[PATCH v2 3/4] aarch64 DWARF: add new CFI directive for PAuth_LR

[Matthieu Longo]

This patch adds a new CFI directive (cfi_negate_ra_state_with_pc) which
set an additional bit in the RA state to inform that RA was signed with
SP but also PC as an additional diversifier.

RA state | Description
0b00     | Return address not signed (default if no cfi_negate_ra_state*)
0b01     | Return address signed with SP (cfi_negate_ra_state)
0b10     | Invalid state
0b11     | Return address signed with SP+PC (cfi_negate_ra_state_with_pc)
---
 bfd/elf-eh-frame.c |  1 +
 binutils/dwarf.c   |  5 +++++
 gas/dw2gencfi.c    | 10 ++++++++++
 gas/scfidw2gen.c   |  1 +
 include/dwarf2.def |  2 ++
 5 files changed, 19 insertions(+)

diff --git a/bfd/elf-eh-frame.c b/bfd/elf-eh-frame.c
index 6e0da8c4dd8..e8244bc0444 100644
--- a/bfd/elf-eh-frame.c
+++ b/bfd/elf-eh-frame.c
@@ -359,6 +359,7 @@ skip_cfa_op (bfd_byte **iter, bfd_byte *end, unsigned int encoded_ptr_width)
     case DW_CFA_remember_state:
     case DW_CFA_restore_state:
     case DW_CFA_GNU_window_save:
+    case DW_CFA_AARCH64_negate_ra_state_with_pc:
       /* No arguments.  */
       return true;
 
diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index 79a18e39ccd..582efafcf88 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -10354,6 +10354,11 @@ display_debug_frames (struct dwarf_section *section,
 	      fc->pc_begin += ofs;
 	      break;
 
+	    case DW_CFA_AARCH64_negate_ra_state_with_pc:
+	      if (! do_debug_frames_interp)
+		printf ("  DW_CFA_AARCH64_negate_ra_state_with_pc\n");
+	      break;
+
 	    case DW_CFA_GNU_window_save:
 	      if (! do_debug_frames_interp)
 		printf ("  %s\n", DW_CFA_GNU_window_save_name[is_aarch64]);
diff --git a/gas/dw2gencfi.c b/gas/dw2gencfi.c
index 14b73ef33c5..5071a161576 100644
--- a/gas/dw2gencfi.c
+++ b/gas/dw2gencfi.c
@@ -718,6 +718,7 @@ const pseudo_typeS cfi_pseudo_table[] =
     { "cfi_restore_state", dot_cfi, DW_CFA_restore_state },
     { "cfi_window_save", dot_cfi, DW_CFA_GNU_window_save },
     { "cfi_negate_ra_state", dot_cfi, DW_CFA_AARCH64_negate_ra_state },
+    { "cfi_negate_ra_state_with_pc", dot_cfi, DW_CFA_AARCH64_negate_ra_state_with_pc },
     { "cfi_escape", dot_cfi_escape, 0 },
     { "cfi_signal_frame", dot_cfi, CFI_signal_frame },
     { "cfi_personality", dot_cfi_personality, 0 },
@@ -918,6 +919,10 @@ dot_cfi (int arg)
       cfi_add_CFA_insn (DW_CFA_GNU_window_save);
       break;
 
+    case DW_CFA_AARCH64_negate_ra_state_with_pc:
+      cfi_add_CFA_insn (DW_CFA_AARCH64_negate_ra_state_with_pc);
+      break;
+
     case CFI_signal_frame:
       frchain_now->frch_cfi_data->cur_fde_data->signal_frame = 1;
       break;
@@ -1758,6 +1763,10 @@ output_cfi_insn (struct cfi_insn_data *insn)
       out_one (DW_CFA_GNU_window_save);
       break;
 
+    case DW_CFA_AARCH64_negate_ra_state_with_pc:
+      out_one (DW_CFA_AARCH64_negate_ra_state_with_pc);
+      break;
+
     case CFI_escape:
       {
 	struct cfi_escape_data *e;
@@ -2216,6 +2225,7 @@ cfi_change_reg_numbers (struct cfi_insn_data *insn, segT ccseg)
 	case DW_CFA_remember_state:
 	case DW_CFA_restore_state:
 	case DW_CFA_GNU_window_save:
+	case DW_CFA_AARCH64_negate_ra_state_with_pc:
 	case CFI_escape:
 	case CFI_label:
 	  break;
diff --git a/gas/scfidw2gen.c b/gas/scfidw2gen.c
index 2b018fac8bd..1fd0cd832e5 100644
--- a/gas/scfidw2gen.c
+++ b/gas/scfidw2gen.c
@@ -113,6 +113,7 @@ const pseudo_typeS scfi_pseudo_table[] =
     { "cfi_restore_state", dot_scfi_ignore, 0 },
     { "cfi_window_save", dot_scfi_ignore, 0 },
     { "cfi_negate_ra_state", dot_scfi_ignore, 0 },
+    { "cfi_negate_ra_state_with_pc", dot_scfi_ignore, 0 },
     { "cfi_escape", dot_scfi_ignore, 0 },
     { "cfi_personality", dot_scfi_ignore, 0 },
     { "cfi_personality_id", dot_scfi_ignore, 0 },
diff --git a/include/dwarf2.def b/include/dwarf2.def
index 66c7fa1220f..538198b3026 100644
--- a/include/dwarf2.def
+++ b/include/dwarf2.def
@@ -785,6 +785,8 @@ DW_CFA (DW_CFA_hi_user, 0x3f)
 
 /* SGI/MIPS specific.  */
 DW_CFA (DW_CFA_MIPS_advance_loc8, 0x1d)
+/* AArch64 extensions. */
+DW_CFA (DW_CFA_AARCH64_negate_ra_state_with_pc, 0x2c)
 /* GNU extensions.
    NOTE: DW_CFA_GNU_window_save is multiplexed on Sparc and AArch64.  */
 DW_CFA (DW_CFA_GNU_window_save, 0x2d)
-- 
2.47.1