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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.2.2/] [libmudflap/] [mf-hooks3.c] - Rev 179
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/* Mudflap: narrow-pointer bounds-checking by tree rewriting. Copyright (C) 2002, 2003, 2004, 2005 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 2, or (at your option) any later version. In addition to the permissions in the GNU General Public License, the Free Software Foundation gives you unlimited permission to link the compiled version of this file into combinations with other programs, and to distribute those combinations without any restriction coming from the use of this file. (The General Public License restrictions do apply in other respects; for example, they cover modification of the file, and distribution when not linked into a combine executable.) 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. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING. If not, write to the Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ #include "config.h" #ifndef HAVE_SOCKLEN_T #define socklen_t int #endif /* These attempt to coax various unix flavours to declare all our needed tidbits in the system headers. */ #if !defined(__FreeBSD__) && !defined(__APPLE__) #define _POSIX_SOURCE #endif /* Some BSDs break <sys/socket.h> if this is defined. */ #define _GNU_SOURCE #define _XOPEN_SOURCE #define _BSD_TYPES #define __EXTENSIONS__ #define _ALL_SOURCE #define _LARGE_FILE_API #define _XOPEN_SOURCE_EXTENDED 1 #include <string.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <assert.h> #include <errno.h> #include <stdbool.h> #include "mf-runtime.h" #include "mf-impl.h" #ifdef _MUDFLAP #error "Do not compile this file with -fmudflap!" #endif #ifndef LIBMUDFLAPTH #error "pthreadstuff is to be included only in libmudflapth" #endif /* ??? Why isn't this done once in the header files. */ DECLARE(void *, malloc, size_t sz); DECLARE(void, free, void *ptr); DECLARE(int, pthread_create, pthread_t *thr, const pthread_attr_t *attr, void * (*start) (void *), void *arg); /* Multithreading support hooks. */ #ifndef HAVE_TLS /* We don't have TLS. Ordinarily we could use pthread keys, but since we're commandeering malloc/free that presents a few problems. The first is that we'll recurse from __mf_get_state to pthread_setspecific to malloc back to __mf_get_state during thread startup. This can be solved with clever uses of a mutex. The second problem is that thread shutdown is indistinguishable from thread startup, since libpthread is deallocating our state variable. I've no good solution for this. Which leaves us to handle this mess by totally by hand. */ /* Yes, we want this prime. If pthread_t is a pointer, it's almost always page aligned, and if we use a smaller power of 2, this results in "%N" being the worst possible hash -- all threads hash to zero. */ #define LIBMUDFLAPTH_THREADS_MAX 1021 struct mf_thread_data { pthread_t self; unsigned char used_p; unsigned char state; }; static struct mf_thread_data mf_thread_data[LIBMUDFLAPTH_THREADS_MAX]; static pthread_mutex_t mf_thread_data_lock = PTHREAD_MUTEX_INITIALIZER; #define PTHREAD_HASH(p) ((unsigned long) (p) % LIBMUDFLAPTH_THREADS_MAX) static struct mf_thread_data * __mf_find_threadinfo (int alloc) { pthread_t self = pthread_self (); unsigned long hash = PTHREAD_HASH (self); unsigned long rehash; #ifdef __alpha__ /* Alpha has the loosest memory ordering rules of all. We need a memory barrier to flush the reorder buffer before considering a *read* of a shared variable. Since we're not always taking a lock, we have to do this by hand. */ __sync_synchronize (); #endif rehash = hash; while (1) { if (mf_thread_data[rehash].used_p && mf_thread_data[rehash].self == self) return &mf_thread_data[rehash]; rehash += 7; if (rehash >= LIBMUDFLAPTH_THREADS_MAX) rehash -= LIBMUDFLAPTH_THREADS_MAX; if (rehash == hash) break; } if (alloc) { pthread_mutex_lock (&mf_thread_data_lock); rehash = hash; while (1) { if (!mf_thread_data[rehash].used_p) { mf_thread_data[rehash].self = self; __sync_synchronize (); mf_thread_data[rehash].used_p = 1; pthread_mutex_unlock (&mf_thread_data_lock); return &mf_thread_data[rehash]; } rehash += 7; if (rehash >= LIBMUDFLAPTH_THREADS_MAX) rehash -= LIBMUDFLAPTH_THREADS_MAX; if (rehash == hash) break; } pthread_mutex_unlock (&mf_thread_data_lock); } return NULL; } enum __mf_state_enum __mf_get_state (void) { struct mf_thread_data *data = __mf_find_threadinfo (0); if (data) return data->state; /* If we've never seen this thread before, consider it to be in the reentrant state. The state gets reset to active for the main thread in __mf_init, and for child threads in __mf_pthread_spawner. The trickiest bit here is that the LinuxThreads pthread_manager thread should *always* be considered to be reentrant, so that none of our hooks actually do anything. Why? Because that thread isn't a real thread from the point of view of the thread library, and so lots of stuff isn't initialized, leading to SEGV very quickly. Even calling pthread_self is a bit suspect, but it happens to work. */ return reentrant; } void __mf_set_state (enum __mf_state_enum new_state) { struct mf_thread_data *data = __mf_find_threadinfo (1); data->state = new_state; } #endif /* The following two functions are used only with __mf_opts.heur_std_data. We're interested in recording the location of the thread-local errno variable. Note that this doesn't handle TLS references in general; we have no visibility into __tls_get_data for when that memory is allocated at runtime. Hopefully we get to see the malloc or mmap operation that eventually allocates the backing store. */ /* Describe the startup information for a new user thread. */ struct mf_thread_start_info { /* The user's thread entry point and argument. */ void * (*user_fn)(void *); void *user_arg; }; static void __mf_pthread_cleanup (void *arg) { if (__mf_opts.heur_std_data) __mf_unregister (&errno, sizeof (errno), __MF_TYPE_GUESS); #ifndef HAVE_TLS struct mf_thread_data *data = __mf_find_threadinfo (0); if (data) data->used_p = 0; #endif } static void * __mf_pthread_spawner (void *arg) { void *result = NULL; __mf_set_state (active); /* NB: We could use __MF_TYPE_STATIC here, but we guess that the thread errno is coming out of some dynamically allocated pool that we already know of as __MF_TYPE_HEAP. */ if (__mf_opts.heur_std_data) __mf_register (&errno, sizeof (errno), __MF_TYPE_GUESS, "errno area (thread)"); /* We considered using pthread_key_t objects instead of these cleanup stacks, but they were less cooperative with the interposed malloc hooks in libmudflap. */ /* ??? The pthread_key_t problem is solved above... */ pthread_cleanup_push (__mf_pthread_cleanup, NULL); /* Extract given entry point and argument. */ struct mf_thread_start_info *psi = arg; void * (*user_fn)(void *) = psi->user_fn; void *user_arg = psi->user_arg; CALL_REAL (free, arg); result = (*user_fn)(user_arg); pthread_cleanup_pop (1 /* execute */); return result; } #if PIC /* A special bootstrap variant. */ int __mf_0fn_pthread_create (pthread_t *thr, const pthread_attr_t *attr, void * (*start) (void *), void *arg) { return -1; } #endif #undef pthread_create WRAPPER(int, pthread_create, pthread_t *thr, const pthread_attr_t *attr, void * (*start) (void *), void *arg) { struct mf_thread_start_info *si; TRACE ("pthread_create\n"); /* Fill in startup-control fields. */ si = CALL_REAL (malloc, sizeof (*si)); si->user_fn = start; si->user_arg = arg; /* Actually create the thread. */ return CALL_REAL (pthread_create, thr, attr, __mf_pthread_spawner, si); }
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