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/* Target-dependent code for GNU/Linux m32r.

   Copyright (C) 2004, 2007, 2008 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "gdbcore.h"

#include "frame.h"

#include "value.h"

#include "regcache.h"

#include "inferior.h"

#include "osabi.h"

#include "reggroups.h"

#include "regset.h"

#include "gdb_string.h"

#include "glibc-tdep.h"

#include "solib-svr4.h"

#include "symtab.h"

#include "trad-frame.h"

#include "frame-unwind.h"

#include "m32r-tdep.h"

/* Recognizing signal handler frames.  */

/* GNU/Linux has two flavors of signals.  Normal signal handlers, and

   "realtime" (RT) signals.  The RT signals can provide additional

   information to the signal handler if the SA_SIGINFO flag is set

   when establishing a signal handler using `sigaction'.  It is not

   unlikely that future versions of GNU/Linux will support SA_SIGINFO

   for normal signals too.  */

/* When the m32r Linux kernel calls a signal handler and the

   SA_RESTORER flag isn't set, the return address points to a bit of

   code on the stack.  This function returns whether the PC appears to

   be within this bit of code.

   The instruction sequence for normal signals is

       ldi    r7, #__NR_sigreturn

       trap   #2

   or 0x67 0x77 0x10 0xf2.

   Checking for the code sequence should be somewhat reliable, because

   the effect is to call the system call sigreturn.  This is unlikely

   to occur anywhere other than in a signal trampoline.

   It kind of sucks that we have to read memory from the process in

   order to identify a signal trampoline, but there doesn't seem to be

   any other way.  Therefore we only do the memory reads if no

   function name could be identified, which should be the case since

   the code is on the stack.

   Detection of signal trampolines for handlers that set the

   SA_RESTORER flag is in general not possible.  Unfortunately this is

   what the GNU C Library has been doing for quite some time now.

   However, as of version 2.1.2, the GNU C Library uses signal

   trampolines (named __restore and __restore_rt) that are identical

   to the ones used by the kernel.  Therefore, these trampolines are

   supported too.  */

static const gdb_byte linux_sigtramp_code[] = {

  0x67, 0x77, 0x10, 0xf2,

};

/* If PC is in a sigtramp routine, return the address of the start of

   the routine.  Otherwise, return 0.  */

static CORE_ADDR

m32r_linux_sigtramp_start (CORE_ADDR pc, struct frame_info *next_frame)

{

  gdb_byte buf[4];

  /* We only recognize a signal trampoline if PC is at the start of

     one of the instructions.  We optimize for finding the PC at the

     start of the instruction sequence, as will be the case when the

     trampoline is not the first frame on the stack.  We assume that

     in the case where the PC is not at the start of the instruction

     sequence, there will be a few trailing readable bytes on the

     stack.  */

  if (pc % 2 != 0)

    {

      if (!safe_frame_unwind_memory (next_frame, pc, buf, 2))

        return 0;

      if (memcmp (buf, linux_sigtramp_code, 2) == 0)

        pc -= 2;

      else

        return 0;

    }

  if (!safe_frame_unwind_memory (next_frame, pc, buf, 4))

    return 0;

  if (memcmp (buf, linux_sigtramp_code, 4) != 0)

    return 0;

  return pc;

}

/* This function does the same for RT signals.  Here the instruction

   sequence is

       ldi    r7, #__NR_rt_sigreturn

       trap   #2

   or 0x97 0xf0 0x00 0xad 0x10 0xf2 0xf0 0x00.

   The effect is to call the system call rt_sigreturn.  */

static const gdb_byte linux_rt_sigtramp_code[] = {

  0x97, 0xf0, 0x00, 0xad, 0x10, 0xf2, 0xf0, 0x00,

};

/* If PC is in a RT sigtramp routine, return the address of the start

   of the routine.  Otherwise, return 0.  */

static CORE_ADDR

m32r_linux_rt_sigtramp_start (CORE_ADDR pc, struct frame_info *next_frame)

{

  gdb_byte buf[4];

  /* We only recognize a signal trampoline if PC is at the start of

     one of the instructions.  We optimize for finding the PC at the

     start of the instruction sequence, as will be the case when the

     trampoline is not the first frame on the stack.  We assume that

     in the case where the PC is not at the start of the instruction

     sequence, there will be a few trailing readable bytes on the

     stack.  */

  if (pc % 2 != 0)

    return 0;

  if (!safe_frame_unwind_memory (next_frame, pc, buf, 4))

    return 0;

  if (memcmp (buf, linux_rt_sigtramp_code, 4) == 0)

    {

      if (!safe_frame_unwind_memory (next_frame, pc + 4, buf, 4))

        return 0;

      if (memcmp (buf, linux_rt_sigtramp_code + 4, 4) == 0)

        return pc;

    }

  else if (memcmp (buf, linux_rt_sigtramp_code + 4, 4) == 0)

    {

      if (!safe_frame_unwind_memory (next_frame, pc - 4, buf, 4))

        return 0;

      if (memcmp (buf, linux_rt_sigtramp_code, 4) == 0)

        return pc - 4;

    }

  return 0;

}

static int

m32r_linux_pc_in_sigtramp (CORE_ADDR pc, char *name,

                           struct frame_info *next_frame)

{

  /* If we have NAME, we can optimize the search.  The trampolines are

     named __restore and __restore_rt.  However, they aren't dynamically

     exported from the shared C library, so the trampoline may appear to

     be part of the preceding function.  This should always be sigaction,

     __sigaction, or __libc_sigaction (all aliases to the same function).  */

  if (name == NULL || strstr (name, "sigaction") != NULL)

    return (m32r_linux_sigtramp_start (pc, next_frame) != 0

            || m32r_linux_rt_sigtramp_start (pc, next_frame) != 0);

  return (strcmp ("__restore", name) == 0

          || strcmp ("__restore_rt", name) == 0);

}

/* From <asm/sigcontext.h>.  */

static int m32r_linux_sc_reg_offset[] = {

  4 * 4,                        /* r0 */

  5 * 4,                        /* r1 */

  6 * 4,                        /* r2 */

  7 * 4,                        /* r3 */

  1 * 4,                        /* r5 */

  2 * 4,                        /* r6 */

  8 * 4,                        /* r7 */

  9 * 4,                        /* r8 */

  10 * 4,                       /* r9 */

  11 * 4,                       /* r10 */

  12 * 4,                       /* r11 */

  13 * 4,                       /* r12 */

  21 * 4,                       /* fp */

  22 * 4,                       /* lr */

  -1 * 4,                       /* sp */

  16 * 4,                       /* psw */

  -1 * 4,                       /* cbr */

  23 * 4,                       /* spi */

  20 * 4,                       /* spu */

  19 * 4,                       /* bpc */

  17 * 4,                       /* pc */

  15 * 4,                       /* accl */

  14 * 4                        /* acch */

};

struct m32r_frame_cache

{

  CORE_ADDR base, pc;

  struct trad_frame_saved_reg *saved_regs;

};

static struct m32r_frame_cache *

m32r_linux_sigtramp_frame_cache (struct frame_info *next_frame,

                                 void **this_cache)

{

  struct m32r_frame_cache *cache;

  CORE_ADDR sigcontext_addr, addr;

  int regnum;

  if ((*this_cache) != NULL)

    return (*this_cache);

  cache = FRAME_OBSTACK_ZALLOC (struct m32r_frame_cache);

  (*this_cache) = cache;

  cache->saved_regs = trad_frame_alloc_saved_regs (next_frame);

  cache->base = frame_unwind_register_unsigned (next_frame, M32R_SP_REGNUM);

  sigcontext_addr = cache->base + 4;

  cache->pc = frame_pc_unwind (next_frame);

  addr = m32r_linux_sigtramp_start (cache->pc, next_frame);

  if (addr == 0)

    {

      /* If this is a RT signal trampoline, adjust SIGCONTEXT_ADDR

         accordingly.  */

      addr = m32r_linux_rt_sigtramp_start (cache->pc, next_frame);

      if (addr)

        sigcontext_addr += 128;

      else

        addr = frame_func_unwind (next_frame, NORMAL_FRAME);

    }

  cache->pc = addr;

  cache->saved_regs = trad_frame_alloc_saved_regs (next_frame);

  for (regnum = 0; regnum < sizeof (m32r_linux_sc_reg_offset) / 4; regnum++)

    {

      if (m32r_linux_sc_reg_offset[regnum] >= 0)

        cache->saved_regs[regnum].addr =

          sigcontext_addr + m32r_linux_sc_reg_offset[regnum];

    }

  return cache;

}

static void

m32r_linux_sigtramp_frame_this_id (struct frame_info *next_frame,

                                   void **this_cache,

                                   struct frame_id *this_id)

{

  struct m32r_frame_cache *cache =

    m32r_linux_sigtramp_frame_cache (next_frame, this_cache);

  (*this_id) = frame_id_build (cache->base, cache->pc);

}

static void

m32r_linux_sigtramp_frame_prev_register (struct frame_info *next_frame,

                                         void **this_cache,

                                         int regnum, int *optimizedp,

                                         enum lval_type *lvalp,

                                         CORE_ADDR *addrp,

                                         int *realnump, gdb_byte *valuep)

{

  struct m32r_frame_cache *cache =

    m32r_linux_sigtramp_frame_cache (next_frame, this_cache);

  trad_frame_get_prev_register (next_frame, cache->saved_regs, regnum,

                                optimizedp, lvalp, addrp, realnump, valuep);

}

static const struct frame_unwind m32r_linux_sigtramp_frame_unwind = {

  SIGTRAMP_FRAME,

  m32r_linux_sigtramp_frame_this_id,

  m32r_linux_sigtramp_frame_prev_register

};

static const struct frame_unwind *

m32r_linux_sigtramp_frame_sniffer (struct frame_info *next_frame)

{

  CORE_ADDR pc = frame_pc_unwind (next_frame);

  char *name;

  find_pc_partial_function (pc, &name, NULL, NULL);

  if (m32r_linux_pc_in_sigtramp (pc, name, next_frame))

    return &m32r_linux_sigtramp_frame_unwind;

  return NULL;

}

/* Mapping between the registers in `struct pt_regs'

   format and GDB's register array layout.  */

static int m32r_pt_regs_offset[] = {

  4 * 4,                        /* r0 */

  4 * 5,                        /* r1 */

  4 * 6,                        /* r2 */

  4 * 7,                        /* r3 */

  4 * 0,                 /* r4 */

  4 * 1,                        /* r5 */

  4 * 2,                        /* r6 */

  4 * 8,                        /* r7 */

  4 * 9,                        /* r8 */

  4 * 10,                       /* r9 */

  4 * 11,                       /* r10 */

  4 * 12,                       /* r11 */

  4 * 13,                       /* r12 */

  4 * 24,                       /* fp */

  4 * 25,                       /* lr */

  4 * 23,                       /* sp */

  4 * 19,                       /* psw */

  4 * 19,                       /* cbr */

  4 * 26,                       /* spi */

  4 * 23,                       /* spu */

  4 * 22,                       /* bpc */

  4 * 20,                       /* pc */

  4 * 16,                       /* accl */

  4 * 15                        /* acch */

};

#define PSW_OFFSET (4 * 19)

#define BBPSW_OFFSET (4 * 21)

#define SPU_OFFSET (4 * 23)

#define SPI_OFFSET (4 * 26)

static void

m32r_linux_supply_gregset (const struct regset *regset,

                           struct regcache *regcache, int regnum,

                           const void *gregs, size_t size)

{

  const char *regs = gregs;

  unsigned long psw, bbpsw;

  int i;

  psw = *((unsigned long *) (regs + PSW_OFFSET));

  bbpsw = *((unsigned long *) (regs + BBPSW_OFFSET));

  for (i = 0; i < sizeof (m32r_pt_regs_offset) / 4; i++)

    {

      if (regnum != -1 && regnum != i)

        continue;

      switch (i)

        {

        case PSW_REGNUM:

          *((unsigned long *) (regs + m32r_pt_regs_offset[i])) =

            ((0x00c1 & bbpsw) << 8) | ((0xc100 & psw) >> 8);

          break;

        case CBR_REGNUM:

          *((unsigned long *) (regs + m32r_pt_regs_offset[i])) =

            ((psw >> 8) & 1);

          break;

        case M32R_SP_REGNUM:

          if (psw & 0x8000)

            *((unsigned long *) (regs + m32r_pt_regs_offset[i])) =

              *((unsigned long *) (regs + SPU_OFFSET));

          else

            *((unsigned long *) (regs + m32r_pt_regs_offset[i])) =

              *((unsigned long *) (regs + SPI_OFFSET));

          break;

        }

      regcache_raw_supply (regcache, i,

                           regs + m32r_pt_regs_offset[i]);

    }

}

static struct regset m32r_linux_gregset = {

  NULL, m32r_linux_supply_gregset

};

static const struct regset *

m32r_linux_regset_from_core_section (struct gdbarch *core_arch,

                                     const char *sect_name, size_t sect_size)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (core_arch);

  if (strcmp (sect_name, ".reg") == 0)

    return &m32r_linux_gregset;

  return NULL;

}

static void

m32r_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* Since EVB register is not available for native debug, we reduce

     the number of registers.  */

  set_gdbarch_num_regs (gdbarch, M32R_NUM_REGS - 1);

  frame_unwind_append_sniffer (gdbarch, m32r_linux_sigtramp_frame_sniffer);

  /* GNU/Linux uses SVR4-style shared libraries.  */

  set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);

  set_solib_svr4_fetch_link_map_offsets

    (gdbarch, svr4_ilp32_fetch_link_map_offsets);

  /* Core file support.  */

  set_gdbarch_regset_from_core_section

    (gdbarch, m32r_linux_regset_from_core_section);

  /* Enable TLS support.  */

  set_gdbarch_fetch_tls_load_module_address (gdbarch,

                                             svr4_fetch_objfile_link_map);

}

/* Provide a prototype to silence -Wmissing-prototypes.  */

extern void _initialize_m32r_linux_tdep (void);

void

_initialize_m32r_linux_tdep (void)

{

  gdbarch_register_osabi (bfd_arch_m32r, 0, GDB_OSABI_LINUX,

                          m32r_linux_init_abi);

}