gdb/sparc-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux SPARC.
   2
   3    Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011
   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 #include "xml-syscall.h"
  36 #include "linux-tdep.h"
  37
  38 /* The syscall's XML filename for sparc 32-bit.  */
  39 #define XML_SYSCALL_FILENAME_SPARC32 "syscalls/sparc-linux.xml"
  40
  41 #include "sparc-tdep.h"
  42
  43 /* Signal trampoline support.  */
  44
  45 static void sparc32_linux_sigframe_init (const struct tramp_frame *self,
  46                                          struct frame_info *this_frame,
  47                                          struct trad_frame_cache *this_cache,
  48                                          CORE_ADDR func);
  49
  50 /* GNU/Linux has two flavors of signals.  Normal signal handlers, and
  51    "realtime" (RT) signals.  The RT signals can provide additional
  52    information to the signal handler if the SA_SIGINFO flag is set
  53    when establishing a signal handler using `sigaction'.  It is not
  54    unlikely that future versions of GNU/Linux will support SA_SIGINFO
  55    for normal signals too.  */
  56
  57 /* When the sparc Linux kernel calls a signal handler and the
  58    SA_RESTORER flag isn't set, the return address points to a bit of
  59    code on the stack.  This code checks whether the PC appears to be
  60    within this bit of code.
  61
  62    The instruction sequence for normal signals is encoded below.
  63    Checking for the code sequence should be somewhat reliable, because
  64    the effect is to call the system call sigreturn.  This is unlikely
  65    to occur anywhere other than a signal trampoline.  */
  66
  67 static const struct tramp_frame sparc32_linux_sigframe =
  68 {
  69   SIGTRAMP_FRAME,
  70   4,
  71   {
  72     { 0x821020d8, -1 },         /* mov __NR_sugreturn, %g1 */
  73     { 0x91d02010, -1 },         /* ta  0x10 */
  74     { TRAMP_SENTINEL_INSN, -1 }
  75   },
  76   sparc32_linux_sigframe_init
  77 };
  78
  79 /* The instruction sequence for RT signals is slightly different.  The
  80    effect is to call the system call rt_sigreturn.  */
  81
  82 static const struct tramp_frame sparc32_linux_rt_sigframe =
  83 {
  84   SIGTRAMP_FRAME,
  85   4,
  86   {
  87     { 0x82102065, -1 },         /* mov __NR_rt_sigreturn, %g1 */
  88     { 0x91d02010, -1 },         /* ta  0x10 */
  89     { TRAMP_SENTINEL_INSN, -1 }
  90   },
  91   sparc32_linux_sigframe_init
  92 };
  93
  94 static void
  95 sparc32_linux_sigframe_init (const struct tramp_frame *self,
  96                              struct frame_info *this_frame,
  97                              struct trad_frame_cache *this_cache,
  98                              CORE_ADDR func)
  99 {
 100   CORE_ADDR base, addr, sp_addr;
 101   int regnum;
 102
 103   base = get_frame_register_unsigned (this_frame, SPARC_O1_REGNUM);
 104   if (self == &sparc32_linux_rt_sigframe)
 105     base += 128;
 106
 107   /* Offsets from <bits/sigcontext.h>.  */
 108
 109   trad_frame_set_reg_addr (this_cache, SPARC32_PSR_REGNUM, base + 0);
 110   trad_frame_set_reg_addr (this_cache, SPARC32_PC_REGNUM, base + 4);
 111   trad_frame_set_reg_addr (this_cache, SPARC32_NPC_REGNUM, base + 8);
 112   trad_frame_set_reg_addr (this_cache, SPARC32_Y_REGNUM, base + 12);
 113
 114   /* Since %g0 is always zero, keep the identity encoding.  */
 115   addr = base + 20;
 116   sp_addr = base + 16 + ((SPARC_SP_REGNUM - SPARC_G0_REGNUM) * 4);
 117   for (regnum = SPARC_G1_REGNUM; regnum <= SPARC_O7_REGNUM; regnum++)
 118     {
 119       trad_frame_set_reg_addr (this_cache, regnum, addr);
 120       addr += 4;
 121     }
 122
 123   base = get_frame_register_unsigned (this_frame, SPARC_SP_REGNUM);
 124   addr = get_frame_memory_unsigned (this_frame, sp_addr, 4);
 125
 126   for (regnum = SPARC_L0_REGNUM; regnum <= SPARC_I7_REGNUM; regnum++)
 127     {
 128       trad_frame_set_reg_addr (this_cache, regnum, addr);
 129       addr += 4;
 130     }
 131   trad_frame_set_id (this_cache, frame_id_build (base, func));
 132 }
 133 \f
 134 /* Return the address of a system call's alternative return
 135    address.  */
 136
 137 static CORE_ADDR
 138 sparc32_linux_step_trap (struct frame_info *frame, unsigned long insn)
 139 {
 140   if (insn == 0x91d02010)
 141     {
 142       ULONGEST sc_num = get_frame_register_unsigned (frame, SPARC_G1_REGNUM);
 143
 144       /* __NR_rt_sigreturn is 101 and __NR_sigreturn is 216  */
 145       if (sc_num == 101 || sc_num == 216)
 146         {
 147           struct gdbarch *gdbarch = get_frame_arch (frame);
 148           enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 149
 150           ULONGEST sp, pc_offset;
 151
 152           sp = get_frame_register_unsigned (frame, SPARC_SP_REGNUM);
 153
 154           /* The kernel puts the sigreturn registers on the stack,
 155              and this is where the signal unwinding state is take from
 156              when returning from a signal.
 157
 158              For __NR_sigreturn, this register area sits 96 bytes from
 159              the base of the stack.  The saved PC sits 4 bytes into the
 160              sigreturn register save area.
 161
 162              For __NR_rt_sigreturn a siginfo_t, which is 128 bytes, sits
 163              right before the sigreturn register save area.  */
 164
 165           pc_offset = 96 + 4;
 166           if (sc_num == 101)
 167             pc_offset += 128;
 168
 169           return read_memory_unsigned_integer (sp + pc_offset, 4, byte_order);
 170         }
 171     }
 172
 173   return 0;
 174 }
 175 \f
 176
 177 const struct sparc_gregset sparc32_linux_core_gregset =
 178 {
 179   32 * 4,                       /* %psr */
 180   33 * 4,                       /* %pc */
 181   34 * 4,                       /* %npc */
 182   35 * 4,                       /* %y */
 183   -1,                           /* %wim */
 184   -1,                           /* %tbr */
 185   1 * 4,                        /* %g1 */
 186   16 * 4,                       /* %l0 */
 187   4,                            /* y size */
 188 };
 189 \f
 190
 191 static void
 192 sparc32_linux_supply_core_gregset (const struct regset *regset,
 193                                    struct regcache *regcache,
 194                                    int regnum, const void *gregs, size_t len)
 195 {
 196   sparc32_supply_gregset (&sparc32_linux_core_gregset, regcache, regnum, gregs);
 197 }
 198
 199 static void
 200 sparc32_linux_collect_core_gregset (const struct regset *regset,
 201                                     const struct regcache *regcache,
 202                                     int regnum, void *gregs, size_t len)
 203 {
 204   sparc32_collect_gregset (&sparc32_linux_core_gregset, regcache, regnum, gregs);
 205 }
 206
 207 static void
 208 sparc32_linux_supply_core_fpregset (const struct regset *regset,
 209                                     struct regcache *regcache,
 210                                     int regnum, const void *fpregs, size_t len)
 211 {
 212   sparc32_supply_fpregset (regcache, regnum, fpregs);
 213 }
 214
 215 static void
 216 sparc32_linux_collect_core_fpregset (const struct regset *regset,
 217                                      const struct regcache *regcache,
 218                                      int regnum, void *fpregs, size_t len)
 219 {
 220   sparc32_collect_fpregset (regcache, regnum, fpregs);
 221 }
 222
 223 /* Set the program counter for process PTID to PC.  */
 224
 225 #define PSR_SYSCALL     0x00004000
 226
 227 static void
 228 sparc_linux_write_pc (struct regcache *regcache, CORE_ADDR pc)
 229 {
 230   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 231   ULONGEST psr;
 232
 233   regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
 234   regcache_cooked_write_unsigned (regcache, tdep->npc_regnum, pc + 4);
 235
 236   /* Clear the "in syscall" bit to prevent the kernel from
 237      messing with the PCs we just installed, if we happen to be
 238      within an interrupted system call that the kernel wants to
 239      restart.
 240
 241      Note that after we return from the dummy call, the PSR et al.
 242      registers will be automatically restored, and the kernel
 243      continues to restart the system call at this point.  */
 244   regcache_cooked_read_unsigned (regcache, SPARC32_PSR_REGNUM, &psr);
 245   psr &= ~PSR_SYSCALL;
 246   regcache_cooked_write_unsigned (regcache, SPARC32_PSR_REGNUM, psr);
 247 }
 248
 249 static LONGEST
 250 sparc32_linux_get_syscall_number (struct gdbarch *gdbarch,
 251                                   ptid_t ptid)
 252 {
 253   struct regcache *regcache = get_thread_regcache (ptid);
 254   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 255   /* The content of a register.  */
 256   gdb_byte buf[4];
 257   /* The result.  */
 258   LONGEST ret;
 259
 260   /* Getting the system call number from the register.
 261      When dealing with the sparc architecture, this information
 262      is stored at the %g1 register.  */
 263   regcache_cooked_read (regcache, SPARC_G1_REGNUM, buf);
 264
 265   ret = extract_signed_integer (buf, 4, byte_order);
 266
 267   return ret;
 268 }
 269
 270 \f
 271
 272 static void
 273 sparc32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 274 {
 275   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 276
 277   linux_init_abi (info, gdbarch);
 278
 279   tdep->gregset = regset_alloc (gdbarch, sparc32_linux_supply_core_gregset,
 280                                 sparc32_linux_collect_core_gregset);
 281   tdep->sizeof_gregset = 152;
 282
 283   tdep->fpregset = regset_alloc (gdbarch, sparc32_linux_supply_core_fpregset,
 284                                  sparc32_linux_collect_core_fpregset);
 285   tdep->sizeof_fpregset = 396;
 286
 287   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_sigframe);
 288   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_rt_sigframe);
 289
 290   /* GNU/Linux has SVR4-style shared libraries...  */
 291   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 292   set_solib_svr4_fetch_link_map_offsets
 293     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 294
 295   /* ...which means that we need some special handling when doing
 296      prologue analysis.  */
 297   tdep->plt_entry_size = 12;
 298
 299   /* Enable TLS support.  */
 300   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 301                                              svr4_fetch_objfile_link_map);
 302
 303   /* Make sure we can single-step over signal return system calls.  */
 304   tdep->step_trap = sparc32_linux_step_trap;
 305
 306   /* Hook in the DWARF CFI frame unwinder.  */
 307   dwarf2_append_unwinders (gdbarch);
 308
 309   set_gdbarch_write_pc (gdbarch, sparc_linux_write_pc);
 310
 311   /* Functions for 'catch syscall'.  */
 312   set_xml_syscall_file_name (XML_SYSCALL_FILENAME_SPARC32);
 313   set_gdbarch_get_syscall_number (gdbarch,
 314                                   sparc32_linux_get_syscall_number);
 315 }
 316
 317 /* Provide a prototype to silence -Wmissing-prototypes.  */
 318 extern void _initialize_sparc_linux_tdep (void);
 319
 320 void
 321 _initialize_sparc_linux_tdep (void)
 322 {
 323   gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_LINUX,
 324                           sparc32_linux_init_abi);
 325 }