gdb/sparc-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux SPARC.
   2
   3    Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009
   4    Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "dwarf2-frame.h"
  23 #include "frame.h"
  24 #include "frame-unwind.h"
  25 #include "gdbtypes.h"
  26 #include "regset.h"
  27 #include "gdbarch.h"
  28 #include "gdbcore.h"
  29 #include "osabi.h"
  30 #include "regcache.h"
  31 #include "solib-svr4.h"
  32 #include "symtab.h"
  33 #include "trad-frame.h"
  34 #include "tramp-frame.h"
  35
  36 #include "sparc-tdep.h"
  37
  38 /* Signal trampoline support.  */
  39
  40 static void sparc32_linux_sigframe_init (const struct tramp_frame *self,
  41                                          struct frame_info *this_frame,
  42                                          struct trad_frame_cache *this_cache,
  43                                          CORE_ADDR func);
  44
  45 /* GNU/Linux has two flavors of signals.  Normal signal handlers, and
  46    "realtime" (RT) signals.  The RT signals can provide additional
  47    information to the signal handler if the SA_SIGINFO flag is set
  48    when establishing a signal handler using `sigaction'.  It is not
  49    unlikely that future versions of GNU/Linux will support SA_SIGINFO
  50    for normal signals too.  */
  51
  52 /* When the sparc Linux kernel calls a signal handler and the
  53    SA_RESTORER flag isn't set, the return address points to a bit of
  54    code on the stack.  This code checks whether the PC appears to be
  55    within this bit of code.
  56
  57    The instruction sequence for normal signals is encoded below.
  58    Checking for the code sequence should be somewhat reliable, because
  59    the effect is to call the system call sigreturn.  This is unlikely
  60    to occur anywhere other than a signal trampoline.  */
  61
  62 static const struct tramp_frame sparc32_linux_sigframe =
  63 {
  64   SIGTRAMP_FRAME,
  65   4,
  66   {
  67     { 0x821020d8, -1 },         /* mov __NR_sugreturn, %g1 */
  68     { 0x91d02010, -1 },         /* ta  0x10 */
  69     { TRAMP_SENTINEL_INSN, -1 }
  70   },
  71   sparc32_linux_sigframe_init
  72 };
  73
  74 /* The instruction sequence for RT signals is slightly different.  The
  75    effect is to call the system call rt_sigreturn.  */
  76
  77 static const struct tramp_frame sparc32_linux_rt_sigframe =
  78 {
  79   SIGTRAMP_FRAME,
  80   4,
  81   {
  82     { 0x82102065, -1 },         /* mov __NR_rt_sigreturn, %g1 */
  83     { 0x91d02010, -1 },         /* ta  0x10 */
  84     { TRAMP_SENTINEL_INSN, -1 }
  85   },
  86   sparc32_linux_sigframe_init
  87 };
  88
  89 static void
  90 sparc32_linux_sigframe_init (const struct tramp_frame *self,
  91                              struct frame_info *this_frame,
  92                              struct trad_frame_cache *this_cache,
  93                              CORE_ADDR func)
  94 {
  95   CORE_ADDR base, addr, sp_addr;
  96   int regnum;
  97
  98   base = get_frame_register_unsigned (this_frame, SPARC_O1_REGNUM);
  99   if (self == &sparc32_linux_rt_sigframe)
 100     base += 128;
 101
 102   /* Offsets from <bits/sigcontext.h>.  */
 103
 104   trad_frame_set_reg_addr (this_cache, SPARC32_PSR_REGNUM, base + 0);
 105   trad_frame_set_reg_addr (this_cache, SPARC32_PC_REGNUM, base + 4);
 106   trad_frame_set_reg_addr (this_cache, SPARC32_NPC_REGNUM, base + 8);
 107   trad_frame_set_reg_addr (this_cache, SPARC32_Y_REGNUM, base + 12);
 108
 109   /* Since %g0 is always zero, keep the identity encoding.  */
 110   addr = base + 20;
 111   sp_addr = base + 16 + ((SPARC_SP_REGNUM - SPARC_G0_REGNUM) * 4);
 112   for (regnum = SPARC_G1_REGNUM; regnum <= SPARC_O7_REGNUM; regnum++)
 113     {
 114       trad_frame_set_reg_addr (this_cache, regnum, addr);
 115       addr += 4;
 116     }
 117
 118   base = get_frame_register_unsigned (this_frame, SPARC_SP_REGNUM);
 119   addr = get_frame_memory_unsigned (this_frame, sp_addr, 4);
 120
 121   for (regnum = SPARC_L0_REGNUM; regnum <= SPARC_I7_REGNUM; regnum++)
 122     {
 123       trad_frame_set_reg_addr (this_cache, regnum, addr);
 124       addr += 4;
 125     }
 126   trad_frame_set_id (this_cache, frame_id_build (base, func));
 127 }
 128 \f
 129 /* Return the address of a system call's alternative return
 130    address.  */
 131
 132 static CORE_ADDR
 133 sparc32_linux_step_trap (struct frame_info *frame, unsigned long insn)
 134 {
 135   if (insn == 0x91d02010)
 136     {
 137       ULONGEST sc_num = get_frame_register_unsigned (frame, SPARC_G1_REGNUM);
 138
 139       /* __NR_rt_sigreturn is 101 and __NR_sigreturn is 216  */
 140       if (sc_num == 101 || sc_num == 216)
 141         {
 142           ULONGEST sp, pc_offset;
 143
 144           sp = get_frame_register_unsigned (frame, SPARC_SP_REGNUM);
 145
 146           /* The kernel puts the sigreturn registers on the stack,
 147              and this is where the signal unwinding state is take from
 148              when returning from a signal.
 149
 150              For __NR_sigreturn, this register area sits 96 bytes from
 151              the base of the stack.  The saved PC sits 4 bytes into the
 152              sigreturn register save area.
 153
 154              For __NR_rt_sigreturn a siginfo_t, which is 128 bytes, sits
 155              right before the sigreturn register save area.  */
 156
 157           pc_offset = 96 + 4;
 158           if (sc_num == 101)
 159             pc_offset += 128;
 160
 161           return read_memory_unsigned_integer (sp + pc_offset, 4);
 162         }
 163     }
 164
 165   return 0;
 166 }
 167 \f
 168
 169 const struct sparc_gregset sparc32_linux_core_gregset =
 170 {
 171   32 * 4,                       /* %psr */
 172   33 * 4,                       /* %pc */
 173   34 * 4,                       /* %npc */
 174   35 * 4,                       /* %y */
 175   -1,                           /* %wim */
 176   -1,                           /* %tbr */
 177   1 * 4,                        /* %g1 */
 178   16 * 4,                       /* %l0 */
 179   4,                            /* y size */
 180 };
 181 \f
 182
 183 static void
 184 sparc32_linux_supply_core_gregset (const struct regset *regset,
 185                                    struct regcache *regcache,
 186                                    int regnum, const void *gregs, size_t len)
 187 {
 188   sparc32_supply_gregset (&sparc32_linux_core_gregset, regcache, regnum, gregs);
 189 }
 190
 191 static void
 192 sparc32_linux_collect_core_gregset (const struct regset *regset,
 193                                     const struct regcache *regcache,
 194                                     int regnum, void *gregs, size_t len)
 195 {
 196   sparc32_collect_gregset (&sparc32_linux_core_gregset, regcache, regnum, gregs);
 197 }
 198
 199 static void
 200 sparc32_linux_supply_core_fpregset (const struct regset *regset,
 201                                     struct regcache *regcache,
 202                                     int regnum, const void *fpregs, size_t len)
 203 {
 204   sparc32_supply_fpregset (regcache, regnum, fpregs);
 205 }
 206
 207 static void
 208 sparc32_linux_collect_core_fpregset (const struct regset *regset,
 209                                      const struct regcache *regcache,
 210                                      int regnum, void *fpregs, size_t len)
 211 {
 212   sparc32_collect_fpregset (regcache, regnum, fpregs);
 213 }
 214
 215 /* Set the program counter for process PTID to PC.  */
 216
 217 #define PSR_SYSCALL     0x00004000
 218
 219 static void
 220 sparc_linux_write_pc (struct regcache *regcache, CORE_ADDR pc)
 221 {
 222   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 223   ULONGEST psr;
 224
 225   regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
 226   regcache_cooked_write_unsigned (regcache, tdep->npc_regnum, pc + 4);
 227
 228   /* Clear the "in syscall" bit to prevent the kernel from
 229      messing with the PCs we just installed, if we happen to be
 230      within an interrupted system call that the kernel wants to
 231      restart.
 232
 233      Note that after we return from the dummy call, the PSR et al.
 234      registers will be automatically restored, and the kernel
 235      continues to restart the system call at this point.  */
 236   regcache_cooked_read_unsigned (regcache, SPARC32_PSR_REGNUM, &psr);
 237   psr &= ~PSR_SYSCALL;
 238   regcache_cooked_write_unsigned (regcache, SPARC32_PSR_REGNUM, psr);
 239 }
 240
 241 \f
 242
 243 static void
 244 sparc32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 245 {
 246   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 247
 248   tdep->gregset = regset_alloc (gdbarch, sparc32_linux_supply_core_gregset,
 249                                 sparc32_linux_collect_core_gregset);
 250   tdep->sizeof_gregset = 152;
 251
 252   tdep->fpregset = regset_alloc (gdbarch, sparc32_linux_supply_core_fpregset,
 253                                  sparc32_linux_collect_core_fpregset);
 254   tdep->sizeof_fpregset = 396;
 255
 256   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_sigframe);
 257   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_rt_sigframe);
 258
 259   /* GNU/Linux has SVR4-style shared libraries...  */
 260   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 261   set_solib_svr4_fetch_link_map_offsets
 262     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 263
 264   /* ...which means that we need some special handling when doing
 265      prologue analysis.  */
 266   tdep->plt_entry_size = 12;
 267
 268   /* Enable TLS support.  */
 269   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 270                                              svr4_fetch_objfile_link_map);
 271
 272   /* Make sure we can single-step over signal return system calls.  */
 273   tdep->step_trap = sparc32_linux_step_trap;
 274
 275   /* Hook in the DWARF CFI frame unwinder.  */
 276   dwarf2_append_unwinders (gdbarch);
 277
 278   set_gdbarch_write_pc (gdbarch, sparc_linux_write_pc);
 279 }
 280
 281 /* Provide a prototype to silence -Wmissing-prototypes.  */
 282 extern void _initialize_sparc_linux_tdep (void);
 283
 284 void
 285 _initialize_sparc_linux_tdep (void)
 286 {
 287   gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_LINUX,
 288                           sparc32_linux_init_abi);
 289 }