_flags)
+    if (!bed->elf_backend_section_flags (hdr))
       return FALSE;
 
   /* We do not parse the PT_NOTE segments as we are interested even in the
@@ -1137,7 +1137,7 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
       free (contents);
     }
 
-  if ((flags & SEC_ALLOC) != 0)
+  if ((newsect->flags & SEC_ALLOC) != 0)
     {
       Elf_Internal_Phdr *phdr;
       unsigned int i, nload;
@@ -1163,7 +1163,7 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
 	       || phdr->p_type == PT_TLS)
 	      && ELF_SECTION_IN_SEGMENT (hdr, phdr))
 	    {
-	      if ((flags & SEC_LOAD) == 0)
+	      if ((newsect->flags & SEC_LOAD) == 0)
 		newsect->lma = (phdr->p_paddr
 				+ hdr->sh_addr - phdr->p_vaddr);
 	      else
@@ -1191,7 +1191,7 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
 
   /* Compress/decompress DWARF debug sections with names: .debug_* and
      .zdebug_*, after the section flags is set.  */
-  if ((flags & SEC_DEBUGGING)
+  if ((newsect->flags & SEC_DEBUGGING)
       && ((name[1] == 'd' && name[6] == '_')
 	  || (name[1] == 'z' && name[7] == '_')))
     {
@@ -2900,29 +2900,14 @@ _bfd_elf_new_section_hook (bfd *abfd, asection *sec)
   bed = get_elf_backend_data (abfd);
   sec->use_rela_p = bed->default_use_rela_p;
 
-  /* When we read a file, we don't need to set ELF section type and
+  /* Set up ELF section type and flags for newly created sections, if
-     flags.  They will be overridden in _bfd_elf_make_section_from_shdr
+     there is an ABI mandated section.  */
-     anyway.  We will set ELF section type and flags for all linker
-     created sections.  If user specifies BFD section flags, we will
-     set ELF section type and flags based on BFD section flags in
-     elf_fake_sections.  Special handling for .init_array/.fini_array
-     output sections since they may contain .ctors/.dtors input
-     sections.  We don't want _bfd_elf_init_private_section_data to
-     copy ELF section type from .ctors/.dtors input sections.  */
-  if (abfd->direction != read_direction
-      || (sec->flags & SEC_LINKER_CREATED) != 0)
-    {
   ssect = (*bed->get_sec_type_attr) (abfd, sec);
-      if (ssect != NULL
+  if (ssect != NULL)
-	  && (!sec->flags
-	      || (sec->flags & SEC_LINKER_CREATED) != 0
-	      || ssect->type == SHT_INIT_ARRAY
-	      || ssect->type == SHT_FINI_ARRAY))
     {
       elf_section_type (sec) = ssect->type;
       elf_section_flags (sec) = ssect->attr;
     }
-    }
 
   return _bfd_generic_new_section_hook (abfd, sec);
 }
@@ -7757,10 +7742,19 @@ _bfd_elf_init_private_section_data (bfd *ibfd,
 
   BFD_ASSERT (elf_section_data (osec) != NULL);
 
-  /* For objcopy and relocatable link, don't copy the output ELF
+  /* If this is a known ABI section, ELF section type and flags may
-     section type from input if the output BFD section flags have been
+     have been set up when OSEC was created.  For normal sections we
-     set to something different.  For a final link allow some flags
+     allow the user to override the type and flags other than
-     that the linker clears to differ.  */
+     SHF_MASKOS and SHF_MASKPROC.  */
+  if (elf_section_type (osec) == SHT_PROGBITS
+      || elf_section_type (osec) == SHT_NOTE
+      || elf_section_type (osec) == SHT_NOBITS)
+    elf_section_type (osec) = SHT_NULL;
+  /* For objcopy and relocatable link, copy the ELF section type from
+     the input file if the BFD section flags are the same.  (If they
+     are different the user may be doing something like
+     "objcopy --set-section-flags .text=alloc,data".)  For a final
+     link allow some flags that the linker clears to differ.  */
   if (elf_section_type (osec) == SHT_NULL
       && (osec->flags == isec->flags
 	  || (final_link
@@ -7769,7 +7763,7 @@ _bfd_elf_init_private_section_data (bfd *ibfd,
     elf_section_type (osec) = elf_section_type (isec);
 
   /* FIXME: Is this correct for all OS/PROC specific flags?  */
-  elf_section_flags (osec) |= (elf_section_flags (isec)
+  elf_section_flags (osec) = (elf_section_flags (isec)
 			      & (SHF_MASKOS | SHF_MASKPROC));
 
   /* Copy sh_info from input for mbind section.  */

bfd/elf32-arm.c

@@ -20230,10 +20230,10 @@ elf32_arm_get_synthetic_symtab (bfd *abfd,
 }
 
 static bfd_boolean
-elf32_arm_section_flags (flagword *flags, const Elf_Internal_Shdr * hdr)
+elf32_arm_section_flags (const Elf_Internal_Shdr *hdr)
 {
   if (hdr->sh_flags & SHF_ARM_PURECODE)
-    *flags |= SEC_ELF_PURECODE;
+    hdr->bfd_section->flags |= SEC_ELF_PURECODE;
   return TRUE;
 }
 

bfd/elf32-mep.c

@@ -717,10 +717,10 @@ mep_elf_object_p (bfd * abfd)
 }
 
 static bfd_boolean
-mep_elf_section_flags (flagword * flags, const Elf_Internal_Shdr * hdr)
+mep_elf_section_flags (const Elf_Internal_Shdr *hdr)
 {
   if (hdr->sh_flags & SHF_MEP_VLIW)
-    * flags |= SEC_MEP_VLIW;
+    hdr->bfd_section->flags |= SEC_MEP_VLIW;
   return TRUE;
 }
 

bfd/elf32-nios2.c

@@ -4539,10 +4539,10 @@ nios2_elf32_relocate_section (bfd *output_bfd,
 /* Implement elf-backend_section_flags:
    Convert NIOS2 specific section flags to bfd internal section flags.  */
 static bfd_boolean
-nios2_elf32_section_flags (flagword *flags, const Elf_Internal_Shdr *hdr)
+nios2_elf32_section_flags (const Elf_Internal_Shdr *hdr)
 {
   if (hdr->sh_flags & SHF_NIOS2_GPREL)
-    *flags |= SEC_SMALL_DATA;
+    hdr->bfd_section->flags |= SEC_SMALL_DATA;
 
   return TRUE;
 }

bfd/elf64-alpha.c

@@ -1180,10 +1180,10 @@ elf64_alpha_section_from_shdr (bfd *abfd,
 /* Convert Alpha specific section flags to bfd internal section flags.  */
 
 static bfd_boolean
-elf64_alpha_section_flags (flagword *flags, const Elf_Internal_Shdr *hdr)
+elf64_alpha_section_flags (const Elf_Internal_Shdr *hdr)
 {
   if (hdr->sh_flags & SHF_ALPHA_GPREL)
-    *flags |= SEC_SMALL_DATA;
+    hdr->bfd_section->flags |= SEC_SMALL_DATA;
 
   return TRUE;
 }

bfd/elf64-ia64-vms.c

@@ -822,11 +822,10 @@ is_unwind_section_name (bfd *abfd ATTRIBUTE_UNUSED, const char *name)
    flag.  */
 
 static bfd_boolean
-elf64_ia64_section_flags (flagword *flags,
+elf64_ia64_section_flags (const Elf_Internal_Shdr *hdr)
-			  const Elf_Internal_Shdr *hdr)
 {
   if (hdr->sh_flags & SHF_IA_64_SHORT)
-    *flags |= SEC_SMALL_DATA;
+    hdr->bfd_section->flags |= SEC_SMALL_DATA;
 
   return TRUE;
 }

bfd/elfnn-aarch64.c

@@ -4313,9 +4313,15 @@ elfNN_aarch64_size_stubs (bfd *output_bfd,
 
       for (input_bfd = info->input_bfds;
 	   input_bfd != NULL; input_bfd = input_bfd->link.next)
+	{
+	  if (!is_aarch64_elf (input_bfd)
+	      || (input_bfd->flags & BFD_LINKER_CREATED) != 0)
+	    continue;
+
 	  if (!_bfd_aarch64_erratum_835769_scan (input_bfd, info,
 						 &num_erratum_835769_fixes))
 	    return FALSE;
+	}
 
       _bfd_aarch64_resize_stubs (htab);
       (*htab->layout_sections_again) ();
@@ -4331,6 +4337,10 @@ elfNN_aarch64_size_stubs (bfd *output_bfd,
 	{
 	  asection *section;
 
+	  if (!is_aarch64_elf (input_bfd)
+	      || (input_bfd->flags & BFD_LINKER_CREATED) != 0)
+	    continue;
+
 	  for (section = input_bfd->sections;
 	       section != NULL;
 	       section = section->next)
@@ -4353,6 +4363,10 @@ elfNN_aarch64_size_stubs (bfd *output_bfd,
 	  asection *section;
 	  Elf_Internal_Sym *local_syms = NULL;
 
+	  if (!is_aarch64_elf (input_bfd)
+	      || (input_bfd->flags & BFD_LINKER_CREATED) != 0)
+	    continue;
+
 	  /* We'll need the symbol table in a second.  */
 	  symtab_hdr = &elf_tdata (input_bfd)->symtab_hdr;
 	  if (symtab_hdr->sh_info == 0)

bfd/elfnn-ia64.c

@@ -942,11 +942,10 @@ elfNN_ia64_section_from_shdr (bfd *abfd,
    flag.  */
 
 static bfd_boolean
-elfNN_ia64_section_flags (flagword *flags,
+elfNN_ia64_section_flags (const Elf_Internal_Shdr *hdr)
-			  const Elf_Internal_Shdr *hdr)
 {
   if (hdr->sh_flags & SHF_IA_64_SHORT)
-    *flags |= SEC_SMALL_DATA;
+    hdr->bfd_section->flags |= SEC_SMALL_DATA;
 
   return TRUE;
 }