| 1 | /* Target-dependent code for GNU/Linux on Alpha. |
| 2 | Copyright (C) 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., 51 Franklin Street, Fifth Floor, |
| 19 | Boston, MA 02110-1301, USA. */ |
| 20 | |
| 21 | #include "defs.h" |
| 22 | #include "frame.h" |
| 23 | #include "gdb_assert.h" |
| 24 | #include "osabi.h" |
| 25 | #include "solib-svr4.h" |
| 26 | #include "symtab.h" |
| 27 | |
| 28 | #include "alpha-tdep.h" |
| 29 | |
| 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. |
| 35 | |
| 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 |
| 40 | syscall number, |
| 41 | (3) there is a "normal" sigreturn and an "rt" sigreturn which |
| 42 | has a different stack layout. |
| 43 | */ |
| 44 | |
| 45 | static long |
| 46 | alpha_linux_sigtramp_offset_1 (CORE_ADDR pc) |
| 47 | { |
| 48 | switch (alpha_read_insn (pc)) |
| 49 | { |
| 50 | case 0x47de0410: /* bis $30,$30,$16 */ |
| 51 | case 0x47fe0410: /* bis $31,$30,$16 */ |
| 52 | return 0; |
| 53 | |
| 54 | case 0x43ecf400: /* addq $31,103,$0 */ |
| 55 | case 0x201f0067: /* lda $0,103($31) */ |
| 56 | case 0x201f015f: /* lda $0,351($31) */ |
| 57 | return 4; |
| 58 | |
| 59 | case 0x00000083: /* call_pal callsys */ |
| 60 | return 8; |
| 61 | |
| 62 | default: |
| 63 | return -1; |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | static LONGEST |
| 68 | alpha_linux_sigtramp_offset (CORE_ADDR pc) |
| 69 | { |
| 70 | long i, off; |
| 71 | |
| 72 | if (pc & 3) |
| 73 | return -1; |
| 74 | |
| 75 | /* Guess where we might be in the sequence. */ |
| 76 | off = alpha_linux_sigtramp_offset_1 (pc); |
| 77 | if (off < 0) |
| 78 | return -1; |
| 79 | |
| 80 | /* Verify that the other two insns of the sequence are as we expect. */ |
| 81 | pc -= off; |
| 82 | for (i = 0; i < 12; i += 4) |
| 83 | { |
| 84 | if (i == off) |
| 85 | continue; |
| 86 | if (alpha_linux_sigtramp_offset_1 (pc + i) != i) |
| 87 | return -1; |
| 88 | } |
| 89 | |
| 90 | return off; |
| 91 | } |
| 92 | |
| 93 | static int |
| 94 | alpha_linux_pc_in_sigtramp (CORE_ADDR pc, char *func_name) |
| 95 | { |
| 96 | return alpha_linux_sigtramp_offset (pc) >= 0; |
| 97 | } |
| 98 | |
| 99 | static CORE_ADDR |
| 100 | alpha_linux_sigcontext_addr (struct frame_info *next_frame) |
| 101 | { |
| 102 | CORE_ADDR pc; |
| 103 | ULONGEST sp; |
| 104 | long off; |
| 105 | |
| 106 | pc = frame_pc_unwind (next_frame); |
| 107 | frame_unwind_unsigned_register (next_frame, ALPHA_SP_REGNUM, &sp); |
| 108 | |
| 109 | off = alpha_linux_sigtramp_offset (pc); |
| 110 | gdb_assert (off >= 0); |
| 111 | |
| 112 | /* __NR_rt_sigreturn has a couple of structures on the stack. This is: |
| 113 | |
| 114 | struct rt_sigframe { |
| 115 | struct siginfo info; |
| 116 | struct ucontext uc; |
| 117 | }; |
| 118 | |
| 119 | offsetof (struct rt_sigframe, uc.uc_mcontext); |
| 120 | */ |
| 121 | if (alpha_read_insn (pc - off + 4) == 0x201f015f) |
| 122 | return sp + 176; |
| 123 | |
| 124 | /* __NR_sigreturn has the sigcontext structure at the top of the stack. */ |
| 125 | return sp; |
| 126 | } |
| 127 | |
| 128 | static void |
| 129 | alpha_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 130 | { |
| 131 | struct gdbarch_tdep *tdep; |
| 132 | |
| 133 | /* Hook into the DWARF CFI frame unwinder. */ |
| 134 | alpha_dwarf2_init_abi (info, gdbarch); |
| 135 | |
| 136 | /* Hook into the MDEBUG frame unwinder. */ |
| 137 | alpha_mdebug_init_abi (info, gdbarch); |
| 138 | |
| 139 | tdep = gdbarch_tdep (gdbarch); |
| 140 | tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset; |
| 141 | tdep->sigcontext_addr = alpha_linux_sigcontext_addr; |
| 142 | tdep->pc_in_sigtramp = alpha_linux_pc_in_sigtramp; |
| 143 | tdep->jb_pc = 2; |
| 144 | tdep->jb_elt_size = 8; |
| 145 | |
| 146 | set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target); |
| 147 | |
| 148 | /* Enable TLS support. */ |
| 149 | set_gdbarch_fetch_tls_load_module_address (gdbarch, |
| 150 | svr4_fetch_objfile_link_map); |
| 151 | } |
| 152 | |
| 153 | void |
| 154 | _initialize_alpha_linux_tdep (void) |
| 155 | { |
| 156 | gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_LINUX, |
| 157 | alpha_linux_init_abi); |
| 158 | } |