gdb: LoongArch: Add initial Linux target support

This commit adds initial Linux target support for LoongArch.

Signed-off-by: Zhensong Liu <liuzhensong@loongson.cn>
Signed-off-by: Qing zhang <zhangqing@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>

gdb/loongarch-linux-tdep.c

@@ -0,0 +1,151 @@
+/* Target-dependent code for GNU/Linux on LoongArch processors.
+
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   Contributed by Loongson Ltd.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include "glibc-tdep.h"
+#include "inferior.h"
+#include "linux-tdep.h"
+#include "loongarch-tdep.h"
+#include "solib-svr4.h"
+#include "target-descriptions.h"
+
+/* Unpack an elf_gregset_t into GDB's register cache.  */
+
+static void
+loongarch_supply_gregset (const struct regset *r,
+			  struct regcache *regcache, int regno,
+			  const void *gprs, size_t len)
+{
+  loongarch_gdbarch_tdep *tdep
+    = (loongarch_gdbarch_tdep *) gdbarch_tdep (regcache->arch ());
+  auto regs = tdep->regs;
+
+  int regsize = register_size (regcache->arch (), regs.r);
+  const gdb_byte *buf = nullptr;
+
+  if (regno == -1)
+    {
+      /* Set $r0 = 0.  */
+      regcache->raw_supply_zeroed (regs.r);
+
+      for (int i = 1; i < 32; i++)
+	{
+	  buf = (const gdb_byte*) gprs + regsize * i;
+	  regcache->raw_supply (regs.r + i, (const void *) buf);
+	}
+
+      /* Size base (pc) = regsize * regs.pc.  */
+      buf = (const gdb_byte*) gprs + regsize * regs.pc;
+      regcache->raw_supply (regs.pc, (const void *) buf);
+
+      /* Size base (badv) = regsize * regs.badv.  */
+      buf = (const gdb_byte*) gprs + regsize * regs.badv;
+      regcache->raw_supply (regs.badv, (const void *) buf);
+    }
+  else if (regs.r == regno)
+    regcache->raw_supply_zeroed (regno);
+  else if ((regs.r < regno && regno < regs.r + 32)
+	   || regs.pc == regno || regs.badv == regno)
+    {
+      /* Offset offset (regno) = regsize * (regno - regs.r).  */
+      buf = (const gdb_byte*) gprs + regsize * (regno - regs.r);
+      regcache->raw_supply (regno, (const void *) buf);
+    }
+}
+
+/* Pack the GDB's register cache value into an elf_gregset_t.  */
+
+static void
+loongarch_fill_gregset (const struct regset *r,
+			const struct regcache *regcache, int regno,
+			void *gprs, size_t len)
+{
+  loongarch_gdbarch_tdep *tdep
+    = (loongarch_gdbarch_tdep *) gdbarch_tdep (regcache->arch ());
+  auto regs = tdep->regs;
+  int regsize = register_size (regcache->arch (), regs.r);
+  gdb_byte *buf = nullptr;
+
+  if (regno == -1)
+    {
+      for (int i = 0; i < 32; i++)
+	{
+	  buf = (gdb_byte *) gprs + regsize * i;
+	  regcache->raw_collect (regs.r + i, (void *) buf);
+	}
+
+      /* Size base (pc) = regsize * regs.pc.  */
+      buf = (gdb_byte *) gprs + regsize * regs.pc;
+      regcache->raw_collect (regs.pc, (void *) buf);
+
+      /* Size base (badv) = regsize * regs.badv.  */
+      buf = (gdb_byte *) gprs + regsize * regs.badv;
+      regcache->raw_collect (regs.badv, (void *) buf);
+    }
+  else if ((regs.r <= regno && regno < regs.r + 32)
+	   || regs.pc == regno || regs.badv == regno)
+    {
+      /* Offset offset (regno) = regsize * (regno - regs.r).  */
+      buf = (gdb_byte *) gprs + regsize * (regno - regs.r);
+      regcache->raw_collect (regno, (void *) buf);
+    }
+}
+
+/* Register set definitions.  */
+
+const struct regset loongarch_gregset =
+{
+  nullptr,
+  loongarch_supply_gregset,
+  loongarch_fill_gregset,
+};
+
+/* Initialize LoongArch Linux ABI info.  */
+
+static void
+loongarch_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  linux_init_abi (info, gdbarch, 0);
+
+  set_solib_svr4_fetch_link_map_offsets (gdbarch,
+					 info.bfd_arch_info->bits_per_address == 32
+					 ? linux_ilp32_fetch_link_map_offsets
+					 : linux_lp64_fetch_link_map_offsets);
+
+  /* GNU/Linux uses SVR4-style shared libraries.  */
+  set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
+
+  /* GNU/Linux uses the dynamic linker included in the GNU C Library.  */
+  set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
+  /* Enable TLS support.  */
+  set_gdbarch_fetch_tls_load_module_address (gdbarch, svr4_fetch_objfile_link_map);
+}
+
+/* Initialize LoongArch Linux target support.  */
+
+void _initialize_loongarch_linux_tdep ();
+void
+_initialize_loongarch_linux_tdep ()
+{
+  gdbarch_register_osabi (bfd_arch_loongarch, bfd_mach_loongarch32,
+                          GDB_OSABI_LINUX, loongarch_linux_init_abi);
+  gdbarch_register_osabi (bfd_arch_loongarch, bfd_mach_loongarch64,
+                          GDB_OSABI_LINUX, loongarch_linux_init_abi);
+}