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/* Target-dependent code for NetBSD/Alpha.
Copyright 2002 Free Software Foundation, Inc.
Contributed by Wasabi Systems, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 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 "gdbcore.h"
#include "value.h"
#include "solib-svr4.h"
#include "alpha-tdep.h"
/* Fetch (and possibly build) an appropriate link_map_offsets
structure for NetBSD/alpha targets using the struct offsets
defined in <link.h> (but without actual reference to that file).
This makes it possible to access NetBSD/alpha shared libraries
from a GDB that was not built on a NetBSD/alpha host (for cross
debugging). */
static struct link_map_offsets *
alphanbsd_solib_svr4_fetch_link_map_offsets (void)
{
static struct link_map_offsets lmo;
static struct link_map_offsets *lmp = NULL;
if (lmp == NULL)
{
lmp = &lmo;
lmo.r_debug_size = 32;
lmo.r_map_offset = 8;
lmo.r_map_size = 8;
lmo.link_map_size = 40;
lmo.l_addr_offset = 0;
lmo.l_addr_size = 8;
lmo.l_name_offset = 8;
lmo.l_name_size = 8;
lmo.l_next_offset = 24;
lmo.l_next_size = 8;
lmo.l_prev_offset = 32;
lmo.l_prev_size = 8;
}
return lmp;
}
/* Under NetBSD/alpha, signal handler invocations can be identified by the
designated code sequence that is used to return from a signal handler.
In particular, the return address of a signal handler points to the
following code sequence:
ldq a0, 0(sp)
lda sp, 16(sp)
lda v0, 295(zero) # __sigreturn14
call_pal callsys
Each instruction has a unique encoding, so we simply attempt to match
the instruction the PC is pointing to with any of the above instructions.
If there is a hit, we know the offset to the start of the designated
sequence and can then check whether we really are executing in the
signal trampoline. If not, -1 is returned, otherwise the offset from the
start of the return sequence is returned. */
static const unsigned int sigtramp_retcode[] =
{
0xa61e0000, /* ldq a0, 0(sp) */
0x23de0010, /* lda sp, 16(sp) */
0x201f0127, /* lda v0, 295(zero) */
0x00000083, /* call_pal callsys */
};
#define RETCODE_NWORDS \
(sizeof (sigtramp_retcode) / sizeof (sigtramp_retcode[0]))
LONGEST
alphanbsd_sigtramp_offset (CORE_ADDR pc)
{
unsigned int ret[4], w;
LONGEST off;
int i;
if (read_memory_nobpt (pc, (char *) &w, 4) != 0)
return -1;
for (i = 0; i < RETCODE_NWORDS; i++)
{
if (w == sigtramp_retcode[i])
break;
}
if (i == RETCODE_NWORDS)
return (-1);
off = i * 4;
pc -= off;
if (read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
return -1;
if (memcmp (ret, sigtramp_retcode, sizeof (sigtramp_retcode)) == 0)
return off;
return -1;
}
static void
alphanbsd_init_abi (struct gdbarch_info info,
struct gdbarch *gdbarch)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
/* NetBSD/alpha does not provide single step support via ptrace(2); we
must use software single-stepping. */
set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
set_solib_svr4_fetch_link_map_offsets (gdbarch,
alphanbsd_solib_svr4_fetch_link_map_offsets);
tdep->dynamic_sigtramp_offset = alphanbsd_sigtramp_offset;
}
void
_initialize_alphanbsd_tdep (void)
{
alpha_gdbarch_register_os_abi (ALPHA_ABI_NETBSD, alphanbsd_init_abi);
}
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