[PATCH 2/2] riscv: enable gdb/sim integration

[Mike Frysinger via Gdb-patches <gdb-patches@sourceware.org>]

Now the simulator can be loaded via gdb using "target sim".

gdb/:

	* configure.tgt (riscv*-*-*): Set gdb_sim.

include/gdb/:

	* sim-riscv.h: New file.
---
 gdb/configure.tgt       |  1 +
 include/gdb/sim-riscv.h | 99 +++++++++++++++++++++++++++++++++++++++++
 sim/riscv/ChangeLog     |  6 +++
 sim/riscv/sim-main.c    | 70 +++++++++++++++++++++++++++++
 4 files changed, 176 insertions(+)
 create mode 100644 include/gdb/sim-riscv.h

diff --git a/gdb/configure.tgt b/gdb/configure.tgt
index 6e0398387482..5440780065f0 100644
--- a/gdb/configure.tgt
+++ b/gdb/configure.tgt
@@ -554,6 +554,7 @@ riscv*-*-linux*)
 riscv*-*-*)
 	# Target: RISC-V architecture
 	gdb_target_obs=""
+	gdb_sim=../sim/riscv/libsim.a
 	;;
 
 rl78-*-elf)
diff --git a/include/gdb/sim-riscv.h b/include/gdb/sim-riscv.h
new file mode 100644
index 000000000000..23e5f766aa6c
--- /dev/null
+++ b/include/gdb/sim-riscv.h
@@ -0,0 +1,99 @@
+/* This file defines the interface between the RISC-V simulator and GDB.
+
+   Copyright (C) 2005-2021 Free Software Foundation, Inc.
+   Contributed by Mike Frysinger.
+
+   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/>.  */
+
+/* Order has to match gdb riscv-tdep list.  */
+enum sim_riscv_regnum {
+  SIM_RISCV_ZERO_REGNUM = 0,
+  SIM_RISCV_RA_REGNUM,
+  SIM_RISCV_SP_REGNUM,
+  SIM_RISCV_GP_REGNUM,
+  SIM_RISCV_TP_REGNUM,
+  SIM_RISCV_T0_REGNUM,
+  SIM_RISCV_T1_REGNUM,
+  SIM_RISCV_T2_REGNUM,
+  SIM_RISCV_S0_REGNUM,
+#define SIM_RISCV_FP_REGNUM SIM_RISCV_S0_REGNUM
+  SIM_RISCV_S1_REGNUM,
+  SIM_RISCV_A0_REGNUM,
+  SIM_RISCV_A1_REGNUM,
+  SIM_RISCV_A2_REGNUM,
+  SIM_RISCV_A3_REGNUM,
+  SIM_RISCV_A4_REGNUM,
+  SIM_RISCV_A5_REGNUM,
+  SIM_RISCV_A6_REGNUM,
+  SIM_RISCV_A7_REGNUM,
+  SIM_RISCV_S2_REGNUM,
+  SIM_RISCV_S3_REGNUM,
+  SIM_RISCV_S4_REGNUM,
+  SIM_RISCV_S5_REGNUM,
+  SIM_RISCV_S6_REGNUM,
+  SIM_RISCV_S7_REGNUM,
+  SIM_RISCV_S8_REGNUM,
+  SIM_RISCV_S9_REGNUM,
+  SIM_RISCV_S10_REGNUM,
+  SIM_RISCV_S11_REGNUM,
+  SIM_RISCV_T3_REGNUM,
+  SIM_RISCV_T4_REGNUM,
+  SIM_RISCV_T5_REGNUM,
+  SIM_RISCV_T6_REGNUM,
+  SIM_RISCV_PC_REGNUM,
+  SIM_RISCV_FT0_REGNUM,
+#define SIM_RISCV_FIRST_FP_REGNUM SIM_RISCV_FT0_REGNUM
+  SIM_RISCV_FT1_REGNUM,
+  SIM_RISCV_FT2_REGNUM,
+  SIM_RISCV_FT3_REGNUM,
+  SIM_RISCV_FT4_REGNUM,
+  SIM_RISCV_FT5_REGNUM,
+  SIM_RISCV_FT6_REGNUM,
+  SIM_RISCV_FT7_REGNUM,
+  SIM_RISCV_FS0_REGNUM,
+  SIM_RISCV_FS1_REGNUM,
+  SIM_RISCV_FA0_REGNUM,
+  SIM_RISCV_FA1_REGNUM,
+  SIM_RISCV_FA2_REGNUM,
+  SIM_RISCV_FA3_REGNUM,
+  SIM_RISCV_FA4_REGNUM,
+  SIM_RISCV_FA5_REGNUM,
+  SIM_RISCV_FA6_REGNUM,
+  SIM_RISCV_FA7_REGNUM,
+  SIM_RISCV_FS2_REGNUM,
+  SIM_RISCV_FS3_REGNUM,
+  SIM_RISCV_FS4_REGNUM,
+  SIM_RISCV_FS5_REGNUM,
+  SIM_RISCV_FS6_REGNUM,
+  SIM_RISCV_FS7_REGNUM,
+  SIM_RISCV_FS8_REGNUM,
+  SIM_RISCV_FS9_REGNUM,
+  SIM_RISCV_FS10_REGNUM,
+  SIM_RISCV_FS11_REGNUM,
+  SIM_RISCV_FT8_REGNUM,
+  SIM_RISCV_FT9_REGNUM,
+  SIM_RISCV_FT10_REGNUM,
+  SIM_RISCV_FT11_REGNUM,
+#define SIM_RISCV_LAST_FP_REGNUM SIM_RISCV_FT11_REGNUM
+
+#define SIM_RISCV_FIRST_CSR_REGNUM SIM_RISCV_LAST_FP_REGNUM + 1
+#define DECLARE_CSR(name, num, ...) SIM_RISCV_ ## num ## _REGNUM,
+#include "opcode/riscv-opc.h"
+#undef DECLARE_CSR
+#define SIM_RISCV_LAST_CSR_REGNUM SIM_RISCV_LAST_REGNUM - 1
+
+  SIM_RISCV_LAST_REGNUM
+};
diff --git a/sim/riscv/ChangeLog b/sim/riscv/ChangeLog
index f152de1e4646..7d588c80babd 100644
--- a/sim/riscv/ChangeLog
+++ b/sim/riscv/ChangeLog
@@ -1,3 +1,9 @@
+2021-01-12  Mike Frysinger  <vapier@gentoo.org>
+
+	* sim-main.c: Include gdb/sim-riscv.h.
+	(reg_fetch, reg_store): Define.
+	(initialize_cpu): Assign reg_fetch & reg_store.
+
 2021-01-12  Mike Frysinger  <vapier@gentoo.org>
 
 	* Makefile.in, configure.ac, interp.c, machs.c, machs.h,
diff --git a/sim/riscv/sim-main.c b/sim/riscv/sim-main.c
index 15a0eb02ae26..2dd7167cc1d0 100644
--- a/sim/riscv/sim-main.c
+++ b/sim/riscv/sim-main.c
@@ -31,6 +31,8 @@
 
 #include "opcode/riscv.h"
 
+#include "gdb/sim-riscv.h"
+
 #include "targ-vals.h"
 \f
 #define TRACE_REG(cpu, reg) \
@@ -1019,6 +1021,72 @@ pc_set (sim_cpu *cpu, sim_cia pc)
   cpu->pc = pc;
 }
 
+static int
+reg_fetch (sim_cpu *cpu, int rn, unsigned char *buf, int len)
+{
+  if (len <= 0 || len > sizeof (unsigned_word))
+    return -1;
+
+  switch (rn)
+    {
+    case SIM_RISCV_ZERO_REGNUM:
+      memset (buf, 0, len);
+      return len;
+    case SIM_RISCV_RA_REGNUM ... SIM_RISCV_T6_REGNUM:
+      memcpy (buf, &cpu->regs[rn], len);
+      return len;
+    case SIM_RISCV_FIRST_FP_REGNUM ... SIM_RISCV_LAST_FP_REGNUM:
+      memcpy (buf, &cpu->fpregs[rn - SIM_RISCV_FIRST_FP_REGNUM], len);
+      return len;
+    case SIM_RISCV_PC_REGNUM:
+      memcpy (buf, &cpu->pc, len);
+      return len;
+
+#define DECLARE_CSR(name, num, ...) \
+    case SIM_RISCV_ ## num ## _REGNUM: \
+      memcpy (buf, &cpu->csr.name, len); \
+      return len;
+#include "opcode/riscv-opc.h"
+#undef DECLARE_CSR
+
+    default:
+      return -1;
+    }
+}
+
+static int
+reg_store (sim_cpu *cpu, int rn, unsigned char *buf, int len)
+{
+  if (len <= 0 || len > sizeof (unsigned_word))
+    return -1;
+
+  switch (rn)
+    {
+    case SIM_RISCV_ZERO_REGNUM:
+      /* Ignore writes.  */
+      return len;
+    case SIM_RISCV_RA_REGNUM ... SIM_RISCV_T6_REGNUM:
+      memcpy (&cpu->regs[rn], buf, len);
+      return len;
+    case SIM_RISCV_FIRST_FP_REGNUM ... SIM_RISCV_LAST_FP_REGNUM:
+      memcpy (&cpu->fpregs[rn - SIM_RISCV_FIRST_FP_REGNUM], buf, len);
+      return len;
+    case SIM_RISCV_PC_REGNUM:
+      memcpy (&cpu->pc, buf, len);
+      return len;
+
+#define DECLARE_CSR(name, num, ...) \
+    case SIM_RISCV_ ## num ## _REGNUM: \
+      memcpy (&cpu->csr.name, buf, len); \
+      return len;
+#include "opcode/riscv-opc.h"
+#undef DECLARE_CSR
+
+    default:
+      return -1;
+    }
+}
+
 /* Initialize the state for a single cpu.  Usuaully this involves clearing all
    registers back to their reset state.  Should also hook up the fetch/store
    helper functions too.  */
@@ -1031,6 +1099,8 @@ void initialize_cpu (SIM_DESC sd, SIM_CPU *cpu, int mhartid)
 
   CPU_PC_FETCH (cpu) = pc_get;
   CPU_PC_STORE (cpu) = pc_set;
+  CPU_REG_FETCH (cpu) = reg_fetch;
+  CPU_REG_STORE (cpu) = reg_store;
 
   if (!riscv_hash[0])
     {
-- 
2.28.0