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/* Native-dependent code for GNU/Linux x86 (i386 and x86-64).
Copyright (C) 1999-2024 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/>. */
#include "inferior.h"
#include "elf/common.h"
#include "gdb_proc_service.h"
#include "nat/gdb_ptrace.h"
#include <sys/user.h>
#include <sys/procfs.h>
#include <sys/uio.h>
#include "x86-nat.h"
#ifndef __x86_64__
#include "nat/i386-linux.h"
#endif
#include "x86-linux-nat.h"
#include "i386-linux-tdep.h"
#ifdef __x86_64__
#include "amd64-linux-tdep.h"
#endif
#include "gdbsupport/x86-xstate.h"
#include "nat/x86-xstate.h"
#include "nat/linux-btrace.h"
#include "nat/linux-nat.h"
#include "nat/x86-linux.h"
#include "nat/x86-linux-dregs.h"
#include "nat/linux-ptrace.h"
#include "nat/x86-linux-tdesc.h"
/* linux_nat_target::low_new_fork implementation. */
void
x86_linux_nat_target::low_new_fork (struct lwp_info *parent, pid_t child_pid)
{
pid_t parent_pid;
struct x86_debug_reg_state *parent_state;
struct x86_debug_reg_state *child_state;
/* NULL means no watchpoint has ever been set in the parent. In
that case, there's nothing to do. */
if (parent->arch_private == NULL)
return;
/* Linux kernel before 2.6.33 commit
72f674d203cd230426437cdcf7dd6f681dad8b0d
will inherit hardware debug registers from parent
on fork/vfork/clone. Newer Linux kernels create such tasks with
zeroed debug registers.
GDB core assumes the child inherits the watchpoints/hw
breakpoints of the parent, and will remove them all from the
forked off process. Copy the debug registers mirrors into the
new process so that all breakpoints and watchpoints can be
removed together. The debug registers mirror will become zeroed
in the end before detaching the forked off process, thus making
this compatible with older Linux kernels too. */
parent_pid = parent->ptid.pid ();
parent_state = x86_debug_reg_state (parent_pid);
child_state = x86_debug_reg_state (child_pid);
*child_state = *parent_state;
}
x86_linux_nat_target::~x86_linux_nat_target ()
{
}
/* Implement the virtual inf_ptrace_target::post_startup_inferior method. */
void
x86_linux_nat_target::post_startup_inferior (ptid_t ptid)
{
x86_cleanup_dregs ();
linux_nat_target::post_startup_inferior (ptid);
}
/* Get Linux/x86 target description from running target. */
const struct target_desc *
x86_linux_nat_target::read_description ()
{
/* The x86_linux_tdesc_for_tid call only reads xcr0 the first time it is
called, the xcr0 value is stored here and reused on subsequent calls. */
static uint64_t xcr0_storage;
if (inferior_ptid == null_ptid)
return this->beneath ()->read_description ();
int tid = inferior_ptid.pid ();
return x86_linux_tdesc_for_tid (tid, &xcr0_storage, &this->m_xsave_layout);
}
/* Enable branch tracing. */
struct btrace_target_info *
x86_linux_nat_target::enable_btrace (thread_info *tp,
const struct btrace_config *conf)
{
struct btrace_target_info *tinfo = nullptr;
ptid_t ptid = tp->ptid;
try
{
tinfo = linux_enable_btrace (ptid, conf);
}
catch (const gdb_exception_error &exception)
{
error (_("Could not enable branch tracing for %s: %s"),
target_pid_to_str (ptid).c_str (), exception.what ());
}
return tinfo;
}
/* Disable branch tracing. */
void
x86_linux_nat_target::disable_btrace (struct btrace_target_info *tinfo)
{
enum btrace_error errcode = linux_disable_btrace (tinfo);
if (errcode != BTRACE_ERR_NONE)
error (_("Could not disable branch tracing."));
}
/* Teardown branch tracing. */
void
x86_linux_nat_target::teardown_btrace (struct btrace_target_info *tinfo)
{
/* Ignore errors. */
linux_disable_btrace (tinfo);
}
enum btrace_error
x86_linux_nat_target::read_btrace (struct btrace_data *data,
struct btrace_target_info *btinfo,
enum btrace_read_type type)
{
return linux_read_btrace (data, btinfo, type);
}
/* See to_btrace_conf in target.h. */
const struct btrace_config *
x86_linux_nat_target::btrace_conf (const struct btrace_target_info *btinfo)
{
return linux_btrace_conf (btinfo);
}
/* Helper for ps_get_thread_area. Sets BASE_ADDR to a pointer to
the thread local storage (or its descriptor) and returns PS_OK
on success. Returns PS_ERR on failure. */
ps_err_e
x86_linux_get_thread_area (pid_t pid, void *addr, unsigned int *base_addr)
{
/* NOTE: cagney/2003-08-26: The definition of this buffer is found
in the kernel header <asm-i386/ldt.h>. It, after padding, is 4 x
4 byte integers in size: `entry_number', `base_addr', `limit',
and a bunch of status bits.
The values returned by this ptrace call should be part of the
regcache buffer, and ps_get_thread_area should channel its
request through the regcache. That way remote targets could
provide the value using the remote protocol and not this direct
call.
Is this function needed? I'm guessing that the `base' is the
address of a descriptor that libthread_db uses to find the
thread local address base that GDB needs. Perhaps that
descriptor is defined by the ABI. Anyway, given that
libthread_db calls this function without prompting (gdb
requesting tls base) I guess it needs info in there anyway. */
unsigned int desc[4];
/* This code assumes that "int" is 32 bits and that
GET_THREAD_AREA returns no more than 4 int values. */
gdb_assert (sizeof (int) == 4);
#ifndef PTRACE_GET_THREAD_AREA
#define PTRACE_GET_THREAD_AREA 25
#endif
if (ptrace (PTRACE_GET_THREAD_AREA, pid, addr, &desc) < 0)
return PS_ERR;
*base_addr = desc[1];
return PS_OK;
}
void _initialize_x86_linux_nat ();
void
_initialize_x86_linux_nat ()
{
/* Initialize the debug register function vectors. */
x86_dr_low.set_control = x86_linux_dr_set_control;
x86_dr_low.set_addr = x86_linux_dr_set_addr;
x86_dr_low.get_addr = x86_linux_dr_get_addr;
x86_dr_low.get_status = x86_linux_dr_get_status;
x86_dr_low.get_control = x86_linux_dr_get_control;
x86_set_debug_register_length (sizeof (void *));
}
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