/* Copyright (C) 2007-2024 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 "win32-low.h"
#include "x86-low.h"
#include "gdbsupport/x86-xstate.h"
#ifdef __x86_64__
#include "arch/amd64.h"
#endif
#include "arch/i386.h"
#include "tdesc.h"
#include "x86-tdesc.h"

using namespace windows_nat;

#ifndef CONTEXT_EXTENDED_REGISTERS
#define CONTEXT_EXTENDED_REGISTERS 0
#endif

#define I386_FISEG_REGNUM 27
#define I386_FOP_REGNUM 31

#define I386_CS_REGNUM 10
#define I386_GS_REGNUM 15

#define AMD64_FISEG_REGNUM 35
#define AMD64_FOP_REGNUM 39

#define AMD64_CS_REGNUM 18
#define AMD64_GS_REGNUM 23

#define FLAG_TRACE_BIT 0x100

static struct x86_debug_reg_state debug_reg_state;

static void
update_debug_registers (thread_info *thread)
{
 auto th = static_cast<windows_thread_info *> (thread->target_data ());

 /* The actual update is done later just before resuming the lwp,
    we just mark that the registers need updating.  */
 th->debug_registers_changed = true;
}

/* Update the inferior's debug register REGNUM from STATE.  */

static void
x86_dr_low_set_addr (int regnum, CORE_ADDR addr)
{
 gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);

 /* Only update the threads of this process.  */
 current_process ()->for_each_thread (update_debug_registers);
}

/* Update the inferior's DR7 debug control register from STATE.  */

static void
x86_dr_low_set_control (unsigned long control)
{
 /* Only update the threads of this process.  */
 current_process ()->for_each_thread (update_debug_registers);
}

/* Return the current value of a DR register of the current thread's
  context.  */

static DWORD64
win32_get_current_dr (int dr)
{
 auto th
   = static_cast<windows_thread_info *> (current_thread->target_data ());

 win32_require_context (th);

 return windows_process.with_context (th, [&] (auto *context) -> DWORD64
   {
#define RET_DR(DR)                              \
     case DR:                                  \
       return context->Dr ## DR

     switch (dr)
       {
         RET_DR (0);
         RET_DR (1);
         RET_DR (2);
         RET_DR (3);
         RET_DR (6);
         RET_DR (7);
       }
#undef RET_DR

     gdb_assert_not_reached ("unhandled dr");
   });
}

static CORE_ADDR
x86_dr_low_get_addr (int regnum)
{
 gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);

 return win32_get_current_dr (regnum - DR_FIRSTADDR);
}

static unsigned long
x86_dr_low_get_control (void)
{
 return win32_get_current_dr (7);
}

/* Get the value of the DR6 debug status register from the inferior
  and record it in STATE.  */

static unsigned long
x86_dr_low_get_status (void)
{
 return win32_get_current_dr (6);
}

/* Low-level function vector.  */
struct x86_dr_low_type x86_dr_low =
 {
   x86_dr_low_set_control,
   x86_dr_low_set_addr,
   x86_dr_low_get_addr,
   x86_dr_low_get_status,
   x86_dr_low_get_control,
   sizeof (void *),
 };

/* Breakpoint/watchpoint support.  */

static int
i386_supports_z_point_type (char z_type)
{
 switch (z_type)
   {
   case Z_PACKET_HW_BP:
   case Z_PACKET_WRITE_WP:
   case Z_PACKET_ACCESS_WP:
     return 1;
   default:
     return 0;
   }
}

static int
i386_insert_point (enum raw_bkpt_type type, CORE_ADDR addr,
                  int size, struct raw_breakpoint *bp)
{
 switch (type)
   {
   case raw_bkpt_type_hw:
   case raw_bkpt_type_write_wp:
   case raw_bkpt_type_access_wp:
     {
       enum target_hw_bp_type hw_type
         = raw_bkpt_type_to_target_hw_bp_type (type);

       return x86_dr_insert_watchpoint (&debug_reg_state,
                                        hw_type, addr, size);
     }
   default:
     /* Unsupported.  */
     return 1;
   }
}

static int
i386_remove_point (enum raw_bkpt_type type, CORE_ADDR addr,
                  int size, struct raw_breakpoint *bp)
{
 switch (type)
   {
   case raw_bkpt_type_hw:
   case raw_bkpt_type_write_wp:
   case raw_bkpt_type_access_wp:
     {
       enum target_hw_bp_type hw_type
         = raw_bkpt_type_to_target_hw_bp_type (type);

       return x86_dr_remove_watchpoint (&debug_reg_state,
                                        hw_type, addr, size);
     }
   default:
     /* Unsupported.  */
     return 1;
   }
}

static int
x86_stopped_by_watchpoint (void)
{
 return x86_dr_stopped_by_watchpoint (&debug_reg_state);
}

static CORE_ADDR
x86_stopped_data_address (void)
{
 CORE_ADDR addr;
 if (x86_dr_stopped_data_address (&debug_reg_state, &addr))
   return addr;
 return 0;
}

static void
i386_initial_stuff (void)
{
 x86_low_init_dregs (&debug_reg_state);
}

static void
i386_get_thread_context (windows_thread_info *th)
{
 windows_process.with_context (th, [&] (auto *context)
   {
     /* Requesting the CONTEXT_EXTENDED_REGISTERS register set fails if
        the system doesn't support extended registers.  */
     static DWORD extended_registers
       = WindowsContext<decltype(context)>::extended;

again:
     context->ContextFlags = (WindowsContext<decltype(context)>::full
                              | WindowsContext<decltype(context)>::floating
                              | WindowsContext<decltype(context)>::debug
                              | extended_registers);

     BOOL ret = get_thread_context (th->h, context);
     if (!ret)
       {
         DWORD e = GetLastError ();

         if (extended_registers && e == ERROR_INVALID_PARAMETER)
           {
             extended_registers = 0;
             goto again;
           }

         error ("GetThreadContext failure %ld\n", (long) e);
       }
   });
}

static void
i386_prepare_to_resume (windows_thread_info *th)
{
 if (th->debug_registers_changed)
   {
     struct x86_debug_reg_state *dr = &debug_reg_state;

     win32_require_context (th);

     windows_process.with_context (th, [&] (auto *context)
       {
         context->Dr0 = dr->dr_mirror[0];
         context->Dr1 = dr->dr_mirror[1];
         context->Dr2 = dr->dr_mirror[2];
         context->Dr3 = dr->dr_mirror[3];
         /* context->Dr6 = dr->dr_status_mirror;
            FIXME: should we set dr6 also ?? */
         context->Dr7 = dr->dr_control_mirror;
       });

     th->debug_registers_changed = false;
   }
}

static void
i386_thread_added (windows_thread_info *th)
{
 th->debug_registers_changed = true;
}

static void
i386_single_step (windows_thread_info *th)
{
 windows_process.with_context (th, [] (auto *context)
   {
     context->EFlags |= FLAG_TRACE_BIT;
   });
}

/* An array of offset mappings into a Win32 Context structure.
  This is a one-to-one mapping which is indexed by gdb's register
  numbers.  It retrieves an offset into the context structure where
  the 4 byte register is located.
  An offset value of -1 indicates that Win32 does not provide this
  register in it's CONTEXT structure.  In this case regptr will return
  a pointer into a dummy register.  */
#ifdef __x86_64__
#define context_offset(x) (offsetof (WOW64_CONTEXT, x))
#else
#define context_offset(x) ((int)&(((CONTEXT *)NULL)->x))
#endif
static const int i386_mappings[] = {
 context_offset (Eax),
 context_offset (Ecx),
 context_offset (Edx),
 context_offset (Ebx),
 context_offset (Esp),
 context_offset (Ebp),
 context_offset (Esi),
 context_offset (Edi),
 context_offset (Eip),
 context_offset (EFlags),
 context_offset (SegCs),
 context_offset (SegSs),
 context_offset (SegDs),
 context_offset (SegEs),
 context_offset (SegFs),
 context_offset (SegGs),
 context_offset (FloatSave.RegisterArea[0 * 10]),
 context_offset (FloatSave.RegisterArea[1 * 10]),
 context_offset (FloatSave.RegisterArea[2 * 10]),
 context_offset (FloatSave.RegisterArea[3 * 10]),
 context_offset (FloatSave.RegisterArea[4 * 10]),
 context_offset (FloatSave.RegisterArea[5 * 10]),
 context_offset (FloatSave.RegisterArea[6 * 10]),
 context_offset (FloatSave.RegisterArea[7 * 10]),
 context_offset (FloatSave.ControlWord),
 context_offset (FloatSave.StatusWord),
 context_offset (FloatSave.TagWord),
 context_offset (FloatSave.ErrorSelector),
 context_offset (FloatSave.ErrorOffset),
 context_offset (FloatSave.DataSelector),
 context_offset (FloatSave.DataOffset),
 context_offset (FloatSave.ErrorSelector),
 /* XMM0-7 */
 context_offset (ExtendedRegisters[10 * 16]),
 context_offset (ExtendedRegisters[11 * 16]),
 context_offset (ExtendedRegisters[12 * 16]),
 context_offset (ExtendedRegisters[13 * 16]),
 context_offset (ExtendedRegisters[14 * 16]),
 context_offset (ExtendedRegisters[15 * 16]),
 context_offset (ExtendedRegisters[16 * 16]),
 context_offset (ExtendedRegisters[17 * 16]),
 /* MXCSR */
 context_offset (ExtendedRegisters[24])
};
#undef context_offset

#ifdef __x86_64__

#define context_offset(x) (offsetof (CONTEXT, x))
static const int amd64_mappings[] =
{
 context_offset (Rax),
 context_offset (Rbx),
 context_offset (Rcx),
 context_offset (Rdx),
 context_offset (Rsi),
 context_offset (Rdi),
 context_offset (Rbp),
 context_offset (Rsp),
 context_offset (R8),
 context_offset (R9),
 context_offset (R10),
 context_offset (R11),
 context_offset (R12),
 context_offset (R13),
 context_offset (R14),
 context_offset (R15),
 context_offset (Rip),
 context_offset (EFlags),
 context_offset (SegCs),
 context_offset (SegSs),
 context_offset (SegDs),
 context_offset (SegEs),
 context_offset (SegFs),
 context_offset (SegGs),
 context_offset (FloatSave.FloatRegisters[0]),
 context_offset (FloatSave.FloatRegisters[1]),
 context_offset (FloatSave.FloatRegisters[2]),
 context_offset (FloatSave.FloatRegisters[3]),
 context_offset (FloatSave.FloatRegisters[4]),
 context_offset (FloatSave.FloatRegisters[5]),
 context_offset (FloatSave.FloatRegisters[6]),
 context_offset (FloatSave.FloatRegisters[7]),
 context_offset (FloatSave.ControlWord),
 context_offset (FloatSave.StatusWord),
 context_offset (FloatSave.TagWord),
 context_offset (FloatSave.ErrorSelector),
 context_offset (FloatSave.ErrorOffset),
 context_offset (FloatSave.DataSelector),
 context_offset (FloatSave.DataOffset),
 context_offset (FloatSave.ErrorSelector)
 /* XMM0-7 */ ,
 context_offset (Xmm0),
 context_offset (Xmm1),
 context_offset (Xmm2),
 context_offset (Xmm3),
 context_offset (Xmm4),
 context_offset (Xmm5),
 context_offset (Xmm6),
 context_offset (Xmm7),
 context_offset (Xmm8),
 context_offset (Xmm9),
 context_offset (Xmm10),
 context_offset (Xmm11),
 context_offset (Xmm12),
 context_offset (Xmm13),
 context_offset (Xmm14),
 context_offset (Xmm15),
 /* MXCSR */
 context_offset (FloatSave.MxCsr)
};
#undef context_offset

#endif /* __x86_64__ */

/* Return true if R is the FISEG register.  */
static bool
is_fiseg_register (int r)
{
#ifdef __x86_64__
 if (!windows_process.wow64_process)
   return r == AMD64_FISEG_REGNUM;
 else
#endif
   return r == I386_FISEG_REGNUM;
}

/* Return true if R is the FOP register.  */
static bool
is_fop_register (int r)
{
#ifdef __x86_64__
 if (!windows_process.wow64_process)
   return r == AMD64_FOP_REGNUM;
 else
#endif
   return r == I386_FOP_REGNUM;
}

/* Return true if R is a segment register.  */
static bool
is_segment_register (int r)
{
#ifdef __x86_64__
 if (!windows_process.wow64_process)
   return r >= AMD64_CS_REGNUM && r <= AMD64_GS_REGNUM;
 else
#endif
   return r >= I386_CS_REGNUM && r <= I386_GS_REGNUM;
}

/* Fetch register from gdbserver regcache data.  */
static void
i386_fetch_inferior_register (struct regcache *regcache,
                             windows_thread_info *th, int r)
{
 const int *mappings;
#ifdef __x86_64__
 if (!windows_process.wow64_process)
   mappings = amd64_mappings;
 else
#endif
   mappings = i386_mappings;

 char *context_offset = windows_process.with_context (th, [&] (auto *context)
   {
     return (char *) context + mappings[r];
   });

 /* GDB treats some registers as 32-bit, where they are in fact only
    16 bits long.  These cases must be handled specially to avoid
    reading extraneous bits from the context.  */
 if (is_fiseg_register (r) || is_segment_register (r))
   {
     gdb_byte bytes[4] = {};
     memcpy (bytes, context_offset, 2);
     supply_register (regcache, r, bytes);
   }
 else if (is_fop_register (r))
   {
     long l = (*((long *) context_offset) >> 16) & ((1 << 11) - 1);
     supply_register (regcache, r, (char *) &l);
   }
 else
   supply_register (regcache, r, context_offset);
}

/* Store a new register value into the thread context of TH.  */
static void
i386_store_inferior_register (struct regcache *regcache,
                             windows_thread_info *th, int r)
{
 const int *mappings;
#ifdef __x86_64__
 if (!windows_process.wow64_process)
   mappings = amd64_mappings;
 else
#endif
   mappings = i386_mappings;

 char *context_offset = windows_process.with_context (th, [&] (auto *context)
   {
     return (char *) context + mappings[r];
   });

 /* GDB treats some registers as 32-bit, where they are in fact only
    16 bits long.  These cases must be handled specially to avoid
    overwriting other registers in the context.  */
 if (is_fiseg_register (r) || is_segment_register (r))
   {
     gdb_byte bytes[4];
     collect_register (regcache, r, bytes);
     memcpy (context_offset, bytes, 2);
   }
 else if (is_fop_register (r))
   {
     gdb_byte bytes[4];
     collect_register (regcache, r, bytes);
     /* The value of FOP occupies the top two bytes in the context,
        so write the two low-order bytes from the cache into the
        appropriate spot.  */
     memcpy (context_offset + 2, bytes, 2);
   }
 else
   collect_register (regcache, r, context_offset);
}

static const unsigned char i386_win32_breakpoint = 0xcc;
#define i386_win32_breakpoint_len 1

static void
i386_arch_setup (void)
{
 struct target_desc *tdesc;

#ifdef __x86_64__
 tdesc = amd64_create_target_description (X86_XSTATE_SSE_MASK, false,
                                          false, false);
 init_target_desc (tdesc, amd64_expedite_regs, WINDOWS_OSABI);
 win32_tdesc = tdesc;
#endif

 tdesc = i386_create_target_description (X86_XSTATE_SSE_MASK, false, false);
 init_target_desc (tdesc, i386_expedite_regs, WINDOWS_OSABI);
#ifdef __x86_64__
 wow64_win32_tdesc = tdesc;
#else
 win32_tdesc = tdesc;
#endif
}

/* Implement win32_target_ops "num_regs" method.  */

static int
i386_win32_num_regs (void)
{
 int num_regs;
#ifdef __x86_64__
 if (!windows_process.wow64_process)
   num_regs = sizeof (amd64_mappings) / sizeof (amd64_mappings[0]);
 else
#endif
   num_regs = sizeof (i386_mappings) / sizeof (i386_mappings[0]);
 return num_regs;
}

/* Implement win32_target_ops "get_pc" method.  */

static CORE_ADDR
i386_win32_get_pc (struct regcache *regcache)
{
 bool use_64bit = register_size (regcache->tdesc, 0) == 8;

 if (use_64bit)
   {
     uint64_t pc;

     collect_register_by_name (regcache, "rip", &pc);
     return (CORE_ADDR) pc;
   }
 else
   {
     uint32_t pc;

     collect_register_by_name (regcache, "eip", &pc);
     return (CORE_ADDR) pc;
   }
}

/* Implement win32_target_ops "set_pc" method.  */

static void
i386_win32_set_pc (struct regcache *regcache, CORE_ADDR pc)
{
 bool use_64bit = register_size (regcache->tdesc, 0) == 8;

 if (use_64bit)
   {
     uint64_t newpc = pc;

     supply_register_by_name (regcache, "rip", &newpc);
   }
 else
   {
     uint32_t newpc = pc;

     supply_register_by_name (regcache, "eip", &newpc);
   }
}

struct win32_target_ops the_low_target = {
 i386_arch_setup,
 i386_win32_num_regs,
 i386_initial_stuff,
 i386_get_thread_context,
 i386_prepare_to_resume,
 i386_thread_added,
 i386_fetch_inferior_register,
 i386_store_inferior_register,
 i386_single_step,
 &i386_win32_breakpoint,
 i386_win32_breakpoint_len,
 1,
 i386_win32_get_pc,
 i386_win32_set_pc,
 i386_supports_z_point_type,
 i386_insert_point,
 i386_remove_point,
 x86_stopped_by_watchpoint,
 x86_stopped_data_address
};

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