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The XSAVE function set is organized in state components, which are a set of registers or parts of registers. So-called XSAVE-supported features are organized using state-component bitmaps, each bit corresponding to a single state component. The Intel Software Developer's Manual uses the term xstate_bv for a state-component bitmap, which is defined as XCR0 | IA32_XSS. The control register XCR0 only contains a state-component bitmap that specifies user state components, while IA32_XSS contains a state-component bitmap that specifies supervisor state components. Until now, XCR0 is used as input for target description creation in GDB. However, a following patch will add userspace support for the CET shadow stack feature by Intel. The CET state is configured in IA32_XSS and consists of 2 state components: - State component 11 used for the 2 MSRs controlling user-mode functionality for CET (CET_U state) - State component 12 used for the 3 MSRs containing shadow-stack pointers for privilege levels 0-2 (CET_S state). Reading the CET shadow stack pointer register on linux requires a separate ptrace call using NT_X86_SHSTK. To pass the CET shadow stack enablement state we would like to pass the xstate_bv value instead of xcr0 for target description creation. To prepare for that, we rename the xcr0 mask values for target description creation to xstate_bv. However, this patch doesn't add any functional changes in GDB. Future states specified in IA32_XSS such as CET will create a combined xstate_bv_mask including xcr0 register value and its corresponding bit in the state component bitmap. This combined mask will then be used to create the target descriptions. Reviewed-By: Thiago Jung Bauermann <thiago.bauermann@linaro.org> Approved-By: Luis Machado <luis.machado@arm.com>
68 lines
2.5 KiB
C
68 lines
2.5 KiB
C
/* Target description related code for GNU/Linux x86 (i386 and x86-64).
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Copyright (C) 2024-2025 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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#ifndef GDB_ARCH_X86_LINUX_TDESC_FEATURES_H
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#define GDB_ARCH_X86_LINUX_TDESC_FEATURES_H
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#include "gdbsupport/x86-xstate.h"
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#include "gdbsupport/gdb_assert.h"
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/* Return a mask of X86_STATE_* feature flags. The returned mask indicates
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the set of features which are checked for when creating the target
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description for each of amd64, x32, and i386. */
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extern uint64_t x86_linux_amd64_xstate_bv_feature_mask ();
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extern uint64_t x86_linux_x32_xstate_bv_feature_mask ();
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extern uint64_t x86_linux_i386_xstate_bv_feature_mask ();
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#ifdef GDBSERVER
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/* Convert an XSTATE_BV value into an integer. XSTATE_BV has the same
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format than the state component bitmap and does include user and
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supervisor state components. The integer will be passed from gdbserver
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to the in-process-agent where it will then be passed through
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x86_linux_tdesc_idx_to_xstate_bv to get back the original value. */
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extern int x86_linux_xstate_bv_to_tdesc_idx (uint64_t xstate_bv);
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#endif /* GDBSERVER */
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#ifdef IN_PROCESS_AGENT
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/* Return the maximum possible number of target descriptions for each of
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amd64, x32, and i386. These are used by the in-process-agent to
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generate every possible target description. */
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extern int x86_linux_amd64_tdesc_count ();
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extern int x86_linux_x32_tdesc_count ();
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extern int x86_linux_i386_tdesc_count ();
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/* Convert an index number (as returned from
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x86_linux_xstate_bv_to_tdesc_idx) into an xstate_bv value which can
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then be used to create a target description.
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The return mask has the same format than the state component bitmap
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and does include user and supervisor state components. */
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extern uint64_t x86_linux_tdesc_idx_to_xstate_bv (int idx);
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#endif /* IN_PROCESS_AGENT */
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#endif /* GDB_ARCH_X86_LINUX_TDESC_FEATURES_H */
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