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- /* Displaced stepping related things.
- Copyright (C) 2020-2022 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 DISPLACED_STEPPING_H
- #define DISPLACED_STEPPING_H
- #include "gdbsupport/array-view.h"
- #include "gdbsupport/byte-vector.h"
- struct gdbarch;
- struct thread_info;
- /* True if we are debugging displaced stepping. */
- extern bool debug_displaced;
- /* Print a "displaced" debug statement. */
- #define displaced_debug_printf(fmt, ...) \
- debug_prefixed_printf_cond (debug_displaced, "displaced",fmt, ##__VA_ARGS__)
- enum displaced_step_prepare_status
- {
- /* A displaced stepping buffer was successfully allocated and prepared. */
- DISPLACED_STEP_PREPARE_STATUS_OK,
- /* This particular instruction can't be displaced stepped, GDB should fall
- back on in-line stepping. */
- DISPLACED_STEP_PREPARE_STATUS_CANT,
- /* Not enough resources are available at this time, try again later. */
- DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE,
- };
- enum displaced_step_finish_status
- {
- /* Either the instruction was stepped and fixed up, or the specified thread
- wasn't executing a displaced step (in which case there's nothing to
- finish). */
- DISPLACED_STEP_FINISH_STATUS_OK,
- /* The thread started a displaced step, but didn't complete it. */
- DISPLACED_STEP_FINISH_STATUS_NOT_EXECUTED,
- };
- /* Data returned by a gdbarch displaced_step_copy_insn method, to be passed to
- the matching displaced_step_fixup method. */
- struct displaced_step_copy_insn_closure
- {
- virtual ~displaced_step_copy_insn_closure () = 0;
- };
- using displaced_step_copy_insn_closure_up
- = std::unique_ptr<displaced_step_copy_insn_closure>;
- /* A simple displaced step closure that contains only a byte buffer. */
- struct buf_displaced_step_copy_insn_closure : displaced_step_copy_insn_closure
- {
- buf_displaced_step_copy_insn_closure (int buf_size)
- : buf (buf_size)
- {}
- /* The content of this buffer is up to the user of the class, but typically
- original instruction bytes, used during fixup to determine what needs to
- be fixed up. */
- gdb::byte_vector buf;
- };
- /* Per-inferior displaced stepping state. */
- struct displaced_step_inferior_state
- {
- displaced_step_inferior_state ()
- {
- reset ();
- }
- /* Put this object back in its original state. */
- void reset ()
- {
- failed_before = false;
- in_progress_count = 0;
- unavailable = false;
- }
- /* True if preparing a displaced step ever failed. If so, we won't
- try displaced stepping for this inferior again. */
- bool failed_before;
- /* Number of displaced steps in progress for this inferior. */
- unsigned int in_progress_count;
- /* If true, this tells GDB that it's not worth asking the gdbarch displaced
- stepping implementation to prepare a displaced step, because it would
- return UNAVAILABLE. This is set and reset by the gdbarch in the
- displaced_step_prepare and displaced_step_finish methods. */
- bool unavailable;
- };
- /* Per-thread displaced stepping state. */
- struct displaced_step_thread_state
- {
- /* Return true if this thread is currently executing a displaced step. */
- bool in_progress () const
- {
- return m_original_gdbarch != nullptr;
- }
- /* Return the gdbarch of the thread prior to the step. */
- gdbarch *get_original_gdbarch () const
- {
- return m_original_gdbarch;
- }
- /* Mark this thread as currently executing a displaced step.
- ORIGINAL_GDBARCH is the current gdbarch of the thread (before the step
- is executed). */
- void set (gdbarch *original_gdbarch)
- {
- m_original_gdbarch = original_gdbarch;
- }
- /* Mark this thread as no longer executing a displaced step. */
- void reset ()
- {
- m_original_gdbarch = nullptr;
- }
- private:
- gdbarch *m_original_gdbarch = nullptr;
- };
- /* Control access to multiple displaced stepping buffers at fixed addresses. */
- struct displaced_step_buffers
- {
- explicit displaced_step_buffers (gdb::array_view<CORE_ADDR> buffer_addrs)
- {
- gdb_assert (buffer_addrs.size () > 0);
- m_buffers.reserve (buffer_addrs.size ());
- for (CORE_ADDR buffer_addr : buffer_addrs)
- m_buffers.emplace_back (buffer_addr);
- }
- displaced_step_prepare_status prepare (thread_info *thread,
- CORE_ADDR &displaced_pc);
- displaced_step_finish_status finish (gdbarch *arch, thread_info *thread,
- gdb_signal sig);
- const displaced_step_copy_insn_closure *
- copy_insn_closure_by_addr (CORE_ADDR addr);
- void restore_in_ptid (ptid_t ptid);
- private:
- /* State of a single buffer. */
- struct displaced_step_buffer
- {
- explicit displaced_step_buffer (CORE_ADDR addr)
- : addr (addr)
- {}
- /* Address of the buffer. */
- const CORE_ADDR addr;
- /* The original PC of the instruction currently being stepped. */
- CORE_ADDR original_pc = 0;
- /* If set, the thread currently using the buffer. If unset, the buffer is not
- used. */
- thread_info *current_thread = nullptr;
- /* Saved copy of the bytes in the displaced buffer, to be restored once the
- buffer is no longer used. */
- gdb::byte_vector saved_copy;
- /* Closure obtained from gdbarch_displaced_step_copy_insn, to be passed to
- gdbarch_displaced_step_fixup_insn. */
- displaced_step_copy_insn_closure_up copy_insn_closure;
- };
- std::vector<displaced_step_buffer> m_buffers;
- };
- #endif /* DISPLACED_STEPPING_H */
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