541 lines
16 KiB
C
541 lines
16 KiB
C
/* Auxiliary vector support for GDB, the GNU debugger.
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Copyright (C) 2004-2014 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "target.h"
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#include "gdbtypes.h"
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#include "command.h"
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#include "inferior.h"
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#include "valprint.h"
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#include "gdb_assert.h"
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#include "gdbcore.h"
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#include "observer.h"
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#include "filestuff.h"
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#include "auxv.h"
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#include "elf/common.h"
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#include <unistd.h>
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#include <fcntl.h>
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/* This function handles access via /proc/PID/auxv, which is a common
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method for native targets. */
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static LONGEST
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procfs_xfer_auxv (gdb_byte *readbuf,
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const gdb_byte *writebuf,
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ULONGEST offset,
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LONGEST len)
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{
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char *pathname;
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int fd;
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LONGEST n;
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pathname = xstrprintf ("/proc/%d/auxv", ptid_get_pid (inferior_ptid));
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fd = gdb_open_cloexec (pathname, writebuf != NULL ? O_WRONLY : O_RDONLY, 0);
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xfree (pathname);
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if (fd < 0)
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return -1;
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if (offset != (ULONGEST) 0
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&& lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
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n = -1;
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else if (readbuf != NULL)
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n = read (fd, readbuf, len);
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else
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n = write (fd, writebuf, len);
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(void) close (fd);
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return n;
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}
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/* This function handles access via ld.so's symbol `_dl_auxv'. */
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static LONGEST
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ld_so_xfer_auxv (gdb_byte *readbuf,
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const gdb_byte *writebuf,
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ULONGEST offset,
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LONGEST len)
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{
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struct minimal_symbol *msym;
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CORE_ADDR data_address, pointer_address;
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struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
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size_t ptr_size = TYPE_LENGTH (ptr_type);
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size_t auxv_pair_size = 2 * ptr_size;
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gdb_byte *ptr_buf = alloca (ptr_size);
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LONGEST retval;
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size_t block;
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msym = lookup_minimal_symbol ("_dl_auxv", NULL, NULL);
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if (msym == NULL)
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return -1;
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if (MSYMBOL_SIZE (msym) != ptr_size)
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return -1;
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/* POINTER_ADDRESS is a location where the `_dl_auxv' variable
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resides. DATA_ADDRESS is the inferior value present in
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`_dl_auxv', therefore the real inferior AUXV address. */
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pointer_address = SYMBOL_VALUE_ADDRESS (msym);
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/* The location of the _dl_auxv symbol may no longer be correct if
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ld.so runs at a different address than the one present in the
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file. This is very common case - for unprelinked ld.so or with a
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PIE executable. PIE executable forces random address even for
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libraries already being prelinked to some address. PIE
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executables themselves are never prelinked even on prelinked
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systems. Prelinking of a PIE executable would block their
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purpose of randomizing load of everything including the
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executable.
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If the memory read fails, return -1 to fallback on another
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mechanism for retrieving the AUXV.
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In most cases of a PIE running under valgrind there is no way to
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find out the base addresses of any of ld.so, executable or AUXV
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as everything is randomized and /proc information is not relevant
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for the virtual executable running under valgrind. We think that
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we might need a valgrind extension to make it work. This is PR
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11440. */
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if (target_read_memory (pointer_address, ptr_buf, ptr_size) != 0)
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return -1;
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data_address = extract_typed_address (ptr_buf, ptr_type);
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/* Possibly still not initialized such as during an inferior
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startup. */
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if (data_address == 0)
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return -1;
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data_address += offset;
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if (writebuf != NULL)
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{
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if (target_write_memory (data_address, writebuf, len) == 0)
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return len;
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else
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return -1;
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}
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/* Stop if trying to read past the existing AUXV block. The final
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AT_NULL was already returned before. */
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if (offset >= auxv_pair_size)
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{
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if (target_read_memory (data_address - auxv_pair_size, ptr_buf,
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ptr_size) != 0)
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return -1;
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if (extract_typed_address (ptr_buf, ptr_type) == AT_NULL)
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return 0;
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}
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retval = 0;
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block = 0x400;
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gdb_assert (block % auxv_pair_size == 0);
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while (len > 0)
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{
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if (block > len)
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block = len;
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/* Reading sizes smaller than AUXV_PAIR_SIZE is not supported.
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Tails unaligned to AUXV_PAIR_SIZE will not be read during a
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call (they should be completed during next read with
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new/extended buffer). */
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block &= -auxv_pair_size;
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if (block == 0)
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return retval;
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if (target_read_memory (data_address, readbuf, block) != 0)
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{
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if (block <= auxv_pair_size)
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return retval;
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block = auxv_pair_size;
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continue;
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}
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data_address += block;
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len -= block;
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/* Check terminal AT_NULL. This function is being called
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indefinitely being extended its READBUF until it returns EOF
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(0). */
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while (block >= auxv_pair_size)
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{
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retval += auxv_pair_size;
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if (extract_typed_address (readbuf, ptr_type) == AT_NULL)
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return retval;
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readbuf += auxv_pair_size;
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block -= auxv_pair_size;
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}
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}
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return retval;
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}
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/* This function is called like a to_xfer_partial hook, but must be
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called with TARGET_OBJECT_AUXV. It handles access to AUXV. */
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LONGEST
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memory_xfer_auxv (struct target_ops *ops,
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enum target_object object,
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const char *annex,
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gdb_byte *readbuf,
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const gdb_byte *writebuf,
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ULONGEST offset,
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LONGEST len)
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{
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gdb_assert (object == TARGET_OBJECT_AUXV);
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gdb_assert (readbuf || writebuf);
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/* ld_so_xfer_auxv is the only function safe for virtual
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executables being executed by valgrind's memcheck. Using
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ld_so_xfer_auxv during inferior startup is problematic, because
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ld.so symbol tables have not yet been relocated. So GDB uses
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this function only when attaching to a process.
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*/
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if (current_inferior ()->attach_flag != 0)
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{
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LONGEST retval;
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retval = ld_so_xfer_auxv (readbuf, writebuf, offset, len);
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if (retval != -1)
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return retval;
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}
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return procfs_xfer_auxv (readbuf, writebuf, offset, len);
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}
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/* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
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Return 0 if *READPTR is already at the end of the buffer.
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Return -1 if there is insufficient buffer for a whole entry.
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Return 1 if an entry was read into *TYPEP and *VALP. */
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static int
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default_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
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gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
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{
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const int sizeof_auxv_field = gdbarch_ptr_bit (target_gdbarch ())
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/ TARGET_CHAR_BIT;
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const enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
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gdb_byte *ptr = *readptr;
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if (endptr == ptr)
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return 0;
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if (endptr - ptr < sizeof_auxv_field * 2)
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return -1;
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*typep = extract_unsigned_integer (ptr, sizeof_auxv_field, byte_order);
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ptr += sizeof_auxv_field;
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*valp = extract_unsigned_integer (ptr, sizeof_auxv_field, byte_order);
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ptr += sizeof_auxv_field;
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*readptr = ptr;
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return 1;
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}
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/* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
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Return 0 if *READPTR is already at the end of the buffer.
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Return -1 if there is insufficient buffer for a whole entry.
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Return 1 if an entry was read into *TYPEP and *VALP. */
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int
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target_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
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gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
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{
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struct target_ops *t;
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for (t = ops; t != NULL; t = t->beneath)
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if (t->to_auxv_parse != NULL)
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return t->to_auxv_parse (t, readptr, endptr, typep, valp);
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return default_auxv_parse (ops, readptr, endptr, typep, valp);
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}
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/* Per-inferior data key for auxv. */
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static const struct inferior_data *auxv_inferior_data;
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/* Auxiliary Vector information structure. This is used by GDB
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for caching purposes for each inferior. This helps reduce the
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overhead of transfering data from a remote target to the local host. */
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struct auxv_info
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{
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LONGEST length;
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gdb_byte *data;
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};
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/* Handles the cleanup of the auxv cache for inferior INF. ARG is ignored.
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Frees whatever allocated space there is to be freed and sets INF's auxv cache
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data pointer to NULL.
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This function is called when the following events occur: inferior_appeared,
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inferior_exit and executable_changed. */
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static void
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auxv_inferior_data_cleanup (struct inferior *inf, void *arg)
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{
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struct auxv_info *info;
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info = inferior_data (inf, auxv_inferior_data);
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if (info != NULL)
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{
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xfree (info->data);
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xfree (info);
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set_inferior_data (inf, auxv_inferior_data, NULL);
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}
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}
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/* Invalidate INF's auxv cache. */
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static void
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invalidate_auxv_cache_inf (struct inferior *inf)
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{
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auxv_inferior_data_cleanup (inf, NULL);
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}
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/* Invalidate current inferior's auxv cache. */
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static void
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invalidate_auxv_cache (void)
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{
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invalidate_auxv_cache_inf (current_inferior ());
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}
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/* Fetch the auxv object from inferior INF. If auxv is cached already,
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return a pointer to the cache. If not, fetch the auxv object from the
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target and cache it. This function always returns a valid INFO pointer. */
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static struct auxv_info *
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get_auxv_inferior_data (struct target_ops *ops)
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{
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struct auxv_info *info;
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struct inferior *inf = current_inferior ();
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info = inferior_data (inf, auxv_inferior_data);
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if (info == NULL)
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{
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info = XCNEW (struct auxv_info);
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info->length = target_read_alloc (ops, TARGET_OBJECT_AUXV,
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NULL, &info->data);
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set_inferior_data (inf, auxv_inferior_data, info);
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}
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return info;
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}
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/* Extract the auxiliary vector entry with a_type matching MATCH.
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Return zero if no such entry was found, or -1 if there was
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an error getting the information. On success, return 1 after
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storing the entry's value field in *VALP. */
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int
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target_auxv_search (struct target_ops *ops, CORE_ADDR match, CORE_ADDR *valp)
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{
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CORE_ADDR type, val;
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gdb_byte *data;
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gdb_byte *ptr;
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struct auxv_info *info;
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info = get_auxv_inferior_data (ops);
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data = info->data;
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ptr = data;
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if (info->length <= 0)
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return info->length;
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while (1)
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switch (target_auxv_parse (ops, &ptr, data + info->length, &type, &val))
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{
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case 1: /* Here's an entry, check it. */
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if (type == match)
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{
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*valp = val;
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return 1;
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}
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break;
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case 0: /* End of the vector. */
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return 0;
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default: /* Bogosity. */
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return -1;
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}
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/*NOTREACHED*/
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}
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/* Print the contents of the target's AUXV on the specified file. */
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int
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fprint_target_auxv (struct ui_file *file, struct target_ops *ops)
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{
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CORE_ADDR type, val;
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gdb_byte *data;
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gdb_byte *ptr;
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struct auxv_info *info;
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int ents = 0;
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info = get_auxv_inferior_data (ops);
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data = info->data;
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ptr = data;
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if (info->length <= 0)
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return info->length;
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while (target_auxv_parse (ops, &ptr, data + info->length, &type, &val) > 0)
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{
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const char *name = "???";
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const char *description = "";
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enum { dec, hex, str } flavor = hex;
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switch (type)
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{
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#define TAG(tag, text, kind) \
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case tag: name = #tag; description = text; flavor = kind; break
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TAG (AT_NULL, _("End of vector"), hex);
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TAG (AT_IGNORE, _("Entry should be ignored"), hex);
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TAG (AT_EXECFD, _("File descriptor of program"), dec);
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TAG (AT_PHDR, _("Program headers for program"), hex);
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TAG (AT_PHENT, _("Size of program header entry"), dec);
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TAG (AT_PHNUM, _("Number of program headers"), dec);
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TAG (AT_PAGESZ, _("System page size"), dec);
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TAG (AT_BASE, _("Base address of interpreter"), hex);
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TAG (AT_FLAGS, _("Flags"), hex);
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TAG (AT_ENTRY, _("Entry point of program"), hex);
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TAG (AT_NOTELF, _("Program is not ELF"), dec);
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TAG (AT_UID, _("Real user ID"), dec);
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TAG (AT_EUID, _("Effective user ID"), dec);
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TAG (AT_GID, _("Real group ID"), dec);
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TAG (AT_EGID, _("Effective group ID"), dec);
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TAG (AT_CLKTCK, _("Frequency of times()"), dec);
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TAG (AT_PLATFORM, _("String identifying platform"), str);
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TAG (AT_HWCAP, _("Machine-dependent CPU capability hints"), hex);
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TAG (AT_FPUCW, _("Used FPU control word"), dec);
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TAG (AT_DCACHEBSIZE, _("Data cache block size"), dec);
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TAG (AT_ICACHEBSIZE, _("Instruction cache block size"), dec);
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TAG (AT_UCACHEBSIZE, _("Unified cache block size"), dec);
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TAG (AT_IGNOREPPC, _("Entry should be ignored"), dec);
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TAG (AT_BASE_PLATFORM, _("String identifying base platform"), str);
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TAG (AT_RANDOM, _("Address of 16 random bytes"), hex);
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TAG (AT_EXECFN, _("File name of executable"), str);
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TAG (AT_SECURE, _("Boolean, was exec setuid-like?"), dec);
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TAG (AT_SYSINFO, _("Special system info/entry points"), hex);
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TAG (AT_SYSINFO_EHDR, _("System-supplied DSO's ELF header"), hex);
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TAG (AT_L1I_CACHESHAPE, _("L1 Instruction cache information"), hex);
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TAG (AT_L1D_CACHESHAPE, _("L1 Data cache information"), hex);
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TAG (AT_L2_CACHESHAPE, _("L2 cache information"), hex);
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TAG (AT_L3_CACHESHAPE, _("L3 cache information"), hex);
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TAG (AT_SUN_UID, _("Effective user ID"), dec);
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TAG (AT_SUN_RUID, _("Real user ID"), dec);
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TAG (AT_SUN_GID, _("Effective group ID"), dec);
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TAG (AT_SUN_RGID, _("Real group ID"), dec);
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TAG (AT_SUN_LDELF, _("Dynamic linker's ELF header"), hex);
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TAG (AT_SUN_LDSHDR, _("Dynamic linker's section headers"), hex);
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TAG (AT_SUN_LDNAME, _("String giving name of dynamic linker"), str);
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TAG (AT_SUN_LPAGESZ, _("Large pagesize"), dec);
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TAG (AT_SUN_PLATFORM, _("Platform name string"), str);
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TAG (AT_SUN_HWCAP, _("Machine-dependent CPU capability hints"), hex);
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TAG (AT_SUN_IFLUSH, _("Should flush icache?"), dec);
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TAG (AT_SUN_CPU, _("CPU name string"), str);
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TAG (AT_SUN_EMUL_ENTRY, _("COFF entry point address"), hex);
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TAG (AT_SUN_EMUL_EXECFD, _("COFF executable file descriptor"), dec);
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TAG (AT_SUN_EXECNAME,
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_("Canonicalized file name given to execve"), str);
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TAG (AT_SUN_MMU, _("String for name of MMU module"), str);
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TAG (AT_SUN_LDDATA, _("Dynamic linker's data segment address"), hex);
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TAG (AT_SUN_AUXFLAGS,
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_("AF_SUN_ flags passed from the kernel"), hex);
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}
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fprintf_filtered (file, "%-4s %-20s %-30s ",
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plongest (type), name, description);
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switch (flavor)
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{
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case dec:
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fprintf_filtered (file, "%s\n", plongest (val));
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break;
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case hex:
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fprintf_filtered (file, "%s\n", paddress (target_gdbarch (), val));
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break;
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case str:
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{
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struct value_print_options opts;
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get_user_print_options (&opts);
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if (opts.addressprint)
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fprintf_filtered (file, "%s ", paddress (target_gdbarch (), val));
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val_print_string (builtin_type (target_gdbarch ())->builtin_char,
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NULL, val, -1, file, &opts);
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fprintf_filtered (file, "\n");
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}
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break;
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}
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++ents;
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if (type == AT_NULL)
|
|
break;
|
|
}
|
|
|
|
return ents;
|
|
}
|
|
|
|
static void
|
|
info_auxv_command (char *cmd, int from_tty)
|
|
{
|
|
if (! target_has_stack)
|
|
error (_("The program has no auxiliary information now."));
|
|
else
|
|
{
|
|
int ents = fprint_target_auxv (gdb_stdout, ¤t_target);
|
|
|
|
if (ents < 0)
|
|
error (_("No auxiliary vector found, or failed reading it."));
|
|
else if (ents == 0)
|
|
error (_("Auxiliary vector is empty."));
|
|
}
|
|
}
|
|
|
|
|
|
extern initialize_file_ftype _initialize_auxv; /* -Wmissing-prototypes; */
|
|
|
|
void
|
|
_initialize_auxv (void)
|
|
{
|
|
add_info ("auxv", info_auxv_command,
|
|
_("Display the inferior's auxiliary vector.\n\
|
|
This is information provided by the operating system at program startup."));
|
|
|
|
/* Set an auxv cache per-inferior. */
|
|
auxv_inferior_data
|
|
= register_inferior_data_with_cleanup (NULL, auxv_inferior_data_cleanup);
|
|
|
|
/* Observers used to invalidate the auxv cache when needed. */
|
|
observer_attach_inferior_exit (invalidate_auxv_cache_inf);
|
|
observer_attach_inferior_appeared (invalidate_auxv_cache_inf);
|
|
observer_attach_executable_changed (invalidate_auxv_cache);
|
|
}
|