Support for dedicated ARM stub section with padding

2016-05-23  Thomas Preud'homme  <thomas.preudhomme@arm.com>

bfd/
	* elf32-arm.c (arm_dedicated_stub_section_padding): New function.
	(elf32_arm_size_stubs): Declare stub_type in a more outer scope and
	account for padding for stub section requiring one.
	(elf32_arm_build_stubs): Add comment to stress the importance of
	zeroing veneer section content.

2 files changed, 43 insertions, 2 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 5a99dcf..8d8c24c 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,5 +1,13 @@
 2016-05-23  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
+	* elf32-arm.c (arm_dedicated_stub_section_padding): New function.
+	(elf32_arm_size_stubs): Declare stub_type in a more outer scope and
+	account for padding for stub section requiring one.
+	(elf32_arm_build_stubs): Add comment to stress the importance of
+	zeroing veneer section content.
+
+2016-05-23  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
 	* bfd-in.h (bfd_elf32_arm_keep_private_stub_output_sections): Declare
 	bfd hook.
 	* bfd-in2.h: Regenerate.
diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index e5c69f5..6375ae4 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -4435,6 +4435,18 @@ arm_stub_sym_claimed (enum elf32_arm_stub_type stub_type)
   return FALSE;
 }
 
+/* Returns the padding needed for the dedicated section used stubs of type
+   STUB_TYPE.  */
+
+static int
+arm_dedicated_stub_section_padding (enum elf32_arm_stub_type stub_type)
+{
+  if (stub_type >= max_stub_type)
+    abort ();  /* Should be unreachable.  */
+
+  return 0;
+}
+
 static bfd_boolean
 arm_build_one_stub (struct bfd_hash_entry *gen_entry,
 		    void * in_arg)
@@ -5411,6 +5423,7 @@ elf32_arm_size_stubs (bfd *output_bfd,
       bfd *input_bfd;
       unsigned int bfd_indx;
       asection *stub_sec;
+      enum elf32_arm_stub_type stub_type;
       bfd_boolean stub_changed = FALSE;
       unsigned prev_num_a8_fixes = num_a8_fixes;
 
@@ -5466,7 +5479,6 @@ elf32_arm_size_stubs (bfd *output_bfd,
 	      for (; irela < irelaend; irela++)
 		{
 		  unsigned int r_type, r_indx;
-		  enum elf32_arm_stub_type stub_type;
 		  asection *sym_sec;
 		  bfd_vma sym_value;
 		  bfd_vma destination;
@@ -5780,7 +5792,27 @@ elf32_arm_size_stubs (bfd *output_bfd,
 	  stub_sec->size = 0;
 	}
 
+      /* Compute stub section size, considering padding.  */
       bfd_hash_traverse (&htab->stub_hash_table, arm_size_one_stub, htab);
+      for (stub_type = arm_stub_none + 1; stub_type < max_stub_type;
+	   stub_type++)
+	{
+	  int size, padding;
+	  asection **stub_sec_p;
+
+	  padding = arm_dedicated_stub_section_padding (stub_type);
+	  stub_sec_p = arm_dedicated_stub_input_section_ptr (htab, stub_type);
+	  /* Skip if no stub input section or no stub section padding
+	     required.  */
+	  if ((stub_sec_p != NULL && *stub_sec_p == NULL) || padding == 0)
+	    continue;
+	  /* Stub section padding required but no dedicated section.  */
+	  BFD_ASSERT (stub_sec_p);
+
+	  size = (*stub_sec_p)->size;
+	  size = (size + padding - 1) & ~(padding - 1);
+	  (*stub_sec_p)->size = size;
+	}
 
       /* Add Cortex-A8 erratum veneers to stub section sizes too.  */
       if (htab->fix_cortex_a8)
@@ -5885,7 +5917,8 @@ elf32_arm_build_stubs (struct bfd_link_info *info)
       if (!strstr (stub_sec->name, STUB_SUFFIX))
 	continue;
 
-      /* Allocate memory to hold the linker stubs.  */
+      /* Allocate memory to hold the linker stubs.  Zeroing the stub sections
+	 must at least be done for stub section requiring padding.  */
       size = stub_sec->size;
       stub_sec->contents = (unsigned char *) bfd_zalloc (htab->stub_bfd, size);
       if (stub_sec->contents == NULL && size != 0)