gdb/sparc-linux-tdep.c

   1 /* Target-dependent code for GNU/Linux SPARC.
   2
   3    Copyright 2003, 2004, 2005 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 2 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, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "floatformat.h"
  24 #include "frame.h"
  25 #include "frame-unwind.h"
  26 #include "tramp-frame.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
  35 #include "sparc-tdep.h"
  36
  37 /* Signal trampoline support.  */
  38
  39 /* GNU/Linux has two flavors of signals.  Normal signal handlers, and
  40    "realtime" (RT) signals.  The RT signals can provide additional
  41    information to the signal handler if the SA_SIGINFO flag is set
  42    when establishing a signal handler using `sigaction'.  It is not
  43    unlikely that future versions of GNU/Linux will support SA_SIGINFO
  44    for normal signals too.  */
  45
  46 /* When the sparc Linux kernel calls a signal handler and the
  47    SA_RESTORER flag isn't set, the return address points to a bit of
  48    code on the stack.  This function returns whether the PC appears to
  49    be within this bit of code.
  50
  51    The instruction sequence for normal signals is
  52         mov __NR_sigreturn, %g1         ! hex: 0x821020d8
  53         ta  0x10                        ! hex: 0x91d02010
  54
  55    Checking for the code sequence should be somewhat reliable, because
  56    the effect is to call the system call sigreturn.  This is unlikely
  57    to occur anywhere other than a signal trampoline.
  58
  59    It kind of sucks that we have to read memory from the process in
  60    order to identify a signal trampoline, but there doesn't seem to be
  61    any other way.  However, sparc32_linux_pc_in_sigtramp arranges to
  62    only call us if no function name could be identified, which should
  63    be the case since the code is on the stack.  */
  64
  65 #define LINUX32_SIGTRAMP_INSN0  0x821020d8      /* mov __NR_sigreturn, %g1 */
  66 #define LINUX32_SIGTRAMP_INSN1  0x91d02010      /* ta  0x10 */
  67
  68 /* The instruction sequence for RT signals is
  69        mov __NR_rt_sigreturn, %g1       ! hex: 0x82102065
  70        ta  {0x10,0x6d}                  ! hex: 0x91d02010
  71
  72    The effect is to call the system call rt_sigreturn.
  73    Note that 64-bit binaries only use this RT signal return method.  */
  74
  75 #define LINUX32_RT_SIGTRAMP_INSN0       0x82102065
  76 #define LINUX32_RT_SIGTRAMP_INSN1       0x91d02010
  77
  78 static void sparc32_linux_sigframe_init (const struct tramp_frame *self,
  79                                          struct frame_info *next_frame,
  80                                          struct trad_frame_cache *this_cache,
  81                                          CORE_ADDR func);
  82
  83 static const struct tramp_frame sparc32_linux_sigframe = {
  84   SIGTRAMP_FRAME,
  85   4,
  86   {
  87     { LINUX32_SIGTRAMP_INSN0, -1 },
  88     { LINUX32_SIGTRAMP_INSN1, -1 },
  89     { TRAMP_SENTINEL_INSN, -1 }
  90   },
  91   sparc32_linux_sigframe_init
  92 };
  93
  94 static const struct tramp_frame sparc32_linux_rt_sigframe = {
  95   SIGTRAMP_FRAME,
  96   4,
  97   {
  98     { LINUX32_RT_SIGTRAMP_INSN0, -1 },
  99     { LINUX32_RT_SIGTRAMP_INSN1, -1 },
 100     { TRAMP_SENTINEL_INSN, -1 }
 101   },
 102   sparc32_linux_sigframe_init
 103 };
 104
 105 static void
 106 sparc32_linux_sigframe_init (const struct tramp_frame *self,
 107                              struct frame_info *next_frame,
 108                              struct trad_frame_cache *this_cache,
 109                              CORE_ADDR func)
 110 {
 111   CORE_ADDR base, addr;
 112   int regnum;
 113
 114   base = frame_unwind_register_unsigned (next_frame, SPARC_O1_REGNUM);
 115   if (self == &sparc32_linux_rt_sigframe)
 116     base += 128;
 117
 118   /* Offsets from <bits/sigcontext.h> */
 119
 120   trad_frame_set_reg_addr (this_cache, SPARC32_PSR_REGNUM, base + 0x00);
 121   trad_frame_set_reg_addr (this_cache, SPARC32_PC_REGNUM,  base + 0x04);
 122   trad_frame_set_reg_addr (this_cache, SPARC32_NPC_REGNUM, base + 0x08);
 123   trad_frame_set_reg_addr (this_cache, SPARC32_Y_REGNUM,   base + 0x0c);
 124
 125   /* Since %g0 is always zero, keep the identity encoding.  */
 126   addr = base + 0x14;
 127   for (regnum = SPARC_G1_REGNUM; regnum <= SPARC_O7_REGNUM; regnum++)
 128     {
 129       trad_frame_set_reg_addr (this_cache, regnum, addr);
 130       addr += 4;
 131     }
 132
 133   base = addr = frame_unwind_register_unsigned (next_frame, SPARC_SP_REGNUM);
 134   for (regnum = SPARC_L0_REGNUM; regnum <= SPARC_I7_REGNUM; regnum++)
 135     {
 136       trad_frame_set_reg_addr (this_cache, regnum, addr);
 137       addr += 4;
 138     }
 139   trad_frame_set_id (this_cache, frame_id_build (base, func));
 140 }
 141
 142 \f
 143
 144 static void
 145 sparc32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 146 {
 147   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 148
 149   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_sigframe);
 150   tramp_frame_prepend_unwinder (gdbarch, &sparc32_linux_rt_sigframe);
 151
 152   /* GNU/Linux has SVR4-style shared libraries...  */
 153   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
 154   set_solib_svr4_fetch_link_map_offsets
 155     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
 156
 157   /* ...which means that we need some special handling when doing
 158      prologue analysis.  */
 159   tdep->plt_entry_size = 12;
 160
 161   /* GNU/Linux doesn't support the 128-bit `long double' from the psABI.  */
 162   set_gdbarch_long_double_bit (gdbarch, 64);
 163   set_gdbarch_long_double_format (gdbarch, &floatformat_ieee_double_big);
 164
 165   /* Enable TLS support.  */
 166   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 167                                              svr4_fetch_objfile_link_map);
 168 }
 169
 170 /* Provide a prototype to silence -Wmissing-prototypes.  */
 171 extern void _initialize_sparc_linux_tdep (void);
 172
 173 void
 174 _initialize_sparc_linux_tdep (void)
 175 {
 176   gdbarch_register_osabi (bfd_arch_sparc, 0, GDB_OSABI_LINUX,
 177                           sparc32_linux_init_abi);
 178 }