gdb/alpha-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux on Alpha.
   2    Copyright (C) 2002, 2003, 2007, 2008, 2009 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
  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
  46 static long
  47 alpha_linux_sigtramp_offset_1 (CORE_ADDR pc)
  48 {
  49   switch (alpha_read_insn (pc))
  50     {
  51     case 0x47de0410:            /* bis $30,$30,$16 */
  52     case 0x47fe0410:            /* bis $31,$30,$16 */
  53       return 0;
  54
  55     case 0x43ecf400:            /* addq $31,103,$0 */
  56     case 0x201f0067:            /* lda $0,103($31) */
  57     case 0x201f015f:            /* lda $0,351($31) */
  58       return 4;
  59
  60     case 0x00000083:            /* call_pal callsys */
  61       return 8;
  62
  63     default:
  64       return -1;
  65     }
  66 }
  67
  68 static LONGEST
  69 alpha_linux_sigtramp_offset (CORE_ADDR pc)
  70 {
  71   long i, off;
  72
  73   if (pc & 3)
  74     return -1;
  75
  76   /* Guess where we might be in the sequence.  */
  77   off = alpha_linux_sigtramp_offset_1 (pc);
  78   if (off < 0)
  79     return -1;
  80
  81   /* Verify that the other two insns of the sequence are as we expect.  */
  82   pc -= off;
  83   for (i = 0; i < 12; i += 4)
  84     {
  85       if (i == off)
  86         continue;
  87       if (alpha_linux_sigtramp_offset_1 (pc + i) != i)
  88         return -1;
  89     }
  90
  91   return off;
  92 }
  93
  94 static int
  95 alpha_linux_pc_in_sigtramp (CORE_ADDR pc, char *func_name)
  96 {
  97   return alpha_linux_sigtramp_offset (pc) >= 0;
  98 }
  99
 100 static CORE_ADDR
 101 alpha_linux_sigcontext_addr (struct frame_info *this_frame)
 102 {
 103   CORE_ADDR pc;
 104   ULONGEST sp;
 105   long off;
 106
 107   pc = get_frame_pc (this_frame);
 108   sp = get_frame_register_unsigned (this_frame, ALPHA_SP_REGNUM);
 109
 110   off = alpha_linux_sigtramp_offset (pc);
 111   gdb_assert (off >= 0);
 112
 113   /* __NR_rt_sigreturn has a couple of structures on the stack.  This is:
 114
 115         struct rt_sigframe {
 116           struct siginfo info;
 117           struct ucontext uc;
 118         };
 119
 120         offsetof (struct rt_sigframe, uc.uc_mcontext);
 121   */
 122   if (alpha_read_insn (pc - off + 4) == 0x201f015f)
 123     return sp + 176;
 124
 125   /* __NR_sigreturn has the sigcontext structure at the top of the stack.  */
 126   return sp;
 127 }
 128
 129 /* Supply register REGNUM from the buffer specified by GREGS and LEN
 130    in the general-purpose register set REGSET to register cache
 131    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
 132
 133 static void
 134 alpha_linux_supply_gregset (const struct regset *regset,
 135                             struct regcache *regcache,
 136                             int regnum, const void *gregs, size_t len)
 137 {
 138   const gdb_byte *regs = gregs;
 139   int i;
 140   gdb_assert (len >= 32 * 8);
 141
 142   for (i = 0; i < ALPHA_ZERO_REGNUM; i++)
 143     {
 144       if (regnum == i || regnum == -1)
 145         regcache_raw_supply (regcache, i, regs + i * 8);
 146     }
 147
 148   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
 149     regcache_raw_supply (regcache, ALPHA_PC_REGNUM, regs + 31 * 8);
 150
 151   if (regnum == ALPHA_UNIQUE_REGNUM || regnum == -1)
 152     regcache_raw_supply (regcache, ALPHA_UNIQUE_REGNUM,
 153                          len >= 33 * 8 ? regs + 32 * 8 : NULL);
 154 }
 155
 156 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
 157    in the floating-point register set REGSET to register cache
 158    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
 159
 160 static void
 161 alpha_linux_supply_fpregset (const struct regset *regset,
 162                              struct regcache *regcache,
 163                              int regnum, const void *fpregs, size_t len)
 164 {
 165   const gdb_byte *regs = fpregs;
 166   int i;
 167   gdb_assert (len >= 32 * 8);
 168
 169   for (i = ALPHA_FP0_REGNUM; i < ALPHA_FP0_REGNUM + 31; i++)
 170     {
 171       if (regnum == i || regnum == -1)
 172         regcache_raw_supply (regcache, i, regs + (i - ALPHA_FP0_REGNUM) * 8);
 173     }
 174
 175   if (regnum == ALPHA_FPCR_REGNUM || regnum == -1)
 176     regcache_raw_supply (regcache, ALPHA_FPCR_REGNUM, regs + 31 * 8);
 177 }
 178
 179 static struct regset alpha_linux_gregset =
 180 {
 181   NULL,
 182   alpha_linux_supply_gregset
 183 };
 184
 185 static struct regset alpha_linux_fpregset =
 186 {
 187   NULL,
 188   alpha_linux_supply_fpregset
 189 };
 190
 191 /* Return the appropriate register set for the core section identified
 192    by SECT_NAME and SECT_SIZE.  */
 193
 194 static const struct regset *
 195 alpha_linux_regset_from_core_section (struct gdbarch *gdbarch,
 196                                       const char *sect_name, size_t sect_size)
 197 {
 198   if (strcmp (sect_name, ".reg") == 0 && sect_size >= 32 * 8)
 199     return &alpha_linux_gregset;
 200
 201   if (strcmp (sect_name, ".reg2") == 0 && sect_size >= 32 * 8)
 202     return &alpha_linux_fpregset;
 203
 204   return NULL;
 205 }
 206
 207 static void
 208 alpha_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 209 {
 210   struct gdbarch_tdep *tdep;
 211
 212   /* Hook into the DWARF CFI frame unwinder.  */
 213   alpha_dwarf2_init_abi (info, gdbarch);
 214
 215   /* Hook into the MDEBUG frame unwinder.  */
 216   alpha_mdebug_init_abi (info, gdbarch);
 217
 218   tdep = gdbarch_tdep (gdbarch);
 219   tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset;
 220   tdep->sigcontext_addr = alpha_linux_sigcontext_addr;
 221   tdep->pc_in_sigtramp = alpha_linux_pc_in_sigtramp;
 222   tdep->jb_pc = 2;
 223   tdep->jb_elt_size = 8;
 224
 225   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 226
 227   set_solib_svr4_fetch_link_map_offsets
 228     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 229
 230   /* Enable TLS support.  */
 231   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 232                                              svr4_fetch_objfile_link_map);
 233
 234   set_gdbarch_regset_from_core_section
 235     (gdbarch, alpha_linux_regset_from_core_section);
 236 }
 237
 238 /* Provide a prototype to silence -Wmissing-prototypes.  */
 239 extern initialize_file_ftype _initialize_alpha_linux_tdep;
 240
 241 void
 242 _initialize_alpha_linux_tdep (void)
 243 {
 244   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_LINUX,
 245                           alpha_linux_init_abi);
 246 }