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Re: [RFC PATCH, binutils, ARM 5/11] Allow veneers to claim veneered symbols
- From: Thomas Preudhomme <thomas dot preudhomme at foss dot arm dot com>
- To: Nick Clifton <nickc at redhat dot com>
- Cc: binutils at sourceware dot org
- Date: Thu, 05 May 2016 11:08:22 +0100
- Subject: Re: [RFC PATCH, binutils, ARM 5/11] Allow veneers to claim veneered symbols
- Authentication-results: sourceware.org; auth=none
- References: <004e01d13d57$bac5a860$3050f920$ at foss dot arm dot com> <1537478 dot Y6W5P8olra at e108577-lin> <56FBF56F dot 2080107 at redhat dot com>
On Tuesday 05 April 2016 11:06:30 Nick Clifton wrote:
> Hi Thomas,
Hi Nick,
>
> >> I don't like that "max_stub_type" is not actually the maximum possible
> >> value for an elf32_arn_stub_type enum. The name is misleading. Maybe
> >> you could use something like "last_non_veneer_stub".
> >
> > Last is confusing because it's last + 1. To be fair, I don't think this
> > should be a stub type, rather a const global variable. I can include that
> > in the Cortex-A8 refactoring patch, what do you think?
>
> I think that would be much cleaner, so yes please.
Please find an updated patch with all your comments addressed. ChangeLog entry
is unchanged:
*** bfd/ChangeLog ***
2016-03-23 Thomas Preud'homme <thomas.preudhomme@arm.com>
* elf32-arm.c (enum elf32_arm_stub_type): New max_stub_type
enumerator.
(arm_stub_sym_claimed): New function.
(elf32_arm_create_stub): Use veneered symbol name and section if
veneer needs to claim its symbol, and keep logic unchanged otherwise.
(arm_stub_claim_sym): New function.
(arm_map_one_stub): Call arm_stub_claim_sym if veneer needs to claim
veneered symbol, otherwise create local symbol as before.
diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index
71d60222cab2cd0634ff61362ee9eb4d84a85f14..02977358ac69deab379f2d826c44bfc5efa49e1a
100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -2632,6 +2632,7 @@ enum elf32_arm_stub_type
{
arm_stub_none,
DEF_STUBS
+ max_stub_type
};
#undef DEF_STUB
@@ -4335,6 +4336,18 @@ arm_stub_required_alignment (enum elf32_arm_stub_type
stub_type)
}
}
+/* Returns whether stubs of type STUB_TYPE take over the symbol they are
+ veneering (TRUE) or have their own symbol (FALSE). */
+
+static bfd_boolean
+arm_stub_sym_claimed (enum elf32_arm_stub_type stub_type)
+{
+ if (stub_type >= max_stub_type)
+ abort (); /* Should be unreachable. */
+
+ return FALSE;
+}
+
static bfd_boolean
arm_build_one_stub (struct bfd_hash_entry *gen_entry,
void * in_arg)
@@ -5141,27 +5154,35 @@ elf32_arm_create_stub (struct
elf32_arm_link_hash_table *htab,
char *stub_name;
struct elf32_arm_stub_hash_entry *stub_entry;
unsigned int r_type;
+ bfd_boolean sym_claimed = arm_stub_sym_claimed (stub_type);
BFD_ASSERT (stub_type != arm_stub_none);
*new_stub = FALSE;
- BFD_ASSERT (irela);
- BFD_ASSERT (section);
+ if (sym_claimed)
+ stub_name = sym_name;
+ else
+ {
+ BFD_ASSERT (irela);
+ BFD_ASSERT (section);
- /* Support for grouping stub sections. */
- id_sec = htab->stub_group[section->id].link_sec;
+ /* Support for grouping stub sections. */
+ id_sec = htab->stub_group[section->id].link_sec;
- /* Get the name of this stub. */
- stub_name = elf32_arm_stub_name (id_sec, sym_sec, hash, irela, stub_type);
- if (!stub_name)
- return FALSE;
+ /* Get the name of this stub. */
+ stub_name = elf32_arm_stub_name (id_sec, sym_sec, hash, irela,
+ stub_type);
+ if (!stub_name)
+ return FALSE;
+ }
stub_entry = arm_stub_hash_lookup (&htab->stub_hash_table, stub_name,
FALSE,
FALSE);
/* The proper stub has already been created, just update its value. */
if (stub_entry != NULL)
{
- free (stub_name);
+ if (!sym_claimed)
+ free (stub_name);
stub_entry->target_value = sym_value;
return TRUE;
}
@@ -5169,7 +5190,8 @@ elf32_arm_create_stub (struct elf32_arm_link_hash_table
*htab,
stub_entry = elf32_arm_add_stub (stub_name, section, htab);
if (stub_entry == NULL)
{
- free (stub_name);
+ if (!sym_claimed)
+ free (stub_name);
return FALSE;
}
@@ -5179,31 +5201,36 @@ elf32_arm_create_stub (struct
elf32_arm_link_hash_table *htab,
stub_entry->h = hash;
stub_entry->branch_type = branch_type;
- if (sym_name == NULL)
- sym_name = "unnamed";
- stub_entry->output_name = (char *)
- bfd_alloc (htab->stub_bfd, sizeof (THUMB2ARM_GLUE_ENTRY_NAME)
- + strlen (sym_name));
- if (stub_entry->output_name == NULL)
+ if (sym_claimed)
+ stub_entry->output_name = sym_name;
+ else
{
- free (stub_name);
- return FALSE;
- }
+ if (sym_name == NULL)
+ sym_name = "unnamed";
+ stub_entry->output_name = (char *)
+ bfd_alloc (htab->stub_bfd, sizeof (THUMB2ARM_GLUE_ENTRY_NAME)
+ + strlen (sym_name));
+ if (stub_entry->output_name == NULL)
+ {
+ free (stub_name);
+ return FALSE;
+ }
- /* For historical reasons, use the existing names for ARM-to-Thumb and
- Thumb-to-ARM stubs. */
- r_type = ELF32_R_TYPE (irela->r_info);
- if ((r_type == (unsigned int) R_ARM_THM_CALL
- || r_type == (unsigned int) R_ARM_THM_JUMP24
- || r_type == (unsigned int) R_ARM_THM_JUMP19)
- && branch_type == ST_BRANCH_TO_ARM)
- sprintf (stub_entry->output_name, THUMB2ARM_GLUE_ENTRY_NAME, sym_name);
- else if ((r_type == (unsigned int) R_ARM_CALL
- || r_type == (unsigned int) R_ARM_JUMP24)
- && branch_type == ST_BRANCH_TO_THUMB)
- sprintf (stub_entry->output_name, ARM2THUMB_GLUE_ENTRY_NAME, sym_name);
- else
- sprintf (stub_entry->output_name, STUB_ENTRY_NAME, sym_name);
+ /* For historical reasons, use the existing names for ARM-to-Thumb and
+ Thumb-to-ARM stubs. */
+ r_type = ELF32_R_TYPE (irela->r_info);
+ if ((r_type == (unsigned int) R_ARM_THM_CALL
+ || r_type == (unsigned int) R_ARM_THM_JUMP24
+ || r_type == (unsigned int) R_ARM_THM_JUMP19)
+ && branch_type == ST_BRANCH_TO_ARM)
+ sprintf (stub_entry->output_name, THUMB2ARM_GLUE_ENTRY_NAME, sym_name);
+ else if ((r_type == (unsigned int) R_ARM_CALL
+ || r_type == (unsigned int) R_ARM_JUMP24)
+ && branch_type == ST_BRANCH_TO_THUMB)
+ sprintf (stub_entry->output_name, ARM2THUMB_GLUE_ENTRY_NAME, sym_name);
+ else
+ sprintf (stub_entry->output_name, STUB_ENTRY_NAME, sym_name);
+ }
*new_stub = TRUE;
return TRUE;
@@ -15853,6 +15880,20 @@ elf32_arm_output_plt_map (struct elf_link_hash_entry
*h, void *inf)
&h->plt, &eh->plt);
}
+/* Bind a veneered symbol to its veneer identified by its hash entry
+ STUB_ENTRY. The veneered location thus loose its symbol. */
+
+static void
+arm_stub_claim_sym (struct elf32_arm_stub_hash_entry *stub_entry)
+{
+ struct elf32_arm_link_hash_entry *hash = stub_entry->h;
+
+ BFD_ASSERT (hash);
+ hash->root.root.u.def.section = stub_entry->stub_sec;
+ hash->root.root.u.def.value = stub_entry->stub_offset;
+ hash->root.size = stub_entry->stub_size;
+}
+
/* Output a single local symbol for a generated stub. */
static bfd_boolean
@@ -15899,24 +15940,30 @@ arm_map_one_stub (struct bfd_hash_entry * gen_entry,
return TRUE;
addr = (bfd_vma) stub_entry->stub_offset;
- stub_name = stub_entry->output_name;
-
template_sequence = stub_entry->stub_template;
- switch (template_sequence[0].type)
+
+ if (arm_stub_sym_claimed (stub_entry->stub_type))
+ arm_stub_claim_sym (stub_entry);
+ else
{
- case ARM_TYPE:
- if (!elf32_arm_output_stub_sym (osi, stub_name, addr, stub_entry-
>stub_size))
- return FALSE;
- break;
- case THUMB16_TYPE:
- case THUMB32_TYPE:
- if (!elf32_arm_output_stub_sym (osi, stub_name, addr | 1,
- stub_entry->stub_size))
- return FALSE;
- break;
- default:
- BFD_FAIL ();
- return 0;
+ stub_name = stub_entry->output_name;
+ switch (template_sequence[0].type)
+ {
+ case ARM_TYPE:
+ if (!elf32_arm_output_stub_sym (osi, stub_name, addr,
+ stub_entry->stub_size))
+ return FALSE;
+ break;
+ case THUMB16_TYPE:
+ case THUMB32_TYPE:
+ if (!elf32_arm_output_stub_sym (osi, stub_name, addr | 1,
+ stub_entry->stub_size))
+ return FALSE;
+ break;
+ default:
+ BFD_FAIL ();
+ return 0;
+ }
}
prev_type = DATA_TYPE;
Best regards,
Thomas