ARM: Fix exidx coverage for relocatable builds.

bfd  * elf-bfd.h: Add callback to count additional relocations.
     * elf32-arm.c (_arm_elf_section_data): Add new counter.
     (insert_cantunwind_after): Increment relocations counter.
     (elf32_arm_fix_exidx_coverage): Remove exidx entries and add
     terminating CANTUNWIND entry only in final builds.
     (elf32_arm_add_relocation): New function.
     (elf32_arm_write_section): Add relocations in relocatable builds.
     (elf32_arm_count_additional_relocs): New function.
     (elf_backend_count_additional_relocs): New define.
     * bfd/elflink.c (bfd_elf_final_link): Use callback and adjust size of
     .rel section.
     * bfd/elfxx-target.h (elf_backend_count_additional_relocs): New define.

ld   * emultempl/armelf.em (gld${EMULATION_NAME}_after_allocation): Call
     elf32_arm_fix_exidx_coverage for relocatable builds.

ld/testsuite
     * ld-arm/arm-elf.exp: New test.
     * ld-arm/unwind-rel.d: New file.
     * ld-arm/unwind-rel1.s: New file.
     * ld-arm/unwind-rel2.s: New file.
     * ld-arm/unwind-rel3.s: New file.

5 files changed, 61 insertions, 0 deletions

diff --git a/ld/testsuite/ld-arm/arm-elf.exp b/ld/testsuite/ld-arm/arm-elf.exp
index a970dba..ac2abf1 100644
--- a/ld/testsuite/ld-arm/arm-elf.exp
+++ b/ld/testsuite/ld-arm/arm-elf.exp
@@ -941,3 +941,9 @@ run_dump_test "gc-hidden-1"
 run_dump_test "protected-data"
 run_dump_test "stm32l4xx-cannot-fix-it-block"
 run_dump_test "stm32l4xx-cannot-fix-far-ldm"
+set arm_unwind_tests {
+    {"unwind-rel" "-r -Tarm.ld" "" "" {unwind-rel1.s unwind-rel2.s unwind-rel3.s}
+     {{readelf -ur unwind-rel.d}}
+     "unwind-rel"}
+}
+run_ld_link_tests $arm_unwind_tests
diff --git a/ld/testsuite/ld-arm/unwind-rel.d b/ld/testsuite/ld-arm/unwind-rel.d
new file mode 100644
index 0000000..b2aa6e2
--- /dev/null
+++ b/ld/testsuite/ld-arm/unwind-rel.d
@@ -0,0 +1,31 @@
+
+Relocation section '\.rel\.text' at offset .* contains 3 entries:
+ Offset     Info    Type            Sym\.Value  Sym\. Name
+00000000  00000028 R_ARM_V4BX       
+00000004  00000028 R_ARM_V4BX       
+00000008  00000028 R_ARM_V4BX       
+
+Relocation section '\.rel\.ARM\.exidx' at offset .* contains 5 entries:
+ Offset     Info    Type            Sym\.Value  Sym\. Name
+00000000  0000012a R_ARM_PREL31      00000000   \.text
+00000000  00000e00 R_ARM_NONE        00000000   __aeabi_unwind_cpp_pr0
+00000008  0000012a R_ARM_PREL31      00000000   \.text
+00000010  0000012a R_ARM_PREL31      00000000   \.text
+00000010  00000e00 R_ARM_NONE        00000000   __aeabi_unwind_cpp_pr0
+
+Unwind table index '\.ARM\.exidx' at offset .* contains 3 entries:
+
+0x0: 0x80a8b0b0
+  Compact model index: 0
+  0xa8      pop {r4, r14}
+  0xb0      finish
+  0xb0      finish
+
+0x4 <test>: 0x1 \[cantunwind\]
+
+0x8 <end>: 0x80a8b0b0
+  Compact model index: 0
+  0xa8      pop {r4, r14}
+  0xb0      finish
+  0xb0      finish
+
diff --git a/ld/testsuite/ld-arm/unwind-rel1.s b/ld/testsuite/ld-arm/unwind-rel1.s
new file mode 100644
index 0000000..9efb78b
--- /dev/null
+++ b/ld/testsuite/ld-arm/unwind-rel1.s
@@ -0,0 +1,9 @@
+	.syntax unified
+	.text
+	.global _start
+	.type _start, %function
+_start:
+	.fnstart
+	.save {r4, lr}
+	bx lr
+	.fnend
diff --git a/ld/testsuite/ld-arm/unwind-rel2.s b/ld/testsuite/ld-arm/unwind-rel2.s
new file mode 100644
index 0000000..1001743
--- /dev/null
+++ b/ld/testsuite/ld-arm/unwind-rel2.s
@@ -0,0 +1,6 @@
+	.syntax unified
+	.text
+	.global test
+	.type test, %function
+test:
+	bx lr
diff --git a/ld/testsuite/ld-arm/unwind-rel3.s b/ld/testsuite/ld-arm/unwind-rel3.s
new file mode 100644
index 0000000..8511339
--- /dev/null
+++ b/ld/testsuite/ld-arm/unwind-rel3.s
@@ -0,0 +1,9 @@
+	.syntax unified
+	.text
+	.global end
+	.type end, %function
+end:
+	.fnstart
+	.save {r4, lr}
+	bx lr
+	.fnend