backends: Add abi_cfi and register_info callbacks for LoongArch

LoongArch Reference Manual - Volume 1:
https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html

LoongArch ELF ABI:
https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html

Signed-off-by: Liwei Ge <geliwei@openanolis.org>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>

1 files changed, 83 insertions, 0 deletions

diff --git a/backends/loongarch_cfi.c b/backends/loongarch_cfi.c
new file mode 100644
index 00000000..5f3cd2c7
--- /dev/null
+++ b/backends/loongarch_cfi.c
@@ -0,0 +1,83 @@
+/* LoongArch ABI-specified defaults for DWARF CFI.
+   Copyright (C) 2023 OpenAnolis community LoongArch SIG.
+   Copyright (C) 2023 Loongson Technology Corporation Limted.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <dwarf.h>
+
+#define BACKEND loongarch_
+#include "libebl_CPU.h"
+
+/* LoongArch ELF ABI specification:
+https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html#_register_convention
+*/
+int
+loongarch_abi_cfi (Ebl *ebl __attribute__ ((unused)), Dwarf_CIE *abi_info)
+{
+  static const uint8_t abi_cfi[] =
+    {
+      /* The initial Canonical Frame Address is the value of the
+         Stack Pointer ($r3) as setup in the previous frame. */
+      DW_CFA_def_cfa, ULEB128_7 (3), ULEB128_7 (0),
+
+      /* The Stack Pointer ($r3) is restored from CFA address by default.  */
+      DW_CFA_val_offset, ULEB128_7 (3), ULEB128_7 (0),
+
+#define SV(n) DW_CFA_same_value, ULEB128_7 (n)
+      /* The return address register contains the return address setup by
+	 caller.  */
+      SV (1),
+
+      /* Callee-saved registers $s0-$s7.  */
+      SV (23), SV (24), SV (25), SV (26), SV (27), SV (28),
+      SV (29), SV (30), SV (31),
+
+      /* The Frame Pointer ($fp, $r22) */
+      SV(22),
+
+      /* Callee-saved registers $fs0-$fs7.  */
+      SV (56), SV (57), SV (58), SV (59), SV (60), SV (61),
+      SV (62), SV (63),
+#undef SV
+
+      /* XXX Note: registers intentionally unused by the program,
+	 for example as a consequence of the procedure call standard
+	 should be initialized as if by DW_CFA_same_value.  */
+    };
+
+  abi_info->initial_instructions = abi_cfi;
+  abi_info->initial_instructions_end = &abi_cfi[sizeof abi_cfi];
+  abi_info->data_alignment_factor = -4;
+
+  abi_info->return_address_register = 1; /* ra.  */
+
+  return 0;
+}