| /* Target-dependent code for GNU/Linux on Alpha. |
| Copyright 2002, 2003 Free Software Foundation, 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 "frame.h" |
| #include "gdbcore.h" |
| #include "value.h" |
| #include "osabi.h" |
| |
| #include "alpha-tdep.h" |
| |
| /* Under GNU/Linux, 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 sequence (the first instruction is quadword |
| aligned): |
| |
| bis $30,$30,$16 |
| addq $31,0x67,$0 |
| 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 a designated sequence. If not, -1 is returned, |
| otherwise the offset from the start of the desingated sequence is |
| returned. |
| |
| There is a slight chance of false hits: code could jump into the |
| middle of the designated sequence, in which case there is no |
| guarantee that we are in the middle of a sigreturn syscall. Don't |
| think this will be a problem in praxis, though. */ |
| LONGEST |
| alpha_linux_sigtramp_offset (CORE_ADDR pc) |
| { |
| unsigned int i[3], w; |
| long off; |
| |
| if (read_memory_nobpt (pc, (char *) &w, 4) != 0) |
| return -1; |
| |
| off = -1; |
| switch (w) |
| { |
| case 0x47de0410: |
| off = 0; |
| break; /* bis $30,$30,$16 */ |
| case 0x43ecf400: |
| off = 4; |
| break; /* addq $31,0x67,$0 */ |
| case 0x00000083: |
| off = 8; |
| break; /* call_pal callsys */ |
| default: |
| return -1; |
| } |
| pc -= off; |
| if (pc & 0x7) |
| { |
| /* designated sequence is not quadword aligned */ |
| return -1; |
| } |
| if (read_memory_nobpt (pc, (char *) i, sizeof (i)) != 0) |
| return -1; |
| |
| if (i[0] == 0x47de0410 && i[1] == 0x43ecf400 && i[2] == 0x00000083) |
| return off; |
| |
| return -1; |
| } |
| |
| static int |
| alpha_linux_pc_in_sigtramp (CORE_ADDR pc, char *func_name) |
| { |
| return (alpha_linux_sigtramp_offset (pc) >= 0); |
| } |
| |
| static CORE_ADDR |
| alpha_linux_sigcontext_addr (struct frame_info *frame) |
| { |
| return (get_frame_base (frame) - 0x298); /* sizeof(struct sigcontext) */ |
| } |
| |
| static void |
| alpha_linux_init_abi (struct gdbarch_info info, |
| struct gdbarch *gdbarch) |
| { |
| struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| |
| set_gdbarch_pc_in_sigtramp (gdbarch, alpha_linux_pc_in_sigtramp); |
| |
| tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset; |
| tdep->sigcontext_addr = alpha_linux_sigcontext_addr; |
| |
| tdep->jb_pc = 2; |
| tdep->jb_elt_size = 8; |
| } |
| |
| void |
| _initialize_alpha_linux_tdep (void) |
| { |
| gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_LINUX, |
| alpha_linux_init_abi); |
| } |