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