binutils-gdb/gdb/arch-utils.h
Luis Machado 5133a31537 Recognize more program breakpoint patterns
New in v3:

- Code cleanups based on reviews.

New in v2:

- Fixed misc problems based on reviews.
- Switched to using gdbarch_program_breakpoint_here_p as opposed to
gdbarch_insn_is_breakpoint.
- Fixed matching of brk instructions. Previously the mask was incorrect, which
was showing up as a few failures in the testsuite. Now it is clean.
- New testcase (separate patch).
- Moved program_breakpoint_here () to arch-utils.c and made it the default
implementation of gdbarch_program_breakpoint_here_p.

--

It was reported to me that program breakpoints (permanent ones inserted into
the code itself) other than the one GDB uses for AArch64 (0xd4200000) do not
generate visible stops when continuing, and GDB will continue spinning
infinitely.

This happens because GDB, upon hitting one of those program breakpoints, thinks
the SIGTRAP came from a delayed breakpoint hit...

(gdb) x/i $pc
=> 0x4005c0 <problem_function>: brk     #0x90f
(gdb) c
Continuing.
infrun: clear_proceed_status_thread (process 14198)
infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: proceed: resuming process 14198
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0
infrun: infrun_async(1)
infrun: prepare_to_wait
infrun: target_wait (-1.0.0, status) =
infrun:   14198.14198.0 [process 14198],
infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: stop_pc = 0x4005c0
infrun: delayed software breakpoint trap, ignoring
infrun: no stepping, continue
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0
infrun: prepare_to_wait
infrun: target_wait (-1.0.0, status) =
infrun:   14198.14198.0 [process 14198],
infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: stop_pc = 0x4005c0
infrun: delayed software breakpoint trap, ignoring
infrun: no stepping, continue
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0
infrun: prepare_to_wait
infrun: target_wait (-1.0.0, status) =
infrun:   14198.14198.0 [process 14198],
infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: stop_pc = 0x4005c0
infrun: delayed software breakpoint trap, ignoring
infrun: no stepping, continue
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0
infrun: prepare_to_wait
infrun: target_wait (-1.0.0, status) =
infrun:   14198.14198.0 [process 14198],
infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: stop_pc = 0x4005c0
infrun: delayed software breakpoint trap, ignoring
infrun: no stepping, continue
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0
infrun: prepare_to_wait
infrun: target_wait (-1.0.0, status) =
infrun:   14198.14198.0 [process 14198],
infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
...

... which is not the case.

If the program breakpoint is one GDB recognizes, then it will stop when it
hits it.

(gdb) x/i $pc
=> 0x4005c0 <problem_function>: brk     #0x0
(gdb) c
Continuing.
infrun: clear_proceed_status_thread (process 14193)
infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: proceed: resuming process 14193
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14193] at 0x4005c0
infrun: infrun_async(1)
infrun: prepare_to_wait
infrun: target_wait (-1.0.0, status) =
infrun:   14193.14193.0 [process 14193],
infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: stop_pc = 0x4005c0
infrun: random signal (GDB_SIGNAL_TRAP)
infrun: stop_waiting
infrun: stop_all_threads
infrun: stop_all_threads, pass=0, iterations=0
infrun:   process 14193 not executing
infrun: stop_all_threads, pass=1, iterations=1
infrun:   process 14193 not executing
infrun: stop_all_threads done

Program received signal SIGTRAP, Trace/breakpoint trap.
problem_function () at brk_0.c:7
7        asm("brk %0\n\t" ::"n"(0x0));
infrun: infrun_async(0)

Otherwise GDB will keep trying to resume the inferior and will keep
seeing the SIGTRAP's, without stopping.

To the user it appears GDB has gone into an infinite loop, interruptible only
by Ctrl-C.

Also, windbg seems to use a different variation of AArch64 breakpoint compared
to GDB. This causes problems when debugging Windows on ARM binaries, when
program breakpoints are being used.

The proposed patch creates a new gdbarch method (gdbarch_program_breakpoint_here_p)
that tells GDB whether the underlying instruction is a breakpoint instruction
or not.

This is more general than only checking for the instruction GDB uses as
breakpoint.

The existing logic is still preserved for targets that do not implement this
new gdbarch method.

The end result is like so:

(gdb) x/i $pc
=> 0x4005c0 <problem_function>: brk     #0x90f
(gdb) c
Continuing.
infrun: clear_proceed_status_thread (process 16417)
infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: proceed: resuming process 16417
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 16417] at 0x4005c0
infrun: infrun_async(1)
infrun: prepare_to_wait
infrun: target_wait (-1.0.0, status) =
infrun:   16417.16417.0 [process 16417],
infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: stop_pc = 0x4005c0
infrun: random signal (GDB_SIGNAL_TRAP)
infrun: stop_waiting
infrun: stop_all_threads
infrun: stop_all_threads, pass=0, iterations=0
infrun:   process 16417 not executing
infrun: stop_all_threads, pass=1, iterations=1
infrun:   process 16417 not executing
infrun: stop_all_threads done

Program received signal SIGTRAP, Trace/breakpoint trap.
problem_function () at brk.c:7
7        asm("brk %0\n\t" ::"n"(0x900 + 0xf));
infrun: infrun_async(0)

gdb/ChangeLog:

2020-01-29  Luis Machado  <luis.machado@linaro.org>

	* aarch64-tdep.c (BRK_INSN_MASK): Define to 0xffe0001f.
	(BRK_INSN_MASK): Define to 0xd4200000.
	(aarch64_program_breakpoint_here_p): New function.
	(aarch64_gdbarch_init): Set gdbarch_program_breakpoint_here_p hook.
	* arch-utils.c (default_program_breakpoint_here_p): Moved from
	breakpoint.c.
	* arch-utils.h (default_program_breakpoint_here_p): Moved from
	breakpoint.h
	* breakpoint.c (bp_loc_is_permanent): Changed return type to bool and
	call gdbarch_program_breakpoint_here_p.
	(program_breakpoint_here): Moved to arch-utils.c, renamed to
	default_program_breakpoint_here_p, changed return type to bool and
	simplified.
	* breakpoint.h (program_breakpoint_here): Moved prototype to
	arch-utils.h, renamed to default_program_breakpoint_here_p and changed
	return type to bool.
	* gdbarch.c: Regenerate.
	* gdbarch.h: Regenerate.
	* gdbarch.sh (program_breakpoint_here_p): New method.
	* infrun.c (handle_signal_stop): Call
	gdbarch_program_breakpoint_here_p.
2020-01-29 11:25:10 -03:00

284 lines
9.9 KiB
C++

/* Dynamic architecture support for GDB, the GNU debugger.
Copyright (C) 1998-2020 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/>. */
#ifndef ARCH_UTILS_H
#define ARCH_UTILS_H
#include "gdbarch.h"
struct frame_info;
struct minimal_symbol;
struct type;
struct gdbarch_info;
struct dwarf2_frame_state;
template <size_t bp_size, const gdb_byte *break_insn>
struct bp_manipulation
{
static int
kind_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr)
{
return bp_size;
}
static const gdb_byte *
bp_from_kind (struct gdbarch *gdbarch, int kind, int *size)
{
*size = kind;
return break_insn;
}
};
template <size_t bp_size,
const gdb_byte *break_insn_little,
const gdb_byte *break_insn_big>
struct bp_manipulation_endian
{
static int
kind_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pcptr)
{
return bp_size;
}
static const gdb_byte *
bp_from_kind (struct gdbarch *gdbarch, int kind, int *size)
{
*size = kind;
if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
return break_insn_big;
else
return break_insn_little;
}
};
#define BP_MANIPULATION(BREAK_INSN) \
bp_manipulation<sizeof (BREAK_INSN), BREAK_INSN>
#define BP_MANIPULATION_ENDIAN(BREAK_INSN_LITTLE, BREAK_INSN_BIG) \
bp_manipulation_endian<sizeof (BREAK_INSN_LITTLE), \
BREAK_INSN_LITTLE, BREAK_INSN_BIG>
/* Default implementation of gdbarch_displaced_hw_singlestep. */
extern int
default_displaced_step_hw_singlestep (struct gdbarch *,
struct displaced_step_closure *);
/* Possible value for gdbarch_displaced_step_location:
Place displaced instructions at the program's entry point,
leaving space for inferior function call return breakpoints. */
extern CORE_ADDR displaced_step_at_entry_point (struct gdbarch *gdbarch);
/* The only possible cases for inner_than. */
extern int core_addr_lessthan (CORE_ADDR lhs, CORE_ADDR rhs);
extern int core_addr_greaterthan (CORE_ADDR lhs, CORE_ADDR rhs);
/* Identity functions on a CORE_ADDR. Just return the "addr". */
extern CORE_ADDR core_addr_identity (struct gdbarch *gdbarch, CORE_ADDR addr);
extern gdbarch_convert_from_func_ptr_addr_ftype convert_from_func_ptr_addr_identity;
/* No-op conversion of reg to regnum. */
extern int no_op_reg_to_regnum (struct gdbarch *gdbarch, int reg);
/* Do nothing version of coff_make_msymbol_special. */
void default_coff_make_msymbol_special (int val, struct minimal_symbol *msym);
/* Do nothing default implementation of gdbarch_make_symbol_special. */
void default_make_symbol_special (struct symbol *sym, struct objfile *objfile);
/* Do nothing default implementation of gdbarch_adjust_dwarf2_addr. */
CORE_ADDR default_adjust_dwarf2_addr (CORE_ADDR pc);
/* Do nothing default implementation of gdbarch_adjust_dwarf2_line. */
CORE_ADDR default_adjust_dwarf2_line (CORE_ADDR addr, int rel);
/* Default DWARF vendor CFI handler. */
bool default_execute_dwarf_cfa_vendor_op (struct gdbarch *gdbarch, gdb_byte op,
struct dwarf2_frame_state *fs);
/* Version of cannot_fetch_register() / cannot_store_register() that
always fails. */
int cannot_register_not (struct gdbarch *gdbarch, int regnum);
/* Legacy version of target_virtual_frame_pointer(). Assumes that
there is an gdbarch_deprecated_fp_regnum and that it is the same, cooked or
raw. */
extern gdbarch_virtual_frame_pointer_ftype legacy_virtual_frame_pointer;
/* Default implementation of gdbarch_floatformat_for_type. */
extern const struct floatformat **
default_floatformat_for_type (struct gdbarch *gdbarch,
const char *name, int len);
extern CORE_ADDR generic_skip_trampoline_code (struct frame_info *frame,
CORE_ADDR pc);
extern CORE_ADDR generic_skip_solib_resolver (struct gdbarch *gdbarch,
CORE_ADDR pc);
extern int generic_in_solib_return_trampoline (struct gdbarch *gdbarch,
CORE_ADDR pc, const char *name);
extern int generic_stack_frame_destroyed_p (struct gdbarch *gdbarch,
CORE_ADDR pc);
extern int default_code_of_frame_writable (struct gdbarch *gdbarch,
struct frame_info *frame);
/* By default, registers are not convertible. */
extern int generic_convert_register_p (struct gdbarch *gdbarch, int regnum,
struct type *type);
extern int default_stabs_argument_has_addr (struct gdbarch *gdbarch,
struct type *type);
extern int generic_instruction_nullified (struct gdbarch *gdbarch,
struct regcache *regcache);
int default_remote_register_number (struct gdbarch *gdbarch,
int regno);
/* For compatibility with older architectures, returns
(LEGACY_SIM_REGNO_IGNORE) when the register doesn't have a valid
name. */
extern int legacy_register_sim_regno (struct gdbarch *gdbarch, int regnum);
/* Return the selected byte order, or BFD_ENDIAN_UNKNOWN if no byte
order was explicitly selected. */
extern enum bfd_endian selected_byte_order (void);
/* Return the selected architecture's name, or NULL if no architecture
was explicitly selected. */
extern const char *selected_architecture_name (void);
/* Initialize a ``struct info''. Can't use memset(0) since some
default values are not zero. "fill" takes all available
information and fills in any unspecified fields. */
extern void gdbarch_info_init (struct gdbarch_info *info);
/* Similar to init, but this time fill in the blanks. Information is
obtained from the global "set ..." options and explicitly
initialized INFO fields. */
extern void gdbarch_info_fill (struct gdbarch_info *info);
/* Return the architecture for ABFD. If no suitable architecture
could be find, return NULL. */
extern struct gdbarch *gdbarch_from_bfd (bfd *abfd);
/* Return "current" architecture. If the target is running, this is the
architecture of the selected frame. Otherwise, the "current" architecture
defaults to the target architecture.
This function should normally be called solely by the command interpreter
routines to determine the architecture to execute a command in. */
extern struct gdbarch *get_current_arch (void);
extern int default_has_shared_address_space (struct gdbarch *);
extern int default_fast_tracepoint_valid_at (struct gdbarch *gdbarch,
CORE_ADDR addr, std::string *msg);
extern const gdb_byte *default_breakpoint_from_pc (struct gdbarch *gdbarch,
CORE_ADDR *pcptr,
int *lenptr);
extern int default_breakpoint_kind_from_current_state (struct gdbarch *gdbarch,
struct regcache *regcache,
CORE_ADDR *pcptr);
extern void default_gen_return_address (struct gdbarch *gdbarch,
struct agent_expr *ax,
struct axs_value *value,
CORE_ADDR scope);
extern const char *default_auto_charset (void);
extern const char *default_auto_wide_charset (void);
extern int default_return_in_first_hidden_param_p (struct gdbarch *,
struct type *);
extern int default_insn_is_call (struct gdbarch *, CORE_ADDR);
extern int default_insn_is_ret (struct gdbarch *, CORE_ADDR);
extern int default_insn_is_jump (struct gdbarch *, CORE_ADDR);
/* Default implementation of gdbarch_program_breakpoint_here_p. */
extern bool default_program_breakpoint_here_p (struct gdbarch *gdbarch,
CORE_ADDR addr);
/* Do-nothing version of vsyscall_range. Returns false. */
extern int default_vsyscall_range (struct gdbarch *gdbarch, struct mem_range *range);
/* Default way to advance the PC to the next instruction in order to
skip a permanent breakpoint. Increments the PC by the size of a
software breakpoint instruction, as determined with
gdbarch_breakpoint_from_pc. This matches how the breakpoints
module determines whether a breakpoint is permanent. */
extern void default_skip_permanent_breakpoint (struct regcache *regcache);
/* Symbols for gdbarch_infcall_mmap; their Linux PROT_* system
definitions would be dependent on compilation host. */
#define GDB_MMAP_PROT_READ 0x1 /* Page can be read. */
#define GDB_MMAP_PROT_WRITE 0x2 /* Page can be written. */
#define GDB_MMAP_PROT_EXEC 0x4 /* Page can be executed. */
extern CORE_ADDR default_infcall_mmap (CORE_ADDR size, unsigned prot);
extern void default_infcall_munmap (CORE_ADDR addr, CORE_ADDR size);
extern std::string default_gcc_target_options (struct gdbarch *gdbarch);
extern const char *default_gnu_triplet_regexp (struct gdbarch *gdbarch);
extern int default_addressable_memory_unit_size (struct gdbarch *gdbarch);
extern void default_guess_tracepoint_registers (struct gdbarch *gdbarch,
struct regcache *regcache,
CORE_ADDR addr);
extern int default_print_insn (bfd_vma memaddr, disassemble_info *info);
/* Wrapper to gdbarch_skip_prologue, but doesn't throw exception. Catch
exception thrown from gdbarch_skip_prologue, and return PC. */
extern CORE_ADDR gdbarch_skip_prologue_noexcept (gdbarch *gdbarch,
CORE_ADDR pc) noexcept;
/* Default implementation of gdbarch_in_indirect_branch_thunk that returns
false. */
extern bool default_in_indirect_branch_thunk (gdbarch *gdbarch,
CORE_ADDR pc);
/* Default implementation of gdbarch type_align method. */
extern ULONGEST default_type_align (struct gdbarch *gdbarch,
struct type *type);
/* Default implementation of gdbarch get_pc_address_flags method. */
extern std::string default_get_pc_address_flags (frame_info *frame,
CORE_ADDR pc);
#endif /* ARCH_UTILS_H */