+++ /dev/null
-/*
- * compat_arch_x86.c
- *
- * Userspace RCU library - x86 compatibility checks
- *
- * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library 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
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include <stdio.h>
-#include <pthread.h>
-#include <signal.h>
-#include <assert.h>
-#include <urcu/uatomic.h>
-
-/*
- * Using attribute "weak" for __rcu_cas_avail and
- * __urcu_x86_compat_mutex. Those are globally visible by the entire
- * program, even though many shared objects may have their own version.
- * The first version that gets loaded will be used by the entire
- * program (executable and all shared objects).
- */
-
-/*
- * It does not really matter if the constructor is called before using
- * the library, as long as the caller checks if __rcu_cas_avail < 0 and calls
- * compat_arch_init() explicitely if needed.
- */
-int __attribute__((constructor)) __rcu_cas_init(void);
-
-/*
- * -1: unknown
- * 1: available
- * 0: unavailable
- */
-__attribute__((weak))
-int __rcu_cas_avail = -1;
-
-__attribute__((weak))
-pthread_mutex_t __urcu_x86_compat_mutex = PTHREAD_MUTEX_INITIALIZER;
-
-/*
- * get_eflags/set_eflags/compare_and_swap_is_available imported from glibc
- * 2.3.5. linuxthreads/sysdeps/i386/pt-machine.h.
- */
-
-static int get_eflags (void)
-{
- int res;
- __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : );
- return res;
-}
-
-static void set_eflags (int newflags)
-{
- __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc");
-}
-
-static int compare_and_swap_is_available (void)
-{
- int oldflags = get_eflags ();
- int changed;
- /* Flip AC bit in EFLAGS. */
- set_eflags (oldflags ^ 0x40000);
- /* See if bit changed. */
- changed = (get_eflags () ^ oldflags) & 0x40000;
- /* Restore EFLAGS. */
- set_eflags (oldflags);
- /* If the AC flag did not change, it's a 386 and it lacks cmpxchg.
- Otherwise, it's a 486 or above and it has cmpxchg. */
- return changed != 0;
-}
-
-static void mutex_lock_signal_save(pthread_mutex_t *mutex, sigset_t *oldmask)
-{
- sigset_t newmask;
- int ret;
-
- /* Disable signals */
- ret = sigfillset(&newmask);
- assert(!ret);
- ret = pthread_sigmask(SIG_BLOCK, &newmask, oldmask);
- assert(!ret);
- ret = pthread_mutex_lock(&__urcu_x86_compat_mutex);
- assert(!ret);
-}
-
-static void mutex_lock_signal_restore(pthread_mutex_t *mutex, sigset_t *oldmask)
-{
- int ret;
-
- ret = pthread_mutex_unlock(&__urcu_x86_compat_mutex);
- assert(!ret);
- ret = pthread_sigmask(SIG_SETMASK, oldmask, NULL);
- assert(!ret);
-}
-
-unsigned long _compat_uatomic_set(void *addr, unsigned long _new, int len)
-{
- sigset_t mask;
- unsigned long result;
-
- mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask);
- switch (len) {
- case 1:
- *(unsigned char *)addr = (unsigned char)_new;
- result = *(unsigned char *)addr;
- break;
- case 2:
- *(unsigned short *)addr = (unsigned short)_new;
- result = *(unsigned short *)addr;
- break;
- case 4:
- *(unsigned int *)addr = (unsigned int)_new;
- result = *(unsigned int *)addr;
- break;
- default:
- /*
- * generate an illegal instruction. Cannot catch this with
- * linker tricks when optimizations are disabled.
- */
- result = 0;
- __asm__ __volatile__("ud2");
- }
- mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask);
- return result;
-}
-
-unsigned long _compat_uatomic_xchg(void *addr, unsigned long _new, int len)
-{
- sigset_t mask;
- unsigned long retval;
-
- mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask);
- switch (len) {
- case 1:
- retval = *(unsigned char *)addr;
- *(unsigned char *)addr = (unsigned char)_new;
- break;
- case 2:
- retval = *(unsigned short *)addr;
- *(unsigned short *)addr = (unsigned short)_new;
- break;
- case 4:
- retval = *(unsigned int *)addr;
- *(unsigned int *)addr = (unsigned int)_new;
- break;
- default:
- /*
- * generate an illegal instruction. Cannot catch this with
- * linker tricks when optimizations are disabled.
- */
- retval = 0; /* silence gcc warnings */
- __asm__ __volatile__("ud2");
- }
- mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask);
- return retval;
-}
-
-unsigned long _compat_uatomic_cmpxchg(void *addr, unsigned long old,
- unsigned long _new, int len)
-{
- unsigned long retval;
- sigset_t mask;
-
- mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask);
- switch (len) {
- case 1:
- {
- unsigned char result = *(unsigned char *)addr;
- if (result == (unsigned char)old)
- *(unsigned char *)addr = (unsigned char)_new;
- retval = result;
- break;
- }
- case 2:
- {
- unsigned short result = *(unsigned short *)addr;
- if (result == (unsigned short)old)
- *(unsigned short *)addr = (unsigned short)_new;
- retval = result;
- break;
- }
- case 4:
- {
- unsigned int result = *(unsigned int *)addr;
- if (result == (unsigned int)old)
- *(unsigned int *)addr = (unsigned int)_new;
- retval = result;
- break;
- }
- default:
- /*
- * generate an illegal instruction. Cannot catch this with
- * linker tricks when optimizations are disabled.
- */
- retval = 0; /* silence gcc warnings */
- __asm__ __volatile__("ud2");
- }
- mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask);
- return retval;
-}
-
-void _compat_uatomic_or(void *addr, unsigned long v, int len)
-{
- sigset_t mask;
-
- mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask);
- switch (len) {
- case 1:
- *(unsigned char *)addr |= (unsigned char)v;
- break;
- case 2:
- *(unsigned short *)addr |= (unsigned short)v;
- break;
- case 4:
- *(unsigned int *)addr |= (unsigned int)v;
- break;
- default:
- /*
- * generate an illegal instruction. Cannot catch this with
- * linker tricks when optimizations are disabled.
- */
- __asm__ __volatile__("ud2");
- }
- mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask);
-}
-
-void _compat_uatomic_and(void *addr, unsigned long v, int len)
-{
- sigset_t mask;
-
- mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask);
- switch (len) {
- case 1:
- *(unsigned char *)addr &= (unsigned char)v;
- break;
- case 2:
- *(unsigned short *)addr &= (unsigned short)v;
- break;
- case 4:
- *(unsigned int *)addr &= (unsigned int)v;
- break;
- default:
- /*
- * generate an illegal instruction. Cannot catch this with
- * linker tricks when optimizations are disabled.
- */
- __asm__ __volatile__("ud2");
- }
- mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask);
-}
-
-unsigned long _compat_uatomic_add_return(void *addr, unsigned long v, int len)
-{
- sigset_t mask;
- unsigned long result;
-
- mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask);
- switch (len) {
- case 1:
- *(unsigned char *)addr += (unsigned char)v;
- result = *(unsigned char *)addr;
- break;
- case 2:
- *(unsigned short *)addr += (unsigned short)v;
- result = *(unsigned short *)addr;
- break;
- case 4:
- *(unsigned int *)addr += (unsigned int)v;
- result = *(unsigned int *)addr;
- break;
- default:
- /*
- * generate an illegal instruction. Cannot catch this with
- * linker tricks when optimizations are disabled.
- */
- result = 0; /* silence gcc warnings */
- __asm__ __volatile__("ud2");
- }
- mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask);
- return result;
-}
-
-int __rcu_cas_init(void)
-{
- if (__rcu_cas_avail < 0)
- __rcu_cas_avail = compare_and_swap_is_available();
- return __rcu_cas_avail;
-}
projects / urcu.git / blobdiff