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/* GNU/Linux/Nios II specific low level interface, for the remote server for
GDB.
Copyright (C) 2008-2020 Free Software Foundation, Inc.
Contributed by Mentor Graphics, 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 "server.h"
#include "linux-low.h"
#include "elf/common.h"
#include "nat/gdb_ptrace.h"
#include <endian.h>
#include "gdb_proc_service.h"
#include <asm/ptrace.h>
#ifndef PTRACE_GET_THREAD_AREA
#define PTRACE_GET_THREAD_AREA 25
#endif
/* The following definition must agree with the number of registers
defined in "struct user_regs" in GLIBC
(sysdeps/unix/sysv/linux/nios2/sys/user.h), and also with
NIOS2_NUM_REGS in GDB proper. */
#define nios2_num_regs 49
/* Defined in auto-generated file nios2-linux.c. */
void init_registers_nios2_linux (void);
extern const struct target_desc *tdesc_nios2_linux;
/* This union is used to convert between int and byte buffer
representations of register contents. */
union nios2_register
{
unsigned char buf[4];
int reg32;
};
/* Return the ptrace ``address'' of register REGNO. */
static int nios2_regmap[] = {
-1, 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 29, 30, 31,
32, 33, 34, 35, 36, 37, 38, 39,
40, 41, 42, 43, 44, 45, 46, 47,
48,
0
};
/* Implement the arch_setup linux_target_ops method. */
static void
nios2_arch_setup (void)
{
current_process ()->tdesc = tdesc_nios2_linux;
}
/* Implement the cannot_fetch_register linux_target_ops method. */
static int
nios2_cannot_fetch_register (int regno)
{
if (nios2_regmap[regno] == -1)
return 1;
return 0;
}
/* Implement the cannot_store_register linux_target_ops method. */
static int
nios2_cannot_store_register (int regno)
{
if (nios2_regmap[regno] == -1)
return 1;
return 0;
}
/* Breakpoint support. Also see comments on nios2_breakpoint_from_pc
in nios2-tdep.c. */
#if defined(__nios2_arch__) && __nios2_arch__ == 2
#define NIOS2_BREAKPOINT 0xb7fd0020
#define CDX_BREAKPOINT 0xd7c9
#else
#define NIOS2_BREAKPOINT 0x003b6ffa
#endif
/* We only register the 4-byte breakpoint, even on R2 targets which also
support 2-byte breakpoints. Since there is no supports_z_point_type
function provided, gdbserver never inserts software breakpoints itself
and instead relies on GDB to insert the breakpoint of the correct length
via a memory write. */
static const unsigned int nios2_breakpoint = NIOS2_BREAKPOINT;
#define nios2_breakpoint_len 4
/* Implementation of linux_target_ops method "sw_breakpoint_from_kind". */
static const gdb_byte *
nios2_sw_breakpoint_from_kind (int kind, int *size)
{
*size = nios2_breakpoint_len;
return (const gdb_byte *) &nios2_breakpoint;
}
/* Implement the breakpoint_at linux_target_ops method. */
static int
nios2_breakpoint_at (CORE_ADDR where)
{
unsigned int insn;
/* For R2, first check for the 2-byte CDX trap.n breakpoint encoding. */
#if defined(__nios2_arch__) && __nios2_arch__ == 2
(*the_target->read_memory) (where, (unsigned char *) &insn, 2);
if (insn == CDX_BREAKPOINT)
return 1;
#endif
(*the_target->read_memory) (where, (unsigned char *) &insn, 4);
if (insn == nios2_breakpoint)
return 1;
return 0;
}
/* Fetch the thread-local storage pointer for libthread_db. */
ps_err_e
ps_get_thread_area (struct ps_prochandle *ph,
lwpid_t lwpid, int idx, void **base)
{
if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)
return PS_ERR;
/* IDX is the bias from the thread pointer to the beginning of the
thread descriptor. It has to be subtracted due to implementation
quirks in libthread_db. */
*base = (void *) ((char *) *base - idx);
return PS_OK;
}
/* Helper functions to collect/supply a single register REGNO. */
static void
nios2_collect_register (struct regcache *regcache, int regno,
union nios2_register *reg)
{
union nios2_register tmp_reg;
collect_register (regcache, regno, &tmp_reg.reg32);
reg->reg32 = tmp_reg.reg32;
}
static void
nios2_supply_register (struct regcache *regcache, int regno,
const union nios2_register *reg)
{
supply_register (regcache, regno, reg->buf);
}
/* We have only a single register set on Nios II. */
static void
nios2_fill_gregset (struct regcache *regcache, void *buf)
{
union nios2_register *regset = (union nios2_register *) buf;
int i;
for (i = 1; i < nios2_num_regs; i++)
nios2_collect_register (regcache, i, regset + i);
}
static void
nios2_store_gregset (struct regcache *regcache, const void *buf)
{
const union nios2_register *regset = (union nios2_register *) buf;
int i;
for (i = 0; i < nios2_num_regs; i++)
nios2_supply_register (regcache, i, regset + i);
}
static struct regset_info nios2_regsets[] =
{
{ PTRACE_GETREGSET, PTRACE_SETREGSET, NT_PRSTATUS,
nios2_num_regs * 4, GENERAL_REGS,
nios2_fill_gregset, nios2_store_gregset },
NULL_REGSET
};
static struct regsets_info nios2_regsets_info =
{
nios2_regsets, /* regsets */
0, /* num_regsets */
NULL, /* disabled_regsets */
};
static struct usrregs_info nios2_usrregs_info =
{
nios2_num_regs,
nios2_regmap,
};
static struct regs_info regs_info =
{
NULL, /* regset_bitmap */
&nios2_usrregs_info,
&nios2_regsets_info
};
static const struct regs_info *
nios2_regs_info (void)
{
return ®s_info;
}
struct linux_target_ops the_low_target =
{
nios2_arch_setup,
nios2_regs_info,
nios2_cannot_fetch_register,
nios2_cannot_store_register,
NULL,
linux_get_pc_32bit,
linux_set_pc_32bit,
NULL, /* breakpoint_kind_from_pc */
nios2_sw_breakpoint_from_kind,
NULL, /* get_next_pcs */
0,
nios2_breakpoint_at,
};
void
initialize_low_arch (void)
{
init_registers_nios2_linux ();
initialize_regsets_info (&nios2_regsets_info);
}
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