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- /* -*- mode:c; c-file-style:"k&r"; c-basic-offset: 4; tab-width:4; indent-tabs-mode:nil; mode:auto-fill; fill-column:78; -*- */
- /* vim: set ts=4 sw=4 et tw=78 fo=cqt wm=0: */
- /* Copyright (C) 2014 Stony Brook University
- This file is part of Graphene Library OS.
- Graphene Library OS 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 3 of the
- License, or (at your option) any later version.
- Graphene Library OS 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 program. If not, see <http://www.gnu.org/licenses/>. */
- /*
- * shim_futex.c
- *
- * Implementation of system call "futex", "set_robust_list" and
- * "get_robust_list".
- */
- #include <shim_internal.h>
- #include <shim_table.h>
- #include <shim_thread.h>
- #include <shim_checkpoint.h>
- #include <shim_utils.h>
- #include <pal.h>
- #include <pal_error.h>
- #include <list.h>
- #include <sys/syscall.h>
- #include <sys/mman.h>
- #include <asm/prctl.h>
- #include <linux/futex.h>
- #include <errno.h>
- #define FUTEX_MIN_VALUE 0
- #define FUTEX_MAX_VALUE 255
- /* futex_waiters are linked off of shim_futex_handle by the waiters
- * listp */
- struct futex_waiter {
- struct shim_thread * thread;
- uint32_t bitset;
- LIST_TYPE(futex_waiter) list;
- };
- // Links shim_futex_handle by the list field
- DEFINE_LISTP(shim_futex_handle);
- static LISTP_TYPE(shim_futex_handle) futex_list = LISTP_INIT;
- static LOCKTYPE futex_list_lock;
- int shim_do_futex (unsigned int * uaddr, int op, int val, void * utime,
- unsigned int * uaddr2, int val3)
- {
- struct shim_futex_handle * tmp = NULL, * futex = NULL, * futex2 = NULL;
- struct shim_handle * hdl = NULL, * hdl2 = NULL;
- uint32_t futex_op = (op & FUTEX_CMD_MASK);
- uint32_t val2 = 0;
- int ret = 0;
- if (!uaddr || ((uintptr_t) uaddr % sizeof(unsigned int)))
- return -EINVAL;
- create_lock_runtime(&futex_list_lock);
- lock(futex_list_lock);
- listp_for_each_entry(tmp, &futex_list, list)
- if (tmp->uaddr == uaddr) {
- futex = tmp;
- break;
- }
- if (futex) {
- hdl = container_of(futex, struct shim_handle, info.futex);
- get_handle(hdl);
- } else {
- if (!(hdl = get_new_handle())) {
- unlock(futex_list_lock);
- return -ENOMEM;
- }
- hdl->type = TYPE_FUTEX;
- futex = &hdl->info.futex;
- futex->uaddr = uaddr;
- get_handle(hdl);
- INIT_LISTP(&futex->waiters);
- INIT_LIST_HEAD(futex, list);
- listp_add_tail(futex, &futex_list, list);
- }
- if (futex_op == FUTEX_WAKE_OP || futex_op == FUTEX_REQUEUE ||
- futex_op == FUTEX_CMP_REQUEUE) {
- listp_for_each_entry(tmp, &futex_list, list)
- if (tmp->uaddr == uaddr2) {
- futex2 = tmp;
- break;
- }
- if (futex2) {
- hdl2 = container_of(futex2, struct shim_handle, info.futex);
- get_handle(hdl2);
- } else {
- if (!(hdl2 = get_new_handle())) {
- unlock(futex_list_lock);
- return -ENOMEM;
- }
- hdl2->type = TYPE_FUTEX;
- futex2 = &hdl2->info.futex;
- futex2->uaddr = uaddr2;
- get_handle(hdl2);
- INIT_LISTP(&futex2->waiters);
- INIT_LIST_HEAD(futex2, list);
- listp_add_tail(futex2, &futex_list, list);
- }
- val2 = (uint32_t)(uint64_t) utime;
- }
- unlock(futex_list_lock);
- lock(hdl->lock);
- uint64_t timeout_us = NO_TIMEOUT;
- switch (futex_op) {
- case FUTEX_WAIT_BITSET:
- if (utime && timeout_us == NO_TIMEOUT) {
- struct timespec *ts = (struct timespec*) utime;
- // Round to microsecs
- timeout_us = (ts->tv_sec * 1000000) + (ts->tv_nsec / 1000);
- // Check for the CLOCK_REALTIME flag
- if (futex_op == FUTEX_WAIT_BITSET) {
- // DEP 1/28/17: Should really differentiate clocks, but
- // Graphene only has one for now.
- //&& 0 != (op & FUTEX_CLOCK_REALTIME)) {
- uint64_t current_time = DkSystemTimeQuery();
- if (current_time == 0) {
- ret = -EINVAL;
- break;
- }
- timeout_us -= current_time;
- }
- }
- /* Note: for FUTEX_WAIT, timeout is interpreted as a relative
- * value. This differs from other futex operations, where
- * timeout is interpreted as an absolute value. To obtain the
- * equivalent of FUTEX_WAIT with an absolute timeout, employ
- * FUTEX_WAIT_BITSET with val3 specified as
- * FUTEX_BITSET_MATCH_ANY. */
- case FUTEX_WAIT:
- if (utime && timeout_us == NO_TIMEOUT) {
- struct timespec *ts = (struct timespec*) utime;
- // Round to microsecs
- timeout_us = (ts->tv_sec * 1000000) + (ts->tv_nsec / 1000);
- }
- {
- uint32_t bitset = (futex_op == FUTEX_WAIT_BITSET) ? val3 :
- 0xffffffff;
- debug("FUTEX_WAIT: %p (val = %d) vs %d mask = %08x, timeout ptr %p\n",
- uaddr, *uaddr, val, bitset, utime);
- if (*uaddr != val) {
- ret = -EAGAIN;
- break;
- }
- struct futex_waiter waiter;
- thread_setwait(&waiter.thread, NULL);
- INIT_LIST_HEAD(&waiter, list);
- waiter.bitset = bitset;
- listp_add_tail(&waiter, &futex->waiters, list);
- unlock(hdl->lock);
- ret = thread_sleep(timeout_us);
- /* DEP 1/28/17: Should return ETIMEDOUT, not EAGAIN, on timeout. */
- if (ret == -EAGAIN)
- ret = -ETIMEDOUT;
- if (ret == -ETIMEDOUT)
- listp_del(&waiter, &futex->waiters, list);
- lock(hdl->lock);
- /* Chia-Che 10/17/17: FUTEX_WAKE should remove the waiter
- * from the list; if not, we should remove it now. */
- if (!list_empty(&waiter, list))
- listp_del(&waiter, &futex->waiters, list);
- break;
- }
- case FUTEX_WAKE:
- case FUTEX_WAKE_BITSET: {
- struct futex_waiter * waiter, * wtmp;
- int nwaken = 0;
- uint32_t bitset = (futex_op == FUTEX_WAKE_BITSET) ? val3 :
- 0xffffffff;
-
- debug("FUTEX_WAKE: %p (val = %d) count = %d mask = %08x\n",
- uaddr, *uaddr, val, bitset);
- listp_for_each_entry_safe(waiter, wtmp, &futex->waiters, list) {
- if (!(bitset & waiter->bitset))
- continue;
- debug("FUTEX_WAKE wake thread %d: %p (val = %d)\n",
- waiter->thread->tid, uaddr, *uaddr);
- listp_del_init(waiter, &futex->waiters, list);
- thread_wakeup(waiter->thread);
- nwaken++;
- if (nwaken >= val) break;
- }
- ret = nwaken;
- debug("FUTEX_WAKE done: %p (val = %d) woke %d threads\n", uaddr, *uaddr, ret);
- break;
- }
- case FUTEX_WAKE_OP: {
- assert(futex2);
- int oldval = *(int *) uaddr2, newval, cmpval;
- newval = (val3 >> 12) & 0xfff;
- switch ((val3 >> 28) & 0xf) {
- case FUTEX_OP_SET: break;
- case FUTEX_OP_ADD: newval = oldval + newval; break;
- case FUTEX_OP_OR: newval = oldval | newval; break;
- case FUTEX_OP_ANDN: newval = oldval & ~newval; break;
- case FUTEX_OP_XOR: newval = oldval ^ newval; break;
- }
- cmpval = val3 & 0xfff;
- switch ((val3 >> 24) & 0xf) {
- case FUTEX_OP_CMP_EQ: cmpval = (oldval == cmpval); break;
- case FUTEX_OP_CMP_NE: cmpval = (oldval != cmpval); break;
- case FUTEX_OP_CMP_LT: cmpval = (oldval < cmpval); break;
- case FUTEX_OP_CMP_LE: cmpval = (oldval <= cmpval); break;
- case FUTEX_OP_CMP_GT: cmpval = (oldval > cmpval); break;
- case FUTEX_OP_CMP_GE: cmpval = (oldval >= cmpval); break;
- }
- *(int *) uaddr2 = newval;
- struct futex_waiter * waiter, * wtmp;
- int nwaken = 0;
- debug("FUTEX_WAKE_OP: %p (val = %d) count = %d\n", uaddr, *uaddr, val);
- listp_for_each_entry_safe(waiter, wtmp, &futex->waiters, list) {
- debug("FUTEX_WAKE_OP wake thread %d: %p (val = %d)\n",
- waiter->thread->tid, uaddr, *uaddr);
- listp_del_init(waiter, &futex->waiters, list);
- thread_wakeup(waiter->thread);
- nwaken++;
- }
- if (cmpval) {
- unlock(hdl->lock);
- put_handle(hdl);
- hdl = hdl2;
- lock(hdl->lock);
- debug("FUTEX_WAKE: %p (val = %d) count = %d\n", uaddr2,
- *uaddr2, val2);
- listp_for_each_entry_safe(waiter, wtmp, &futex2->waiters, list) {
- debug("FUTEX_WAKE_OP(2) wake thread %d: %p (val = %d)\n",
- waiter->thread->tid, uaddr2, *uaddr2);
- listp_del_init(waiter, &futex2->waiters, list);
- thread_wakeup(waiter->thread);
- nwaken++;
- }
- }
- ret = nwaken;
- break;
- }
- case FUTEX_CMP_REQUEUE:
- if (*uaddr != val3) {
- ret = -EAGAIN;
- break;
- }
- case FUTEX_REQUEUE: {
- assert(futex2);
- struct futex_waiter * waiter, * wtmp;
- int nwaken = 0;
- listp_for_each_entry_safe(waiter, wtmp, &futex->waiters, list) {
- listp_del_init(waiter, &futex->waiters, list);
- thread_wakeup(waiter->thread);
- nwaken++;
- if (nwaken >= val)
- break;
- }
- lock(hdl2->lock);
- listp_splice_init(&futex->waiters, &futex2->waiters, list, futex_waiter);
- unlock(hdl2->lock);
- put_handle(hdl2);
- ret = nwaken;
- break;
- }
- case FUTEX_FD:
- ret = set_new_fd_handle(hdl, 0, NULL);
- break;
- default:
- debug("unsupported futex op: 0x%x\n", op);
- ret = -ENOSYS;
- break;
- }
- unlock(hdl->lock);
- put_handle(hdl);
- return ret;
- }
- int shim_do_set_robust_list (struct robust_list_head * head, size_t len)
- {
- struct shim_thread * self = get_cur_thread();
- assert(self);
- if (len != sizeof(struct robust_list_head))
- return -EINVAL;
- self->robust_list = head;
- return 0;
- }
- int shim_do_get_robust_list (pid_t pid, struct robust_list_head ** head,
- size_t * len)
- {
- if (!head)
- return -EFAULT;
- struct shim_thread * thread;
- if (pid) {
- thread = lookup_thread(pid);
- if (!thread)
- return -ESRCH;
- } else {
- thread = get_cur_thread();
- }
- *head = (struct robust_list_head *) thread->robust_list;
- *len = sizeof(struct robust_list_head);
- return 0;
- }
- void release_robust_list (struct robust_list_head * head)
- {
- long futex_offset = head->futex_offset;
- struct robust_list * robust, * prev = &head->list;
- create_lock_runtime(&futex_list_lock);
- for (robust = prev->next ; robust && robust != prev ;
- prev = robust, robust = robust->next) {
- void * futex_addr = (void *) robust + futex_offset;
- struct shim_futex_handle * tmp, * futex = NULL;
- lock(futex_list_lock);
- listp_for_each_entry(tmp, &futex_list, list)
- if (tmp->uaddr == futex_addr) {
- futex = tmp;
- break;
- }
- unlock(futex_list_lock);
- if (!futex)
- continue;
- struct futex_waiter * waiter, * wtmp;
- struct shim_handle * hdl =
- container_of(futex, struct shim_handle, info.futex);
- get_handle(hdl);
- lock(hdl->lock);
- debug("release robust list: %p\n", futex_addr);
- *(int *) futex_addr = 0;
- listp_for_each_entry_safe(waiter, wtmp, &futex->waiters, list) {
- listp_del_init(waiter, &futex->waiters, list);
- thread_wakeup(waiter->thread);
- }
- unlock(hdl->lock);
- put_handle(hdl);
- }
- }
- void release_clear_child_id (int * clear_child_tid)
- {
- debug("clear child tid at %p\n", clear_child_tid);
- *clear_child_tid = 0;
- create_lock_runtime(&futex_list_lock);
- struct shim_futex_handle * tmp, * futex = NULL;
- lock(futex_list_lock);
- listp_for_each_entry(tmp, &futex_list, list)
- if (tmp->uaddr == (void *) clear_child_tid) {
- futex = tmp;
- break;
- }
- unlock(futex_list_lock);
- if (!futex)
- return;
- struct futex_waiter * waiter, * wtmp;
- struct shim_handle * hdl =
- container_of(futex, struct shim_handle, info.futex);
- get_handle(hdl);
- lock(hdl->lock);
- debug("release futex at %p\n", clear_child_tid);
- *clear_child_tid = 0;
- listp_for_each_entry_safe(waiter, wtmp, &futex->waiters, list) {
- listp_del_init(waiter, &futex->waiters, list);
- thread_wakeup(waiter->thread);
- }
- unlock(hdl->lock);
- put_handle(hdl);
- }
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