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01ed1674d4
This patch is part of a series that has the aim of making the code that, for x86, reads the target description for a native process shared between GDB and gdbserver. Within GDB part of this process involves reading the cs and ds state from the 'struct user_regs_struct' using a ptrace call. This isn't done by gdbserver, which is part of the motivation for this whole series; the approach gdbserver takes is inferior to the approach GDB takes. This commit moves the reading of cs and ds, which is used to figure out if a thread is 32-bit or 64-bit (or in x32 mode), into the gdb/nat directory so that the code could be shared with gdbserver, but at this point I'm not actually using the code in gdbserver, that will come later. As such there should be no user visible changes after this commit, GDB continues to do things as it did before (reading cs/ds), while gdbserver continues to use its own approach (which doesn't require reading cs/ds). Approved-By: John Baldwin <jhb@FreeBSD.org>
130 lines
3.1 KiB
C
130 lines
3.1 KiB
C
/* Native-dependent code for GNU/Linux x86 (i386 and x86-64).
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Copyright (C) 1999-2024 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "gdbsupport/common-defs.h"
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#include "x86-linux.h"
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#include "x86-linux-dregs.h"
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#include "nat/gdb_ptrace.h"
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#include <sys/user.h>
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/* Per-thread arch-specific data we want to keep. */
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struct arch_lwp_info
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{
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/* Non-zero if our copy differs from what's recorded in the
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thread. */
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int debug_registers_changed;
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};
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/* See nat/x86-linux.h. */
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void
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lwp_set_debug_registers_changed (struct lwp_info *lwp, int value)
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{
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if (lwp_arch_private_info (lwp) == NULL)
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lwp_set_arch_private_info (lwp, XCNEW (struct arch_lwp_info));
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lwp_arch_private_info (lwp)->debug_registers_changed = value;
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}
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/* See nat/x86-linux.h. */
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int
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lwp_debug_registers_changed (struct lwp_info *lwp)
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{
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struct arch_lwp_info *info = lwp_arch_private_info (lwp);
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/* NULL means either that this is the main thread still going
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through the shell, or that no watchpoint has been set yet.
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The debug registers are unchanged in either case. */
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if (info == NULL)
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return 0;
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return info->debug_registers_changed;
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}
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/* See nat/x86-linux.h. */
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void
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x86_linux_new_thread (struct lwp_info *lwp)
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{
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lwp_set_debug_registers_changed (lwp, 1);
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}
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/* See nat/x86-linux.h. */
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void
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x86_linux_delete_thread (struct arch_lwp_info *arch_lwp)
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{
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xfree (arch_lwp);
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}
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/* See nat/x86-linux.h. */
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void
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x86_linux_prepare_to_resume (struct lwp_info *lwp)
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{
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x86_linux_update_debug_registers (lwp);
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}
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#ifdef __x86_64__
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/* Value of CS segment register:
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64bit process: 0x33
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32bit process: 0x23 */
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#define AMD64_LINUX_USER64_CS 0x33
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/* Value of DS segment register:
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LP64 process: 0x0
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X32 process: 0x2b */
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#define AMD64_LINUX_X32_DS 0x2b
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#endif
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/* See nat/x86-linux.h. */
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x86_linux_arch_size
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x86_linux_ptrace_get_arch_size (int tid)
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{
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#ifdef __x86_64__
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unsigned long cs;
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unsigned long ds;
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/* Get CS register. */
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errno = 0;
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cs = ptrace (PTRACE_PEEKUSER, tid,
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offsetof (struct user_regs_struct, cs), 0);
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if (errno != 0)
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perror_with_name (_("Couldn't get CS register"));
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bool is_64bit = cs == AMD64_LINUX_USER64_CS;
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/* Get DS register. */
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errno = 0;
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ds = ptrace (PTRACE_PEEKUSER, tid,
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offsetof (struct user_regs_struct, ds), 0);
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if (errno != 0)
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perror_with_name (_("Couldn't get DS register"));
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bool is_x32 = ds == AMD64_LINUX_X32_DS;
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return x86_linux_arch_size (is_64bit, is_x32);
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#else
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return x86_linux_arch_size (false, false);
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#endif
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}
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