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[PATCH, binutils, ARM] Fix Thumb-2 BL detection
- From: Thomas Preudhomme <thomas dot preudhomme at foss dot arm dot com>
- To: binutils at sourceware dot org
- Date: Wed, 29 Jun 2016 10:22:23 +0100
- Subject: [PATCH, binutils, ARM] Fix Thumb-2 BL detection
- Authentication-results: sourceware.org; auth=none
Commit 60a019a089177f3f58f636580857414d769b8c11 (Fix feature checks based on
ARM architecture value) fixed the logic in using_thumb2 () to detect what
architecture have Thumb-2 technology. However, that function was also use to
detect the availability of Thumb-2 BL which is available in all post-ARMv6T2
architecture, including ARMv6-M. This patch introduces a new function
using_thumb2_bl () to detect availability of this instruction and changes the
place depending on this information to use this new function instead of
using_thumb2 (). It also adds a patch to check that the logic works for ARMv6-
M.
ChangeLog entries are as follow:
*** bfd/ChangeLog ***
2016-06-20 Thomas Preud'homme <thomas.preudhomme@arm.com>
* elf32-arm.c (using_thumb2_bl): New function.
(arm_type_of_stub): Declare thumb2 variable together and change type
to bfd_boolean. Use using_thumb2_bl () to determine whether
THM_MAX_FWD_BRANCH_OFFSET or THM2_MAX_FWD_BRANCH_OFFSET should be
checked for BL range.
(elf32_arm_final_link_relocate): Use using_thumb2_bl () to determine
the bit size of BL offset.
*** ld/ChangeLog ***
2016-06-20 Thomas Preud'homme <thomas.preudhomme@arm.com>
* testsuite/ld-arm/arm-elf.exp (Thumb-2 BL): Assemble for ARMv7.
(Thumb-2 BL on ARMv6-M): New testcase.
* testsuite/ld-arm/thumb2-bl.d: Do not try to match testcase filename.
* testsuite/ld-arm/thumb2-bl.s: Do not select architecture.
binutils testsuite run did not show any regression, nor did GCC testsuite when
running it for ARM7TDMI (pre-ARMv6T2 Thumb-1), Cortex-M0 (Thumb-1 with Thumb-2
BL) and Cortex-M3 (Thumb-2).
Is this ok for master branch?
Best regards.
Thomasdiff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index a7964c12b928789f43c9b83085fad49d35a42a15..843d8f09395f5c6c6f7640101ffcd883c1f61269 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -3569,6 +3569,24 @@ using_thumb2 (struct elf32_arm_link_hash_table *globals)
|| arch == TAG_CPU_ARCH_V8M_MAIN);
}
+/* Determine whether Thumb-2 BL instruction is available. */
+
+static bfd_boolean
+using_thumb2_bl (struct elf32_arm_link_hash_table *globals)
+{
+ int arch =
+ bfd_elf_get_obj_attr_int (globals->obfd, OBJ_ATTR_PROC, Tag_CPU_arch);
+
+ /* Force return logic to be reviewed for each new architecture. */
+ BFD_ASSERT (arch <= TAG_CPU_ARCH_V8
+ || arch == TAG_CPU_ARCH_V8M_BASE
+ || arch == TAG_CPU_ARCH_V8M_MAIN);
+
+ /* Architecture was introduced after ARMv6T2 (eg. ARMv6-M). */
+ return (arch == TAG_CPU_ARCH_V6T2
+ || arch >= TAG_CPU_ARCH_V7);
+}
+
/* Create .plt, .rel(a).plt, .got, .got.plt, .rel(a).got, .dynbss, and
.rel(a).bss sections in DYNOBJ, and set up shortcuts to them in our
hash table. */
@@ -3823,8 +3841,7 @@ arm_type_of_stub (struct bfd_link_info *info,
bfd_signed_vma branch_offset;
unsigned int r_type;
struct elf32_arm_link_hash_table * globals;
- int thumb2;
- int thumb_only;
+ bfd_boolean thumb2, thumb2_bl, thumb_only;
enum elf32_arm_stub_type stub_type = arm_stub_none;
int use_plt = 0;
enum arm_st_branch_type branch_type = *actual_branch_type;
@@ -3839,8 +3856,8 @@ arm_type_of_stub (struct bfd_link_info *info,
return stub_type;
thumb_only = using_thumb_only (globals);
-
thumb2 = using_thumb2 (globals);
+ thumb2_bl = using_thumb2_bl (globals);
/* Determine where the call point is. */
location = (input_sec->output_offset
@@ -3906,10 +3923,10 @@ arm_type_of_stub (struct bfd_link_info *info,
but only if this call is not through a PLT entry. Indeed,
PLT stubs handle mode switching already.
*/
- if ((!thumb2
+ if ((!thumb2_bl
&& (branch_offset > THM_MAX_FWD_BRANCH_OFFSET
|| (branch_offset < THM_MAX_BWD_BRANCH_OFFSET)))
- || (thumb2
+ || (thumb2_bl
&& (branch_offset > THM2_MAX_FWD_BRANCH_OFFSET
|| (branch_offset < THM2_MAX_BWD_BRANCH_OFFSET)))
|| (thumb2
@@ -9838,6 +9855,7 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto,
bfd_signed_vma signed_check;
int bitsize;
const int thumb2 = using_thumb2 (globals);
+ const int thumb2_bl = using_thumb2_bl (globals);
/* A branch to an undefined weak symbol is turned into a jump to
the next instruction unless a PLT entry will be created.
@@ -10014,7 +10032,7 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto,
this relocation according to whether we're relocating for
Thumb-2 or not. */
bitsize = howto->bitsize;
- if (!thumb2)
+ if (!thumb2_bl)
bitsize -= 2;
reloc_signed_max = (1 << (bitsize - 1)) - 1;
reloc_signed_min = ~reloc_signed_max;
diff --git a/ld/testsuite/ld-arm/arm-elf.exp b/ld/testsuite/ld-arm/arm-elf.exp
index a5d4c8757cbe96367ecc4defe75397b4d9645c51..597bdcf4ccbc9db7e78df20b34ecc7a6f4ea6410 100644
--- a/ld/testsuite/ld-arm/arm-elf.exp
+++ b/ld/testsuite/ld-arm/arm-elf.exp
@@ -604,9 +604,12 @@ set armeabitests_nonacl {
{{objdump -d fix-arm1176-off.d}}
"fix-arm1176-6"}
- {"Thumb-2 BL" "-Ttext 0x1000 --section-start .foo=0x1001000" "" "" {thumb2-bl.s}
+ {"Thumb-2 BL" "-Ttext 0x1000 --section-start .foo=0x1001000" "" "-march=armv7" {thumb2-bl.s}
{{objdump -dr thumb2-bl.d}}
"thumb2-bl"}
+ {"Thumb-2 BL on ARMv6-M" "-Ttext 0x1000 --section-start .foo=0x1001000" "" "-march=armv6-m" {thumb2-bl.s}
+ {{objdump -dr thumb2-bl.d}}
+ "thumb2-armv6m-bl"}
{"Thumb-2 Interworked branch" "-T arm.ld" "" "" {thumb2-b-interwork.s}
{{objdump -dr thumb2-b-interwork.d}}
"thumb2-b-interwork"}
diff --git a/ld/testsuite/ld-arm/thumb2-bl.d b/ld/testsuite/ld-arm/thumb2-bl.d
index 298a0446a0cefc26e45332c40146222340646ac4..8dab0c048f472389987f0191f303013a9feeaaa8 100644
--- a/ld/testsuite/ld-arm/thumb2-bl.d
+++ b/ld/testsuite/ld-arm/thumb2-bl.d
@@ -1,5 +1,5 @@
-.*thumb2-bl: file format elf32-.*arm.*
+.*: file format elf32-.*arm.*
Disassembly of section .text:
diff --git a/ld/testsuite/ld-arm/thumb2-bl.s b/ld/testsuite/ld-arm/thumb2-bl.s
index ddb1cd33fcb65f3ff113987fcc1e220f3145b747..80af8108b8f13049dde75afcf973bf984fa9e0d9 100644
--- a/ld/testsuite/ld-arm/thumb2-bl.s
+++ b/ld/testsuite/ld-arm/thumb2-bl.s
@@ -1,7 +1,6 @@
@ Test to ensure that a Thumb-2 BL works with an offset that is
@ not permissable for Thumb-1.
- .arch armv7
.global _start
.syntax unified