gdb/alpha-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux on Alpha.
   2    Copyright (C) 2002, 2003, 2007, 2008, 2009, 2010
   3    Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "frame.h"
  22 #include "gdb_assert.h"
  23 #include "gdb_string.h"
  24 #include "osabi.h"
  25 #include "solib-svr4.h"
  26 #include "symtab.h"
  27 #include "regset.h"
  28 #include "regcache.h"
  29 #include "linux-tdep.h"
  30 #include "alpha-tdep.h"
  31
  32 /* Under GNU/Linux, signal handler invocations can be identified by
  33    the designated code sequence that is used to return from a signal
  34    handler.  In particular, the return address of a signal handler
  35    points to a sequence that copies $sp to $16, loads $0 with the
  36    appropriate syscall number, and finally enters the kernel.
  37
  38    This is somewhat complicated in that:
  39      (1) the expansion of the "mov" assembler macro has changed over
  40          time, from "bis src,src,dst" to "bis zero,src,dst",
  41      (2) the kernel has changed from using "addq" to "lda" to load the
  42          syscall number,
  43      (3) there is a "normal" sigreturn and an "rt" sigreturn which
  44          has a different stack layout.
  45 */
  46
  47 static long
  48 alpha_linux_sigtramp_offset_1 (struct gdbarch *gdbarch, CORE_ADDR pc)
  49 {
  50   switch (alpha_read_insn (gdbarch, pc))
  51     {
  52     case 0x47de0410:            /* bis $30,$30,$16 */
  53     case 0x47fe0410:            /* bis $31,$30,$16 */
  54       return 0;
  55
  56     case 0x43ecf400:            /* addq $31,103,$0 */
  57     case 0x201f0067:            /* lda $0,103($31) */
  58     case 0x201f015f:            /* lda $0,351($31) */
  59       return 4;
  60
  61     case 0x00000083:            /* call_pal callsys */
  62       return 8;
  63
  64     default:
  65       return -1;
  66     }
  67 }
  68
  69 static LONGEST
  70 alpha_linux_sigtramp_offset (struct gdbarch *gdbarch, CORE_ADDR pc)
  71 {
  72   long i, off;
  73
  74   if (pc & 3)
  75     return -1;
  76
  77   /* Guess where we might be in the sequence.  */
  78   off = alpha_linux_sigtramp_offset_1 (gdbarch, pc);
  79   if (off < 0)
  80     return -1;
  81
  82   /* Verify that the other two insns of the sequence are as we expect.  */
  83   pc -= off;
  84   for (i = 0; i < 12; i += 4)
  85     {
  86       if (i == off)
  87         continue;
  88       if (alpha_linux_sigtramp_offset_1 (gdbarch, pc + i) != i)
  89         return -1;
  90     }
  91
  92   return off;
  93 }
  94
  95 static int
  96 alpha_linux_pc_in_sigtramp (struct gdbarch *gdbarch,
  97                             CORE_ADDR pc, char *func_name)
  98 {
  99   return alpha_linux_sigtramp_offset (gdbarch, pc) >= 0;
 100 }
 101
 102 static CORE_ADDR
 103 alpha_linux_sigcontext_addr (struct frame_info *this_frame)
 104 {
 105   struct gdbarch *gdbarch = get_frame_arch (this_frame);
 106   CORE_ADDR pc;
 107   ULONGEST sp;
 108   long off;
 109
 110   pc = get_frame_pc (this_frame);
 111   sp = get_frame_register_unsigned (this_frame, ALPHA_SP_REGNUM);
 112
 113   off = alpha_linux_sigtramp_offset (gdbarch, pc);
 114   gdb_assert (off >= 0);
 115
 116   /* __NR_rt_sigreturn has a couple of structures on the stack.  This is:
 117
 118         struct rt_sigframe {
 119           struct siginfo info;
 120           struct ucontext uc;
 121         };
 122
 123         offsetof (struct rt_sigframe, uc.uc_mcontext);
 124   */
 125   if (alpha_read_insn (gdbarch, pc - off + 4) == 0x201f015f)
 126     return sp + 176;
 127
 128   /* __NR_sigreturn has the sigcontext structure at the top of the stack.  */
 129   return sp;
 130 }
 131
 132 /* Supply register REGNUM from the buffer specified by GREGS and LEN
 133    in the general-purpose register set REGSET to register cache
 134    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
 135
 136 static void
 137 alpha_linux_supply_gregset (const struct regset *regset,
 138                             struct regcache *regcache,
 139                             int regnum, const void *gregs, size_t len)
 140 {
 141   const gdb_byte *regs = gregs;
 142   int i;
 143   gdb_assert (len >= 32 * 8);
 144
 145   for (i = 0; i < ALPHA_ZERO_REGNUM; i++)
 146     {
 147       if (regnum == i || regnum == -1)
 148         regcache_raw_supply (regcache, i, regs + i * 8);
 149     }
 150
 151   if (regnum == ALPHA_PC_REGNUM || regnum == -1)
 152     regcache_raw_supply (regcache, ALPHA_PC_REGNUM, regs + 31 * 8);
 153
 154   if (regnum == ALPHA_UNIQUE_REGNUM || regnum == -1)
 155     regcache_raw_supply (regcache, ALPHA_UNIQUE_REGNUM,
 156                          len >= 33 * 8 ? regs + 32 * 8 : NULL);
 157 }
 158
 159 /* Supply register REGNUM from the buffer specified by FPREGS and LEN
 160    in the floating-point register set REGSET to register cache
 161    REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
 162
 163 static void
 164 alpha_linux_supply_fpregset (const struct regset *regset,
 165                              struct regcache *regcache,
 166                              int regnum, const void *fpregs, size_t len)
 167 {
 168   const gdb_byte *regs = fpregs;
 169   int i;
 170   gdb_assert (len >= 32 * 8);
 171
 172   for (i = ALPHA_FP0_REGNUM; i < ALPHA_FP0_REGNUM + 31; i++)
 173     {
 174       if (regnum == i || regnum == -1)
 175         regcache_raw_supply (regcache, i, regs + (i - ALPHA_FP0_REGNUM) * 8);
 176     }
 177
 178   if (regnum == ALPHA_FPCR_REGNUM || regnum == -1)
 179     regcache_raw_supply (regcache, ALPHA_FPCR_REGNUM, regs + 31 * 8);
 180 }
 181
 182 static struct regset alpha_linux_gregset =
 183 {
 184   NULL,
 185   alpha_linux_supply_gregset
 186 };
 187
 188 static struct regset alpha_linux_fpregset =
 189 {
 190   NULL,
 191   alpha_linux_supply_fpregset
 192 };
 193
 194 /* Return the appropriate register set for the core section identified
 195    by SECT_NAME and SECT_SIZE.  */
 196
 197 static const struct regset *
 198 alpha_linux_regset_from_core_section (struct gdbarch *gdbarch,
 199                                       const char *sect_name, size_t sect_size)
 200 {
 201   if (strcmp (sect_name, ".reg") == 0 && sect_size >= 32 * 8)
 202     return &alpha_linux_gregset;
 203
 204   if (strcmp (sect_name, ".reg2") == 0 && sect_size >= 32 * 8)
 205     return &alpha_linux_fpregset;
 206
 207   return NULL;
 208 }
 209
 210 static void
 211 alpha_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 212 {
 213   struct gdbarch_tdep *tdep;
 214
 215   linux_init_abi (info, gdbarch);
 216
 217   /* Hook into the DWARF CFI frame unwinder.  */
 218   alpha_dwarf2_init_abi (info, gdbarch);
 219
 220   /* Hook into the MDEBUG frame unwinder.  */
 221   alpha_mdebug_init_abi (info, gdbarch);
 222
 223   tdep = gdbarch_tdep (gdbarch);
 224   tdep->dynamic_sigtramp_offset = alpha_linux_sigtramp_offset;
 225   tdep->sigcontext_addr = alpha_linux_sigcontext_addr;
 226   tdep->pc_in_sigtramp = alpha_linux_pc_in_sigtramp;
 227   tdep->jb_pc = 2;
 228   tdep->jb_elt_size = 8;
 229
 230   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 231
 232   set_solib_svr4_fetch_link_map_offsets
 233     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 234
 235   /* Enable TLS support.  */
 236   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 237                                              svr4_fetch_objfile_link_map);
 238
 239   set_gdbarch_regset_from_core_section
 240     (gdbarch, alpha_linux_regset_from_core_section);
 241 }
 242
 243 /* Provide a prototype to silence -Wmissing-prototypes.  */
 244 extern initialize_file_ftype _initialize_alpha_linux_tdep;
 245
 246 void
 247 _initialize_alpha_linux_tdep (void)
 248 {
 249   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_LINUX,
 250                           alpha_linux_init_abi);
 251 }