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9848bf8375
Note that this uses the CPUID instruction to determine the total size of the XSAVE register set. If there is a way to fetch the register set size using ptrace that would probably be better. Approved-By: Simon Marchi <simon.marchi@efficios.com>
725 lines
19 KiB
C
725 lines
19 KiB
C
/* Native-dependent code for GNU/Linux i386.
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Copyright (C) 1999-2023 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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#include "defs.h"
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#include "inferior.h"
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#include "gdbcore.h"
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#include "regcache.h"
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#include "elf/common.h"
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#include "nat/gdb_ptrace.h"
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#include <sys/uio.h>
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#include "gregset.h"
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#include "gdb_proc_service.h"
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#include "i386-linux-nat.h"
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#include "i387-tdep.h"
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#include "i386-tdep.h"
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#include "i386-linux-tdep.h"
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#include "gdbsupport/x86-xstate.h"
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#include "x86-linux-nat.h"
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#include "nat/linux-ptrace.h"
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#include "inf-ptrace.h"
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struct i386_linux_nat_target final : public x86_linux_nat_target
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{
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/* Add our register access methods. */
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void fetch_registers (struct regcache *, int) override;
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void store_registers (struct regcache *, int) override;
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/* Override the default ptrace resume method. */
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void low_resume (ptid_t ptid, int step, enum gdb_signal sig) override;
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};
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static i386_linux_nat_target the_i386_linux_nat_target;
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/* The register sets used in GNU/Linux ELF core-dumps are identical to
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the register sets in `struct user' that is used for a.out
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core-dumps, and is also used by `ptrace'. The corresponding types
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are `elf_gregset_t' for the general-purpose registers (with
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`elf_greg_t' the type of a single GP register) and `elf_fpregset_t'
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for the floating-point registers.
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Those types used to be available under the names `gregset_t' and
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`fpregset_t' too, and this file used those names in the past. But
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those names are now used for the register sets used in the
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`mcontext_t' type, and have a different size and layout. */
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/* Which ptrace request retrieves which registers?
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These apply to the corresponding SET requests as well. */
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#define GETREGS_SUPPLIES(regno) \
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((0 <= (regno) && (regno) <= 15) || (regno) == I386_LINUX_ORIG_EAX_REGNUM)
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#define GETFPXREGS_SUPPLIES(regno) \
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(I386_ST0_REGNUM <= (regno) && (regno) < I386_SSE_NUM_REGS)
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#define GETXSTATEREGS_SUPPLIES(regno) \
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(I386_ST0_REGNUM <= (regno) && (regno) < I386_PKEYS_NUM_REGS)
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/* Does the current host support the GETREGS request? */
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int have_ptrace_getregs =
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#ifdef HAVE_PTRACE_GETREGS
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1
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#else
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0
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#endif
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;
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/* Does the current host support the GETFPXREGS request? The header
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file may or may not define it, and even if it is defined, the
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kernel will return EIO if it's running on a pre-SSE processor.
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My instinct is to attach this to some architecture- or
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target-specific data structure, but really, a particular GDB
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process can only run on top of one kernel at a time. So it's okay
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for this to be a simple variable. */
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int have_ptrace_getfpxregs =
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#ifdef HAVE_PTRACE_GETFPXREGS
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-1
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#else
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0
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#endif
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;
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/* Accessing registers through the U area, one at a time. */
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/* Fetch one register. */
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static void
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fetch_register (struct regcache *regcache, int regno)
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{
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pid_t tid;
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int val;
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gdb_assert (!have_ptrace_getregs);
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if (i386_linux_gregset_reg_offset[regno] == -1)
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{
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regcache->raw_supply (regno, NULL);
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return;
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}
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tid = get_ptrace_pid (regcache->ptid ());
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errno = 0;
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val = ptrace (PTRACE_PEEKUSER, tid,
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i386_linux_gregset_reg_offset[regno], 0);
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if (errno != 0)
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error (_("Couldn't read register %s (#%d): %s."),
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gdbarch_register_name (regcache->arch (), regno),
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regno, safe_strerror (errno));
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regcache->raw_supply (regno, &val);
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}
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/* Store one register. */
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static void
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store_register (const struct regcache *regcache, int regno)
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{
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pid_t tid;
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int val;
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gdb_assert (!have_ptrace_getregs);
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if (i386_linux_gregset_reg_offset[regno] == -1)
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return;
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tid = get_ptrace_pid (regcache->ptid ());
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errno = 0;
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regcache->raw_collect (regno, &val);
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ptrace (PTRACE_POKEUSER, tid,
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i386_linux_gregset_reg_offset[regno], val);
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if (errno != 0)
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error (_("Couldn't write register %s (#%d): %s."),
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gdbarch_register_name (regcache->arch (), regno),
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regno, safe_strerror (errno));
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}
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/* Transfering the general-purpose registers between GDB, inferiors
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and core files. */
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/* Fill GDB's register array with the general-purpose register values
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in *GREGSETP. */
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void
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supply_gregset (struct regcache *regcache, const elf_gregset_t *gregsetp)
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{
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const gdb_byte *regp = (const gdb_byte *) gregsetp;
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int i;
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for (i = 0; i < I386_NUM_GREGS; i++)
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regcache->raw_supply (i, regp + i386_linux_gregset_reg_offset[i]);
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if (I386_LINUX_ORIG_EAX_REGNUM
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< gdbarch_num_regs (regcache->arch ()))
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regcache->raw_supply
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(I386_LINUX_ORIG_EAX_REGNUM,
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regp + i386_linux_gregset_reg_offset[I386_LINUX_ORIG_EAX_REGNUM]);
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}
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/* Fill register REGNO (if it is a general-purpose register) in
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*GREGSETPS with the value in GDB's register array. If REGNO is -1,
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do this for all registers. */
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void
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fill_gregset (const struct regcache *regcache,
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elf_gregset_t *gregsetp, int regno)
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{
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gdb_byte *regp = (gdb_byte *) gregsetp;
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int i;
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for (i = 0; i < I386_NUM_GREGS; i++)
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if (regno == -1 || regno == i)
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regcache->raw_collect (i, regp + i386_linux_gregset_reg_offset[i]);
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if ((regno == -1 || regno == I386_LINUX_ORIG_EAX_REGNUM)
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&& I386_LINUX_ORIG_EAX_REGNUM
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< gdbarch_num_regs (regcache->arch ()))
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regcache->raw_collect
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(I386_LINUX_ORIG_EAX_REGNUM,
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regp + i386_linux_gregset_reg_offset[I386_LINUX_ORIG_EAX_REGNUM]);
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}
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#ifdef HAVE_PTRACE_GETREGS
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/* Fetch all general-purpose registers from process/thread TID and
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store their values in GDB's register array. */
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static void
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fetch_regs (struct regcache *regcache, int tid)
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{
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elf_gregset_t regs;
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elf_gregset_t *regs_p = ®s;
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if (ptrace (PTRACE_GETREGS, tid, 0, (int) ®s) < 0)
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{
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if (errno == EIO)
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{
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/* The kernel we're running on doesn't support the GETREGS
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request. Reset `have_ptrace_getregs'. */
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have_ptrace_getregs = 0;
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return;
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}
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perror_with_name (_("Couldn't get registers"));
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}
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supply_gregset (regcache, (const elf_gregset_t *) regs_p);
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}
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/* Store all valid general-purpose registers in GDB's register array
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into the process/thread specified by TID. */
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static void
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store_regs (const struct regcache *regcache, int tid, int regno)
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{
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elf_gregset_t regs;
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if (ptrace (PTRACE_GETREGS, tid, 0, (int) ®s) < 0)
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perror_with_name (_("Couldn't get registers"));
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fill_gregset (regcache, ®s, regno);
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if (ptrace (PTRACE_SETREGS, tid, 0, (int) ®s) < 0)
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perror_with_name (_("Couldn't write registers"));
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}
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#else
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static void fetch_regs (struct regcache *regcache, int tid) {}
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static void store_regs (const struct regcache *regcache, int tid, int regno) {}
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#endif
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/* Transfering floating-point registers between GDB, inferiors and cores. */
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/* Fill GDB's register array with the floating-point register values in
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*FPREGSETP. */
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void
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supply_fpregset (struct regcache *regcache, const elf_fpregset_t *fpregsetp)
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{
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i387_supply_fsave (regcache, -1, fpregsetp);
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}
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/* Fill register REGNO (if it is a floating-point register) in
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*FPREGSETP with the value in GDB's register array. If REGNO is -1,
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do this for all registers. */
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void
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fill_fpregset (const struct regcache *regcache,
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elf_fpregset_t *fpregsetp, int regno)
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{
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i387_collect_fsave (regcache, regno, fpregsetp);
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}
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#ifdef HAVE_PTRACE_GETREGS
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/* Fetch all floating-point registers from process/thread TID and store
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thier values in GDB's register array. */
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static void
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fetch_fpregs (struct regcache *regcache, int tid)
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{
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elf_fpregset_t fpregs;
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if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
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perror_with_name (_("Couldn't get floating point status"));
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supply_fpregset (regcache, (const elf_fpregset_t *) &fpregs);
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}
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/* Store all valid floating-point registers in GDB's register array
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into the process/thread specified by TID. */
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static void
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store_fpregs (const struct regcache *regcache, int tid, int regno)
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{
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elf_fpregset_t fpregs;
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if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
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perror_with_name (_("Couldn't get floating point status"));
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fill_fpregset (regcache, &fpregs, regno);
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if (ptrace (PTRACE_SETFPREGS, tid, 0, (int) &fpregs) < 0)
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perror_with_name (_("Couldn't write floating point status"));
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}
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#else
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static void
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fetch_fpregs (struct regcache *regcache, int tid)
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{
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}
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static void
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store_fpregs (const struct regcache *regcache, int tid, int regno)
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{
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}
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#endif
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/* Transfering floating-point and SSE registers to and from GDB. */
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/* Fetch all registers covered by the PTRACE_GETREGSET request from
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process/thread TID and store their values in GDB's register array.
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Return non-zero if successful, zero otherwise. */
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static int
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fetch_xstateregs (struct regcache *regcache, int tid)
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{
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struct gdbarch *gdbarch = regcache->arch ();
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const i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
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char xstateregs[tdep->xsave_layout.sizeof_xsave];
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struct iovec iov;
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if (have_ptrace_getregset != TRIBOOL_TRUE)
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return 0;
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iov.iov_base = xstateregs;
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iov.iov_len = sizeof(xstateregs);
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if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
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&iov) < 0)
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perror_with_name (_("Couldn't read extended state status"));
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i387_supply_xsave (regcache, -1, xstateregs);
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return 1;
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}
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/* Store all valid registers in GDB's register array covered by the
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PTRACE_SETREGSET request into the process/thread specified by TID.
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Return non-zero if successful, zero otherwise. */
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static int
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store_xstateregs (const struct regcache *regcache, int tid, int regno)
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{
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struct gdbarch *gdbarch = regcache->arch ();
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const i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
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char xstateregs[tdep->xsave_layout.sizeof_xsave];
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struct iovec iov;
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if (have_ptrace_getregset != TRIBOOL_TRUE)
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return 0;
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iov.iov_base = xstateregs;
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iov.iov_len = sizeof(xstateregs);
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if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
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&iov) < 0)
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perror_with_name (_("Couldn't read extended state status"));
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i387_collect_xsave (regcache, regno, xstateregs, 0);
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if (ptrace (PTRACE_SETREGSET, tid, (unsigned int) NT_X86_XSTATE,
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(int) &iov) < 0)
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perror_with_name (_("Couldn't write extended state status"));
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return 1;
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}
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#ifdef HAVE_PTRACE_GETFPXREGS
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/* Fetch all registers covered by the PTRACE_GETFPXREGS request from
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process/thread TID and store their values in GDB's register array.
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Return non-zero if successful, zero otherwise. */
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static int
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fetch_fpxregs (struct regcache *regcache, int tid)
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{
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elf_fpxregset_t fpxregs;
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if (! have_ptrace_getfpxregs)
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return 0;
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if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
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{
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if (errno == EIO)
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{
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have_ptrace_getfpxregs = 0;
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return 0;
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}
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perror_with_name (_("Couldn't read floating-point and SSE registers"));
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}
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i387_supply_fxsave (regcache, -1, (const elf_fpxregset_t *) &fpxregs);
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return 1;
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}
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/* Store all valid registers in GDB's register array covered by the
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PTRACE_SETFPXREGS request into the process/thread specified by TID.
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Return non-zero if successful, zero otherwise. */
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static int
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store_fpxregs (const struct regcache *regcache, int tid, int regno)
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{
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elf_fpxregset_t fpxregs;
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if (! have_ptrace_getfpxregs)
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return 0;
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if (ptrace (PTRACE_GETFPXREGS, tid, 0, &fpxregs) == -1)
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{
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if (errno == EIO)
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{
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have_ptrace_getfpxregs = 0;
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return 0;
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}
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perror_with_name (_("Couldn't read floating-point and SSE registers"));
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}
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i387_collect_fxsave (regcache, regno, &fpxregs);
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if (ptrace (PTRACE_SETFPXREGS, tid, 0, &fpxregs) == -1)
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perror_with_name (_("Couldn't write floating-point and SSE registers"));
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return 1;
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}
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#else
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static int
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fetch_fpxregs (struct regcache *regcache, int tid)
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{
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return 0;
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}
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static int
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store_fpxregs (const struct regcache *regcache, int tid, int regno)
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{
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return 0;
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}
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#endif /* HAVE_PTRACE_GETFPXREGS */
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/* Transferring arbitrary registers between GDB and inferior. */
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/* Fetch register REGNO from the child process. If REGNO is -1, do
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this for all registers (including the floating point and SSE
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registers). */
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void
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i386_linux_nat_target::fetch_registers (struct regcache *regcache, int regno)
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{
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pid_t tid;
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/* Use the old method of peeking around in `struct user' if the
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GETREGS request isn't available. */
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if (!have_ptrace_getregs)
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{
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int i;
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for (i = 0; i < gdbarch_num_regs (regcache->arch ()); i++)
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if (regno == -1 || regno == i)
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fetch_register (regcache, i);
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return;
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}
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tid = get_ptrace_pid (regcache->ptid ());
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/* Use the PTRACE_GETFPXREGS request whenever possible, since it
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transfers more registers in one system call, and we'll cache the
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results. But remember that fetch_fpxregs can fail, and return
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zero. */
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if (regno == -1)
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{
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fetch_regs (regcache, tid);
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/* The call above might reset `have_ptrace_getregs'. */
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if (!have_ptrace_getregs)
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{
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fetch_registers (regcache, regno);
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return;
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}
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if (fetch_xstateregs (regcache, tid))
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return;
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if (fetch_fpxregs (regcache, tid))
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return;
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fetch_fpregs (regcache, tid);
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return;
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}
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if (GETREGS_SUPPLIES (regno))
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{
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fetch_regs (regcache, tid);
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return;
|
||
}
|
||
|
||
if (GETXSTATEREGS_SUPPLIES (regno))
|
||
{
|
||
if (fetch_xstateregs (regcache, tid))
|
||
return;
|
||
}
|
||
|
||
if (GETFPXREGS_SUPPLIES (regno))
|
||
{
|
||
if (fetch_fpxregs (regcache, tid))
|
||
return;
|
||
|
||
/* Either our processor or our kernel doesn't support the SSE
|
||
registers, so read the FP registers in the traditional way,
|
||
and fill the SSE registers with dummy values. It would be
|
||
more graceful to handle differences in the register set using
|
||
gdbarch. Until then, this will at least make things work
|
||
plausibly. */
|
||
fetch_fpregs (regcache, tid);
|
||
return;
|
||
}
|
||
|
||
internal_error (_("Got request for bad register number %d."), regno);
|
||
}
|
||
|
||
/* Store register REGNO back into the child process. If REGNO is -1,
|
||
do this for all registers (including the floating point and SSE
|
||
registers). */
|
||
void
|
||
i386_linux_nat_target::store_registers (struct regcache *regcache, int regno)
|
||
{
|
||
pid_t tid;
|
||
|
||
/* Use the old method of poking around in `struct user' if the
|
||
SETREGS request isn't available. */
|
||
if (!have_ptrace_getregs)
|
||
{
|
||
int i;
|
||
|
||
for (i = 0; i < gdbarch_num_regs (regcache->arch ()); i++)
|
||
if (regno == -1 || regno == i)
|
||
store_register (regcache, i);
|
||
|
||
return;
|
||
}
|
||
|
||
tid = get_ptrace_pid (regcache->ptid ());
|
||
|
||
/* Use the PTRACE_SETFPXREGS requests whenever possible, since it
|
||
transfers more registers in one system call. But remember that
|
||
store_fpxregs can fail, and return zero. */
|
||
if (regno == -1)
|
||
{
|
||
store_regs (regcache, tid, regno);
|
||
if (store_xstateregs (regcache, tid, regno))
|
||
return;
|
||
if (store_fpxregs (regcache, tid, regno))
|
||
return;
|
||
store_fpregs (regcache, tid, regno);
|
||
return;
|
||
}
|
||
|
||
if (GETREGS_SUPPLIES (regno))
|
||
{
|
||
store_regs (regcache, tid, regno);
|
||
return;
|
||
}
|
||
|
||
if (GETXSTATEREGS_SUPPLIES (regno))
|
||
{
|
||
if (store_xstateregs (regcache, tid, regno))
|
||
return;
|
||
}
|
||
|
||
if (GETFPXREGS_SUPPLIES (regno))
|
||
{
|
||
if (store_fpxregs (regcache, tid, regno))
|
||
return;
|
||
|
||
/* Either our processor or our kernel doesn't support the SSE
|
||
registers, so just write the FP registers in the traditional
|
||
way. */
|
||
store_fpregs (regcache, tid, regno);
|
||
return;
|
||
}
|
||
|
||
internal_error (_("Got request to store bad register number %d."), regno);
|
||
}
|
||
|
||
|
||
/* Called by libthread_db. Returns a pointer to the thread local
|
||
storage (or its descriptor). */
|
||
|
||
ps_err_e
|
||
ps_get_thread_area (struct ps_prochandle *ph,
|
||
lwpid_t lwpid, int idx, void **base)
|
||
{
|
||
unsigned int base_addr;
|
||
ps_err_e result;
|
||
|
||
result = x86_linux_get_thread_area (lwpid, (void *) idx, &base_addr);
|
||
|
||
if (result == PS_OK)
|
||
*(int *) base = base_addr;
|
||
|
||
return result;
|
||
}
|
||
|
||
|
||
/* The instruction for a GNU/Linux system call is:
|
||
int $0x80
|
||
or 0xcd 0x80. */
|
||
|
||
static const unsigned char linux_syscall[] = { 0xcd, 0x80 };
|
||
|
||
#define LINUX_SYSCALL_LEN (sizeof linux_syscall)
|
||
|
||
/* The system call number is stored in the %eax register. */
|
||
#define LINUX_SYSCALL_REGNUM I386_EAX_REGNUM
|
||
|
||
/* We are specifically interested in the sigreturn and rt_sigreturn
|
||
system calls. */
|
||
|
||
#ifndef SYS_sigreturn
|
||
#define SYS_sigreturn 0x77
|
||
#endif
|
||
#ifndef SYS_rt_sigreturn
|
||
#define SYS_rt_sigreturn 0xad
|
||
#endif
|
||
|
||
/* Offset to saved processor flags, from <asm/sigcontext.h>. */
|
||
#define LINUX_SIGCONTEXT_EFLAGS_OFFSET (64)
|
||
|
||
/* Resume execution of the inferior process.
|
||
If STEP is nonzero, single-step it.
|
||
If SIGNAL is nonzero, give it that signal. */
|
||
|
||
void
|
||
i386_linux_nat_target::low_resume (ptid_t ptid, int step, enum gdb_signal signal)
|
||
{
|
||
int pid = ptid.lwp ();
|
||
int request;
|
||
|
||
if (catch_syscall_enabled () > 0)
|
||
request = PTRACE_SYSCALL;
|
||
else
|
||
request = PTRACE_CONT;
|
||
|
||
if (step)
|
||
{
|
||
struct regcache *regcache = get_thread_regcache (this, ptid);
|
||
struct gdbarch *gdbarch = regcache->arch ();
|
||
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
|
||
ULONGEST pc;
|
||
gdb_byte buf[LINUX_SYSCALL_LEN];
|
||
|
||
request = PTRACE_SINGLESTEP;
|
||
|
||
regcache_cooked_read_unsigned (regcache,
|
||
gdbarch_pc_regnum (gdbarch), &pc);
|
||
|
||
/* Returning from a signal trampoline is done by calling a
|
||
special system call (sigreturn or rt_sigreturn, see
|
||
i386-linux-tdep.c for more information). This system call
|
||
restores the registers that were saved when the signal was
|
||
raised, including %eflags. That means that single-stepping
|
||
won't work. Instead, we'll have to modify the signal context
|
||
that's about to be restored, and set the trace flag there. */
|
||
|
||
/* First check if PC is at a system call. */
|
||
if (target_read_memory (pc, buf, LINUX_SYSCALL_LEN) == 0
|
||
&& memcmp (buf, linux_syscall, LINUX_SYSCALL_LEN) == 0)
|
||
{
|
||
ULONGEST syscall;
|
||
regcache_cooked_read_unsigned (regcache,
|
||
LINUX_SYSCALL_REGNUM, &syscall);
|
||
|
||
/* Then check the system call number. */
|
||
if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn)
|
||
{
|
||
ULONGEST sp, addr;
|
||
unsigned long int eflags;
|
||
|
||
regcache_cooked_read_unsigned (regcache, I386_ESP_REGNUM, &sp);
|
||
if (syscall == SYS_rt_sigreturn)
|
||
addr = read_memory_unsigned_integer (sp + 8, 4, byte_order)
|
||
+ 20;
|
||
else
|
||
addr = sp;
|
||
|
||
/* Set the trace flag in the context that's about to be
|
||
restored. */
|
||
addr += LINUX_SIGCONTEXT_EFLAGS_OFFSET;
|
||
read_memory (addr, (gdb_byte *) &eflags, 4);
|
||
eflags |= 0x0100;
|
||
write_memory (addr, (gdb_byte *) &eflags, 4);
|
||
}
|
||
}
|
||
}
|
||
|
||
if (ptrace (request, pid, 0, gdb_signal_to_host (signal)) == -1)
|
||
perror_with_name (("ptrace"));
|
||
}
|
||
|
||
void _initialize_i386_linux_nat ();
|
||
void
|
||
_initialize_i386_linux_nat ()
|
||
{
|
||
linux_target = &the_i386_linux_nat_target;
|
||
|
||
/* Add the target. */
|
||
add_inf_child_target (linux_target);
|
||
}
|