| 1 | /* Target-dependent code for GNU/Linux on Alpha. |
| 2 | Copyright (C) 2002, 2003, 2007 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 "gdb_string.h" |
| 25 | #include "osabi.h" |
| 26 | #include "solib-svr4.h" |
| 27 | #include "symtab.h" |
| 28 | #include "regset.h" |
| 29 | #include "regcache.h" |
| 30 | |
| 31 | #include "alpha-tdep.h" |
| 32 | |
| 33 | /* Under GNU/Linux, signal handler invocations can be identified by |
| 34 | the designated code sequence that is used to return from a signal |
| 35 | handler. In particular, the return address of a signal handler |
| 36 | points to a sequence that copies $sp to $16, loads $0 with the |
| 37 | appropriate syscall number, and finally enters the kernel. |
| 38 | |
| 39 | This is somewhat complicated in that: |
| 40 | (1) the expansion of the "mov" assembler macro has changed over |
| 41 | time, from "bis src,src,dst" to "bis zero,src,dst", |
| 42 | (2) the kernel has changed from using "addq" to "lda" to load the |
| 43 | syscall number, |
| 44 | (3) there is a "normal" sigreturn and an "rt" sigreturn which |
| 45 | has a different stack layout. |
| 46 | */ |
| 47 | |
| 48 | static long |
| 49 | alpha_linux_sigtramp_offset_1 (CORE_ADDR pc) |
| 50 | { |
| 51 | switch (alpha_read_insn (pc)) |
| 52 | { |
| 53 | case 0x47de0410: /* bis $30,$30,$16 */ |
| 54 | case 0x47fe0410: /* bis $31,$30,$16 */ |
| 55 | return 0; |
| 56 | |
| 57 | case 0x43ecf400: /* addq $31,103,$0 */ |
| 58 | case 0x201f0067: /* lda $0,103($31) */ |
| 59 | case 0x201f015f: /* lda $0,351($31) */ |
| 60 | return 4; |
| 61 | |
| 62 | case 0x00000083: /* call_pal callsys */ |
| 63 | return 8; |
| 64 | |
| 65 | default: |
| 66 | return -1; |
| 67 | } |
| 68 | } |
| 69 | |
| 70 | static LONGEST |
| 71 | alpha_linux_sigtramp_offset (CORE_ADDR pc) |
| 72 | { |
| 73 | long i, off; |
| 74 | |
| 75 | if (pc & 3) |
| 76 | return -1; |
| 77 | |
| 78 | /* Guess where we might be in the sequence. */ |
| 79 | off = alpha_linux_sigtramp_offset_1 (pc); |
| 80 | if (off < 0) |
| 81 | return -1; |
| 82 | |
| 83 | /* Verify that the other two insns of the sequence are as we expect. */ |
| 84 | pc -= off; |
| 85 | for (i = 0; i < 12; i += 4) |
| 86 | { |
| 87 | if (i == off) |
| 88 | continue; |
| 89 | if (alpha_linux_sigtramp_offset_1 (pc + i) != i) |
| 90 | return -1; |
| 91 | } |
| 92 | |
| 93 | return off; |
| 94 | } |
| 95 | |
| 96 | static int |
| 97 | alpha_linux_pc_in_sigtramp (CORE_ADDR pc, char *func_name) |
| 98 | { |
| 99 | return alpha_linux_sigtramp_offset (pc) >= 0; |
| 100 | } |
| 101 | |
| 102 | static CORE_ADDR |
| 103 | alpha_linux_sigcontext_addr (struct frame_info *next_frame) |
| 104 | { |
| 105 | CORE_ADDR pc; |
| 106 | ULONGEST sp; |
| 107 | long off; |
| 108 | |
| 109 | pc = frame_pc_unwind (next_frame); |
| 110 | frame_unwind_unsigned_register (next_frame, ALPHA_SP_REGNUM, &sp); |
| 111 | |
| 112 | off = alpha_linux_sigtramp_offset (pc); |
| 113 | gdb_assert (off >= 0); |
| 114 | |
| 115 | /* __NR_rt_sigreturn has a couple of structures on the stack. This is: |
| 116 | |
| 117 | struct rt_sigframe { |
| 118 | struct siginfo info; |
| 119 | struct ucontext uc; |
| 120 | }; |
| 121 | |
| 122 | offsetof (struct rt_sigframe, uc.uc_mcontext); |
| 123 | */ |
| 124 | if (alpha_read_insn (pc - off + 4) == 0x201f015f) |
| 125 | return sp + 176; |
| 126 | |
| 127 | /* __NR_sigreturn has the sigcontext structure at the top of the stack. */ |
| 128 | return sp; |
| 129 | } |
| 130 | |
| 131 | /* Supply register REGNUM from the buffer specified by GREGS and LEN |
| 132 | in the general-purpose register set REGSET to register cache |
| 133 | REGCACHE. If REGNUM is -1, do this for all registers in REGSET. */ |
| 134 | |
| 135 | static void |
| 136 | alpha_linux_supply_gregset (const struct regset *regset, |
| 137 | struct regcache *regcache, |
| 138 | int regnum, const void *gregs, size_t len) |
| 139 | { |
| 140 | const gdb_byte *regs = gregs; |
| 141 | int i; |
| 142 | gdb_assert (len >= 32 * 8); |
| 143 | |
| 144 | for (i = 0; i < ALPHA_ZERO_REGNUM; i++) |
| 145 | { |
| 146 | if (regnum == i || regnum == -1) |
| 147 | regcache_raw_supply (regcache, i, regs + i * 8); |
| 148 | } |
| 149 | |
| 150 | if (regnum == ALPHA_PC_REGNUM || regnum == -1) |
| 151 | regcache_raw_supply (regcache, ALPHA_PC_REGNUM, regs + 31 * 8); |
| 152 | |
| 153 | if (regnum == ALPHA_UNIQUE_REGNUM || regnum == -1) |
| 154 | regcache_raw_supply (regcache, ALPHA_UNIQUE_REGNUM, |
| 155 | len >= 33 * 8 ? regs + 32 * 8 : NULL); |
| 156 | } |
| 157 | |
| 158 | /* Supply register REGNUM from the buffer specified by FPREGS and LEN |
| 159 | in the floating-point register set REGSET to register cache |
| 160 | REGCACHE. If REGNUM is -1, do this for all registers in REGSET. */ |
| 161 | |
| 162 | static void |
| 163 | alpha_linux_supply_fpregset (const struct regset *regset, |
| 164 | struct regcache *regcache, |
| 165 | int regnum, const void *fpregs, size_t len) |
| 166 | { |
| 167 | const gdb_byte *regs = fpregs; |
| 168 | int i; |
| 169 | gdb_assert (len >= 32 * 8); |
| 170 | |
| 171 | for (i = ALPHA_FP0_REGNUM; i < ALPHA_FP0_REGNUM + 31; i++) |
| 172 | { |
| 173 | if (regnum == i || regnum == -1) |
| 174 | regcache_raw_supply (regcache, i, regs + (i - ALPHA_FP0_REGNUM) * 8); |
| 175 | } |
| 176 | |
| 177 | if (regnum == ALPHA_FPCR_REGNUM || regnum == -1) |
| 178 | regcache_raw_supply (regcache, ALPHA_FPCR_REGNUM, regs + 31 * 8); |
| 179 | } |
| 180 | |
| 181 | static struct regset alpha_linux_gregset = |
| 182 | { |
| 183 | NULL, |
| 184 | alpha_linux_supply_gregset |
| 185 | }; |
| 186 | |
| 187 | static struct regset alpha_linux_fpregset = |
| 188 | { |
| 189 | NULL, |
| 190 | alpha_linux_supply_fpregset |
| 191 | }; |
| 192 | |
| 193 | /* Return the appropriate register set for the core section identified |
| 194 | by SECT_NAME and SECT_SIZE. */ |
| 195 | |
| 196 | const struct regset * |
| 197 | alpha_linux_regset_from_core_section (struct gdbarch *gdbarch, |
| 198 | const char *sect_name, size_t sect_size) |
| 199 | { |
| 200 | if (strcmp (sect_name, ".reg") == 0 && sect_size >= 32 * 8) |
| 201 | return &alpha_linux_gregset; |
| 202 | |
| 203 | if (strcmp (sect_name, ".reg2") == 0 && sect_size >= 32 * 8) |
| 204 | return &alpha_linux_fpregset; |
| 205 | |
| 206 | return NULL; |
| 207 | } |
| 208 | |
| 209 | static void |
| 210 | alpha_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 211 | { |
| 212 | struct gdbarch_tdep *tdep; |
| 213 | |
| 214 | /* Hook into the DWARF CFI frame unwinder. */ |
| 215 | alpha_dwarf2_init_abi (info, gdbarch); |
| 216 | |
| 217 | /* Hook into the MDEBUG frame unwinder. */ |
| 218 | alpha_mdebug_init_abi (info, gdbarch); |
| 219 | |
| 220 | tdep = gdbarch_tdep (gdbarch); |
| 221 | tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset; |
| 222 | tdep->sigcontext_addr = alpha_linux_sigcontext_addr; |
| 223 | tdep->pc_in_sigtramp = alpha_linux_pc_in_sigtramp; |
| 224 | tdep->jb_pc = 2; |
| 225 | tdep->jb_elt_size = 8; |
| 226 | |
| 227 | set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target); |
| 228 | |
| 229 | /* Enable TLS support. */ |
| 230 | set_gdbarch_fetch_tls_load_module_address (gdbarch, |
| 231 | svr4_fetch_objfile_link_map); |
| 232 | |
| 233 | set_gdbarch_regset_from_core_section |
| 234 | (gdbarch, alpha_linux_regset_from_core_section); |
| 235 | } |
| 236 | |
| 237 | void |
| 238 | _initialize_alpha_linux_tdep (void) |
| 239 | { |
| 240 | gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_LINUX, |
| 241 | alpha_linux_init_abi); |
| 242 | } |