| 1 | /* Target-dependent code for GNU/Linux on Alpha. |
| 2 | Copyright 2002, 2003 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GDB. |
| 5 | |
| 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. |
| 10 | |
| 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. |
| 15 | |
| 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. */ |
| 20 | |
| 21 | #include "defs.h" |
| 22 | #include "frame.h" |
| 23 | #include "gdb_assert.h" |
| 24 | #include "osabi.h" |
| 25 | |
| 26 | #include "alpha-tdep.h" |
| 27 | |
| 28 | /* Under GNU/Linux, signal handler invocations can be identified by |
| 29 | the designated code sequence that is used to return from a signal |
| 30 | handler. In particular, the return address of a signal handler |
| 31 | points to a sequence that copies $sp to $16, loads $0 with the |
| 32 | appropriate syscall number, and finally enters the kernel. |
| 33 | |
| 34 | This is somewhat complicated in that: |
| 35 | (1) the expansion of the "mov" assembler macro has changed over |
| 36 | time, from "bis src,src,dst" to "bis zero,src,dst", |
| 37 | (2) the kernel has changed from using "addq" to "lda" to load the |
| 38 | syscall number, |
| 39 | (3) there is a "normal" sigreturn and an "rt" sigreturn which |
| 40 | has a different stack layout. |
| 41 | */ |
| 42 | |
| 43 | static long |
| 44 | alpha_linux_sigtramp_offset_1 (CORE_ADDR pc) |
| 45 | { |
| 46 | switch (alpha_read_insn (pc)) |
| 47 | { |
| 48 | case 0x47de0410: /* bis $30,$30,$16 */ |
| 49 | case 0x47fe0410: /* bis $31,$30,$16 */ |
| 50 | return 0; |
| 51 | |
| 52 | case 0x43ecf400: /* addq $31,103,$0 */ |
| 53 | case 0x201f0067: /* lda $0,103($31) */ |
| 54 | case 0x201f015f: /* lda $0,351($31) */ |
| 55 | return 4; |
| 56 | |
| 57 | case 0x00000083: /* call_pal callsys */ |
| 58 | return 8; |
| 59 | |
| 60 | default: |
| 61 | return -1; |
| 62 | } |
| 63 | } |
| 64 | |
| 65 | static LONGEST |
| 66 | alpha_linux_sigtramp_offset (CORE_ADDR pc) |
| 67 | { |
| 68 | long i, off; |
| 69 | |
| 70 | if (pc & 3) |
| 71 | return -1; |
| 72 | |
| 73 | /* Guess where we might be in the sequence. */ |
| 74 | off = alpha_linux_sigtramp_offset_1 (pc); |
| 75 | if (off < 0) |
| 76 | return -1; |
| 77 | |
| 78 | /* Verify that the other two insns of the sequence are as we expect. */ |
| 79 | pc -= off; |
| 80 | for (i = 0; i < 12; i += 4) |
| 81 | { |
| 82 | if (i == off) |
| 83 | continue; |
| 84 | if (alpha_linux_sigtramp_offset_1 (pc + i) != i) |
| 85 | return -1; |
| 86 | } |
| 87 | |
| 88 | return off; |
| 89 | } |
| 90 | |
| 91 | static int |
| 92 | alpha_linux_pc_in_sigtramp (CORE_ADDR pc, char *func_name) |
| 93 | { |
| 94 | return alpha_linux_sigtramp_offset (pc) >= 0; |
| 95 | } |
| 96 | |
| 97 | static CORE_ADDR |
| 98 | alpha_linux_sigcontext_addr (struct frame_info *next_frame) |
| 99 | { |
| 100 | CORE_ADDR pc; |
| 101 | ULONGEST sp; |
| 102 | long off; |
| 103 | |
| 104 | pc = frame_pc_unwind (next_frame); |
| 105 | frame_unwind_unsigned_register (next_frame, ALPHA_SP_REGNUM, &sp); |
| 106 | |
| 107 | off = alpha_linux_sigtramp_offset (pc); |
| 108 | gdb_assert (off >= 0); |
| 109 | |
| 110 | /* __NR_rt_sigreturn has a couple of structures on the stack. This is: |
| 111 | |
| 112 | struct rt_sigframe { |
| 113 | struct siginfo info; |
| 114 | struct ucontext uc; |
| 115 | }; |
| 116 | |
| 117 | offsetof (struct rt_sigframe, uc.uc_mcontext); |
| 118 | */ |
| 119 | if (alpha_read_insn (pc - off + 4) == 0x201f015f) |
| 120 | return sp + 176; |
| 121 | |
| 122 | /* __NR_sigreturn has the sigcontext structure at the top of the stack. */ |
| 123 | return sp; |
| 124 | } |
| 125 | |
| 126 | static void |
| 127 | alpha_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 128 | { |
| 129 | struct gdbarch_tdep *tdep; |
| 130 | |
| 131 | /* Hook into the DWARF CFI frame unwinder. */ |
| 132 | alpha_dwarf2_init_abi (info, gdbarch); |
| 133 | |
| 134 | /* Hook into the MDEBUG frame unwinder. */ |
| 135 | alpha_mdebug_init_abi (info, gdbarch); |
| 136 | |
| 137 | tdep = gdbarch_tdep (gdbarch); |
| 138 | tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset; |
| 139 | tdep->sigcontext_addr = alpha_linux_sigcontext_addr; |
| 140 | tdep->pc_in_sigtramp = alpha_linux_pc_in_sigtramp; |
| 141 | tdep->jb_pc = 2; |
| 142 | tdep->jb_elt_size = 8; |
| 143 | } |
| 144 | |
| 145 | void |
| 146 | _initialize_alpha_linux_tdep (void) |
| 147 | { |
| 148 | gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_LINUX, |
| 149 | alpha_linux_init_abi); |
| 150 | } |