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/* Target dependent code for GNU/Linux ARC.
Copyright 2020 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/>. */
/* GDB header files. */
#include "defs.h"
#include "linux-tdep.h"
#include "objfiles.h"
#include "opcode/arc.h"
#include "osabi.h"
#include "solib-svr4.h"
/* ARC header files. */
#include "opcodes/arc-dis.h"
#include "arc-tdep.h"
/* Implement the "cannot_fetch_register" gdbarch method. */
static int
arc_linux_cannot_fetch_register (struct gdbarch *gdbarch, int regnum)
{
/* Assume that register is readable if it is unknown. */
switch (regnum)
{
case ARC_ILINK_REGNUM:
case ARC_RESERVED_REGNUM:
case ARC_LIMM_REGNUM:
return true;
case ARC_R30_REGNUM:
case ARC_R58_REGNUM:
case ARC_R59_REGNUM:
return !arc_mach_is_arcv2 (gdbarch);
}
return (regnum > ARC_BLINK_REGNUM) && (regnum < ARC_LP_COUNT_REGNUM);
}
/* Implement the "cannot_store_register" gdbarch method. */
static int
arc_linux_cannot_store_register (struct gdbarch *gdbarch, int regnum)
{
/* Assume that register is writable if it is unknown. */
switch (regnum)
{
case ARC_ILINK_REGNUM:
case ARC_RESERVED_REGNUM:
case ARC_LIMM_REGNUM:
case ARC_PCL_REGNUM:
return true;
case ARC_R30_REGNUM:
case ARC_R58_REGNUM:
case ARC_R59_REGNUM:
return !arc_mach_is_arcv2 (gdbarch);
}
return (regnum > ARC_BLINK_REGNUM) && (regnum < ARC_LP_COUNT_REGNUM);
}
/* For ARC Linux, breakpoints use the 16-bit TRAP_S 1 instruction, which
is 0x3e78 (little endian) or 0x783e (big endian). */
static const gdb_byte arc_linux_trap_s_be[] = { 0x78, 0x3e };
static const gdb_byte arc_linux_trap_s_le[] = { 0x3e, 0x78 };
static const int trap_size = 2; /* Number of bytes to insert "trap". */
/* Implement the "breakpoint_kind_from_pc" gdbarch method. */
static int
arc_linux_breakpoint_kind_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr)
{
return trap_size;
}
/* Implement the "sw_breakpoint_from_kind" gdbarch method. */
static const gdb_byte *
arc_linux_sw_breakpoint_from_kind (struct gdbarch *gdbarch,
int kind, int *size)
{
*size = kind;
return ((gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
? arc_linux_trap_s_be
: arc_linux_trap_s_le);
}
/* Implement the "software_single_step" gdbarch method. */
static std::vector<CORE_ADDR>
arc_linux_software_single_step (struct regcache *regcache)
{
struct gdbarch *gdbarch = regcache->arch ();
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
struct disassemble_info di = arc_disassemble_info (gdbarch);
/* Read current instruction. */
struct arc_instruction curr_insn;
arc_insn_decode (regcache_read_pc (regcache), &di, arc_delayed_print_insn,
&curr_insn);
CORE_ADDR next_pc = arc_insn_get_linear_next_pc (curr_insn);
std::vector<CORE_ADDR> next_pcs;
/* For instructions with delay slots, the fall thru is not the
instruction immediately after the current instruction, but the one
after that. */
if (curr_insn.has_delay_slot)
{
struct arc_instruction next_insn;
arc_insn_decode (next_pc, &di, arc_delayed_print_insn, &next_insn);
next_pcs.push_back (arc_insn_get_linear_next_pc (next_insn));
}
else
next_pcs.push_back (next_pc);
ULONGEST status32;
regcache_cooked_read_unsigned (regcache, gdbarch_ps_regnum (gdbarch),
&status32);
if (curr_insn.is_control_flow)
{
CORE_ADDR branch_pc = arc_insn_get_branch_target (curr_insn);
if (branch_pc != next_pc)
next_pcs.push_back (branch_pc);
}
/* Is current instruction the last in a loop body? */
else if (tdep->has_hw_loops)
{
/* If STATUS32.L is 1, then ZD-loops are disabled. */
if ((status32 & ARC_STATUS32_L_MASK) == 0)
{
ULONGEST lp_end, lp_start, lp_count;
regcache_cooked_read_unsigned (regcache, ARC_LP_START_REGNUM,
&lp_start);
regcache_cooked_read_unsigned (regcache, ARC_LP_END_REGNUM, &lp_end);
regcache_cooked_read_unsigned (regcache, ARC_LP_COUNT_REGNUM,
&lp_count);
if (arc_debug)
{
debug_printf ("arc-linux: lp_start = %s, lp_end = %s, "
"lp_count = %s, next_pc = %s\n",
paddress (gdbarch, lp_start),
paddress (gdbarch, lp_end),
pulongest (lp_count),
paddress (gdbarch, next_pc));
}
if (next_pc == lp_end && lp_count > 1)
{
/* The instruction is in effect a jump back to the start of
the loop. */
next_pcs.push_back (lp_start);
}
}
}
/* Is this a delay slot? Then next PC is in BTA register. */
if ((status32 & ARC_STATUS32_DE_MASK) != 0)
{
ULONGEST bta;
regcache_cooked_read_unsigned (regcache, ARC_BTA_REGNUM, &bta);
next_pcs.push_back (bta);
}
return next_pcs;
}
/* Implement the "skip_solib_resolver" gdbarch method.
See glibc_skip_solib_resolver for details. */
static CORE_ADDR
arc_linux_skip_solib_resolver (struct gdbarch *gdbarch, CORE_ADDR pc)
{
/* For uClibc 0.9.26+.
An unresolved PLT entry points to "__dl_linux_resolve", which calls
"_dl_linux_resolver" to do the resolving and then eventually jumps to
the function.
So we look for the symbol `_dl_linux_resolver', and if we are there,
gdb sets a breakpoint at the return address, and continues. */
struct bound_minimal_symbol resolver
= lookup_minimal_symbol ("_dl_linux_resolver", NULL, NULL);
if (arc_debug)
{
if (resolver.minsym != nullptr)
{
CORE_ADDR res_addr = BMSYMBOL_VALUE_ADDRESS (resolver);
debug_printf ("arc-linux: skip_solib_resolver (): "
"pc = %s, resolver at %s\n",
print_core_address (gdbarch, pc),
print_core_address (gdbarch, res_addr));
}
else
{
debug_printf ("arc-linux: skip_solib_resolver (): "
"pc = %s, no resolver found\n",
print_core_address (gdbarch, pc));
}
}
if (resolver.minsym != nullptr && BMSYMBOL_VALUE_ADDRESS (resolver) == pc)
{
/* Find the return address. */
return frame_unwind_caller_pc (get_current_frame ());
}
else
{
/* No breakpoint required. */
return 0;
}
}
/* Initialization specific to Linux environment. */
static void
arc_linux_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
if (arc_debug)
debug_printf ("arc-linux: GNU/Linux OS/ABI initialization.\n");
/* If we are using Linux, we have in uClibc
(libc/sysdeps/linux/arc/bits/setjmp.h):
typedef int __jmp_buf[13+1+1+1]; //r13-r25, fp, sp, blink
Where "blink" is a stored PC of a caller function.
*/
tdep->jb_pc = 15;
linux_init_abi (info, gdbarch);
/* Set up target dependent GDB architecture entries. */
set_gdbarch_cannot_fetch_register (gdbarch, arc_linux_cannot_fetch_register);
set_gdbarch_cannot_store_register (gdbarch, arc_linux_cannot_store_register);
set_gdbarch_breakpoint_kind_from_pc (gdbarch,
arc_linux_breakpoint_kind_from_pc);
set_gdbarch_sw_breakpoint_from_kind (gdbarch,
arc_linux_sw_breakpoint_from_kind);
set_gdbarch_fetch_tls_load_module_address (gdbarch,
svr4_fetch_objfile_link_map);
set_gdbarch_software_single_step (gdbarch, arc_linux_software_single_step);
set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
set_gdbarch_skip_solib_resolver (gdbarch, arc_linux_skip_solib_resolver);
/* GNU/Linux uses SVR4-style shared libraries, with 32-bit ints, longs
and pointers (ILP32). */
set_solib_svr4_fetch_link_map_offsets (gdbarch,
svr4_ilp32_fetch_link_map_offsets);
}
/* Suppress warning from -Wmissing-prototypes. */
extern initialize_file_ftype _initialize_arc_linux_tdep;
void
_initialize_arc_linux_tdep ()
{
gdbarch_register_osabi (bfd_arch_arc, 0, GDB_OSABI_LINUX,
arc_linux_init_osabi);
}
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