99 lines
2.9 KiB
C
99 lines
2.9 KiB
C
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/* Target-dependent code for GNU/Linux on Alpha.
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Copyright 2002 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., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include "defs.h"
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#include "value.h"
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#include "alpha-tdep.h"
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/* Under GNU/Linux, signal handler invocations can be identified by the
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designated code sequence that is used to return from a signal
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handler. In particular, the return address of a signal handler
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points to the following sequence (the first instruction is quadword
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aligned):
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bis $30,$30,$16
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addq $31,0x67,$0
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call_pal callsys
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Each instruction has a unique encoding, so we simply attempt to
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match the instruction the pc is pointing to with any of the above
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instructions. If there is a hit, we know the offset to the start
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of the designated sequence and can then check whether we really are
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executing in a designated sequence. If not, -1 is returned,
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otherwise the offset from the start of the desingated sequence is
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returned.
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There is a slight chance of false hits: code could jump into the
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middle of the designated sequence, in which case there is no
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guarantee that we are in the middle of a sigreturn syscall. Don't
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think this will be a problem in praxis, though. */
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long
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alpha_linux_sigtramp_offset (CORE_ADDR pc)
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{
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unsigned int i[3], w;
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long off;
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if (read_memory_nobpt (pc, (char *) &w, 4) != 0)
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return -1;
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off = -1;
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switch (w)
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{
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case 0x47de0410:
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off = 0;
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break; /* bis $30,$30,$16 */
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case 0x43ecf400:
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off = 4;
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break; /* addq $31,0x67,$0 */
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case 0x00000083:
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off = 8;
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break; /* call_pal callsys */
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default:
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return -1;
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}
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pc -= off;
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if (pc & 0x7)
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{
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/* designated sequence is not quadword aligned */
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return -1;
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}
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if (read_memory_nobpt (pc, (char *) i, sizeof (i)) != 0)
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return -1;
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if (i[0] == 0x47de0410 && i[1] == 0x43ecf400 && i[2] == 0x00000083)
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return off;
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return -1;
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}
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static void
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alpha_linux_init_abi (struct gdbarch_info info,
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struct gdbarch *gdbarch)
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{
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/* Place holder. */
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}
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void
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_initialize_alpha_linux_tdep (void)
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{
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alpha_gdbarch_register_os_abi (ALPHA_ABI_LINUX, alpha_linux_init_abi);
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}
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