gdb/alpha-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux on Alpha.
   2    Copyright (C) 2002-2003, 2007-2012 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 3 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, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include "defs.h"
  20 #include "frame.h"
  21 #include "gdb_assert.h"
  22 #include "gdb_string.h"
  23 #include "osabi.h"
  24 #include "solib-svr4.h"
  25 #include "symtab.h"
  26 #include "regset.h"
  27 #include "regcache.h"
  28 #include "linux-tdep.h"
  29 #include "alpha-tdep.h"
  30
  31 /* Under GNU/Linux, signal handler invocations can be identified by
  32    the designated code sequence that is used to return from a signal
  33    handler.  In particular, the return address of a signal handler
  34    points to a sequence that copies $sp to $16, loads $0 with the
  35    appropriate syscall number, and finally enters the kernel.
  36
  37    This is somewhat complicated in that:
  38      (1) the expansion of the "mov" assembler macro has changed over
  39          time, from "bis src,src,dst" to "bis zero,src,dst",
  40      (2) the kernel has changed from using "addq" to "lda" to load the
  41          syscall number,
  42      (3) there is a "normal" sigreturn and an "rt" sigreturn which
  43          has a different stack layout.  */
  44
  45 static long
  46 alpha_linux_sigtramp_offset_1 (struct gdbarch *gdbarch, CORE_ADDR pc)
  47 {
  48   switch (alpha_read_insn (gdbarch, 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 (struct gdbarch *gdbarch, 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 (gdbarch, 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 (gdbarch, pc + i) != i)
  87         return -1;
  88     }
  89
  90   return off;
  91 }
  92
  93 static int
  94 alpha_linux_pc_in_sigtramp (struct gdbarch *gdbarch,
  95                             CORE_ADDR pc, const char *func_name)
  96 {
  97   return alpha_linux_sigtramp_offset (gdbarch, pc) >= 0;
  98 }
  99
 100 static CORE_ADDR
 101 alpha_linux_sigcontext_addr (struct frame_info *this_frame)
 102 {
 103   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 104   CORE_ADDR pc;
 105   ULONGEST sp;
 106   long off;
 107
 108   pc = get_frame_pc (this_frame);
 109   sp = get_frame_register_unsigned (this_frame, ALPHA_SP_REGNUM);
 110
 111   off = alpha_linux_sigtramp_offset (gdbarch, pc);
 112   gdb_assert (off >= 0);
 113
 114   /* __NR_rt_sigreturn has a couple of structures on the stack.  This is:
 115
 116         struct rt_sigframe {
 117           struct siginfo info;
 118           struct ucontext uc;
 119         };
 120
 121         offsetof (struct rt_sigframe, uc.uc_mcontext);  */
 122
 123   if (alpha_read_insn (gdbarch, pc - off + 4) == 0x201f015f)
 124     return sp + 176;
 125
 126   /* __NR_sigreturn has the sigcontext structure at the top of the stack.  */
 127   return sp;
 128 }
 129
 130 /* Supply register REGNUM from the buffer specified by GREGS and LEN
 131    in the general-purpose register set REGSET to register cache
 132    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
 133
 134 static void
 135 alpha_linux_supply_gregset (const struct regset *regset,
 136                             struct regcache *regcache,
 137                             int regnum, const void *gregs, size_t len)
 138 {
 139   const gdb_byte *regs = gregs;
 140   int i;
 141   gdb_assert (len >= 32 * 8);
 142
 143   for (i = 0; i < ALPHA_ZERO_REGNUM; i++)
 144     {
 145       if (regnum == i || regnum == -1)
 146         regcache_raw_supply (regcache, i, regs + i * 8);
 147     }
 148
 149   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
 150     regcache_raw_supply (regcache, ALPHA_PC_REGNUM, regs + 31 * 8);
 151
 152   if (regnum == ALPHA_UNIQUE_REGNUM || regnum == -1)
 153     regcache_raw_supply (regcache, ALPHA_UNIQUE_REGNUM,
 154                          len >= 33 * 8 ? regs + 32 * 8 : NULL);
 155 }
 156
 157 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
 158    in the floating-point register set REGSET to register cache
 159    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
 160
 161 static void
 162 alpha_linux_supply_fpregset (const struct regset *regset,
 163                              struct regcache *regcache,
 164                              int regnum, const void *fpregs, size_t len)
 165 {
 166   const gdb_byte *regs = fpregs;
 167   int i;
 168   gdb_assert (len >= 32 * 8);
 169
 170   for (i = ALPHA_FP0_REGNUM; i < ALPHA_FP0_REGNUM + 31; i++)
 171     {
 172       if (regnum == i || regnum == -1)
 173         regcache_raw_supply (regcache, i, regs + (i - ALPHA_FP0_REGNUM) * 8);
 174     }
 175
 176   if (regnum == ALPHA_FPCR_REGNUM || regnum == -1)
 177     regcache_raw_supply (regcache, ALPHA_FPCR_REGNUM, regs + 31 * 8);
 178 }
 179
 180 static struct regset alpha_linux_gregset =
 181 {
 182   NULL,
 183   alpha_linux_supply_gregset
 184 };
 185
 186 static struct regset alpha_linux_fpregset =
 187 {
 188   NULL,
 189   alpha_linux_supply_fpregset
 190 };
 191
 192 /* Return the appropriate register set for the core section identified
 193    by SECT_NAME and SECT_SIZE.  */
 194
 195 static const struct regset *
 196 alpha_linux_regset_from_core_section (struct gdbarch *gdbarch,
 197                                       const char *sect_name, size_t sect_size)
 198 {
 199   if (strcmp (sect_name, ".reg") == 0 && sect_size >= 32 * 8)
 200     return &alpha_linux_gregset;
 201
 202   if (strcmp (sect_name, ".reg2") == 0 && sect_size >= 32 * 8)
 203     return &alpha_linux_fpregset;
 204
 205   return NULL;
 206 }
 207
 208 static void
 209 alpha_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 210 {
 211   struct gdbarch_tdep *tdep;
 212
 213   linux_init_abi (info, gdbarch);
 214
 215   /* Hook into the DWARF CFI frame unwinder.  */
 216   alpha_dwarf2_init_abi (info, gdbarch);
 217
 218   /* Hook into the MDEBUG frame unwinder.  */
 219   alpha_mdebug_init_abi (info, gdbarch);
 220
 221   tdep = gdbarch_tdep (gdbarch);
 222   tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset;
 223   tdep->sigcontext_addr = alpha_linux_sigcontext_addr;
 224   tdep->pc_in_sigtramp = alpha_linux_pc_in_sigtramp;
 225   tdep->jb_pc = 2;
 226   tdep->jb_elt_size = 8;
 227
 228   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 229
 230   set_solib_svr4_fetch_link_map_offsets
 231     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 232
 233   /* Enable TLS support.  */
 234   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 235                                              svr4_fetch_objfile_link_map);
 236
 237   set_gdbarch_regset_from_core_section
 238     (gdbarch, alpha_linux_regset_from_core_section);
 239 }
 240
 241 /* Provide a prototype to silence -Wmissing-prototypes.  */
 242 extern initialize_file_ftype _initialize_alpha_linux_tdep;
 243
 244 void
 245 _initialize_alpha_linux_tdep (void)
 246 {
 247   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_LINUX,
 248                           alpha_linux_init_abi);
 249 }