ARM CMSE symbols

This patch removes use of st_target_internal to cache the result of
comparing symbol names against CMSE_PREFIX.  The problem with setting
a bit in st_target_internal in swap_symbol_in is that calling
bfd_elf_sym_name from swap_symbol_in requires symtab_hdr, and you
don't know for sure whether swap_symbol_in is operating on dynsyms
(and thus elf_tdata (abfd)->dynsymtab_hdr should be used) or on the
normal symtab (thus elf_tdata (abfd)->symtab_hdr).  You can make an
educated guess based on abfd->flags & DYNAMIC but that relies on
knowing a lot about calls to bfd_elf_get_elf_syms, and is fragile in
the face of possible future changes.

include/
	* elf/arm.h (ARM_GET_SYM_CMSE_SPCL, ARM_SET_SYM_CMSE_SPCL): Delete.
bfd/
	* elf32-arm.c (cmse_scan): Don't use ARM_GET_SYM_CMSE_SPCL,
	instead recognize CMSE_PREFIX in symbol name.
	(elf32_arm_gc_mark_extra_sections): Likewise.
	(elf32_arm_filter_cmse_symbols): Don't test ARM_GET_SYM_CMSE_SPCL.
	(elf32_arm_swap_symbol_in): Don't invoke ARM_SET_SYM_CMSE_SPCL.

4 files changed, 18 insertions, 27 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 97d3726..a725504 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,11 @@
+2019-08-22  Alan Modra  <amodra@gmail.com>
+
+	* elf32-arm.c (cmse_scan): Don't use ARM_GET_SYM_CMSE_SPCL,
+	instead recognize CMSE_PREFIX in symbol name.
+	(elf32_arm_gc_mark_extra_sections): Likewise.
+	(elf32_arm_filter_cmse_symbols): Don't test ARM_GET_SYM_CMSE_SPCL.
+	(elf32_arm_swap_symbol_in): Don't invoke ARM_SET_SYM_CMSE_SPCL.
+
 2019-08-20  Dennis Zhang  <dennis.zhang@arm.com>
 
 	* cpu-aarch64.c: New entries for Cortex-A34, Cortex-A65,
diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index d1548d6..b675fc6 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -6002,12 +6002,12 @@ cmse_scan (bfd *input_bfd, struct elf32_arm_link_hash_table *htab,
       if (i < ext_start)
 	{
 	  cmse_sym = &local_syms[i];
-	  /* Not a special symbol.  */
-	  if (!ARM_GET_SYM_CMSE_SPCL (cmse_sym->st_target_internal))
-	    continue;
 	  sym_name = bfd_elf_string_from_elf_section (input_bfd,
 						      symtab_hdr->sh_link,
 						      cmse_sym->st_name);
+	  if (!sym_name || !CONST_STRNEQ (sym_name, CMSE_PREFIX))
+	    continue;
+
 	  /* Special symbol with local binding.  */
 	  cmse_invalid = TRUE;
 	}
@@ -6015,9 +6015,7 @@ cmse_scan (bfd *input_bfd, struct elf32_arm_link_hash_table *htab,
 	{
 	  cmse_hash = elf32_arm_hash_entry (sym_hashes[i - ext_start]);
 	  sym_name = (char *) cmse_hash->root.root.root.string;
-
-	  /* Not a special symbol.  */
-	  if (!ARM_GET_SYM_CMSE_SPCL (cmse_hash->root.target_internal))
+	  if (!CONST_STRNEQ (sym_name, CMSE_PREFIX))
 	    continue;
 
 	  /* Special symbol has incorrect binding or type.  */
@@ -15990,7 +15988,8 @@ elf32_arm_gc_mark_extra_sections (struct bfd_link_info *info,
 
 		  /* Assume it is a special symbol.  If not, cmse_scan will
 		     warn about it and user can do something about it.  */
-		  if (ARM_GET_SYM_CMSE_SPCL (cmse_hash->root.target_internal))
+		  if (CONST_STRNEQ (cmse_hash->root.root.root.string,
+				    CMSE_PREFIX))
 		    {
 		      cmse_sec = cmse_hash->root.root.u.def.section;
 		      if (!cmse_sec->gc_mark
@@ -18610,9 +18609,6 @@ elf32_arm_filter_cmse_symbols (bfd *abfd ATTRIBUTE_UNUSED,
 	  || cmse_hash->root.type != STT_FUNC)
 	continue;
 
-      if (!ARM_GET_SYM_CMSE_SPCL (cmse_hash->root.target_internal))
-	continue;
-
       syms[dst_count++] = sym;
     }
   free (cmse_name);
@@ -19935,9 +19931,6 @@ elf32_arm_swap_symbol_in (bfd * abfd,
 			  const void *pshn,
 			  Elf_Internal_Sym *dst)
 {
-  Elf_Internal_Shdr *symtab_hdr;
-  const char *name = NULL;
-
   if (!bfd_elf32_swap_symbol_in (abfd, psrc, pshn, dst))
     return FALSE;
   dst->st_target_internal = 0;
@@ -19966,13 +19959,6 @@ elf32_arm_swap_symbol_in (bfd * abfd,
   else
     ARM_SET_SYM_BRANCH_TYPE (dst->st_target_internal, ST_BRANCH_UNKNOWN);
 
-  /* Mark CMSE special symbols.  */
-  symtab_hdr = & elf_symtab_hdr (abfd);
-  if (symtab_hdr->sh_size)
-    name = bfd_elf_sym_name (abfd, symtab_hdr, dst, NULL);
-  if (name && CONST_STRNEQ (name, CMSE_PREFIX))
-    ARM_SET_SYM_CMSE_SPCL (dst->st_target_internal);
-
   return TRUE;
 }
 
diff --git a/include/ChangeLog b/include/ChangeLog
index 1813cb3..e779c17 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,7 @@
+2019-08-22  Alan Modra  <amodra@gmail.com>
+
+	* elf/arm.h (ARM_GET_SYM_CMSE_SPCL, ARM_SET_SYM_CMSE_SPCL): Delete.
+
 2019-08-09  Mihailo Stojanovic  <mihailo.stojanovic@rt-rk.com>
 
 	* elf/mips.h (SHT_GNU_XHASH): New define.
diff --git a/include/elf/arm.h b/include/elf/arm.h
index 5cb9970..75fb5e2 100644
--- a/include/elf/arm.h
+++ b/include/elf/arm.h
@@ -399,11 +399,4 @@ enum arm_st_branch_type {
 	   | ((TYPE) & ENUM_ARM_ST_BRANCH_TYPE_BITMASK))
 #endif
 
-/* Get or set whether a symbol is a special symbol of an entry function of CMSE
-   secure code.  */
-#define ARM_GET_SYM_CMSE_SPCL(SYM_TARGET_INTERNAL) \
-  (((SYM_TARGET_INTERNAL) >> 2) & 1)
-#define ARM_SET_SYM_CMSE_SPCL(SYM_TARGET_INTERNAL) \
-  (SYM_TARGET_INTERNAL) |= 4
-
 #endif /* _ELF_ARM_H */