RISC-V: Add linux target support.

Add initial target support for riscv*-linux*.

	gdb/
	* riscv-linux-tdep.c: New file.

2 files changed, 98 insertions, 0 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index c2013ea..ae6bceb 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2018-08-09  Jim Wilson  <jimw@sifive.com>
+
+	* riscv-linux-tdep.c: New file.
+
 2018-08-09  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	* infrun.c (resume): Make static, add forward declaration.
diff --git a/gdb/riscv-linux-tdep.c b/gdb/riscv-linux-tdep.c
new file mode 100644
index 0000000..47c2ab6
--- /dev/null
+++ b/gdb/riscv-linux-tdep.c
@@ -0,0 +1,94 @@
+/* Target-dependent code for GNU/Linux on RISC-V processors.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+
+   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 "riscv-tdep.h"
+#include "osabi.h"
+#include "glibc-tdep.h"
+#include "linux-tdep.h"
+#include "solib-svr4.h"
+#include "regset.h"
+
+/* Define the general register mapping.  The kernel puts the PC at offset 0,
+   gdb puts it at offset 32.  Register x0 is always 0 and can be ignored.
+   Registers x1 to x31 are in the same place.  */
+
+static const struct regcache_map_entry riscv_linux_gregmap[] =
+{
+  { 1,  RISCV_PC_REGNUM, 0 },
+  { 31, RISCV_RA_REGNUM, 0 }, /* x1 to x31 */
+  { 0 }
+};
+
+/* Define the general register regset.  */
+
+static const struct regset riscv_linux_gregset =
+{
+  riscv_linux_gregmap, regcache_supply_regset, regcache_collect_regset
+};
+
+/* Define hook for core file support.  */
+
+static void
+riscv_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
+                                          iterate_over_regset_sections_cb *cb,
+                                          void *cb_data,
+                                          const struct regcache *regcache)
+{
+  cb (".reg", (32 * riscv_isa_xlen (gdbarch)),
+      &riscv_linux_gregset, NULL, cb_data);
+
+  /* TODO: Add FP register support.  */
+}
+
+/* Initialize RISC-V Linux ABI info.  */
+
+static void
+riscv_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  linux_init_abi (info, gdbarch);
+
+  set_gdbarch_software_single_step (gdbarch, riscv_software_single_step);
+
+  set_solib_svr4_fetch_link_map_offsets (gdbarch,
+					 (riscv_isa_xlen (gdbarch) == 4
+					  ? svr4_ilp32_fetch_link_map_offsets
+					  : svr4_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);
+
+  set_gdbarch_iterate_over_regset_sections
+    (gdbarch, riscv_linux_iterate_over_regset_sections);
+}
+
+/* Initialize RISC-V Linux target support.  */
+
+void
+_initialize_riscv_linux_tdep (void)
+{
+  gdbarch_register_osabi (bfd_arch_riscv, 0, GDB_OSABI_LINUX,
+			  riscv_linux_init_abi);
+}