--- /dev/null
+/* Mudflap: narrow-pointer bounds-checking by tree rewriting.
+ Copyright (C) 2002, 2003, 2009 Free Software Foundation, Inc.
+ Contributed by Frank Ch. Eigler <fche@redhat.com>
+ and Graydon Hoare <graydon@redhat.com>
+
+This file is part of GCC.
+
+GCC 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, or (at your option) any later
+version.
+
+GCC 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.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+<http://www.gnu.org/licenses/>. */
+
+#include "config.h"
+
+#include <stdio.h>
+
+#include "mf-runtime.h"
+#include "mf-impl.h"
+
+#ifdef _MUDFLAP
+#error "Do not compile this file with -fmudflap!"
+#endif
+
+
+extern char _end[];
+extern char ENTRY_POINT[];
+
+
+/* Run some quick validation of the given region.
+ Return -1 / 0 / 1 if the access known-invalid, possibly-valid, or known-valid.
+*/
+int
+__mf_heuristic_check (uintptr_t ptr, uintptr_t ptr_high)
+{
+ VERBOSE_TRACE ("mf: heuristic check\n");
+
+ /* XXX: Disable the stack bounding check for libmudflapth. We do
+ actually have enough information to track stack bounds (see
+ __mf_pthread_info in mf-hooks.c), so with a bit of future work,
+ this heuristic can be turned on. */
+#ifndef LIBMUDFLAPTH
+
+ /* The first heuristic is to check stack bounds. This is a
+ transient condition and quick to check. */
+ if (__mf_opts.heur_stack_bound)
+ {
+ uintptr_t stack_top_guess = (uintptr_t)__builtin_frame_address(0);
+#if defined(__i386__) && defined (__linux__)
+ uintptr_t stack_segment_base = 0xC0000000; /* XXX: Bad assumption. */
+#else
+ /* Cause tests to fail. */
+ uintptr_t stack_segment_base = 0;
+#endif
+
+ VERBOSE_TRACE ("mf: stack estimated as %p-%p\n",
+ (void *) stack_top_guess, (void *) stack_segment_base);
+
+ if (ptr_high <= stack_segment_base &&
+ ptr >= stack_top_guess &&
+ ptr_high >= ptr)
+ {
+ return 1;
+ }
+ }
+#endif
+
+
+ /* The second heuristic is to scan the range of memory regions
+ listed in /proc/self/maps, a special file provided by the Linux
+ kernel. Its results may be cached, and in fact, a GUESS object
+ may as well be recorded for interesting matching sections. */
+ if (__mf_opts.heur_proc_map)
+ {
+ /* Keep a record of seen records from /proc/self/map. */
+ enum { max_entries = 500 };
+ struct proc_self_map_entry
+ {
+ uintptr_t low;
+ uintptr_t high;
+ };
+ static struct proc_self_map_entry entry [max_entries];
+ static unsigned entry_used [max_entries];
+
+ /* Look for a known proc_self_map entry that may cover this
+ region. If one exists, then this heuristic has already run,
+ and should not be run again. The check should be allowed to
+ fail. */
+ unsigned i;
+ unsigned deja_vu = 0;
+ for (i=0; i<max_entries; i++)
+ {
+ if (entry_used[i] &&
+ (entry[i].low <= ptr) &&
+ (entry[i].high >= ptr_high))
+ deja_vu = 1;
+ }
+
+ if (! deja_vu)
+ {
+ /* Time to run the heuristic. Rescan /proc/self/maps; update the
+ entry[] array; XXX: remove expired entries, add new ones.
+ XXX: Consider entries that have grown (e.g., stack). */
+ char buf[512];
+ char flags[4];
+ void *low, *high;
+ FILE *fp;
+
+ fp = fopen ("/proc/self/maps", "r");
+ if (fp)
+ {
+ while (fgets (buf, sizeof(buf), fp))
+ {
+ if (sscanf (buf, "%p-%p %4c", &low, &high, flags) == 3)
+ {
+ if ((uintptr_t) low <= ptr &&
+ (uintptr_t) high >= ptr_high)
+ {
+ for (i=0; i<max_entries; i++)
+ {
+ if (! entry_used[i])
+ {
+ entry[i].low = (uintptr_t) low;
+ entry[i].high = (uintptr_t) high;
+ entry_used[i] = 1;
+ break;
+ }
+ }
+
+ VERBOSE_TRACE ("mf: registering region #%d "
+ "%p-%p given %s",
+ i, (void *) low, (void *) high, buf);
+
+ __mfu_register ((void *) low, (size_t) (high-low),
+ __MF_TYPE_GUESS,
+ "/proc/self/maps segment");
+
+ return 0; /* undecided (tending to cachable) */
+ }
+ }
+ }
+ fclose (fp);
+ }
+ }
+ }
+
+
+ /* The third heuristic is to approve all accesses between _start (or its
+ equivalent for the given target) and _end, which should include all
+ text and initialized data. */
+ if (__mf_opts.heur_start_end)
+ if (ptr >= (uintptr_t) & ENTRY_POINT && ptr_high <= (uintptr_t) & _end)
+ return 1; /* uncacheable */
+
+ return 0; /* unknown */
+}
projects / msp430-gcc.git / blobdiff