/* Native-dependent code for NetBSD/amd64.

   Copyright (C) 2003-2024 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 "target.h"

#include "netbsd-nat.h"
#include "amd64-tdep.h"
#include "amd64-bsd-nat.h"
#include "amd64-nat.h"
#include "regcache.h"
#include "gdbcore.h"
#include "bsd-kvm.h"

#include <machine/frame.h>
#include <machine/pcb.h>
#include <machine/reg.h>

/* Mapping between the general-purpose registers in NetBSD/amd64
   `struct reg' format and GDB's register cache layout for
   NetBSD/i386.

   Note that most (if not all) NetBSD/amd64 registers are 64-bit,
   while the NetBSD/i386 registers are all 32-bit, but since we're
   little-endian we get away with that.  */

/* From <machine/reg.h>.  */
static int amd64nbsd32_r_reg_offset[] =
{
  14 * 8,			/* %eax */
  3 * 8,			/* %ecx */
  2 * 8,			/* %edx */
  13 * 8,			/* %ebx */
  24 * 8,			/* %esp */
  12 * 8,			/* %ebp */
  1 * 8,			/* %esi */
  0 * 8,			/* %edi */
  21 * 8,			/* %eip */
  23 * 8,			/* %eflags */
  22 * 8,			/* %cs */
  25 * 8,			/* %ss */
  18 * 8,			/* %ds */
  17 * 8,			/* %es */
  16 * 8,			/* %fs */
  15 * 8			/* %gs */
};

static int
amd64nbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
{
  struct switchframe sf;

  /* The following is true for NetBSD/amd64:

     The pcb contains the stack pointer at the point of the context
     switch in cpu_switchto().  At that point we have a stack frame as
     described by `struct switchframe', which for NetBSD/amd64 has the
     following layout:

     interrupt level
     %r15
     %r14
     %r13
     %r12
     %rbx
     return address

     Together with %rsp in the pcb, this accounts for all callee-saved
     registers specified by the psABI.  From this information we
     reconstruct the register state as it would look when we just
     returned from cpu_switchto().

     For kernel core dumps, dumpsys() builds a fake switchframe for us. */

  /* The stack pointer shouldn't be zero.  */
  if (pcb->pcb_rsp == 0)
    return 0;

  /* Read the stack frame, and check its validity.  */
  read_memory (pcb->pcb_rsp, (gdb_byte *) &sf, sizeof sf);
  pcb->pcb_rsp += sizeof (struct switchframe);
  regcache->raw_supply (12, &sf.sf_r12);
  regcache->raw_supply (13, &sf.sf_r13);
  regcache->raw_supply (14, &sf.sf_r14);
  regcache->raw_supply (15, &sf.sf_r15);
  regcache->raw_supply (AMD64_RBX_REGNUM, &sf.sf_rbx);
  regcache->raw_supply (AMD64_RIP_REGNUM, &sf.sf_rip);

  regcache->raw_supply (AMD64_RSP_REGNUM, &pcb->pcb_rsp);
  regcache->raw_supply (AMD64_RBP_REGNUM, &pcb->pcb_rbp);
  regcache->raw_supply (AMD64_FS_REGNUM, &pcb->pcb_fs);
  regcache->raw_supply (AMD64_GS_REGNUM, &pcb->pcb_gs);

  return 1;
}

static amd64_bsd_nat_target<nbsd_nat_target> the_amd64_nbsd_nat_target;

void _initialize_amd64nbsd_nat ();
void
_initialize_amd64nbsd_nat ()
{
  amd64_native_gregset32_reg_offset = amd64nbsd32_r_reg_offset;
  amd64_native_gregset32_num_regs = ARRAY_SIZE (amd64nbsd32_r_reg_offset);
  amd64_native_gregset64_reg_offset = amd64nbsd_r_reg_offset;

  add_inf_child_target (&the_amd64_nbsd_nat_target);

  bsd_kvm_add_target (amd64nbsd_supply_pcb);
}