Fix ld-arm bug in encoding of blx calls jumping from thumb to arm instructions

	PR 28924
	* elf32-arm.c (THM_MAX_FWD_BRANCH_OFFSET): Fix definition.
	(THM2_MAX_FWD_BRANCH_OFFSET): Likewise.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 414646c84f0feeb06ec74b5d1d045bd60926dbe4..6ac8b96c57adef812005f0caf3db227794ce6ef5 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,9 @@
+2022-03-18  Viorel Preoteasa  <viorel.preoteasa@gmail.com>
+
+       PR 28924
+       * elf32-arm.c (THM_MAX_FWD_BRANCH_OFFSET): Fix definition.
+       (THM2_MAX_FWD_BRANCH_OFFSET): Likewise.
+
 2022-03-16  Simon Marchi  <simon.marchi@efficios.com>
 
        * Makefile.am (ALL_MACHINES, ALL_MACHINES_CFILES):

diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index 616efe60ad1fd14f4a2483d30c93daee7b5a3bc0..5b8f5e5a0e6c8b781e6159f77fd43a6b82a42e05 100644 (file)
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -2536,11 +2536,23 @@ static const bfd_vma elf32_arm_nacl_plt_entry [] =
   0xea000000,          /* b    .Lplt_tail                      */
 };
 
+/* PR 28924:
+   There was a bug due to too high values of THM_MAX_FWD_BRANCH_OFFSET and
+   THM2_MAX_FWD_BRANCH_OFFSET.  The first macro concerns the case when Thumb-2
+   is not available, and second macro when Thumb-2 is available.  Among other
+   things, they affect the range of branches represented as BLX instructions
+   in Encoding T2 defined in Section A8.8.25 of the ARM Architecture
+   Reference Manual ARMv7-A and ARMv7-R edition issue C.d.  Such branches are
+   specified there to have a maximum forward offset that is a multiple of 4.
+   Previously, the respective values defined here were multiples of 2 but not
+   4 and they are included in comments for reference.  */
 #define ARM_MAX_FWD_BRANCH_OFFSET  ((((1 << 23) - 1) << 2) + 8)
-#define ARM_MAX_BWD_BRANCH_OFFSET  ((-((1 << 23) << 2)) + 8)
-#define THM_MAX_FWD_BRANCH_OFFSET  ((1 << 22) -2 + 4)
+#define ARM_MAX_BWD_BRANCH_OFFSET ((-((1 << 23) << 2)) + 8)
+#define THM_MAX_FWD_BRANCH_OFFSET   ((1 << 22) - 4 + 4)
+/* #def THM_MAX_FWD_BRANCH_OFFSET   ((1 << 22) - 2 + 4) */
 #define THM_MAX_BWD_BRANCH_OFFSET  (-(1 << 22) + 4)
-#define THM2_MAX_FWD_BRANCH_OFFSET (((1 << 24) - 2) + 4)
+#define THM2_MAX_FWD_BRANCH_OFFSET (((1 << 24) - 4) + 4)
+/* #def THM2_MAX_FWD_BRANCH_OFFSET (((1 << 24) - 2) + 4) */
 #define THM2_MAX_BWD_BRANCH_OFFSET (-(1 << 24) + 4)
 #define THM2_MAX_FWD_COND_BRANCH_OFFSET (((1 << 20) -2) + 4)
 #define THM2_MAX_BWD_COND_BRANCH_OFFSET (-(1 << 20) + 4)