/* Auxiliary vector support for GDB, the GNU debugger.
- Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
- Free Software Foundation, Inc.
+ Copyright (C) 2004-2012 Free Software Foundation, Inc.
This file is part of GDB.
#include "valprint.h"
#include "gdb_assert.h"
#include "gdbcore.h"
+#include "observer.h"
#include "auxv.h"
#include "elf/common.h"
#include <fcntl.h>
-/* This function handles access via /proc/PID/auxv, which is a common method
- for native targets. */
+/* This function handles access via /proc/PID/auxv, which is a common
+ method for native targets. */
static LONGEST
procfs_xfer_auxv (gdb_byte *readbuf,
if (MSYMBOL_SIZE (msym) != ptr_size)
return -1;
- /* POINTER_ADDRESS is a location where the `_dl_auxv' variable resides.
- DATA_ADDRESS is the inferior value present in `_dl_auxv', therefore the
- real inferior AUXV address. */
+ /* POINTER_ADDRESS is a location where the `_dl_auxv' variable
+ resides. DATA_ADDRESS is the inferior value present in
+ `_dl_auxv', therefore the real inferior AUXV address. */
pointer_address = SYMBOL_VALUE_ADDRESS (msym);
- data_address = read_memory_typed_address (pointer_address, ptr_type);
+ /* The location of the _dl_auxv symbol may no longer be correct if
+ ld.so runs at a different address than the one present in the
+ file. This is very common case - for unprelinked ld.so or with a
+ PIE executable. PIE executable forces random address even for
+ libraries already being prelinked to some address. PIE
+ executables themselves are never prelinked even on prelinked
+ systems. Prelinking of a PIE executable would block their
+ purpose of randomizing load of everything including the
+ executable.
+
+ If the memory read fails, return -1 to fallback on another
+ mechanism for retrieving the AUXV.
+
+ In most cases of a PIE running under valgrind there is no way to
+ find out the base addresses of any of ld.so, executable or AUXV
+ as everything is randomized and /proc information is not relevant
+ for the virtual executable running under valgrind. We think that
+ we might need a valgrind extension to make it work. This is PR
+ 11440. */
+
+ if (target_read_memory (pointer_address, ptr_buf, ptr_size) != 0)
+ return -1;
+
+ data_address = extract_typed_address (ptr_buf, ptr_type);
- /* Possibly still not initialized such as during an inferior startup. */
+ /* Possibly still not initialized such as during an inferior
+ startup. */
if (data_address == 0)
return -1;
return -1;
}
- /* Stop if trying to read past the existing AUXV block. The final AT_NULL
- was already returned before. */
+ /* Stop if trying to read past the existing AUXV block. The final
+ AT_NULL was already returned before. */
if (offset >= auxv_pair_size)
{
if (block > len)
block = len;
- /* Reading sizes smaller than AUXV_PAIR_SIZE is not supported. Tails
- unaligned to AUXV_PAIR_SIZE will not be read during a call (they
- should be completed during next read with new/extended buffer). */
+ /* Reading sizes smaller than AUXV_PAIR_SIZE is not supported.
+ Tails unaligned to AUXV_PAIR_SIZE will not be read during a
+ call (they should be completed during next read with
+ new/extended buffer). */
block &= -auxv_pair_size;
if (block == 0)
data_address += block;
len -= block;
- /* Check terminal AT_NULL. This function is being called indefinitely
- being extended its READBUF until it returns EOF (0). */
+ /* Check terminal AT_NULL. This function is being called
+ indefinitely being extended its READBUF until it returns EOF
+ (0). */
while (block >= auxv_pair_size)
{
gdb_assert (object == TARGET_OBJECT_AUXV);
gdb_assert (readbuf || writebuf);
- /* ld_so_xfer_auxv is the only function safe for virtual executables being
- executed by valgrind's memcheck. As using ld_so_xfer_auxv is problematic
- during inferior startup GDB does call it only for attached processes. */
+ /* ld_so_xfer_auxv is the only function safe for virtual
+ executables being executed by valgrind's memcheck. Using
+ ld_so_xfer_auxv during inferior startup is problematic, because
+ ld.so symbol tables have not yet been relocated. So GDB uses
+ this function only when attaching to a process.
+ */
if (current_inferior ()->attach_flag != 0)
{
gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
{
struct target_ops *t;
+
for (t = ops; t != NULL; t = t->beneath)
if (t->to_auxv_parse != NULL)
return t->to_auxv_parse (t, readptr, endptr, typep, valp);
return default_auxv_parse (ops, readptr, endptr, typep, valp);
}
+
+/* Per-inferior data key for auxv. */
+static const struct inferior_data *auxv_inferior_data;
+
+/* Auxiliary Vector information structure. This is used by GDB
+ for caching purposes for each inferior. This helps reduce the
+ overhead of transfering data from a remote target to the local host. */
+struct auxv_info
+{
+ LONGEST length;
+ gdb_byte *data;
+};
+
+/* Handles the cleanup of the auxv cache for inferior INF. ARG is ignored.
+ Frees whatever allocated space there is to be freed and sets INF's auxv cache
+ data pointer to NULL.
+
+ This function is called when the following events occur: inferior_appeared,
+ inferior_exit and executable_changed. */
+
+static void
+auxv_inferior_data_cleanup (struct inferior *inf, void *arg)
+{
+ struct auxv_info *info;
+
+ info = inferior_data (inf, auxv_inferior_data);
+ if (info != NULL)
+ {
+ xfree (info->data);
+ xfree (info);
+ set_inferior_data (inf, auxv_inferior_data, NULL);
+ }
+}
+
+/* Invalidate INF's auxv cache. */
+
+static void
+invalidate_auxv_cache_inf (struct inferior *inf)
+{
+ auxv_inferior_data_cleanup (inf, NULL);
+}
+
+/* Invalidate current inferior's auxv cache. */
+
+static void
+invalidate_auxv_cache (void)
+{
+ invalidate_auxv_cache_inf (current_inferior ());
+}
+
+/* Fetch the auxv object from inferior INF. If auxv is cached already,
+ return a pointer to the cache. If not, fetch the auxv object from the
+ target and cache it. This function always returns a valid INFO pointer. */
+
+static struct auxv_info *
+get_auxv_inferior_data (struct target_ops *ops)
+{
+ struct auxv_info *info;
+ struct inferior *inf = current_inferior ();
+
+ info = inferior_data (inf, auxv_inferior_data);
+ if (info == NULL)
+ {
+ info = XZALLOC (struct auxv_info);
+ info->length = target_read_alloc (ops, TARGET_OBJECT_AUXV,
+ NULL, &info->data);
+ set_inferior_data (inf, auxv_inferior_data, info);
+ }
+
+ return info;
+}
+
/* Extract the auxiliary vector entry with a_type matching MATCH.
Return zero if no such entry was found, or -1 if there was
an error getting the information. On success, return 1 after
{
CORE_ADDR type, val;
gdb_byte *data;
- LONGEST n = target_read_alloc (ops, TARGET_OBJECT_AUXV, NULL, &data);
- gdb_byte *ptr = data;
+ gdb_byte *ptr;
+ struct auxv_info *info;
+
+ info = get_auxv_inferior_data (ops);
- if (n <= 0)
- return n;
+ data = info->data;
+ ptr = data;
+
+ if (info->length <= 0)
+ return info->length;
while (1)
- switch (target_auxv_parse (ops, &ptr, data + n, &type, &val))
+ switch (target_auxv_parse (ops, &ptr, data + info->length, &type, &val))
{
case 1: /* Here's an entry, check it. */
if (type == match)
{
- xfree (data);
*valp = val;
return 1;
}
break;
case 0: /* End of the vector. */
- xfree (data);
return 0;
default: /* Bogosity. */
- xfree (data);
return -1;
}
}
-/* Print the contents of the target's AUXV on the specified file. */
+/* Print the contents of the target's AUXV on the specified file. */
int
fprint_target_auxv (struct ui_file *file, struct target_ops *ops)
{
CORE_ADDR type, val;
gdb_byte *data;
- LONGEST len = target_read_alloc (ops, TARGET_OBJECT_AUXV, NULL,
- &data);
- gdb_byte *ptr = data;
+ gdb_byte *ptr;
+ struct auxv_info *info;
int ents = 0;
- if (len <= 0)
- return len;
+ info = get_auxv_inferior_data (ops);
+
+ data = info->data;
+ ptr = data;
+ if (info->length <= 0)
+ return info->length;
- while (target_auxv_parse (ops, &ptr, data + len, &type, &val) > 0)
+ while (target_auxv_parse (ops, &ptr, data + info->length, &type, &val) > 0)
{
const char *name = "???";
const char *description = "";
case str:
{
struct value_print_options opts;
+
get_user_print_options (&opts);
if (opts.addressprint)
fprintf_filtered (file, "%s", paddress (target_gdbarch, val));
val_print_string (builtin_type (target_gdbarch)->builtin_char,
- val, -1, file, &opts);
+ NULL, val, -1, file, &opts);
fprintf_filtered (file, "\n");
}
break;
break;
}
- xfree (data);
-
return ents;
}
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)
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 (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);
}
projects / deliverable / binutils-gdb.git / blobdiff