/* Target-dependent code for GNU/Linux on OpenRISC 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 "or1k-tdep.h"
#include "osabi.h"
#include "glibc-tdep.h"
#include "linux-tdep.h"
#include "solib-svr4.h"
#include "regset.h"
#include "tramp-frame.h"
#include "trad-frame.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 or1k_linux_gregmap[] =
{
  { 32, OR1K_ZERO_REGNUM, 4 }, /* r0 to r31 */
  { 1,  OR1K_NPC_REGNUM, 4 },
  { 0 }
};

/* Define the general register regset.  */

static const struct regset or1k_linux_gregset =
{
  or1k_linux_gregmap, regcache_supply_regset, regcache_collect_regset
};

/* Define hook for core file support.  */

static void
or1k_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
					 iterate_over_regset_sections_cb *cb,
					 void *cb_data,
					 const struct regcache *regcache)
{
  cb (".reg", (33 * 4), (33 * 4), &or1k_linux_gregset, NULL, cb_data);
}

/* Signal trampoline support.  */

static void or1k_linux_sigframe_init (const struct tramp_frame *self,
				       struct frame_info *this_frame,
				       struct trad_frame_cache *this_cache,
				       CORE_ADDR func);

#define OR1K_RT_SIGRETURN		139

#define OR1K_INST_L_ORI_R11_R0_IMM	0xa9600000
#define OR1K_INST_L_SYS_1		0x20000001
#define OR1K_INST_L_NOP			0x15000000

static const struct tramp_frame or1k_linux_sigframe = {
  SIGTRAMP_FRAME,
  4,
  {
    { OR1K_INST_L_ORI_R11_R0_IMM | OR1K_RT_SIGRETURN, ULONGEST_MAX },
    { OR1K_INST_L_SYS_1, ULONGEST_MAX },
    { OR1K_INST_L_NOP, ULONGEST_MAX },
    { TRAMP_SENTINEL_INSN }
  },
  or1k_linux_sigframe_init,
  NULL
};

/* Runtime signal frames look like this:
  struct rt_sigframe {
    struct siginfo info;
    struct ucontext uc;
    unsigned char retcode[16];
  };

  struct ucontext {
    unsigned long     uc_flags;     - 4
    struct ucontext  *uc_link;      - 4
    stack_t           uc_stack;     - 4 * 3
    struct sigcontext uc_mcontext;
    sigset_t          uc_sigmask;
  };

  struct sigcontext {
    struct user_regs_struct regs;
    unsigned long oldmask;
  };

  struct user_regs_struct {
    unsigned long gpr[32];
    unsigned long pc;
    unsigned long sr;
  };  */

#define SIGFRAME_SIGINFO_SIZE		128
#define UCONTEXT_MCONTEXT_OFFSET	20

static void
or1k_linux_sigframe_init (const struct tramp_frame *self,
			   struct frame_info *this_frame,
			   struct trad_frame_cache *this_cache,
			   CORE_ADDR func)
{
  CORE_ADDR frame_sp = get_frame_sp (this_frame);
  CORE_ADDR mcontext_base;
  CORE_ADDR regs_base;

  mcontext_base = frame_sp + SIGFRAME_SIGINFO_SIZE + UCONTEXT_MCONTEXT_OFFSET;

  /* Handle the general registers 0-31 followed by the PC.  */
  regs_base = mcontext_base;
  for (int i = 0; i < 32; i++)
    trad_frame_set_reg_addr (this_cache, OR1K_ZERO_REGNUM + i,
			     regs_base + (i * 4));
  trad_frame_set_reg_addr (this_cache, OR1K_NPC_REGNUM, regs_base + (32 * 4));
  trad_frame_set_reg_addr (this_cache, OR1K_SR_REGNUM, regs_base + (33 * 4));

  /* Choice of the bottom of the sigframe is somewhat arbitrary.  */
  trad_frame_set_id (this_cache, frame_id_build (frame_sp, func));
}

/* Initialize OpenRISC Linux ABI info.  */

static void
or1k_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
  linux_init_abi (info, gdbarch);

  set_solib_svr4_fetch_link_map_offsets (gdbarch,
					 svr4_ilp32_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, or1k_linux_iterate_over_regset_sections);

  tramp_frame_prepend_unwinder (gdbarch, &or1k_linux_sigframe);
}

/* Initialize OpenRISC Linux target support.  */

void
_initialize_or1k_linux_tdep (void)
{
  gdbarch_register_osabi (bfd_arch_or1k, 0, GDB_OSABI_LINUX,
			  or1k_linux_init_abi);
}