849 lines
22 KiB
C
849 lines
22 KiB
C
/* Native-dependent code for GNU/Linux i386.
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Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
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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 2 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, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA. */
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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 "target.h"
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#include "linux-nat.h"
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#include "gdb_assert.h"
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#include "gdb_string.h"
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#include <sys/ptrace.h>
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#include <sys/user.h>
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#include <sys/procfs.h>
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#ifdef HAVE_SYS_REG_H
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#include <sys/reg.h>
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#endif
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#ifndef ORIG_EAX
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#define ORIG_EAX -1
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#endif
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#ifdef HAVE_SYS_DEBUGREG_H
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#include <sys/debugreg.h>
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#endif
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#ifndef DR_FIRSTADDR
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#define DR_FIRSTADDR 0
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#endif
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#ifndef DR_LASTADDR
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#define DR_LASTADDR 3
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#endif
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#ifndef DR_STATUS
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#define DR_STATUS 6
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#endif
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#ifndef DR_CONTROL
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#define DR_CONTROL 7
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#endif
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/* Prototypes for supply_gregset etc. */
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#include "gregset.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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/* Defines ps_err_e, struct ps_prochandle. */
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#include "gdb_proc_service.h"
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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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/* Mapping between the general-purpose registers in `struct user'
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format and GDB's register array layout. */
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static int regmap[] =
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{
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EAX, ECX, EDX, EBX,
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UESP, EBP, ESI, EDI,
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EIP, EFL, CS, SS,
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DS, ES, FS, GS,
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-1, -1, -1, -1, /* st0, st1, st2, st3 */
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-1, -1, -1, -1, /* st4, st5, st6, st7 */
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-1, -1, -1, -1, /* fctrl, fstat, ftag, fiseg */
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-1, -1, -1, -1, /* fioff, foseg, fooff, fop */
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-1, -1, -1, -1, /* xmm0, xmm1, xmm2, xmm3 */
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-1, -1, -1, -1, /* xmm4, xmm5, xmm6, xmm6 */
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-1, /* mxcsr */
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ORIG_EAX
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};
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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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/* 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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/* Support for the user struct. */
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/* Return the address of register REGNUM. BLOCKEND is the value of
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u.u_ar0, which should point to the registers. */
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CORE_ADDR
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register_u_addr (CORE_ADDR blockend, int regnum)
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{
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return (blockend + 4 * regmap[regnum]);
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}
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/* Return the size of the user struct. */
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int
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kernel_u_size (void)
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{
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return (sizeof (struct user));
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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 (int regno)
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{
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int tid;
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int val;
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gdb_assert (!have_ptrace_getregs);
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if (cannot_fetch_register (regno))
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{
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regcache_raw_supply (current_regcache, regno, NULL);
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return;
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}
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/* GNU/Linux LWP ID's are process ID's. */
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tid = TIDGET (inferior_ptid);
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if (tid == 0)
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tid = PIDGET (inferior_ptid); /* Not a threaded program. */
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errno = 0;
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val = ptrace (PTRACE_PEEKUSER, tid, register_addr (regno, 0), 0);
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if (errno != 0)
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error (_("Couldn't read register %s (#%d): %s."), REGISTER_NAME (regno),
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regno, safe_strerror (errno));
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regcache_raw_supply (current_regcache, 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 (int regno)
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{
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int tid;
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int val;
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gdb_assert (!have_ptrace_getregs);
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if (cannot_store_register (regno))
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return;
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/* GNU/Linux LWP ID's are process ID's. */
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tid = TIDGET (inferior_ptid);
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if (tid == 0)
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tid = PIDGET (inferior_ptid); /* Not a threaded program. */
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errno = 0;
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regcache_raw_collect (current_regcache, regno, &val);
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ptrace (PTRACE_POKEUSER, tid, register_addr (regno, 0), val);
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if (errno != 0)
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error (_("Couldn't write register %s (#%d): %s."), REGISTER_NAME (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 (elf_gregset_t *gregsetp)
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{
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elf_greg_t *regp = (elf_greg_t *) 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 (current_regcache, i, regp + regmap[i]);
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if (I386_LINUX_ORIG_EAX_REGNUM < NUM_REGS)
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regcache_raw_supply (current_regcache, I386_LINUX_ORIG_EAX_REGNUM,
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regp + ORIG_EAX);
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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 (elf_gregset_t *gregsetp, int regno)
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{
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elf_greg_t *regp = (elf_greg_t *) 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 (current_regcache, i, regp + regmap[i]);
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if ((regno == -1 || regno == I386_LINUX_ORIG_EAX_REGNUM)
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&& I386_LINUX_ORIG_EAX_REGNUM < NUM_REGS)
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regcache_raw_collect (current_regcache, I386_LINUX_ORIG_EAX_REGNUM,
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regp + ORIG_EAX);
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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 (int tid)
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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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{
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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 (®s);
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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 (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 (®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 (int tid) {}
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static void store_regs (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 (elf_fpregset_t *fpregsetp)
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{
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i387_supply_fsave (current_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 (elf_fpregset_t *fpregsetp, int regno)
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{
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i387_fill_fsave ((char *) fpregsetp, regno);
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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 (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 (&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 (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 (&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 fetch_fpregs (int tid) {}
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static void store_fpregs (int tid, int regno) {}
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#endif
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/* Transfering floating-point and SSE registers to and from GDB. */
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#ifdef HAVE_PTRACE_GETFPXREGS
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/* Fill GDB's register array with the floating-point and SSE register
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values in *FPXREGSETP. */
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void
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supply_fpxregset (elf_fpxregset_t *fpxregsetp)
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{
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i387_supply_fxsave (current_regcache, -1, fpxregsetp);
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||
}
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||
|
||
/* Fill register REGNO (if it is a floating-point or SSE register) in
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*FPXREGSETP with the value in GDB's register array. If REGNO is
|
||
-1, do this for all registers. */
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||
|
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void
|
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fill_fpxregset (elf_fpxregset_t *fpxregsetp, int regno)
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{
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i387_fill_fxsave ((char *) fpxregsetp, regno);
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}
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|
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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 (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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||
|
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if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
|
||
{
|
||
if (errno == EIO)
|
||
{
|
||
have_ptrace_getfpxregs = 0;
|
||
return 0;
|
||
}
|
||
|
||
perror_with_name (_("Couldn't read floating-point and SSE registers"));
|
||
}
|
||
|
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supply_fpxregset (&fpxregs);
|
||
return 1;
|
||
}
|
||
|
||
/* Store all valid registers in GDB's register array covered by the
|
||
PTRACE_SETFPXREGS request into the process/thread specified by TID.
|
||
Return non-zero if successful, zero otherwise. */
|
||
|
||
static int
|
||
store_fpxregs (int tid, int regno)
|
||
{
|
||
elf_fpxregset_t fpxregs;
|
||
|
||
if (! have_ptrace_getfpxregs)
|
||
return 0;
|
||
|
||
if (ptrace (PTRACE_GETFPXREGS, tid, 0, &fpxregs) == -1)
|
||
{
|
||
if (errno == EIO)
|
||
{
|
||
have_ptrace_getfpxregs = 0;
|
||
return 0;
|
||
}
|
||
|
||
perror_with_name (_("Couldn't read floating-point and SSE registers"));
|
||
}
|
||
|
||
fill_fpxregset (&fpxregs, regno);
|
||
|
||
if (ptrace (PTRACE_SETFPXREGS, tid, 0, &fpxregs) == -1)
|
||
perror_with_name (_("Couldn't write floating-point and SSE registers"));
|
||
|
||
return 1;
|
||
}
|
||
|
||
#else
|
||
|
||
static int fetch_fpxregs (int tid) { return 0; }
|
||
static int store_fpxregs (int tid, int regno) { return 0; }
|
||
|
||
#endif /* HAVE_PTRACE_GETFPXREGS */
|
||
|
||
|
||
/* Transferring arbitrary registers between GDB and inferior. */
|
||
|
||
/* Check if register REGNO in the child process is accessible.
|
||
If we are accessing registers directly via the U area, only the
|
||
general-purpose registers are available.
|
||
All registers should be accessible if we have GETREGS support. */
|
||
|
||
int
|
||
cannot_fetch_register (int regno)
|
||
{
|
||
gdb_assert (regno >= 0 && regno < NUM_REGS);
|
||
return (!have_ptrace_getregs && regmap[regno] == -1);
|
||
}
|
||
|
||
int
|
||
cannot_store_register (int regno)
|
||
{
|
||
gdb_assert (regno >= 0 && regno < NUM_REGS);
|
||
return (!have_ptrace_getregs && regmap[regno] == -1);
|
||
}
|
||
|
||
/* Fetch register REGNO from the child process. If REGNO is -1, do
|
||
this for all registers (including the floating point and SSE
|
||
registers). */
|
||
|
||
static void
|
||
i386_linux_fetch_inferior_registers (int regno)
|
||
{
|
||
int tid;
|
||
|
||
/* Use the old method of peeking around in `struct user' if the
|
||
GETREGS request isn't available. */
|
||
if (!have_ptrace_getregs)
|
||
{
|
||
int i;
|
||
|
||
for (i = 0; i < NUM_REGS; i++)
|
||
if (regno == -1 || regno == i)
|
||
fetch_register (i);
|
||
|
||
return;
|
||
}
|
||
|
||
/* GNU/Linux LWP ID's are process ID's. */
|
||
tid = TIDGET (inferior_ptid);
|
||
if (tid == 0)
|
||
tid = PIDGET (inferior_ptid); /* Not a threaded program. */
|
||
|
||
/* Use the PTRACE_GETFPXREGS request whenever possible, since it
|
||
transfers more registers in one system call, and we'll cache the
|
||
results. But remember that fetch_fpxregs can fail, and return
|
||
zero. */
|
||
if (regno == -1)
|
||
{
|
||
fetch_regs (tid);
|
||
|
||
/* The call above might reset `have_ptrace_getregs'. */
|
||
if (!have_ptrace_getregs)
|
||
{
|
||
i386_linux_fetch_inferior_registers (regno);
|
||
return;
|
||
}
|
||
|
||
if (fetch_fpxregs (tid))
|
||
return;
|
||
fetch_fpregs (tid);
|
||
return;
|
||
}
|
||
|
||
if (GETREGS_SUPPLIES (regno))
|
||
{
|
||
fetch_regs (tid);
|
||
return;
|
||
}
|
||
|
||
if (GETFPXREGS_SUPPLIES (regno))
|
||
{
|
||
if (fetch_fpxregs (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 (tid);
|
||
return;
|
||
}
|
||
|
||
internal_error (__FILE__, __LINE__,
|
||
_("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). */
|
||
static void
|
||
i386_linux_store_inferior_registers (int regno)
|
||
{
|
||
int 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 < NUM_REGS; i++)
|
||
if (regno == -1 || regno == i)
|
||
store_register (i);
|
||
|
||
return;
|
||
}
|
||
|
||
/* GNU/Linux LWP ID's are process ID's. */
|
||
tid = TIDGET (inferior_ptid);
|
||
if (tid == 0)
|
||
tid = PIDGET (inferior_ptid); /* Not a threaded program. */
|
||
|
||
/* 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 (tid, regno);
|
||
if (store_fpxregs (tid, regno))
|
||
return;
|
||
store_fpregs (tid, regno);
|
||
return;
|
||
}
|
||
|
||
if (GETREGS_SUPPLIES (regno))
|
||
{
|
||
store_regs (tid, regno);
|
||
return;
|
||
}
|
||
|
||
if (GETFPXREGS_SUPPLIES (regno))
|
||
{
|
||
if (store_fpxregs (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 (tid, regno);
|
||
return;
|
||
}
|
||
|
||
internal_error (__FILE__, __LINE__,
|
||
_("Got request to store bad register number %d."), regno);
|
||
}
|
||
|
||
|
||
/* Support for debug registers. */
|
||
|
||
static unsigned long
|
||
i386_linux_dr_get (int regnum)
|
||
{
|
||
int tid;
|
||
unsigned long value;
|
||
|
||
/* FIXME: kettenis/2001-01-29: It's not clear what we should do with
|
||
multi-threaded processes here. For now, pretend there is just
|
||
one thread. */
|
||
tid = PIDGET (inferior_ptid);
|
||
|
||
/* FIXME: kettenis/2001-03-27: Calling perror_with_name if the
|
||
ptrace call fails breaks debugging remote targets. The correct
|
||
way to fix this is to add the hardware breakpoint and watchpoint
|
||
stuff to the target vector. For now, just return zero if the
|
||
ptrace call fails. */
|
||
errno = 0;
|
||
value = ptrace (PTRACE_PEEKUSER, tid,
|
||
offsetof (struct user, u_debugreg[regnum]), 0);
|
||
if (errno != 0)
|
||
#if 0
|
||
perror_with_name (_("Couldn't read debug register"));
|
||
#else
|
||
return 0;
|
||
#endif
|
||
|
||
return value;
|
||
}
|
||
|
||
static void
|
||
i386_linux_dr_set (int regnum, unsigned long value)
|
||
{
|
||
int tid;
|
||
|
||
/* FIXME: kettenis/2001-01-29: It's not clear what we should do with
|
||
multi-threaded processes here. For now, pretend there is just
|
||
one thread. */
|
||
tid = PIDGET (inferior_ptid);
|
||
|
||
errno = 0;
|
||
ptrace (PTRACE_POKEUSER, tid,
|
||
offsetof (struct user, u_debugreg[regnum]), value);
|
||
if (errno != 0)
|
||
perror_with_name (_("Couldn't write debug register"));
|
||
}
|
||
|
||
void
|
||
i386_linux_dr_set_control (unsigned long control)
|
||
{
|
||
i386_linux_dr_set (DR_CONTROL, control);
|
||
}
|
||
|
||
void
|
||
i386_linux_dr_set_addr (int regnum, CORE_ADDR addr)
|
||
{
|
||
gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
|
||
|
||
i386_linux_dr_set (DR_FIRSTADDR + regnum, addr);
|
||
}
|
||
|
||
void
|
||
i386_linux_dr_reset_addr (int regnum)
|
||
{
|
||
gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
|
||
|
||
i386_linux_dr_set (DR_FIRSTADDR + regnum, 0L);
|
||
}
|
||
|
||
unsigned long
|
||
i386_linux_dr_get_status (void)
|
||
{
|
||
return i386_linux_dr_get (DR_STATUS);
|
||
}
|
||
|
||
|
||
/* Called by libthread_db. Returns a pointer to the thread local
|
||
storage (or its descriptor). */
|
||
|
||
ps_err_e
|
||
ps_get_thread_area (const struct ps_prochandle *ph,
|
||
lwpid_t lwpid, int idx, void **base)
|
||
{
|
||
/* NOTE: cagney/2003-08-26: The definition of this buffer is found
|
||
in the kernel header <asm-i386/ldt.h>. It, after padding, is 4 x
|
||
4 byte integers in size: `entry_number', `base_addr', `limit',
|
||
and a bunch of status bits.
|
||
|
||
The values returned by this ptrace call should be part of the
|
||
regcache buffer, and ps_get_thread_area should channel its
|
||
request through the regcache. That way remote targets could
|
||
provide the value using the remote protocol and not this direct
|
||
call.
|
||
|
||
Is this function needed? I'm guessing that the `base' is the
|
||
address of a a descriptor that libthread_db uses to find the
|
||
thread local address base that GDB needs. Perhaps that
|
||
descriptor is defined by the ABI. Anyway, given that
|
||
libthread_db calls this function without prompting (gdb
|
||
requesting tls base) I guess it needs info in there anyway. */
|
||
unsigned int desc[4];
|
||
gdb_assert (sizeof (int) == 4);
|
||
|
||
#ifndef PTRACE_GET_THREAD_AREA
|
||
#define PTRACE_GET_THREAD_AREA 25
|
||
#endif
|
||
|
||
if (ptrace (PTRACE_GET_THREAD_AREA, lwpid,
|
||
(void *) idx, (unsigned long) &desc) < 0)
|
||
return PS_ERR;
|
||
|
||
*(int *)base = desc[1];
|
||
return PS_OK;
|
||
}
|
||
|
||
|
||
/* 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. */
|
||
|
||
static void
|
||
i386_linux_resume (ptid_t ptid, int step, enum target_signal signal)
|
||
{
|
||
int pid = PIDGET (ptid);
|
||
|
||
int request = PTRACE_CONT;
|
||
|
||
if (pid == -1)
|
||
/* Resume all threads. */
|
||
/* I think this only gets used in the non-threaded case, where "resume
|
||
all threads" and "resume inferior_ptid" are the same. */
|
||
pid = PIDGET (inferior_ptid);
|
||
|
||
if (step)
|
||
{
|
||
CORE_ADDR pc = read_pc_pid (pid_to_ptid (pid));
|
||
gdb_byte buf[LINUX_SYSCALL_LEN];
|
||
|
||
request = PTRACE_SINGLESTEP;
|
||
|
||
/* 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 (read_memory_nobpt (pc, buf, LINUX_SYSCALL_LEN) == 0
|
||
&& memcmp (buf, linux_syscall, LINUX_SYSCALL_LEN) == 0)
|
||
{
|
||
int syscall = read_register_pid (LINUX_SYSCALL_REGNUM,
|
||
pid_to_ptid (pid));
|
||
|
||
/* Then check the system call number. */
|
||
if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn)
|
||
{
|
||
CORE_ADDR sp = read_register (I386_ESP_REGNUM);
|
||
CORE_ADDR addr = sp;
|
||
unsigned long int eflags;
|
||
|
||
if (syscall == SYS_rt_sigreturn)
|
||
addr = read_memory_integer (sp + 8, 4) + 20;
|
||
|
||
/* 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, target_signal_to_host (signal)) == -1)
|
||
perror_with_name (("ptrace"));
|
||
}
|
||
|
||
static void (*super_post_startup_inferior) (ptid_t ptid);
|
||
|
||
static void
|
||
i386_linux_child_post_startup_inferior (ptid_t ptid)
|
||
{
|
||
i386_cleanup_dregs ();
|
||
super_post_startup_inferior (ptid);
|
||
}
|
||
|
||
void
|
||
_initialize_i386_linux_nat (void)
|
||
{
|
||
struct target_ops *t;
|
||
|
||
/* Fill in the generic GNU/Linux methods. */
|
||
t = linux_target ();
|
||
|
||
/* Override the default ptrace resume method. */
|
||
t->to_resume = i386_linux_resume;
|
||
|
||
/* Override the GNU/Linux inferior startup hook. */
|
||
super_post_startup_inferior = t->to_post_startup_inferior;
|
||
t->to_post_startup_inferior = i386_linux_child_post_startup_inferior;
|
||
|
||
/* Add our register access methods. */
|
||
t->to_fetch_registers = i386_linux_fetch_inferior_registers;
|
||
t->to_store_registers = i386_linux_store_inferior_registers;
|
||
|
||
/* Register the target. */
|
||
linux_nat_add_target (t);
|
||
}
|