Add support for the x86 XSAVE extended state on FreeBSD/x86.

Recognize NT_X86_XSTATE notes in FreeBSD process cores.  Recent
FreeBSD versions include a note containing the XSAVE state for each
thread in the process when XSAVE is in use.  The note stores a copy of
the current XSAVE mask in a reserved section of the machine-defined
XSAVE state at the same offset as Linux's NT_X86_XSTATE note.

For native processes, use the PT_GETXSTATE_INFO ptrace request to
determine if XSAVE is enabled, and if so the active XSAVE state mask
(that is, the value of %xcr0 for the target process) as well as the
size of XSAVE state area.  Use the PT_GETXSTATE and PT_SETXSTATE requests
to fetch and store the XSAVE state, respectively, in the BSD x86
native targets.

In addition, the FreeBSD amd64 and i386 native targets now include
"read_description" target methods to determine the correct x86 target
description for the current XSAVE mask.  On FreeBSD amd64 this also
properly returns an i386 target description for 32-bit binaries which
allows the 64-bit GDB to run 32-bit binaries.

Note that the ptrace changes are in the BSD native targets, not the
FreeBSD-specific native targets since that is where the other ptrace
register accesses occur.  Of the other BSDs, NetBSD and DragonFly use
XSAVE in the kernel but do not currently export the extended state via
ptrace(2).  OpenBSD does not currently support XSAVE.

bfd/ChangeLog:

	* elf.c (elfcore_grok_note): Recognize NT_X86_XSTATE on
	FreeBSD.
	(elfcore_write_xstatereg): Use correct note name on FreeBSD.

gdb/ChangeLog:

	* amd64-tdep.c (amd64_target_description): New function.
	* amd64-tdep.h: Export amd64_target_description and tdesc_amd64.
	* amd64bsd-nat.c [PT_GETXSTATE_INFO]: New variable amd64bsd_xsave_len.
	(amd64bsd_fetch_inferior_registers) [PT_GETXSTATE_INFO]: Handle
	x86 extended save area.
	(amd64bsd_store_inferior_registers) [PT_GETXSTATE_INFO]: Likewise.
	* amd64bsd-nat.h: Export amd64bsd_xsave_len.
	* amd64fbsd-nat.c (amd64fbsd_read_description): New function.
	(_initialize_amd64fbsd_nat): Set "to_read_description" to
	"amd64fbsd_read_description".
	* amd64fbsd-tdep.c (amd64fbsd_core_read_description): New function.
	(amd64fbsd_supply_xstateregset): New function.
	(amd64fbsd_collect_xstateregset): New function.
	Add "amd64fbsd_xstateregset".
	(amd64fbsd_iterate_over_regset_sections): New function.
	(amd64fbsd_init_abi): Set "xsave_xcr0_offset" to
	"I386_FBSD_XSAVE_XCR0_OFFSET".
	Add "iterate_over_regset_sections" gdbarch method.
	Add "core_read_description" gdbarch method.
	* i386-tdep.c (i386_target_description): New function.
	* i386-tdep.h: Export i386_target_description and tdesc_i386.
	* i386bsd-nat.c [PT_GETXSTATE_INFO]: New variable i386bsd_xsave_len.
	(i386bsd_fetch_inferior_registers) [PT_GETXSTATE_INFO]: Handle
	x86 extended save area.
	(i386bsd_store_inferior_registers) [PT_GETXSTATE_INFO]: Likewise.
	* i386bsd-nat.h: Export i386bsd_xsave_len.
	* i386fbsd-nat.c (i386fbsd_read_description): New function.
	(_initialize_i386fbsd_nat): Set "to_read_description" to
	"i386fbsd_read_description".
	* i386fbsd-tdep.c (i386fbsd_core_read_xcr0): New function.
	(i386fbsd_core_read_description): New function.
	(i386fbsd_supply_xstateregset): New function.
	(i386fbsd_collect_xstateregset): New function.
	Add "i386fbsd_xstateregset".
	(i386fbsd_iterate_over_regset_sections): New function.
	(i386fbsd4_init_abi): Set "xsave_xcr0_offset" to
	"I386_FBSD_XSAVE_XCR0_OFFSET".
	Add "iterate_over_regset_sections" gdbarch method.
	Add "core_read_description" gdbarch method.
	* i386fbsd-tdep.h: New file.

1 files changed, 31 insertions, 0 deletions

diff --git a/gdb/i386fbsd-tdep.h b/gdb/i386fbsd-tdep.h
new file mode 100644
index 00000000000..8d6f9985f86
--- /dev/null
+++ b/gdb/i386fbsd-tdep.h
@@ -0,0 +1,31 @@
+/* Target-dependent code for FreeBSD x86.
+
+   Copyright (C) 2015 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 I386FBSD_TDEP_H
+#define I386FBSD_TDEP_H
+
+/* Get XSAVE extended state xcr0 from core dump.  */
+extern uint64_t i386fbsd_core_read_xcr0 (bfd *abfd);
+
+/* The format of the XSAVE extended area is determined by hardware.
+   Cores store the XSAVE extended area in a NT_X86_XSTATE note that
+   matches the layout on Linux.  */
+#define I386_FBSD_XSAVE_XCR0_OFFSET 464
+
+#endif /* i386fbsd-tdep.h */