gdbserver/csky add csky gdbserver support

Add new files:
  gdb/arch/csky.c
  gdb/arch/csky.h
  gdb/features/cskyv2-linux.c
  gdbserver/linux-csky-low.cc

1. In gdb/arch/csky.c file, add function "csky_create_target_description()"
for csky_target::low_arch_setup(). later, it can be used for csky native gdb.

2. In gdb/features/cskyv2-linux.c file, create target_tdesc for csky, include
gprs, pc, hi, lo, float, vector and float control registers.

3. In gdbserver/linux-csky-low.cc file, using PTRACE_GET/SET_RGESET to
get/set registers. The main data structures in asm/ptrace.h are:
struct pt_regs {
    unsigned long   tls;
    unsigned long   lr;
    unsigned long   pc;
    unsigned long   sr;
    unsigned long   usp;

    /*
     * a0, a1, a2, a3:
     * r0, r1, r2, r3
     */
    unsigned long   orig_a0;
    unsigned long   a0;
    unsigned long   a1;
    unsigned long   a2;
    unsigned long   a3;

    /*
     * r4 ~ r13
     */
    unsigned long   regs[10];

    /* r16 ~ r30 */
    unsigned long   exregs[15];

    unsigned long   rhi;
    unsigned long   rlo;
    unsigned long   dcsr;
};

struct user_fp {
    unsigned long   vr[96];
    unsigned long   fcr;
    unsigned long   fesr;
    unsigned long   fid;
    unsigned long   reserved;
};

4 files changed, 198 insertions, 0 deletions

diff --git a/gdb/NEWS b/gdb/NEWS
index dee0ac2..555ef2d 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -118,6 +118,8 @@ maintenance info line-table
 
 GNU/Linux/LoongArch (gdbserver)	loongarch*-*-linux*
 
+GNU/Linux/CSKY (gdbserver) csky*-*linux*
+
 * Python API
 
   ** GDB will now reformat the doc string for gdb.Command and
@@ -194,6 +196,8 @@ GNU/Linux/LoongArch (gdbserver)	loongarch*-*-linux*
 * New features in the GDB remote stub, GDBserver
 
   ** GDBserver is now supported on LoongArch GNU/Linux.
+  
+  ** GDBserver is now supported on CSKY GNU/Linux.
 
 * LoongArch floating-point support
 
diff --git a/gdb/arch/csky.c b/gdb/arch/csky.c
new file mode 100644
index 0000000..8877967
--- /dev/null
+++ b/gdb/arch/csky.c
@@ -0,0 +1,38 @@
+/* Copyright (C) 2022 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 "gdbsupport/common-defs.h"
+#include "csky.h"
+#include <stdlib.h>
+
+#include "../features/cskyv2-linux.c"
+
+target_desc_up
+csky_create_target_description (void)
+{
+  /* Now we should create a new target description.  */
+  target_desc_up tdesc = allocate_target_description ();
+
+#ifndef IN_PROCESS_AGENT
+  std::string arch_name = "csky";
+  set_tdesc_architecture (tdesc.get (), arch_name.c_str ());
+#endif
+
+  create_feature_cskyv2_linux (tdesc.get ());
+
+  return tdesc;
+}
diff --git a/gdb/arch/csky.h b/gdb/arch/csky.h
new file mode 100644
index 0000000..1c147a9
--- /dev/null
+++ b/gdb/arch/csky.h
@@ -0,0 +1,29 @@
+/* Common target-dependent functionality for CSKY
+
+   Copyright (C) 2022 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/>.  */
+
+#ifndef ARCH_CSKY_H
+#define ARCH_CSKy_H
+
+#include "gdbsupport/tdesc.h"
+
+/* Used for gdbserver.  */
+
+target_desc_up csky_create_target_description (void);
+
+#endif /* ARCH_CSKY_H */
diff --git a/gdb/features/cskyv2-linux.c b/gdb/features/cskyv2-linux.c
new file mode 100644
index 0000000..e49b68c
--- /dev/null
+++ b/gdb/features/cskyv2-linux.c
@@ -0,0 +1,127 @@
+/* THIS FILE IS GENERATED.  -*- buffer-read-only: t -*- vi:set ro:
+   Original: cskyv2-linux.xml */
+
+#include "gdbsupport/tdesc.h"
+
+static void
+create_feature_cskyv2_linux (struct target_desc *result)
+{
+  struct tdesc_feature *feature;
+
+  feature = tdesc_create_feature (result, "org.gnu.gdb.csky.abiv2");
+  tdesc_create_reg (feature, "r0", 0, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r1", 1, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r2", 2, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r3", 3, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r4", 4, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r5", 5, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r6", 6, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r7", 7, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r8", 8, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r9", 9, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r10", 10, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r11", 11, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r12", 12, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r13", 13, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r14", 14, 1, NULL, 32, "data_ptr");
+  tdesc_create_reg (feature, "r15", 15, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r16", 16, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r17", 17, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r18", 18, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r19", 19, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r20", 20, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r21", 21, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r22", 22, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r23", 23, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r24", 24, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r25", 25, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r26", 26, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r27", 27, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r28", 28, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r29", 29, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r30", 30, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "r31", 31, 1, NULL, 32, "int");
+
+  tdesc_create_reg (feature, "lo", 36, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "hi", 37, 1, NULL, 32, "int");
+
+  tdesc_create_reg (feature, "fr0", 40, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr1", 41, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr2", 42, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr3", 43, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr4", 44, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr5", 45, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr6", 46, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr7", 47, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr8", 48, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr9", 49, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr10", 50, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr11", 51, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr12", 52, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr13", 53, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr14", 54, 1, NULL, 64, "ieee_double");
+  tdesc_create_reg (feature, "fr15", 55, 1, NULL, 64, "ieee_double");
+
+  tdesc_type *element_type;
+  element_type = tdesc_named_type (feature, "ieee_single");
+  tdesc_create_vector (feature, "v4f", element_type, 4);
+
+  element_type = tdesc_named_type (feature, "ieee_double");
+  tdesc_create_vector (feature, "v2d", element_type, 2);
+
+  element_type = tdesc_named_type (feature, "int8");
+  tdesc_create_vector (feature, "v16i8", element_type, 16);
+
+  element_type = tdesc_named_type (feature, "int16");
+  tdesc_create_vector (feature, "v8i16", element_type, 8);
+
+  element_type = tdesc_named_type (feature, "int32");
+  tdesc_create_vector (feature, "v4i32", element_type, 4);
+
+  element_type = tdesc_named_type (feature, "int64");
+  tdesc_create_vector (feature, "v2i64", element_type, 2);
+
+  tdesc_type_with_fields *type_with_fields;
+  type_with_fields = tdesc_create_union (feature, "vec128");
+  tdesc_type *field_type;
+  field_type = tdesc_named_type (feature, "v4f");
+  tdesc_add_field (type_with_fields, "v4_float", field_type);
+  field_type = tdesc_named_type (feature, "v2d");
+  tdesc_add_field (type_with_fields, "v2_double", field_type);
+  field_type = tdesc_named_type (feature, "v16i8");
+  tdesc_add_field (type_with_fields, "v16_int8", field_type);
+  field_type = tdesc_named_type (feature, "v8i16");
+  tdesc_add_field (type_with_fields, "v8_int16", field_type);
+  field_type = tdesc_named_type (feature, "v4i32");
+  tdesc_add_field (type_with_fields, "v4_int32", field_type);
+  field_type = tdesc_named_type (feature, "v2i64");
+  tdesc_add_field (type_with_fields, "v2_int64", field_type);
+  field_type = tdesc_named_type (feature, "uint128");
+  tdesc_add_field (type_with_fields, "uint128", field_type);
+
+
+  tdesc_create_reg (feature, "vr0", 56, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr1", 57, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr2", 58, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr3", 59, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr4", 60, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr5", 61, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr6", 62, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr7", 63, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr8", 64, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr9", 65, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr10", 66, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr11", 67, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr12", 68, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr13", 69, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr14", 70, 1, NULL, 128, "vec128");
+  tdesc_create_reg (feature, "vr15", 71, 1, NULL, 128, "vec128");
+
+  tdesc_create_reg (feature, "pc", 72, 1, NULL, 32, "code_ptr");
+  tdesc_create_reg (feature, "psr", 89, 1, NULL, 32, "int");
+
+  tdesc_create_reg (feature, "fid", 121, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "fcr", 122, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "fesr", 123, 1, NULL, 32, "int");
+  tdesc_create_reg (feature, "usp", 127, 1, NULL, 32, "int");
+}