[RFD 3/5] ld: aarch64: make EH Frame parsing aware of augmentation char 'G'

[Indu Bhagat]

As per the DWARF for the Arm 64-bit Architecture (AArch64)
specification, the augmentation char 'G' indicates that associated
frames may modify MTE tags on the stack space they use.

Add knowledge of the 'G' augmentation char to the EH Frame parsing code.

ChangeLog:

        * bfd/elf-eh-frame.c (_bfd_elf_parse_eh_frame): Accommodate
	augmentation char 'G'.
        * ld/testsuite/ld-aarch64/aarch64-elf.exp: New test.
        * ld/testsuite/ld-aarch64/mte-tagged-frame-bar.s: New test.
        * ld/testsuite/ld-aarch64/mte-tagged-frame-foo.s: New test.
        * ld/testsuite/ld-aarch64/mte-tagged-frame.d: New test.
---
 bfd/elf-eh-frame.c                            |  2 ++
 ld/testsuite/ld-aarch64/aarch64-elf.exp       |  2 ++
 .../ld-aarch64/mte-tagged-frame-bar.s         | 17 +++++++++++
 .../ld-aarch64/mte-tagged-frame-foo.s         | 16 ++++++++++
 ld/testsuite/ld-aarch64/mte-tagged-frame.d    | 29 +++++++++++++++++++
 5 files changed, 66 insertions(+)
 create mode 100644 ld/testsuite/ld-aarch64/mte-tagged-frame-bar.s
 create mode 100644 ld/testsuite/ld-aarch64/mte-tagged-frame-foo.s
 create mode 100644 ld/testsuite/ld-aarch64/mte-tagged-frame.d

diff --git a/bfd/elf-eh-frame.c b/bfd/elf-eh-frame.c
index 6e0da8c4dd8..34f9797eeb1 100644
--- a/bfd/elf-eh-frame.c
+++ b/bfd/elf-eh-frame.c
@@ -840,6 +840,8 @@ _bfd_elf_parse_eh_frame (bfd *abfd, struct bfd_link_info *info,
 		      REQUIRE (skip_bytes (&buf, end, per_width));
 		    }
 		    break;
+		  case 'G':
+		    break;
 		  default:
 		    /* Unrecognized augmentation. Better bail out.  */
 		    goto free_no_table;
diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
index e65d4ce5a3d..04ea4cfbd5d 100644
--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
+++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
@@ -376,6 +376,8 @@ run_dump_test_lp64 "variant_pcs-r"
 run_dump_test_lp64 "variant_pcs-shared"
 run_dump_test_lp64 "variant_pcs-now"
 
+run_dump_test_lp64 "mte-tagged-frame"
+
 set aarch64elflinktests {
   {"ld-aarch64/so with global symbol" "-shared" "" "" {copy-reloc-so.s}
     {} "copy-reloc-so.so"}
diff --git a/ld/testsuite/ld-aarch64/mte-tagged-frame-bar.s b/ld/testsuite/ld-aarch64/mte-tagged-frame-bar.s
new file mode 100644
index 00000000000..0bd56191912
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/mte-tagged-frame-bar.s
@@ -0,0 +1,17 @@
+	.text
+	.global bar
+	.type bar, %function
+bar:
+	.cfi_startproc
+	.cfi_mte_tagged_frame
+        stp     x19, x20, [sp, -144]!
+        .cfi_def_cfa_offset 144
+        .cfi_offset 19, -144
+        .cfi_offset 20, -136
+        ldp     x19, x20, [sp], 144
+        .cfi_restore 20
+        .cfi_restore 19
+        .cfi_def_cfa_offset 0
+        ret
+	.cfi_endproc
+	.size bar, .-bar
diff --git a/ld/testsuite/ld-aarch64/mte-tagged-frame-foo.s b/ld/testsuite/ld-aarch64/mte-tagged-frame-foo.s
new file mode 100644
index 00000000000..af5a8c42f95
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/mte-tagged-frame-foo.s
@@ -0,0 +1,16 @@
+	.text
+	.global foo
+	.type foo, %function
+foo:
+	.cfi_startproc
+        stp     x19, x20, [sp, -32]!
+        .cfi_def_cfa_offset 32
+        .cfi_offset 19, -32
+        .cfi_offset 20, -16
+        ldp     x19, x20, [sp], 32
+        .cfi_restore 20
+        .cfi_restore 19
+        .cfi_def_cfa_offset 0
+        ret
+	.cfi_endproc
+	.size foo, .-foo
diff --git a/ld/testsuite/ld-aarch64/mte-tagged-frame.d b/ld/testsuite/ld-aarch64/mte-tagged-frame.d
new file mode 100644
index 00000000000..f7000ff671c
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/mte-tagged-frame.d
@@ -0,0 +1,29 @@
+#source: mte-tagged-frame-foo.s
+#source: mte-tagged-frame-bar.s
+#ld: -shared
+#objdump: -WF
+
+#...
+Contents of the .eh_frame section:
+
+
+0+0 0+10 0+0 CIE "zR" cf=4 df=-8 ra=30
+ +LOC +CFA +
+0+0 sp\+0 +
+
+0+14 0+20 0+18 FDE cie=0+0 pc=0+17c..0+188
+ +LOC +CFA +x19 +x20 +
+0+17c sp\+0 +u +u +
+0+180 sp\+32 +c-32  c-16  
+0+184 sp\+0 +u +u +
+
+0+38 0+14 0+0 CIE "zRG" cf=4 df=-8 ra=30
+ +LOC +CFA +
+0+0 sp\+0 +
+
+0+50 0+1c 0+1c FDE cie=0+38 pc=0+188..0+194
+ +LOC +CFA +x19 +x20 +
+0+188 sp\+0 +u +u +
+0+18c sp\+144 +c-144 c-136 
+0+190 sp\+0 +u +u +
+#...
-- 
2.43.0