1 /* Target-dependent code for GNU/Linux on Alpha.
2 Copyright 2002, 2003 Free Software Foundation, Inc.
4 This file is part of GDB.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
26 #include "gdb_assert.h"
28 #include "alpha-tdep.h"
30 /* Under GNU/Linux, signal handler invocations can be identified by
31 the designated code sequence that is used to return from a signal
32 handler. In particular, the return address of a signal handler
33 points to a sequence that copies $sp to $16, loads $0 with the
34 appropriate syscall number, and finally enters the kernel.
36 This is somewhat complicated in that:
37 (1) the expansion of the "mov" assembler macro has changed over
38 time, from "bis src,src,dst" to "bis zero,src,dst",
39 (2) the kernel has changed from using "addq" to "lda" to load the
41 (3) there is a "normal" sigreturn and an "rt" sigreturn which
42 has a different stack layout.
46 alpha_linux_sigtramp_offset_1 (CORE_ADDR pc)
48 switch (alpha_read_insn (pc))
50 case 0x47de0410: /* bis $30,$30,$16 */
51 case 0x47fe0410: /* bis $31,$30,$16 */
54 case 0x43ecf400: /* addq $31,103,$0 */
55 case 0x201f0067: /* lda $0,103($31) */
56 case 0x201f015f: /* lda $0,351($31) */
59 case 0x00000083: /* call_pal callsys */
68 alpha_linux_sigtramp_offset (CORE_ADDR pc)
75 /* Guess where we might be in the sequence. */
76 off = alpha_linux_sigtramp_offset_1 (pc);
80 /* Verify that the other two insns of the sequence are as we expect. */
82 for (i = 0; i < 12; i += 4)
86 if (alpha_linux_sigtramp_offset_1 (pc + i) != i)
94 alpha_linux_pc_in_sigtramp (CORE_ADDR pc, char *func_name)
96 return alpha_linux_sigtramp_offset (pc) >= 0;
100 alpha_linux_sigcontext_addr (struct frame_info *next_frame)
106 pc = frame_pc_unwind (next_frame);
107 frame_unwind_unsigned_register (next_frame, ALPHA_SP_REGNUM, &sp);
109 off = alpha_linux_sigtramp_offset (pc);
110 gdb_assert (off >= 0);
112 /* __NR_rt_sigreturn has a couple of structures on the stack. This is:
119 offsetof (struct rt_sigframe, uc.uc_mcontext);
121 if (alpha_read_insn (pc - off + 4) == 0x201f015f)
124 /* __NR_sigreturn has the sigcontext structure at the top of the stack. */
129 alpha_linux_init_abi (struct gdbarch_info info,
130 struct gdbarch *gdbarch)
132 struct gdbarch_tdep *tdep;
134 alpha_mdebug_init_abi (info, gdbarch);
136 set_gdbarch_pc_in_sigtramp (gdbarch, alpha_linux_pc_in_sigtramp);
138 tdep = gdbarch_tdep (gdbarch);
139 tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset;
140 tdep->sigcontext_addr = alpha_linux_sigcontext_addr;
142 tdep->jb_elt_size = 8;
146 _initialize_alpha_linux_tdep (void)
148 gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_LINUX,
149 alpha_linux_init_abi);