Files
binutils-gdb/gdb/arch/aarch64.c
Thiago Jung Bauermann ff62d39aa4 GDB, gdbserver: aarch64-linux: Initial Guarded Control Stack support
Add the org.gnu.gdb.aarch64.gcs feature with the GCSPR register, and the
org.gnu.gdb.aarch64.gcs.linux feature with "registers" to represent the
Linux kernel ptrace and prctl knobs that enable and lock specific GCS
functionality.

This code supports GCS only in Linux userspace applications, so the
GCSPR that is exposed is the one at EL0.

Also, support for calling inferior functions is enabled by adding an
implementation for the shadow_stack_push gdbarch method.

If for some reason a target description contains the
org.gnu.gdb.aarch64.gcs feature but not the
org.gnu.gdb.aarch64.gcs.linux feature then GCS support is disabled and
GDB continues the debugging session.  Features that need GCS
support (for example, calling inferior functions) will not work and the
inferior will get a segmentation fault signal instead.  There's a
testcase for this scenario but it only checks the native debugging case,
even though in practice this problem would only occur in remote
debugging with a broken stub or gdbserver.  I tested manually with a
gdbserver hacked to send a broken target description and it worked as
described.

Testcases gdb.arch/aarch64-gcs.exp, gdb.arch/aarch64-gcs-core.exp and
gdb.arch/aarch64-gcs-wrong-tdesc.exp are included to cover the added
functionality.

Reviewed-By: Christina Schimpe <christina.schimpe@intel.com>
Approved-By: Luis Machado <luis.machado@arm.com>
2025-08-29 18:35:58 -03:00

109 lines
3.1 KiB
C

/* Copyright (C) 2017-2025 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 "aarch64.h"
#include <stdlib.h>
#include "../features/aarch64-core.c"
#include "../features/aarch64-fpu.c"
#include "../features/aarch64-sve.c"
#include "../features/aarch64-pauth.c"
#include "../features/aarch64-mte.c"
#include "../features/aarch64-sme.c"
#include "../features/aarch64-sme2.c"
#include "../features/aarch64-tls.c"
#include "../features/aarch64-gcs.c"
#include "../features/aarch64-gcs-linux.c"
/* See arch/aarch64.h. */
target_desc *
aarch64_create_target_description (const aarch64_features &features)
{
target_desc_up tdesc = allocate_target_description ();
#ifndef IN_PROCESS_AGENT
set_tdesc_architecture (tdesc.get (), "aarch64");
#endif
long regnum = 0;
regnum = create_feature_aarch64_core (tdesc.get (), regnum);
if (features.vq == 0)
regnum = create_feature_aarch64_fpu (tdesc.get (), regnum);
else
regnum = create_feature_aarch64_sve (tdesc.get (), regnum, features.vq);
if (features.pauth)
regnum = create_feature_aarch64_pauth (tdesc.get (), regnum);
/* Memory tagging extension registers. */
if (features.mte)
regnum = create_feature_aarch64_mte (tdesc.get (), regnum);
/* TLS registers. */
if (features.tls > 0)
regnum = create_feature_aarch64_tls (tdesc.get (), regnum, features.tls);
if (features.svq)
regnum = create_feature_aarch64_sme (tdesc.get (), regnum,
sve_vl_from_vq (features.svq));
if (features.sme2)
regnum = create_feature_aarch64_sme2 (tdesc.get (), regnum);
if (features.gcs)
regnum = create_feature_aarch64_gcs (tdesc.get (), regnum);
if (features.gcs_linux)
regnum = create_feature_aarch64_gcs_linux (tdesc.get (), regnum);
return tdesc.release ();
}
/* See arch/aarch64.h. */
CORE_ADDR
aarch64_remove_top_bits (CORE_ADDR pointer, CORE_ADDR mask)
{
/* The VA range select bit is 55. This bit tells us if we have a
kernel-space address or a user-space address. */
bool kernel_address = (pointer & VA_RANGE_SELECT_BIT_MASK) != 0;
/* Remove the top non-address bits. */
pointer &= ~mask;
/* Sign-extend if we have a kernel-space address. */
if (kernel_address)
pointer |= mask;
return pointer;
}
/* See arch/aarch64.h. */
CORE_ADDR
aarch64_mask_from_pac_registers (const CORE_ADDR cmask, const CORE_ADDR dmask)
{
/* If the masks differ, default to using the one with the most coverage. */
if (dmask != cmask)
return dmask > cmask ? dmask : cmask;
return cmask;
}