/tmp/gdb-8.1/gdb/i386-fbsd-tdep.c

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/* Target-dependent code for FreeBSD/i386.

   Copyright (C) 2003-2018 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 "arch-utils.h"
#include "gdbcore.h"
#include "osabi.h"
#include "regcache.h"
#include "regset.h"
#include "i386-fbsd-tdep.h"
#include "x86-xstate.h"

#include "i386-tdep.h"
#include "i387-tdep.h"
#include "fbsd-tdep.h"
#include "solib-svr4.h"

/* Support for signal handlers.  */

/* Return whether THIS_FRAME corresponds to a FreeBSD sigtramp
   routine.  */

/* FreeBSD/i386 supports three different signal trampolines, one for
   versions before 4.0, a second for 4.x, and a third for 5.0 and
   later.  To complicate matters, FreeBSD/i386 binaries running under
   an amd64 kernel use a different set of trampolines.  These
   trampolines differ from the i386 kernel trampolines in that they
   omit a middle section that conditionally restores %gs.  */

static const gdb_byte i386fbsd_sigtramp_start[] =
{
  0x8d, 0x44, 0x24, 0x20,       /* lea     SIGF_UC(%esp),%eax */
  0x50              /* pushl   %eax */
};

static const gdb_byte i386fbsd_sigtramp_middle[] =
{
  0xf7, 0x40, 0x54, 0x00, 0x00, 0x02, 0x00,
                /* testl   $PSL_VM,UC_EFLAGS(%eax) */
  0x75, 0x03,           /* jne     +3 */
  0x8e, 0x68, 0x14      /* mov     UC_GS(%eax),%gs */
};

static const gdb_byte i386fbsd_sigtramp_end[] =
{
  0xb8, 0xa1, 0x01, 0x00, 0x00, /* movl   $SYS_sigreturn,%eax */
  0x50,         /* pushl   %eax */
  0xcd, 0x80            /* int     $0x80 */
};

static const gdb_byte i386fbsd_freebsd4_sigtramp_start[] =
{
  0x8d, 0x44, 0x24, 0x14,   /* lea     SIGF_UC4(%esp),%eax */
  0x50              /* pushl   %eax */
};

static const gdb_byte i386fbsd_freebsd4_sigtramp_middle[] =
{
  0xf7, 0x40, 0x54, 0x00, 0x00, 0x02, 0x00,
                /* testl   $PSL_VM,UC4_EFLAGS(%eax) */
  0x75, 0x03,           /* jne     +3 */
  0x8e, 0x68, 0x14      /* mov     UC4_GS(%eax),%gs */
};

static const gdb_byte i386fbsd_freebsd4_sigtramp_end[] =
{
  0xb8, 0x58, 0x01, 0x00, 0x00, /* movl    $344,%eax */
  0x50,         /* pushl   %eax */
  0xcd, 0x80            /* int     $0x80 */
};

static const gdb_byte i386fbsd_osigtramp_start[] =
{
  0x8d, 0x44, 0x24, 0x14,   /* lea     SIGF_SC(%esp),%eax */
  0x50              /* pushl   %eax */
};

static const gdb_byte i386fbsd_osigtramp_middle[] =
{
  0xf7, 0x40, 0x18, 0x00, 0x00, 0x02, 0x00,
                /* testl   $PSL_VM,SC_PS(%eax) */
  0x75, 0x03,           /* jne     +3 */
  0x8e, 0x68, 0x44      /* mov     SC_GS(%eax),%gs */
};

static const gdb_byte i386fbsd_osigtramp_end[] =
{
  0xb8, 0x67, 0x00, 0x00, 0x00, /* movl    $103,%eax */
  0x50,         /* pushl   %eax */
  0xcd, 0x80            /* int     $0x80 */
};

/* The three different trampolines are all the same size.  */
gdb_static_assert (sizeof i386fbsd_sigtramp_start
           == sizeof i386fbsd_freebsd4_sigtramp_start);
gdb_static_assert (sizeof i386fbsd_sigtramp_start
           == sizeof i386fbsd_osigtramp_start);
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
           == sizeof i386fbsd_freebsd4_sigtramp_middle);
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
           == sizeof i386fbsd_osigtramp_middle);
gdb_static_assert (sizeof i386fbsd_sigtramp_end
           == sizeof i386fbsd_freebsd4_sigtramp_end);
gdb_static_assert (sizeof i386fbsd_sigtramp_end
           == sizeof i386fbsd_osigtramp_end);

/* We assume that the middle is the largest chunk below.  */
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
           > sizeof i386fbsd_sigtramp_start);
gdb_static_assert (sizeof i386fbsd_sigtramp_middle
           > sizeof i386fbsd_sigtramp_end);

static int
i386fbsd_sigtramp_p (struct frame_info *this_frame)
{
  CORE_ADDR pc = get_frame_pc (this_frame);
  gdb_byte buf[sizeof i386fbsd_sigtramp_middle];
  const gdb_byte *middle, *end;

  /* Look for a matching start.  */
  if (!safe_frame_unwind_memory (this_frame, pc, buf,
                 sizeof i386fbsd_sigtramp_start))
    return 0;
  if (memcmp (buf, i386fbsd_sigtramp_start, sizeof i386fbsd_sigtramp_start)
      == 0)
    {
      middle = i386fbsd_sigtramp_middle;
      end = i386fbsd_sigtramp_end;
    }
  else if (memcmp (buf, i386fbsd_freebsd4_sigtramp_start,
           sizeof i386fbsd_freebsd4_sigtramp_start) == 0)
    {
      middle = i386fbsd_freebsd4_sigtramp_middle;
      end = i386fbsd_freebsd4_sigtramp_end;
    }
  else if (memcmp (buf, i386fbsd_osigtramp_start,
           sizeof i386fbsd_osigtramp_start) == 0)
    {
      middle = i386fbsd_osigtramp_middle;
      end = i386fbsd_osigtramp_end;
    }
  else
    return 0;

  /* Since the end is shorter than the middle, check for a matching end
     next.  */
  pc += sizeof i386fbsd_sigtramp_start;
  if (!safe_frame_unwind_memory (this_frame, pc, buf,
                 sizeof i386fbsd_sigtramp_end))
    return 0;
  if (memcmp (buf, end, sizeof i386fbsd_sigtramp_end) == 0)
    return 1;

  /* If the end didn't match, check for a matching middle.  */
  if (!safe_frame_unwind_memory (this_frame, pc, buf,
                 sizeof i386fbsd_sigtramp_middle))
    return 0;
  if (memcmp (buf, middle, sizeof i386fbsd_sigtramp_middle) != 0)
    return 0;

  /* The middle matched, check for a matching end.  */
  pc += sizeof i386fbsd_sigtramp_middle;
  if (!safe_frame_unwind_memory (this_frame, pc, buf,
                 sizeof i386fbsd_sigtramp_end))
    return 0;
  if (memcmp (buf, end, sizeof i386fbsd_sigtramp_end) != 0)
    return 0;

  return 1;
}

/* FreeBSD 3.0-RELEASE or later.  */

/* From <machine/reg.h>.  */
static int i386fbsd_r_reg_offset[] =
{
  9 * 4, 8 * 4, 7 * 4, 6 * 4,   /* %eax, %ecx, %edx, %ebx */
  15 * 4, 4 * 4,        /* %esp, %ebp */
  3 * 4, 2 * 4,         /* %esi, %edi */
  12 * 4, 14 * 4,       /* %eip, %eflags */
  13 * 4, 16 * 4,       /* %cs, %ss */
  1 * 4, 0 * 4, -1, -1      /* %ds, %es, %fs, %gs */
};

/* Sigtramp routine location.  */
CORE_ADDR i386fbsd_sigtramp_start_addr;
CORE_ADDR i386fbsd_sigtramp_end_addr;

/* From <machine/signal.h>.  */
int i386fbsd_sc_reg_offset[] =
{
  8 + 14 * 4,           /* %eax */
  8 + 13 * 4,           /* %ecx */
  8 + 12 * 4,           /* %edx */
  8 + 11 * 4,           /* %ebx */
  8 + 0 * 4,                    /* %esp */
  8 + 1 * 4,                    /* %ebp */
  8 + 10 * 4,                   /* %esi */
  8 + 9 * 4,                    /* %edi */
  8 + 3 * 4,                    /* %eip */
  8 + 4 * 4,                    /* %eflags */
  8 + 7 * 4,                    /* %cs */
  8 + 8 * 4,                    /* %ss */
  8 + 6 * 4,                    /* %ds */
  8 + 5 * 4,                    /* %es */
  8 + 15 * 4,           /* %fs */
  8 + 16 * 4            /* %gs */
};

/* Get XSAVE extended state xcr0 from core dump.  */

uint64_t
i386fbsd_core_read_xcr0 (bfd *abfd)
{
  asection *xstate = bfd_get_section_by_name (abfd, ".reg-xstate");
  uint64_t xcr0;

  if (xstate)
    {
      size_t size = bfd_section_size (abfd, xstate);

      /* Check extended state size.  */
      if (size < X86_XSTATE_AVX_SIZE)
    xcr0 = X86_XSTATE_SSE_MASK;
      else
    {
      char contents[8];

      if (! bfd_get_section_contents (abfd, xstate, contents,
                      I386_FBSD_XSAVE_XCR0_OFFSET,
                      8))
        {
          warning (_("Couldn't read `xcr0' bytes from "
             "`.reg-xstate' section in core file."));
          return X86_XSTATE_SSE_MASK;
        }

      xcr0 = bfd_get_64 (abfd, contents);
    }
    }
  else
    xcr0 = X86_XSTATE_SSE_MASK;

  return xcr0;
}

/* Implement the core_read_description gdbarch method.  */

static const struct target_desc *
i386fbsd_core_read_description (struct gdbarch *gdbarch,
                struct target_ops *target,
                bfd *abfd)
{
  return i386_target_description (i386fbsd_core_read_xcr0 (abfd));
}

/* Similar to i386_supply_fpregset, but use XSAVE extended state.  */

static void
i386fbsd_supply_xstateregset (const struct regset *regset,
                  struct regcache *regcache, int regnum,
                  const void *xstateregs, size_t len)
{
  i387_supply_xsave (regcache, regnum, xstateregs);
}

/* Similar to i386_collect_fpregset, but use XSAVE extended state.  */

static void
i386fbsd_collect_xstateregset (const struct regset *regset,
                   const struct regcache *regcache,
                   int regnum, void *xstateregs, size_t len)
{
  i387_collect_xsave (regcache, regnum, xstateregs, 1);
}

/* Register set definitions.  */

static const struct regset i386fbsd_xstateregset =
  {
    NULL,
    i386fbsd_supply_xstateregset,
    i386fbsd_collect_xstateregset
  };

/* Iterate over core file register note sections.  */

static void
i386fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
                       iterate_over_regset_sections_cb *cb,
                       void *cb_data,
                       const struct regcache *regcache)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  cb (".reg", tdep->sizeof_gregset, &i386_gregset, NULL, cb_data);
  cb (".reg2", tdep->sizeof_fpregset, &i386_fpregset, NULL, cb_data);

  if (tdep->xcr0 & X86_XSTATE_AVX)
    cb (".reg-xstate", X86_XSTATE_SIZE(tdep->xcr0),
    &i386fbsd_xstateregset, "XSAVE extended state", cb_data);
}

static void
i386fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* Obviously FreeBSD is BSD-based.  */
  i386bsd_init_abi (info, gdbarch);

  /* FreeBSD has a different `struct reg', and reserves some space for
     its FPU emulator in `struct fpreg'.  */
  tdep->gregset_reg_offset = i386fbsd_r_reg_offset;
  tdep->gregset_num_regs = ARRAY_SIZE (i386fbsd_r_reg_offset);
  tdep->sizeof_gregset = 18 * 4;
  tdep->sizeof_fpregset = 176;

  /* FreeBSD uses -freg-struct-return by default.  */
  tdep->struct_return = reg_struct_return;

  tdep->sigtramp_p = i386fbsd_sigtramp_p;

  /* FreeBSD uses a different memory layout.  */
  tdep->sigtramp_start = i386fbsd_sigtramp_start_addr;
  tdep->sigtramp_end = i386fbsd_sigtramp_end_addr;

  /* FreeBSD has a more complete `struct sigcontext'.  */
  tdep->sc_reg_offset = i386fbsd_sc_reg_offset;
  tdep->sc_num_regs = ARRAY_SIZE (i386fbsd_sc_reg_offset);

  i386_elf_init_abi (info, gdbarch);

  /* FreeBSD uses SVR4-style shared libraries.  */
  set_solib_svr4_fetch_link_map_offsets
    (gdbarch, svr4_ilp32_fetch_link_map_offsets);
}

/* FreeBSD 4.0-RELEASE or later.  */

/* From <machine/reg.h>.  */
static int i386fbsd4_r_reg_offset[] =
{
  10 * 4, 9 * 4, 8 * 4, 7 * 4,  /* %eax, %ecx, %edx, %ebx */
  16 * 4, 5 * 4,        /* %esp, %ebp */
  4 * 4, 3 * 4,         /* %esi, %edi */
  13 * 4, 15 * 4,       /* %eip, %eflags */
  14 * 4, 17 * 4,       /* %cs, %ss */
  2 * 4, 1 * 4, 0 * 4, 18 * 4   /* %ds, %es, %fs, %gs */
};

/* From <machine/signal.h>.  */
int i386fbsd4_sc_reg_offset[] =
{
  20 + 11 * 4,          /* %eax */
  20 + 10 * 4,          /* %ecx */
  20 + 9 * 4,           /* %edx */
  20 + 8 * 4,           /* %ebx */
  20 + 17 * 4,          /* %esp */
  20 + 6 * 4,           /* %ebp */
  20 + 5 * 4,           /* %esi */
  20 + 4 * 4,           /* %edi */
  20 + 14 * 4,          /* %eip */
  20 + 16 * 4,          /* %eflags */
  20 + 15 * 4,          /* %cs */
  20 + 18 * 4,          /* %ss */
  20 + 3 * 4,           /* %ds */
  20 + 2 * 4,           /* %es */
  20 + 1 * 4,           /* %fs */
  20 + 0 * 4            /* %gs */
};

static void
i386fbsd4_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* Generic FreeBSD support. */
  fbsd_init_abi (info, gdbarch);

  /* Inherit stuff from older releases.  We assume that FreeBSD
     4.0-RELEASE always uses ELF.  */
  i386fbsd_init_abi (info, gdbarch);

  /* FreeBSD 4.0 introduced a new `struct reg'.  */
  tdep->gregset_reg_offset = i386fbsd4_r_reg_offset;
  tdep->gregset_num_regs = ARRAY_SIZE (i386fbsd4_r_reg_offset);
  tdep->sizeof_gregset = 19 * 4;

  /* FreeBSD 4.0 introduced a new `struct sigcontext'.  */
  tdep->sc_reg_offset = i386fbsd4_sc_reg_offset;
  tdep->sc_num_regs = ARRAY_SIZE (i386fbsd4_sc_reg_offset);

  tdep->xsave_xcr0_offset = I386_FBSD_XSAVE_XCR0_OFFSET;

  /* Iterate over core file register note sections.  */
  set_gdbarch_iterate_over_regset_sections
    (gdbarch, i386fbsd_iterate_over_regset_sections);

  set_gdbarch_core_read_description (gdbarch,
                     i386fbsd_core_read_description);
}

void
_initialize_i386fbsd_tdep (void)
{
  gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_FREEBSD,
              i386fbsd4_init_abi);
}