[PATCH 4/5] RISC-V: Add native linux support.

[Jim Wilson <jimw@sifive.com>]

Add initial native support for riscv*-linux*.

	gdb/
	* riscv-linux-nat.c: New file.
---
 gdb/riscv-linux-nat.c | 277 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 277 insertions(+)
 create mode 100644 gdb/riscv-linux-nat.c

diff --git a/gdb/riscv-linux-nat.c b/gdb/riscv-linux-nat.c
new file mode 100644
index 0000000000..b525220759
--- /dev/null
+++ b/gdb/riscv-linux-nat.c
@@ -0,0 +1,277 @@
+/* Native-dependent code for GNU/Linux RISC-V.
+   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 "regcache.h"
+#include "gregset.h"
+#include "linux-nat.h"
+#include "elf.h"
+#include "riscv-tdep.h"
+
+#include <sys/ptrace.h>
+
+class riscv_linux_nat_target final : public linux_nat_target
+{
+public:
+  /* Add our register access methods.  */
+  void fetch_registers (struct regcache *regcache, int regnum) override;
+  void store_registers (struct regcache *regcache, int regnum) override;
+};
+
+static riscv_linux_nat_target the_riscv_linux_nat_target;
+
+/* Copy general purpose register REGNUM (or all gp regs if REGNUM == -1)
+   from regset GREGS into REGCACHE.  */
+
+void
+supply_gregset_regnum (struct regcache *regcache, const prgregset_t *gregs,
+		       int regnum)
+{
+  int i;
+  const elf_greg_t *regp = *gregs;
+
+  if (regnum == -1)
+    {
+      /* We only support the integer registers and PC here.  */
+      for (i = RISCV_ZERO_REGNUM + 1; i < RISCV_PC_REGNUM; i++)
+	regcache->raw_supply (i, regp + i);
+
+      /* GDB stores PC in reg 32.  Linux kernel stores it in reg 0.  */
+      regcache->raw_supply (32, regp + 0);
+
+      /* Fill the inaccessible zero register with zero.  */
+      regcache->raw_supply_zeroed (0);
+    }
+  else if (regnum == RISCV_ZERO_REGNUM)
+    regcache->raw_supply_zeroed (0);
+  else if (regnum > RISCV_ZERO_REGNUM && regnum < RISCV_PC_REGNUM)
+    regcache->raw_supply (regnum, regp + regnum);
+  else if (regnum == RISCV_PC_REGNUM)
+    regcache->raw_supply (32, regp + 0);
+}
+
+/* Copy all general purpose registers from regset GREGS into REGCACHE.  */
+
+void
+supply_gregset (struct regcache *regcache, const prgregset_t *gregs)
+{
+  supply_gregset_regnum (regcache, gregs, -1);
+}
+
+/* Copy floating point register REGNUM (or all fp regs if REGNUM == -1)
+   from regset FPREGS into REGCACHE.  */
+
+void
+supply_fpregset_regnum (struct regcache *regcache, const prfpregset_t *fpregs,
+			int regnum)
+{
+  int i;
+
+  if (regnum == -1)
+    {
+      /* We only support the FP registers and FCSR here.  */
+      for (i = RISCV_FIRST_FP_REGNUM; i <= RISCV_LAST_FP_REGNUM; i++)
+	regcache->raw_supply (i, &fpregs->__d.__f[i - RISCV_FIRST_FP_REGNUM]);
+
+      regcache->raw_supply (RISCV_CSR_FCSR_REGNUM, &fpregs->__d.__fcsr);
+    }
+  else if (regnum >= RISCV_FIRST_FP_REGNUM && regnum <= RISCV_LAST_FP_REGNUM)
+    regcache->raw_supply (regnum,
+			  &fpregs->__d.__f[regnum - RISCV_FIRST_FP_REGNUM]);
+  else if (regnum == RISCV_CSR_FCSR_REGNUM)
+    regcache->raw_supply (RISCV_CSR_FCSR_REGNUM, &fpregs->__d.__fcsr);
+}
+
+/* Copy all floating point registers from regset FPREGS into REGCACHE.  */
+
+void
+supply_fpregset (struct regcache *regcache, const prfpregset_t *fpregs)
+{
+  supply_fpregset_regnum (regcache, fpregs, -1);
+}
+
+/* Copy general purpose register REGNUM (or all gp regs if REGNUM == -1)
+   from REGCACHE into regset GREGS.  */
+
+void
+fill_gregset (const struct regcache *regcache, prgregset_t *gregs, int regnum)
+{
+  elf_greg_t *regp = *gregs;
+
+  if (regnum == -1)
+    {
+      /* We only support the integer registers and PC here.  */
+      for (int i = RISCV_ZERO_REGNUM + 1; i < RISCV_PC_REGNUM; i++)
+	regcache->raw_collect (i, regp + i);
+
+      regcache->raw_collect (32, regp + 0);
+    }
+  else if (regnum == RISCV_ZERO_REGNUM)
+    /* Nothing to do here.  */
+    ;
+  else if (regnum > RISCV_ZERO_REGNUM && regnum < RISCV_PC_REGNUM)
+    regcache->raw_collect (regnum, regp + regnum);
+  else if (regnum == RISCV_PC_REGNUM)
+    regcache->raw_collect (32, regp + 0);
+}
+
+/* Copy floating point register REGNUM (or all fp regs if REGNUM == -1)
+   from REGCACHE into regset FPREGS.  */
+
+void
+fill_fpregset (const struct regcache *regcache, prfpregset_t *fpregs,
+	       int regnum)
+{
+  if (regnum == -1)
+    {
+      /* We only support the FP registers and FCSR here.  */
+      for (int i = RISCV_FIRST_FP_REGNUM; i <= RISCV_LAST_FP_REGNUM; i++)
+	regcache->raw_collect (i, &fpregs->__d.__f[i - RISCV_FIRST_FP_REGNUM]);
+
+      regcache->raw_collect (RISCV_CSR_FCSR_REGNUM, &fpregs->__d.__fcsr);
+    }
+  else if (regnum >= RISCV_FIRST_FP_REGNUM && regnum <= RISCV_LAST_FP_REGNUM)
+    regcache->raw_collect (regnum,
+			   &fpregs->__d.__f[regnum - RISCV_FIRST_FP_REGNUM]);
+  else if (regnum == RISCV_CSR_FCSR_REGNUM)
+    regcache->raw_collect (RISCV_CSR_FCSR_REGNUM, &fpregs->__d.__fcsr);
+}
+
+/* Fetch REGNUM (or all registers if REGNUM == -1) from the target
+   into REGCACHE using PTRACE_GETREGSET.  */
+
+void
+riscv_linux_nat_target::fetch_registers (struct regcache *regcache, int regnum)
+{
+  int tid;
+
+  tid = get_ptrace_pid (regcache->ptid());
+
+  if ((regnum >= RISCV_ZERO_REGNUM && regnum <= RISCV_PC_REGNUM)
+      || (regnum == -1))
+    {
+      struct iovec iov;
+      elf_gregset_t regs;
+
+      iov.iov_base = &regs;
+      iov.iov_len = sizeof (regs);
+
+      if (ptrace (PTRACE_GETREGSET, tid, NT_PRSTATUS,
+		  (PTRACE_TYPE_ARG3) &iov) == -1)
+	perror_with_name (_("Couldn't get registers"));
+      else
+	supply_gregset_regnum (regcache, &regs, regnum);
+    }
+
+  if ((regnum >= RISCV_FIRST_FP_REGNUM
+       && regnum <= RISCV_LAST_FP_REGNUM)
+      || (regnum == RISCV_CSR_FCSR_REGNUM)
+      || (regnum == -1))
+    {
+      struct iovec iov;
+      elf_fpregset_t regs;
+
+      iov.iov_base = &regs;
+      iov.iov_len = sizeof (regs);
+
+      if (ptrace (PTRACE_GETREGSET, tid, NT_PRFPREG,
+		  (PTRACE_TYPE_ARG3) &iov) == -1)
+	perror_with_name (_("Couldn't get registers"));
+      else
+	supply_fpregset_regnum (regcache, &regs, regnum);
+    }
+
+  if (regnum == RISCV_CSR_MISA_REGNUM)
+    {
+      /* TODO: Need to add a ptrace call for this.  */
+      regcache->raw_supply_zeroed (regnum);
+    }
+
+  /* Access to other CSRs has potential security issues, don't support them for
+     now.  */
+}
+
+/* Store REGNUM (or all registers if REGNUM == -1) to the target
+   from REGCACHE using PTRACE_SETREGSET.  */
+
+void
+riscv_linux_nat_target::store_registers (struct regcache *regcache, int regnum)
+{
+  int tid;
+
+  tid = get_ptrace_pid (regcache->ptid ());
+
+  if ((regnum >= RISCV_ZERO_REGNUM && regnum <= RISCV_PC_REGNUM)
+      || (regnum == -1))
+    {
+      struct iovec iov;
+      elf_gregset_t regs;
+
+      iov.iov_base = &regs;
+      iov.iov_len = sizeof (regs);
+
+      if (ptrace (PTRACE_GETREGSET, tid, NT_PRSTATUS,
+		  (PTRACE_TYPE_ARG3) &iov) == -1)
+	perror_with_name (_("Couldn't get registers"));
+      else
+	{
+	  fill_gregset (regcache, &regs, regnum);
+
+	  if (ptrace (PTRACE_SETREGSET, tid, NT_PRSTATUS,
+		      (PTRACE_TYPE_ARG3) &iov) == -1)
+	    perror_with_name (_("Couldn't set registers"));
+	}
+    }
+
+  if ((regnum >= RISCV_FIRST_FP_REGNUM
+       && regnum <= RISCV_LAST_FP_REGNUM)
+      || (regnum == RISCV_CSR_FCSR_REGNUM)
+      || (regnum == -1))
+    {
+      struct iovec iov;
+      elf_fpregset_t regs;
+
+      iov.iov_base = &regs;
+      iov.iov_len = sizeof (regs);
+
+      if (ptrace (PTRACE_GETREGSET, tid, NT_PRFPREG,
+		  (PTRACE_TYPE_ARG3) &iov) == -1)
+	perror_with_name (_("Couldn't get registers"));
+      else
+	{
+	  fill_fpregset (regcache, &regs, regnum);
+
+	  if (ptrace (PTRACE_SETREGSET, tid, NT_PRFPREG,
+		      (PTRACE_TYPE_ARG3) &iov) == -1)
+	    perror_with_name (_("Couldn't set registers"));
+	}
+    }
+
+  /* Access to CSRs has potential security issues, don't support them for
+     now.  */
+}
+
+/* Initialize RISC-V Linux native support.  */
+
+void
+_initialize_riscv_linux_nat (void)
+{
+  /* Register the target.  */
+  linux_target = &the_riscv_linux_nat_target;
+  add_inf_child_target (&the_riscv_linux_nat_target);
+}
-- 
2.17.1