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x86 nat: Add helper functions to save the XSAVE layout for the host.

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x86_xsave_length returns the total length of the XSAVE state area
standard format as queried from CPUID.

x86_fetch_xsave_layout uses CPUID to query the offsets of XSAVE
extended regions from the running host.  The total length of the XSAVE
state area can either be supplied by the caller if known (e.g. from
FreeBSD's PT_GETXSTATEINFO) or it can be queried from the running host
using x86_xsave_length.

Approved-By: Simon Marchi <simon.marchi@efficios.com>
This commit is contained in:
John Baldwin 2023-08-28 14:18:19 -07:00
parent e85aad4ae7
commit 2e639674c5
2 changed files with 102 additions and 0 deletions
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67
gdb/nat/x86-xstate.c Normal file
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/* x86 XSAVE extended state functions.
Copyright (C) 2022-2023 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 "gdbsupport/common-defs.h"
#include "gdbsupport/x86-xstate.h"
#include "nat/x86-cpuid.h"
#include "nat/x86-xstate.h"
/* Fetch the offset of a specific XSAVE extended region. */
static int
xsave_feature_offset (uint64_t xcr0, int feature)
{
uint32_t ebx;
if ((xcr0 & (1ULL << feature)) == 0)
return 0;
if (!x86_cpuid_count (0xd, feature, nullptr, &ebx, nullptr, nullptr))
return 0;
return ebx;
}
/* See x86-xstate.h. */
int
x86_xsave_length ()
{
uint32_t ecx;
if (!x86_cpuid_count (0xd, 0, nullptr, nullptr, &ecx, nullptr))
return 0;
return ecx;
}
/* See x86-xstate.h. */
x86_xsave_layout
x86_fetch_xsave_layout (uint64_t xcr0, int len)
{
x86_xsave_layout layout;
layout.sizeof_xsave = len;
layout.avx_offset = xsave_feature_offset (xcr0, X86_XSTATE_AVX_ID);
layout.bndregs_offset = xsave_feature_offset (xcr0, X86_XSTATE_BNDREGS_ID);
layout.bndcfg_offset = xsave_feature_offset (xcr0, X86_XSTATE_BNDCFG_ID);
layout.k_offset = xsave_feature_offset (xcr0, X86_XSTATE_K_ID);
layout.zmm_h_offset = xsave_feature_offset (xcr0, X86_XSTATE_ZMM_H_ID);
layout.zmm_offset = xsave_feature_offset (xcr0, X86_XSTATE_ZMM_ID);
layout.pkru_offset = xsave_feature_offset (xcr0, X86_XSTATE_PKRU_ID);
return layout;
}

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gdb/nat/x86-xstate.h Normal file
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/* x86 XSAVE extended state functions.
Copyright (C) 2022-2023 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 NAT_X86_XSTATE_H
#define NAT_X86_XSTATE_H
#include "gdbsupport/x86-xstate.h"
/* Return the size of the XSAVE extended state fetched via CPUID. */
int x86_xsave_length ();
/* Return the layout (size and offsets) of the XSAVE extended regions
for the running host. Offsets of each of the enabled regions in
XCR0 are fetched via CPUID. */
x86_xsave_layout x86_fetch_xsave_layout (uint64_t xcr0, int len);
#endif /* NAT_X86_XSTATE_H */