gdb/sparc-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux SPARC.
   2
   3    Copyright (C) 2003-2005, 2007-2012 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "dwarf2-frame.h"
  22 #include "frame.h"
  23 #include "frame-unwind.h"
  24 #include "gdbtypes.h"
  25 #include "regset.h"
  26 #include "gdbarch.h"
  27 #include "gdbcore.h"
  28 #include "osabi.h"
  29 #include "regcache.h"
  30 #include "solib-svr4.h"
  31 #include "symtab.h"
  32 #include "trad-frame.h"
  33 #include "tramp-frame.h"
  34 #include "xml-syscall.h"
  35 #include "linux-tdep.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,
 196                           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,
 205                            regcache, regnum, gregs);
 206 }
 207
 208 static void
 209 sparc32_linux_supply_core_fpregset (const struct regset *regset,
 210                                     struct regcache *regcache,
 211                                     int regnum, const void *fpregs, size_t len)
 212 {
 213   sparc32_supply_fpregset (regcache, regnum, fpregs);
 214 }
 215
 216 static void
 217 sparc32_linux_collect_core_fpregset (const struct regset *regset,
 218                                      const struct regcache *regcache,
 219                                      int regnum, void *fpregs, size_t len)
 220 {
 221   sparc32_collect_fpregset (regcache, regnum, fpregs);
 222 }
 223
 224 /* Set the program counter for process PTID to PC.  */
 225
 226 #define PSR_SYSCALL     0x00004000
 227
 228 static void
 229 sparc_linux_write_pc (struct regcache *regcache, CORE_ADDR pc)
 230 {
 231   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 232   ULONGEST psr;
 233
 234   regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
 235   regcache_cooked_write_unsigned (regcache, tdep->npc_regnum, pc + 4);
 236
 237   /* Clear the "in syscall" bit to prevent the kernel from
 238      messing with the PCs we just installed, if we happen to be
 239      within an interrupted system call that the kernel wants to
 240      restart.
 241
 242      Note that after we return from the dummy call, the PSR et al.
 243      registers will be automatically restored, and the kernel
 244      continues to restart the system call at this point.  */
 245   regcache_cooked_read_unsigned (regcache, SPARC32_PSR_REGNUM, &psr);
 246   psr &= ~PSR_SYSCALL;
 247   regcache_cooked_write_unsigned (regcache, SPARC32_PSR_REGNUM, psr);
 248 }
 249
 250 static LONGEST
 251 sparc32_linux_get_syscall_number (struct gdbarch *gdbarch,
 252                                   ptid_t ptid)
 253 {
 254   struct regcache *regcache = get_thread_regcache (ptid);
 255   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 256   /* The content of a register.  */
 257   gdb_byte buf[4];
 258   /* The result.  */
 259   LONGEST ret;
 260
 261   /* Getting the system call number from the register.
 262      When dealing with the sparc architecture, this information
 263      is stored at the %g1 register.  */
 264   regcache_cooked_read (regcache, SPARC_G1_REGNUM, buf);
 265
 266   ret = extract_signed_integer (buf, 4, byte_order);
 267
 268   return ret;
 269 }
 270
 271 \f
 272
 273 static void
 274 sparc32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 275 {
 276   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 277
 278   linux_init_abi (info, gdbarch);
 279
 280   tdep->gregset = regset_alloc (gdbarch, sparc32_linux_supply_core_gregset,
 281                                 sparc32_linux_collect_core_gregset);
 282   tdep->sizeof_gregset = 152;
 283
 284   tdep->fpregset = regset_alloc (gdbarch, sparc32_linux_supply_core_fpregset,
 285                                  sparc32_linux_collect_core_fpregset);
 286   tdep->sizeof_fpregset = 396;
 287
 288   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_sigframe);
 289   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_rt_sigframe);
 290
 291   /* GNU/Linux has SVR4-style shared libraries...  */
 292   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 293   set_solib_svr4_fetch_link_map_offsets
 294     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 295
 296   /* ...which means that we need some special handling when doing
 297      prologue analysis.  */
 298   tdep->plt_entry_size = 12;
 299
 300   /* Enable TLS support.  */
 301   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 302                                              svr4_fetch_objfile_link_map);
 303
 304   /* Make sure we can single-step over signal return system calls.  */
 305   tdep->step_trap = sparc32_linux_step_trap;
 306
 307   /* Hook in the DWARF CFI frame unwinder.  */
 308   dwarf2_append_unwinders (gdbarch);
 309
 310   set_gdbarch_write_pc (gdbarch, sparc_linux_write_pc);
 311
 312   /* Functions for 'catch syscall'.  */
 313   set_xml_syscall_file_name (XML_SYSCALL_FILENAME_SPARC32);
 314   set_gdbarch_get_syscall_number (gdbarch,
 315                                   sparc32_linux_get_syscall_number);
 316 }
 317
 318 /* Provide a prototype to silence -Wmissing-prototypes.  */
 319 extern void _initialize_sparc_linux_tdep (void);
 320
 321 void
 322 _initialize_sparc_linux_tdep (void)
 323 {
 324   gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_LINUX,
 325                           sparc32_linux_init_abi);
 326 }