gdb/sparc-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux SPARC.
   2
   3    Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009, 2010
   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           struct gdbarch *gdbarch = get_frame_arch (frame);
 143           enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 144
 145           ULONGEST sp, pc_offset;
 146
 147           sp = get_frame_register_unsigned (frame, SPARC_SP_REGNUM);
 148
 149           /* The kernel puts the sigreturn registers on the stack,
 150              and this is where the signal unwinding state is take from
 151              when returning from a signal.
 152
 153              For __NR_sigreturn, this register area sits 96 bytes from
 154              the base of the stack.  The saved PC sits 4 bytes into the
 155              sigreturn register save area.
 156
 157              For __NR_rt_sigreturn a siginfo_t, which is 128 bytes, sits
 158              right before the sigreturn register save area.  */
 159
 160           pc_offset = 96 + 4;
 161           if (sc_num == 101)
 162             pc_offset += 128;
 163
 164           return read_memory_unsigned_integer (sp + pc_offset, 4, byte_order);
 165         }
 166     }
 167
 168   return 0;
 169 }
 170 \f
 171
 172 const struct sparc_gregset sparc32_linux_core_gregset =
 173 {
 174   32 * 4,                       /* %psr */
 175   33 * 4,                       /* %pc */
 176   34 * 4,                       /* %npc */
 177   35 * 4,                       /* %y */
 178   -1,                           /* %wim */
 179   -1,                           /* %tbr */
 180   1 * 4,                        /* %g1 */
 181   16 * 4,                       /* %l0 */
 182   4,                            /* y size */
 183 };
 184 \f
 185
 186 static void
 187 sparc32_linux_supply_core_gregset (const struct regset *regset,
 188                                    struct regcache *regcache,
 189                                    int regnum, const void *gregs, size_t len)
 190 {
 191   sparc32_supply_gregset (&sparc32_linux_core_gregset, regcache, regnum, gregs);
 192 }
 193
 194 static void
 195 sparc32_linux_collect_core_gregset (const struct regset *regset,
 196                                     const struct regcache *regcache,
 197                                     int regnum, void *gregs, size_t len)
 198 {
 199   sparc32_collect_gregset (&sparc32_linux_core_gregset, regcache, regnum, gregs);
 200 }
 201
 202 static void
 203 sparc32_linux_supply_core_fpregset (const struct regset *regset,
 204                                     struct regcache *regcache,
 205                                     int regnum, const void *fpregs, size_t len)
 206 {
 207   sparc32_supply_fpregset (regcache, regnum, fpregs);
 208 }
 209
 210 static void
 211 sparc32_linux_collect_core_fpregset (const struct regset *regset,
 212                                      const struct regcache *regcache,
 213                                      int regnum, void *fpregs, size_t len)
 214 {
 215   sparc32_collect_fpregset (regcache, regnum, fpregs);
 216 }
 217
 218 /* Set the program counter for process PTID to PC.  */
 219
 220 #define PSR_SYSCALL     0x00004000
 221
 222 static void
 223 sparc_linux_write_pc (struct regcache *regcache, CORE_ADDR pc)
 224 {
 225   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 226   ULONGEST psr;
 227
 228   regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
 229   regcache_cooked_write_unsigned (regcache, tdep->npc_regnum, pc + 4);
 230
 231   /* Clear the "in syscall" bit to prevent the kernel from
 232      messing with the PCs we just installed, if we happen to be
 233      within an interrupted system call that the kernel wants to
 234      restart.
 235
 236      Note that after we return from the dummy call, the PSR et al.
 237      registers will be automatically restored, and the kernel
 238      continues to restart the system call at this point.  */
 239   regcache_cooked_read_unsigned (regcache, SPARC32_PSR_REGNUM, &psr);
 240   psr &= ~PSR_SYSCALL;
 241   regcache_cooked_write_unsigned (regcache, SPARC32_PSR_REGNUM, psr);
 242 }
 243
 244 \f
 245
 246 static void
 247 sparc32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 248 {
 249   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 250
 251   tdep->gregset = regset_alloc (gdbarch, sparc32_linux_supply_core_gregset,
 252                                 sparc32_linux_collect_core_gregset);
 253   tdep->sizeof_gregset = 152;
 254
 255   tdep->fpregset = regset_alloc (gdbarch, sparc32_linux_supply_core_fpregset,
 256                                  sparc32_linux_collect_core_fpregset);
 257   tdep->sizeof_fpregset = 396;
 258
 259   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_sigframe);
 260   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_rt_sigframe);
 261
 262   /* GNU/Linux has SVR4-style shared libraries...  */
 263   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 264   set_solib_svr4_fetch_link_map_offsets
 265     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 266
 267   /* ...which means that we need some special handling when doing
 268      prologue analysis.  */
 269   tdep->plt_entry_size = 12;
 270
 271   /* Enable TLS support.  */
 272   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 273                                              svr4_fetch_objfile_link_map);
 274
 275   /* Make sure we can single-step over signal return system calls.  */
 276   tdep->step_trap = sparc32_linux_step_trap;
 277
 278   /* Hook in the DWARF CFI frame unwinder.  */
 279   dwarf2_append_unwinders (gdbarch);
 280
 281   set_gdbarch_write_pc (gdbarch, sparc_linux_write_pc);
 282 }
 283
 284 /* Provide a prototype to silence -Wmissing-prototypes.  */
 285 extern void _initialize_sparc_linux_tdep (void);
 286
 287 void
 288 _initialize_sparc_linux_tdep (void)
 289 {
 290   gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_LINUX,
 291                           sparc32_linux_init_abi);
 292 }