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binutils-gdb/gdb/arc-linux-tdep.c
Andrew Burgess 6f2643dbd2 gdb/arc: fix print_one_insn selftest 
I noticed that the ARC print_one_insn selftest was failing.  The
problem is that in print_one_insn_test the arc case falls through into
the special case that handles nios2, score, and riscv.

The special case for these targets hard codes the breakpoint kind to
'4'.  This is find for bare metal arc (see arc-tdep.c,
arc_sw_breakpoint_from_kind), however, for arc/linux only breakpoint
kind '2' is supported (see arc-linux-tdep.c,
arc_linux_sw_breakpoint_from_kind).

So the code in print_one_insn_test as it is currently written passed
in an invalid breakpoint kind, this leads to GDB trying to disassemble
unexpected memory.

The fix is to reorder the code in print_one_insn_test so that the arc
case falls through into the default case.  In the default we no longer
hard code the breakpoint kind, and everything should be good.

Additionally, given the arc code only expects specific breakpoint kind
values, I thought it would be nice to add some gdb_assert to validate
things.  This assert would have triggered in this case and made it
easier to find the error.

After this commit, configure GDB with --enable-targets=all, then run
gdb.gdb/unittest.exp, there should no longer be any failures.

gdb/ChangeLog:

	* arc-linux-tdep.c (arc_linux_sw_breakpoint_from_kind): Add an
	assert.
	* arc-tdep.c (arc_breakpoint_kind_from_pc): Likewise.
	* disasm-selftests.c (print_one_insn_test): Fall throough from ARC
	case to the default.
2020-11-17 10:11:51 +00:00

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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-linux-tdep.h"
#include "arc-tdep.h"
#include "arch/arc.h"
#define REGOFF(offset) (offset * ARC_REGISTER_SIZE)
/* arc_linux_core_reg_offsets[i] is the offset in the .reg section of GDB
regnum i. Array index is an internal GDB register number, as defined in
arc-tdep.h:arc_regnum.
From include/uapi/asm/ptrace.h in the ARC Linux sources. */
/* The layout of this struct is tightly bound to "arc_regnum" enum
in arc-tdep.h. Any change of order in there, must be reflected
here as well. */
static const int arc_linux_core_reg_offsets[] = {
/* R0 - R12. */
REGOFF (22), REGOFF (21), REGOFF (20), REGOFF (19),
REGOFF (18), REGOFF (17), REGOFF (16), REGOFF (15),
REGOFF (14), REGOFF (13), REGOFF (12), REGOFF (11),
REGOFF (10),
/* R13 - R25. */
REGOFF (37), REGOFF (36), REGOFF (35), REGOFF (34),
REGOFF (33), REGOFF (32), REGOFF (31), REGOFF (30),
REGOFF (29), REGOFF (28), REGOFF (27), REGOFF (26),
REGOFF (25),
REGOFF (9), /* R26 (GP) */
REGOFF (8), /* FP */
REGOFF (23), /* SP */
ARC_OFFSET_NO_REGISTER, /* ILINK */
ARC_OFFSET_NO_REGISTER, /* R30 */
REGOFF (7), /* BLINK */
/* R32 - R59. */
ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
ARC_OFFSET_NO_REGISTER,
REGOFF (4), /* LP_COUNT */
ARC_OFFSET_NO_REGISTER, /* RESERVED */
ARC_OFFSET_NO_REGISTER, /* LIMM */
ARC_OFFSET_NO_REGISTER, /* PCL */
REGOFF (39), /* PC */
REGOFF (5), /* STATUS32 */
REGOFF (2), /* LP_START */
REGOFF (3), /* LP_END */
REGOFF (1), /* BTA */
REGOFF (6) /* ERET */
};
/* 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)
{
gdb_assert (kind == trap_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;
}
}
void
arc_linux_supply_gregset (const struct regset *regset,
struct regcache *regcache,
int regnum, const void *gregs, size_t size)
{
gdb_static_assert (ARC_LAST_REGNUM
< ARRAY_SIZE (arc_linux_core_reg_offsets));
const bfd_byte *buf = (const bfd_byte *) gregs;
for (int reg = 0; reg <= ARC_LAST_REGNUM; reg++)
if (arc_linux_core_reg_offsets[reg] != ARC_OFFSET_NO_REGISTER)
regcache->raw_supply (reg, buf + arc_linux_core_reg_offsets[reg]);
}
void
arc_linux_supply_v2_regset (const struct regset *regset,
struct regcache *regcache, int regnum,
const void *v2_regs, size_t size)
{
const bfd_byte *buf = (const bfd_byte *) v2_regs;
/* user_regs_arcv2 is defined in linux arch/arc/include/uapi/asm/ptrace.h. */
regcache->raw_supply (ARC_R30_REGNUM, buf);
regcache->raw_supply (ARC_R58_REGNUM, buf + REGOFF (1));
regcache->raw_supply (ARC_R59_REGNUM, buf + REGOFF (2));
}
/* Populate BUF with register REGNUM from the REGCACHE. */
static void
collect_register (const struct regcache *regcache, struct gdbarch *gdbarch,
int regnum, gdb_byte *buf)
{
int offset;
/* Skip non-existing registers. */
if (arc_linux_core_reg_offsets[regnum] == ARC_OFFSET_NO_REGISTER)
return;
/* The address where the execution has stopped is in pseudo-register
STOP_PC. However, when kernel code is returning from the exception,
it uses the value from ERET register. Since, TRAP_S (the breakpoint
instruction) commits, the ERET points to the next instruction. In
other words: ERET != STOP_PC. To jump back from the kernel code to
the correct address, ERET must be overwritten by GDB's STOP_PC. Else,
the program will continue at the address after the current instruction.
*/
if (regnum == gdbarch_pc_regnum (gdbarch))
offset = arc_linux_core_reg_offsets[ARC_ERET_REGNUM];
else
offset = arc_linux_core_reg_offsets[regnum];
regcache->raw_collect (regnum, buf + offset);
}
void
arc_linux_collect_gregset (const struct regset *regset,
const struct regcache *regcache,
int regnum, void *gregs, size_t size)
{
gdb_static_assert (ARC_LAST_REGNUM
< ARRAY_SIZE (arc_linux_core_reg_offsets));
gdb_byte *buf = (gdb_byte *) gregs;
struct gdbarch *gdbarch = regcache->arch ();
/* regnum == -1 means writing all the registers. */
if (regnum == -1)
for (int reg = 0; reg <= ARC_LAST_REGNUM; reg++)
collect_register (regcache, gdbarch, reg, buf);
else if (regnum <= ARC_LAST_REGNUM)
collect_register (regcache, gdbarch, regnum, buf);
else
gdb_assert_not_reached ("Invalid regnum in arc_linux_collect_gregset.");
}
void
arc_linux_collect_v2_regset (const struct regset *regset,
const struct regcache *regcache, int regnum,
void *v2_regs, size_t size)
{
bfd_byte *buf = (bfd_byte *) v2_regs;
regcache->raw_collect (ARC_R30_REGNUM, buf);
regcache->raw_collect (ARC_R58_REGNUM, buf + REGOFF (1));
regcache->raw_collect (ARC_R59_REGNUM, buf + REGOFF (2));
}
/* Linux regset definitions. */
static const struct regset arc_linux_gregset = {
arc_linux_core_reg_offsets,
arc_linux_supply_gregset,
arc_linux_collect_gregset,
};
static const struct regset arc_linux_v2_regset = {
NULL,
arc_linux_supply_v2_regset,
arc_linux_collect_v2_regset,
};
/* Implement the `iterate_over_regset_sections` gdbarch method. */
static void
arc_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
iterate_over_regset_sections_cb *cb,
void *cb_data,
const struct regcache *regcache)
{
/* There are 40 registers in Linux user_regs_struct, although some of
them are now just a mere paddings, kept to maintain binary
compatibility with older tools. */
const int sizeof_gregset = 40 * ARC_REGISTER_SIZE;
cb (".reg", sizeof_gregset, sizeof_gregset, &arc_linux_gregset, NULL,
cb_data);
cb (".reg-arc-v2", ARC_LINUX_SIZEOF_V2_REGSET, ARC_LINUX_SIZEOF_V2_REGSET,
&arc_linux_v2_regset, NULL, cb_data);
}
/* Implement the `core_read_description` gdbarch method. */
static const struct target_desc *
arc_linux_core_read_description (struct gdbarch *gdbarch,
struct target_ops *target,
bfd *abfd)
{
arc_arch_features features
= arc_arch_features_create (abfd,
gdbarch_bfd_arch_info (gdbarch)->mach);
return arc_lookup_target_description (features);
}
/* 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);
set_gdbarch_iterate_over_regset_sections
(gdbarch, arc_linux_iterate_over_regset_sections);
set_gdbarch_core_read_description (gdbarch, arc_linux_core_read_description);
/* 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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