/* Mudflap: narrow-pointer bounds-checking by tree rewriting.
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/* Mudflap: narrow-pointer bounds-checking by tree rewriting.
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Copyright (C) 2002, 2003, 2009 Free Software Foundation, Inc.
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Copyright (C) 2002, 2003, 2009 Free Software Foundation, Inc.
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Contributed by Frank Ch. Eigler <fche@redhat.com>
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Contributed by Frank Ch. Eigler <fche@redhat.com>
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and Graydon Hoare <graydon@redhat.com>
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and Graydon Hoare <graydon@redhat.com>
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This file is part of GCC.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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Software Foundation; either version 3, or (at your option) any later
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version.
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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for more details.
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Under Section 7 of GPL version 3, you are granted additional
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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<http://www.gnu.org/licenses/>. */
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#include "config.h"
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#include "config.h"
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#include <stdio.h>
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#include <stdio.h>
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#include "mf-runtime.h"
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#include "mf-runtime.h"
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#include "mf-impl.h"
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#include "mf-impl.h"
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#ifdef _MUDFLAP
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#ifdef _MUDFLAP
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#error "Do not compile this file with -fmudflap!"
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#error "Do not compile this file with -fmudflap!"
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#endif
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#endif
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extern char _end[];
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extern char _end[];
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extern char ENTRY_POINT[];
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extern char ENTRY_POINT[];
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/* Run some quick validation of the given region.
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/* Run some quick validation of the given region.
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Return -1 / 0 / 1 if the access known-invalid, possibly-valid, or known-valid.
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Return -1 / 0 / 1 if the access known-invalid, possibly-valid, or known-valid.
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*/
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*/
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int
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int
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__mf_heuristic_check (uintptr_t ptr, uintptr_t ptr_high)
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__mf_heuristic_check (uintptr_t ptr, uintptr_t ptr_high)
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{
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{
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VERBOSE_TRACE ("mf: heuristic check\n");
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VERBOSE_TRACE ("mf: heuristic check\n");
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/* XXX: Disable the stack bounding check for libmudflapth. We do
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/* XXX: Disable the stack bounding check for libmudflapth. We do
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actually have enough information to track stack bounds (see
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actually have enough information to track stack bounds (see
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__mf_pthread_info in mf-hooks.c), so with a bit of future work,
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__mf_pthread_info in mf-hooks.c), so with a bit of future work,
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this heuristic can be turned on. */
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this heuristic can be turned on. */
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#ifndef LIBMUDFLAPTH
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#ifndef LIBMUDFLAPTH
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/* The first heuristic is to check stack bounds. This is a
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/* The first heuristic is to check stack bounds. This is a
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transient condition and quick to check. */
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transient condition and quick to check. */
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if (__mf_opts.heur_stack_bound)
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if (__mf_opts.heur_stack_bound)
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{
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{
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uintptr_t stack_top_guess = (uintptr_t)__builtin_frame_address(0);
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uintptr_t stack_top_guess = (uintptr_t)__builtin_frame_address(0);
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#if defined(__i386__) && defined (__linux__)
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#if defined(__i386__) && defined (__linux__)
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uintptr_t stack_segment_base = 0xC0000000; /* XXX: Bad assumption. */
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uintptr_t stack_segment_base = 0xC0000000; /* XXX: Bad assumption. */
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#else
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#else
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/* Cause tests to fail. */
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/* Cause tests to fail. */
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uintptr_t stack_segment_base = 0;
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uintptr_t stack_segment_base = 0;
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#endif
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#endif
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VERBOSE_TRACE ("mf: stack estimated as %p-%p\n",
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VERBOSE_TRACE ("mf: stack estimated as %p-%p\n",
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(void *) stack_top_guess, (void *) stack_segment_base);
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(void *) stack_top_guess, (void *) stack_segment_base);
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if (ptr_high <= stack_segment_base &&
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if (ptr_high <= stack_segment_base &&
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ptr >= stack_top_guess &&
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ptr >= stack_top_guess &&
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ptr_high >= ptr)
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ptr_high >= ptr)
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{
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{
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return 1;
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return 1;
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}
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}
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}
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}
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#endif
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#endif
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/* The second heuristic is to scan the range of memory regions
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/* The second heuristic is to scan the range of memory regions
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listed in /proc/self/maps, a special file provided by the Linux
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listed in /proc/self/maps, a special file provided by the Linux
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kernel. Its results may be cached, and in fact, a GUESS object
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kernel. Its results may be cached, and in fact, a GUESS object
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may as well be recorded for interesting matching sections. */
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may as well be recorded for interesting matching sections. */
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if (__mf_opts.heur_proc_map)
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if (__mf_opts.heur_proc_map)
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{
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{
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/* Keep a record of seen records from /proc/self/map. */
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/* Keep a record of seen records from /proc/self/map. */
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enum { max_entries = 500 };
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enum { max_entries = 500 };
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struct proc_self_map_entry
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struct proc_self_map_entry
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{
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{
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uintptr_t low;
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uintptr_t low;
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uintptr_t high;
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uintptr_t high;
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};
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};
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static struct proc_self_map_entry entry [max_entries];
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static struct proc_self_map_entry entry [max_entries];
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static unsigned entry_used [max_entries];
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static unsigned entry_used [max_entries];
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/* Look for a known proc_self_map entry that may cover this
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/* Look for a known proc_self_map entry that may cover this
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region. If one exists, then this heuristic has already run,
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region. If one exists, then this heuristic has already run,
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and should not be run again. The check should be allowed to
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and should not be run again. The check should be allowed to
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fail. */
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fail. */
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unsigned i;
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unsigned i;
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unsigned deja_vu = 0;
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unsigned deja_vu = 0;
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for (i=0; i<max_entries; i++)
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for (i=0; i<max_entries; i++)
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{
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{
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if (entry_used[i] &&
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if (entry_used[i] &&
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(entry[i].low <= ptr) &&
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(entry[i].low <= ptr) &&
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(entry[i].high >= ptr_high))
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(entry[i].high >= ptr_high))
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deja_vu = 1;
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deja_vu = 1;
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}
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}
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if (! deja_vu)
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if (! deja_vu)
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{
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{
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/* Time to run the heuristic. Rescan /proc/self/maps; update the
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/* Time to run the heuristic. Rescan /proc/self/maps; update the
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entry[] array; XXX: remove expired entries, add new ones.
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entry[] array; XXX: remove expired entries, add new ones.
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XXX: Consider entries that have grown (e.g., stack). */
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XXX: Consider entries that have grown (e.g., stack). */
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char buf[512];
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char buf[512];
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char flags[4];
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char flags[4];
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void *low, *high;
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void *low, *high;
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FILE *fp;
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FILE *fp;
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fp = fopen ("/proc/self/maps", "r");
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fp = fopen ("/proc/self/maps", "r");
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if (fp)
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if (fp)
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{
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{
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while (fgets (buf, sizeof(buf), fp))
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while (fgets (buf, sizeof(buf), fp))
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{
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{
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if (sscanf (buf, "%p-%p %4c", &low, &high, flags) == 3)
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if (sscanf (buf, "%p-%p %4c", &low, &high, flags) == 3)
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{
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{
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if ((uintptr_t) low <= ptr &&
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if ((uintptr_t) low <= ptr &&
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(uintptr_t) high >= ptr_high)
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(uintptr_t) high >= ptr_high)
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{
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{
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for (i=0; i<max_entries; i++)
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for (i=0; i<max_entries; i++)
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{
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{
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if (! entry_used[i])
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if (! entry_used[i])
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{
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{
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entry[i].low = (uintptr_t) low;
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entry[i].low = (uintptr_t) low;
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entry[i].high = (uintptr_t) high;
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entry[i].high = (uintptr_t) high;
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entry_used[i] = 1;
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entry_used[i] = 1;
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break;
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break;
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}
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}
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}
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}
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VERBOSE_TRACE ("mf: registering region #%d "
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VERBOSE_TRACE ("mf: registering region #%d "
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"%p-%p given %s",
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"%p-%p given %s",
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i, (void *) low, (void *) high, buf);
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i, (void *) low, (void *) high, buf);
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__mfu_register ((void *) low, (size_t) (high-low),
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__mfu_register ((void *) low, (size_t) (high-low),
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__MF_TYPE_GUESS,
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__MF_TYPE_GUESS,
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"/proc/self/maps segment");
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"/proc/self/maps segment");
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return 0; /* undecided (tending to cachable) */
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return 0; /* undecided (tending to cachable) */
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}
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}
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}
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}
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}
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}
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fclose (fp);
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fclose (fp);
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}
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}
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}
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}
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}
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}
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/* The third heuristic is to approve all accesses between _start (or its
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/* The third heuristic is to approve all accesses between _start (or its
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equivalent for the given target) and _end, which should include all
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equivalent for the given target) and _end, which should include all
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text and initialized data. */
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text and initialized data. */
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if (__mf_opts.heur_start_end)
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if (__mf_opts.heur_start_end)
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if (ptr >= (uintptr_t) & ENTRY_POINT && ptr_high <= (uintptr_t) & _end)
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if (ptr >= (uintptr_t) & ENTRY_POINT && ptr_high <= (uintptr_t) & _end)
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return 1; /* uncacheable */
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return 1; /* uncacheable */
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return 0; /* unknown */
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return 0; /* unknown */
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}
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}
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