binutils-gdb/gdb/i386-linux-nat.c

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/* Native-dependent code for Linux running on i386's, for GDB.
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 2 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, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
#include "defs.h"
#include "inferior.h"
#include "gdbcore.h"
/* For i386_linux_skip_solib_resolver */
#include "symtab.h"
#include "frame.h"
#include "symfile.h"
#include "objfiles.h"
#include <sys/ptrace.h>
#include <sys/user.h>
#include <sys/procfs.h>
#ifdef HAVE_SYS_REG_H
#include <sys/reg.h>
#endif
/* This is a duplicate of the table in i386-xdep.c. */
static int regmap[] =
{
EAX, ECX, EDX, EBX,
UESP, EBP, ESI, EDI,
EIP, EFL, CS, SS,
DS, ES, FS, GS,
};
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/* Which ptrace request retrieves which registers?
These apply to the corresponding SET requests as well. */
#define GETREGS_SUPPLIES(regno) \
(0 <= (regno) && (regno) <= 15)
#define GETFPREGS_SUPPLIES(regno) \
(FP0_REGNUM <= (regno) && (regno) <= LAST_FPU_CTRL_REGNUM)
#define GETXFPREGS_SUPPLIES(regno) \
(FP0_REGNUM <= (regno) && (regno) <= MXCSR_REGNUM)
/* Does the current host support the GETXFPREGS request? The header
file may or may not define it, and even if it is defined, the
kernel will return EIO if it's running on a pre-SSE processor.
My instinct is to attach this to some architecture- or
target-specific data structure, but really, a particular GDB
process can only run on top of one kernel at a time. So it's okay
for this to be a simple variable. */
int have_ptrace_getxfpregs =
#ifdef HAVE_PTRACE_GETXFPREGS
1
#else
0
#endif
;
/* Transfering the general registers between GDB, inferiors and core files. */
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/* Given a pointer to a general register set in struct user format
(gregset_t *), unpack the register contents and supply them as
gdb's idea of the current register values. */
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void
supply_gregset (gregsetp)
gregset_t *gregsetp;
{
register int regi;
register greg_t *regp = (greg_t *) gregsetp;
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for (regi = 0; regi < NUM_GREGS; regi++)
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{
supply_register (regi, (char *) (regp + regmap[regi]));
}
}
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/* Fill in a gregset_t object with selected data from a gdb-format
register file.
- GREGSETP points to the gregset_t object to be filled.
- GDB_REGS points to the GDB-style register file providing the data.
- VALID is an array indicating which registers in GDB_REGS are
valid; the parts of *GREGSETP that would hold registers marked
invalid in GDB_REGS are left unchanged. If VALID is zero, all
registers are assumed to be valid. */
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void
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convert_to_gregset (gregset_t *gregsetp,
char *gdb_regs,
signed char *valid)
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{
int regi;
register greg_t *regp = (greg_t *) gregsetp;
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for (regi = 0; regi < NUM_GREGS; regi++)
if (! valid || valid[regi])
*(regp + regmap[regi]) = * (int *) &registers[REGISTER_BYTE (regi)];
}
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/* Store GDB's value for REGNO in *GREGSETP. If REGNO is -1, do all
of them. */
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void
fill_gregset (gregset_t *gregsetp,
int regno)
{
if (regno == -1)
convert_to_gregset (gregsetp, registers, 0);
else
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{
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signed char valid[NUM_GREGS];
memset (valid, 0, sizeof (valid));
valid[regno] = 1;
convert_to_gregset (gregsetp, valid, valid);
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}
}
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/* Read the general registers from the process, and store them
in registers[]. */
static void
fetch_regs ()
{
int ret, regno;
gregset_t buf;
ret = ptrace (PTRACE_GETREGS, inferior_pid, 0, (int) &buf);
if (ret < 0)
{
warning ("Couldn't get registers");
return;
}
supply_gregset (&buf);
}
/* Set the inferior's general registers to the values in registers[]
--- but only those registers marked as valid. */
static void
store_regs ()
{
int ret, regno;
gregset_t buf;
ret = ptrace (PTRACE_GETREGS, inferior_pid, 0, (int) &buf);
if (ret < 0)
{
warning ("Couldn't get registers");
return;
}
convert_to_gregset (&buf, registers, register_valid);
ret = ptrace (PTRACE_SETREGS, inferior_pid, 0, (int)buf);
if (ret < 0)
{
warning ("Couldn't write registers");
return;
}
}
/* Transfering floating-point registers between GDB, inferiors and cores. */
/* What is the address of st(N) within the fpregset_t structure F? */
#define FPREGSET_T_FPREG_ADDR(f, n) \
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((char *) &(f)->st_space + (n) * 10)
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/* Fill GDB's register file with the floating-point register values in
*FPREGSETP. */
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void
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supply_fpregset (fpregset_t *fpregsetp)
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{
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int i;
/* Supply the floating-point registers. */
for (i = 0; i < 8; i++)
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supply_register (FP0_REGNUM + i, FPREGSET_T_FPREG_ADDR (fpregsetp, i));
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supply_register (FCTRL_REGNUM, (char *) &fpregsetp->cwd);
supply_register (FSTAT_REGNUM, (char *) &fpregsetp->swd);
supply_register (FTAG_REGNUM, (char *) &fpregsetp->twd);
supply_register (FCOFF_REGNUM, (char *) &fpregsetp->fip);
supply_register (FDS_REGNUM, (char *) &fpregsetp->fos);
supply_register (FDOFF_REGNUM, (char *) &fpregsetp->foo);
/* Extract the code segment and opcode from the "fcs" member. */
{
long l;
l = fpregsetp->fcs & 0xffff;
supply_register (FCS_REGNUM, (char *) &l);
l = (fpregsetp->fcs >> 16) & ((1 << 11) - 1);
supply_register (FOP_REGNUM, (char *) &l);
}
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}
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/* Fill in an fpregset_t structure with selected data from a
gdb-format register file.
- FPREGSETP points to the structure to be filled.
- GDB_REGS points to the GDB-style register file providing the data.
- VALID is an array indicating which registers in GDB_REGS are
valid; the parts of *FPREGSETP that would hold registers marked
invalid in GDB_REGS are left unchanged. If VALID is zero, all
registers are assumed to be valid. */
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void
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convert_to_fpregset (fpregset_t *fpregsetp,
char *gdb_regs,
signed char *valid)
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{
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int i;
/* Fill in the floating-point registers. */
for (i = 0; i < 8; i++)
if (!valid || valid[i])
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memcpy (FPREGSET_T_FPREG_ADDR (fpregsetp, i),
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&registers[REGISTER_BYTE (FP0_REGNUM + i)],
REGISTER_RAW_SIZE(FP0_REGNUM + i));
#define fill(MEMBER, REGNO) \
if (! valid || valid[(REGNO)]) \
memcpy (&fpregsetp->MEMBER, &registers[REGISTER_BYTE (REGNO)], \
sizeof (fpregsetp->MEMBER))
fill (cwd, FCTRL_REGNUM);
fill (swd, FSTAT_REGNUM);
fill (twd, FTAG_REGNUM);
fill (fip, FCOFF_REGNUM);
fill (foo, FDOFF_REGNUM);
fill (fos, FDS_REGNUM);
#undef fill
if (! valid || valid[FCS_REGNUM])
fpregsetp->fcs
= ((fpregsetp->fcs & ~0xffff)
| (* (int *) &registers[REGISTER_BYTE (FCS_REGNUM)] & 0xffff));
if (! valid || valid[FOP_REGNUM])
fpregsetp->fcs
= ((fpregsetp->fcs & 0xffff)
| ((*(int *) &registers[REGISTER_BYTE (FOP_REGNUM)] & ((1 << 11) - 1))
<< 16));
}
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/* Given a pointer to a floating point register set in (fpregset_t *)
format, update all of the registers from gdb's idea of the current
floating point register set. */
void
fill_fpregset (fpregset_t *fpregsetp,
int regno)
{
convert_to_fpregset (fpregsetp, registers, 0);
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}
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/* Get the whole floating point state of the process and store the
floating point stack into registers[]. */
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static void
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fetch_fpregs ()
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{
int ret, regno;
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fpregset_t buf;
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ret = ptrace (PTRACE_GETFPREGS, inferior_pid, 0, (int) &buf);
if (ret < 0)
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{
warning ("Couldn't get floating point status");
return;
}
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/* ptrace fills an fpregset_t, so we can use the same function we do
for core files. */
supply_fpregset (&buf);
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}
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/* Set the inferior's floating-point registers to the values in
registers[] --- but only those registers marked valid. */
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static void
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store_fpregs ()
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{
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int ret;
fpregset_t buf;
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ret = ptrace (PTRACE_GETFPREGS, inferior_pid, 0, (int) &buf);
if (ret < 0)
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{
warning ("Couldn't get floating point status");
return;
}
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convert_to_fpregset (&buf, registers, register_valid);
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ret = ptrace (PTRACE_SETFPREGS, inferior_pid, 0, (int) &buf);
if (ret < 0)
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{
warning ("Couldn't write floating point status");
return;
}
}
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/* Transfering floating-point and SSE registers to and from GDB. */
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/* PTRACE_GETXFPREGS is a Cygnus invention, since we wrote our own
Linux kernel patch for SSE support. That patch may or may not
actually make it into the official distribution. If you find that
years have gone by since this code was added, and Linux isn't using
PTRACE_GETXFPREGS, that means that our patch didn't make it, and
you can delete this code. */
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#ifdef HAVE_PTRACE_GETXFPREGS
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static void
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supply_xfpregset (struct user_xfpregs_struct *xfpregs)
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{
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int reg;
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/* Supply the floating-point registers. */
for (reg = 0; reg < 8; reg++)
supply_register (FP0_REGNUM + reg, (char *) &xfpregs->st_space[reg]);
{
supply_register (FCTRL_REGNUM, (char *) &xfpregs->cwd);
supply_register (FSTAT_REGNUM, (char *) &xfpregs->swd);
supply_register (FTAG_REGNUM, (char *) &xfpregs->twd);
supply_register (FCOFF_REGNUM, (char *) &xfpregs->fip);
supply_register (FDS_REGNUM, (char *) &xfpregs->fos);
supply_register (FDOFF_REGNUM, (char *) &xfpregs->foo);
/* Extract the code segment and opcode from the "fcs" member. */
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{
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long l;
l = xfpregs->fcs & 0xffff;
supply_register (FCS_REGNUM, (char *) &l);
l = (xfpregs->fcs >> 16) & ((1 << 11) - 1);
supply_register (FOP_REGNUM, (char *) &l);
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}
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}
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/* Supply the SSE registers. */
for (reg = 0; reg < 8; reg++)
supply_register (XMM0_REGNUM + reg, (char *) &xfpregs->xmm_space[reg]);
supply_register (MXCSR_REGNUM, (char *) &xfpregs->mxcsr);
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}
static void
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convert_to_xfpregset (struct user_xfpregs_struct *xfpregs,
char *gdb_regs,
signed char *valid)
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{
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int reg;
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/* Fill in the floating-point registers. */
for (reg = 0; reg < 8; reg++)
if (!valid || valid[reg])
memcpy (&xfpregs->st_space[reg],
&registers[REGISTER_BYTE (FP0_REGNUM + reg)],
REGISTER_RAW_SIZE(FP0_REGNUM + reg));
#define fill(MEMBER, REGNO) \
if (! valid || valid[(REGNO)]) \
memcpy (&xfpregs->MEMBER, &registers[REGISTER_BYTE (REGNO)], \
sizeof (xfpregs->MEMBER))
fill (cwd, FCTRL_REGNUM);
fill (swd, FSTAT_REGNUM);
fill (twd, FTAG_REGNUM);
fill (fip, FCOFF_REGNUM);
fill (foo, FDOFF_REGNUM);
fill (fos, FDS_REGNUM);
#undef fill
if (! valid || valid[FCS_REGNUM])
xfpregs->fcs
= ((xfpregs->fcs & ~0xffff)
| (* (int *) &registers[REGISTER_BYTE (FCS_REGNUM)] & 0xffff));
if (! valid || valid[FOP_REGNUM])
xfpregs->fcs
= ((xfpregs->fcs & 0xffff)
| ((*(int *) &registers[REGISTER_BYTE (FOP_REGNUM)] & ((1 << 11) - 1))
<< 16));
/* Fill in the XMM registers. */
for (reg = 0; reg < 8; reg++)
if (! valid || valid[reg])
memcpy (&xfpregs->xmm_space[reg],
&registers[REGISTER_BYTE (XMM0_REGNUM + reg)],
REGISTER_RAW_SIZE (XMM0_REGNUM + reg));
}
/* Make a PTRACE_GETXFPREGS request, and supply all the register
values that yields to GDB. */
static int
fetch_xfpregs ()
{
int ret;
struct user_xfpregs_struct xfpregs;
if (! have_ptrace_getxfpregs)
return 0;
ret = ptrace (PTRACE_GETXFPREGS, inferior_pid, 0, &xfpregs);
if (ret == -1)
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{
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if (errno == EIO)
{
have_ptrace_getxfpregs = 0;
return 0;
}
warning ("couldn't read floating-point and SSE registers.");
return 0;
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}
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supply_xfpregset (&xfpregs);
return 1;
}
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/* Send all the valid register values in GDB's register file covered
by the PTRACE_SETXFPREGS request to the inferior. */
static int
store_xfpregs ()
{
int ret;
struct user_xfpregs_struct xfpregs;
if (! have_ptrace_getxfpregs)
return 0;
ret = ptrace (PTRACE_GETXFPREGS, inferior_pid, 0, &xfpregs);
if (ret == -1)
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{
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if (errno == EIO)
{
have_ptrace_getxfpregs = 0;
return 0;
}
warning ("couldn't read floating-point and SSE registers.");
return 0;
}
convert_to_xfpregset (&xfpregs, registers, register_valid);
if (ptrace (PTRACE_SETXFPREGS, inferior_pid, 0, &xfpregs) < 0)
{
warning ("Couldn't write floating-point and SSE registers.");
return 0;
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}
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return 1;
}
/* Fill the XMM registers in the register file with dummy values. For
cases where we don't have access to the XMM registers. I think
this is cleaner than printing a warning. For a cleaner solution,
we should gdbarchify the i386 family. */
static void
dummy_sse_values ()
{
/* C doesn't have a syntax for NaN's, so write it out as an array of
longs. */
static long dummy[4] = { 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff };
static long mxcsr = 0x1f80;
int reg;
for (reg = 0; reg < 8; reg++)
supply_register (XMM0_REGNUM + reg, (char *) dummy);
supply_register (MXCSR_REGNUM, (char *) &mxcsr);
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}
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#else
/* Stub versions of the above routines, for systems that don't have
PTRACE_GETXFPREGS. */
static int store_xfpregs () { return 0; }
static int fetch_xfpregs () { return 0; }
static void dummy_sse_values () {}
#endif
/* Transferring arbitrary registers between GDB and inferior. */
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/* Fetch registers from the child process.
Fetch all if regno == -1, otherwise fetch all ordinary
registers or all floating point registers depending
upon the value of regno. */
void
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fetch_inferior_registers (int regno)
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{
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/* Use the xfpregs requests whenever possible, since they transfer
more registers in one system call, and we'll cache the results.
But remember that fetch_xfpregs can fail, and return zero. */
if (regno == -1)
{
fetch_regs ();
if (fetch_xfpregs ())
return;
fetch_fpregs ();
return;
}
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if (GETREGS_SUPPLIES (regno))
{
fetch_regs ();
return;
}
if (GETXFPREGS_SUPPLIES (regno))
{
if (fetch_xfpregs ())
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 ();
dummy_sse_values ();
return;
}
internal_error ("i386-linux-nat.c (fetch_inferior_registers): "
"got request for bad register number %d", regno);
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}
/* Store our register values back into the inferior.
If REGNO is -1, do this for all registers.
Otherwise, REGNO specifies which register, which
then determines whether we store all ordinary
registers or all of the floating point registers. */
void
store_inferior_registers (regno)
int regno;
{
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/* Use the xfpregs requests whenever possible, since they transfer
more registers in one system call. But remember that
fetch_xfpregs can fail, and return zero. */
if (regno == -1)
{
store_regs ();
if (store_xfpregs ())
return;
store_fpregs ();
return;
}
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if (GETREGS_SUPPLIES (regno))
{
store_regs ();
return;
}
if (GETXFPREGS_SUPPLIES (regno))
{
if (store_xfpregs ())
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 ();
return;
}
internal_error ("i386-linux-nat.c (store_inferior_registers): "
"got request to store bad register number %d", regno);
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}
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/* Calling functions in shared libraries. */
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/* Find the minimal symbol named NAME, and return both the minsym
struct and its objfile. This probably ought to be in minsym.c, but
everything there is trying to deal with things like C++ and
SOFUN_ADDRESS_MAYBE_TURQUOISE, ... Since this is so simple, it may
be considered too special-purpose for general consumption. */
static struct minimal_symbol *
find_minsym_and_objfile (char *name, struct objfile **objfile_p)
{
struct objfile *objfile;
ALL_OBJFILES (objfile)
{
struct minimal_symbol *msym;
ALL_OBJFILE_MSYMBOLS (objfile, msym)
{
if (SYMBOL_NAME (msym)
&& STREQ (SYMBOL_NAME (msym), name))
{
*objfile_p = objfile;
return msym;
}
}
}
return 0;
}
static CORE_ADDR
skip_hurd_resolver (CORE_ADDR pc)
{
/* The HURD dynamic linker is part of the GNU C library, so many
GNU/Linux distributions use it. (All ELF versions, as far as I
know.) An unresolved PLT entry points to "_dl_runtime_resolve",
which calls "fixup" to patch the PLT, and then passes control to
the function.
We look for the symbol `_dl_runtime_resolve', and find `fixup' in
the same objfile. If we are at the entry point of `fixup', then
we set a breakpoint at the return address (at the top of the
stack), and continue.
It's kind of gross to do all these checks every time we're
called, since they don't change once the executable has gotten
started. But this is only a temporary hack --- upcoming versions
of Linux will provide a portable, efficient interface for
debugging programs that use shared libraries. */
struct objfile *objfile;
struct minimal_symbol *resolver
= find_minsym_and_objfile ("_dl_runtime_resolve", &objfile);
if (resolver)
{
struct minimal_symbol *fixup
= lookup_minimal_symbol ("fixup", 0, objfile);
if (fixup && SYMBOL_VALUE_ADDRESS (fixup) == pc)
return (SAVED_PC_AFTER_CALL (get_current_frame ()));
}
return 0;
}
/* See the comments for SKIP_SOLIB_RESOLVER at the top of infrun.c.
This function:
1) decides whether a PLT has sent us into the linker to resolve
a function reference, and
2) if so, tells us where to set a temporary breakpoint that will
trigger when the dynamic linker is done. */
CORE_ADDR
i386_linux_skip_solib_resolver (CORE_ADDR pc)
{
CORE_ADDR result;
/* Plug in functions for other kinds of resolvers here. */
result = skip_hurd_resolver (pc);
if (result)
return result;
return 0;
}