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,
 197                           regcache, regnum, gregs);
 198 }
 199
 200 static void
 201 sparc32_linux_collect_core_gregset (const struct regset *regset,
 202                                     const struct regcache *regcache,
 203                                     int regnum, void *gregs, size_t len)
 204 {
 205   sparc32_collect_gregset (&sparc32_linux_core_gregset,
 206                            regcache, regnum, gregs);
 207 }
 208
 209 static void
 210 sparc32_linux_supply_core_fpregset (const struct regset *regset,
 211                                     struct regcache *regcache,
 212                                     int regnum, const void *fpregs, size_t len)
 213 {
 214   sparc32_supply_fpregset (regcache, regnum, fpregs);
 215 }
 216
 217 static void
 218 sparc32_linux_collect_core_fpregset (const struct regset *regset,
 219                                      const struct regcache *regcache,
 220                                      int regnum, void *fpregs, size_t len)
 221 {
 222   sparc32_collect_fpregset (regcache, regnum, fpregs);
 223 }
 224
 225 /* Set the program counter for process PTID to PC.  */
 226
 227 #define PSR_SYSCALL     0x00004000
 228
 229 static void
 230 sparc_linux_write_pc (struct regcache *regcache, CORE_ADDR pc)
 231 {
 232   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 233   ULONGEST psr;
 234
 235   regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
 236   regcache_cooked_write_unsigned (regcache, tdep->npc_regnum, pc + 4);
 237
 238   /* Clear the "in syscall" bit to prevent the kernel from
 239      messing with the PCs we just installed, if we happen to be
 240      within an interrupted system call that the kernel wants to
 241      restart.
 242
 243      Note that after we return from the dummy call, the PSR et al.
 244      registers will be automatically restored, and the kernel
 245      continues to restart the system call at this point.  */
 246   regcache_cooked_read_unsigned (regcache, SPARC32_PSR_REGNUM, &psr);
 247   psr &= ~PSR_SYSCALL;
 248   regcache_cooked_write_unsigned (regcache, SPARC32_PSR_REGNUM, psr);
 249 }
 250
 251 static LONGEST
 252 sparc32_linux_get_syscall_number (struct gdbarch *gdbarch,
 253                                   ptid_t ptid)
 254 {
 255   struct regcache *regcache = get_thread_regcache (ptid);
 256   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 257   /* The content of a register.  */
 258   gdb_byte buf[4];
 259   /* The result.  */
 260   LONGEST ret;
 261
 262   /* Getting the system call number from the register.
 263      When dealing with the sparc architecture, this information
 264      is stored at the %g1 register.  */
 265   regcache_cooked_read (regcache, SPARC_G1_REGNUM, buf);
 266
 267   ret = extract_signed_integer (buf, 4, byte_order);
 268
 269   return ret;
 270 }
 271
 272 \f
 273
 274 static void
 275 sparc32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 276 {
 277   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 278
 279   linux_init_abi (info, gdbarch);
 280
 281   tdep->gregset = regset_alloc (gdbarch, sparc32_linux_supply_core_gregset,
 282                                 sparc32_linux_collect_core_gregset);
 283   tdep->sizeof_gregset = 152;
 284
 285   tdep->fpregset = regset_alloc (gdbarch, sparc32_linux_supply_core_fpregset,
 286                                  sparc32_linux_collect_core_fpregset);
 287   tdep->sizeof_fpregset = 396;
 288
 289   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_sigframe);
 290   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_rt_sigframe);
 291
 292   /* GNU/Linux has SVR4-style shared libraries...  */
 293   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 294   set_solib_svr4_fetch_link_map_offsets
 295     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 296
 297   /* ...which means that we need some special handling when doing
 298      prologue analysis.  */
 299   tdep->plt_entry_size = 12;
 300
 301   /* Enable TLS support.  */
 302   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 303                                              svr4_fetch_objfile_link_map);
 304
 305   /* Make sure we can single-step over signal return system calls.  */
 306   tdep->step_trap = sparc32_linux_step_trap;
 307
 308   /* Hook in the DWARF CFI frame unwinder.  */
 309   dwarf2_append_unwinders (gdbarch);
 310
 311   set_gdbarch_write_pc (gdbarch, sparc_linux_write_pc);
 312
 313   /* Functions for 'catch syscall'.  */
 314   set_xml_syscall_file_name (XML_SYSCALL_FILENAME_SPARC32);
 315   set_gdbarch_get_syscall_number (gdbarch,
 316                                   sparc32_linux_get_syscall_number);
 317 }
 318
 319 /* Provide a prototype to silence -Wmissing-prototypes.  */
 320 extern void _initialize_sparc_linux_tdep (void);
 321
 322 void
 323 _initialize_sparc_linux_tdep (void)
 324 {
 325   gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_LINUX,
 326                           sparc32_linux_init_abi);
 327 }