1 /* 2 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> and David Xu <davidxu@freebsd.org> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $DragonFly: src/sys/kern/kern_umtx.c,v 1.5 2006/06/05 07:26:10 dillon Exp $ 35 */ 36 37 /* 38 * This module implements userland mutex helper functions. umtx_sleep() 39 * handling blocking and umtx_wakeup() handles wakeups. The sleep/wakeup 40 * functions operate on user addresses. 41 */ 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/kernel.h> 46 #include <sys/sysproto.h> 47 #include <sys/sysunion.h> 48 #include <sys/sysent.h> 49 #include <sys/syscall.h> 50 #include <sys/module.h> 51 52 #include <vm/vm.h> 53 #include <vm/vm_param.h> 54 #include <sys/lock.h> 55 #include <vm/pmap.h> 56 #include <vm/vm_map.h> 57 #include <vm/vm_object.h> 58 #include <vm/vm_page.h> 59 #include <vm/vm_pager.h> 60 #include <vm/vm_pageout.h> 61 #include <vm/vm_extern.h> 62 #include <vm/vm_page.h> 63 #include <vm/vm_kern.h> 64 65 /* 66 * If the contents of the userland-supplied pointer matches the specified 67 * value enter an interruptable sleep for up to <timeout> microseconds. 68 * If the contents does not match then return immediately. 69 * 70 * The specified timeout may not exceed 1 second. 71 * 72 * Returns 0 if we slept and were woken up, -1 and ETIMEDOUT if we slept 73 * and timed out, and EBUSY if the contents of the pointer did not match 74 * the specified value. A timeout of 0 indicates an unlimited sleep. 75 * EINTR is returned if the call was interrupted by a signal. 76 * 77 * This function interlocks against call to umtx_wakeup. It does NOT interlock 78 * against changes in *ptr. However, it does not have to. The standard use 79 * of *ptr is to differentiate between an uncontested and a contested mutex 80 * and call umtx_wakeup when releasing a contested mutex. Therefore we can 81 * safely race against changes in *ptr as long as we are properly interlocked 82 * against the umtx_wakeup() call. 83 * 84 * The VM page associated with the mutex is held to prevent reuse in order 85 * to guarentee that the physical address remains consistent. 86 * 87 * umtx_sleep { const int *ptr, int value, int timeout } 88 */ 89 int 90 sys_umtx_sleep(struct umtx_sleep_args *uap) 91 { 92 int error = EBUSY; 93 vm_paddr_t pa; 94 vm_page_t m; 95 void *waddr; 96 int timeout; 97 98 if ((unsigned int)uap->timeout > 1000000) 99 return (EINVAL); 100 if (vm_fault_quick((caddr_t)__DEQUALIFY(int *, uap->ptr), VM_PROT_READ) < 0) 101 return (EFAULT); 102 103 if (fuword(__DEQUALIFY(const int *, uap->ptr)) == uap->value) { 104 if ((pa = pmap_kextract((vm_offset_t)uap->ptr)) == 0) 105 return (EFAULT); 106 m = PHYS_TO_VM_PAGE(pa); 107 vm_page_hold(m); 108 109 if ((timeout = uap->timeout) != 0) 110 timeout = (timeout * hz + 999999) / 1000000; 111 waddr = (void *)((intptr_t)pa + ((intptr_t)uap->ptr & PAGE_MASK)); 112 error = tsleep(waddr, PCATCH|PDOMAIN_UMTX, "umtxsl", timeout); 113 vm_page_unhold(m); 114 /* Can not restart timeout wait. */ 115 if (timeout != 0 && error == ERESTART) 116 error = EINTR; 117 } else { 118 error = EBUSY; 119 } 120 return(error); 121 } 122 123 /* 124 * umtx_wakeup { const int *ptr, int count } 125 * 126 * Wakeup the specified number of processes held in umtx_sleep() on the 127 * specified user address. A count of 0 wakes up all waiting processes. 128 * 129 * XXX assumes that the physical address space does not exceed the virtual 130 * address space. 131 */ 132 int 133 sys_umtx_wakeup(struct umtx_wakeup_args *uap) 134 { 135 vm_paddr_t pa; 136 void *waddr; 137 138 cpu_mfence(); 139 if (vm_fault_quick((caddr_t)__DEQUALIFY(int *, uap->ptr), VM_PROT_READ) < 0) 140 return (EFAULT); 141 if ((pa = pmap_kextract((vm_offset_t)uap->ptr)) == 0) 142 return (EFAULT); 143 waddr = (void *)((intptr_t)pa + ((intptr_t)uap->ptr & PAGE_MASK)); 144 if (uap->count == 1) { 145 wakeup_domain_one(waddr, PDOMAIN_UMTX); 146 } else { 147 /* XXX wakes them all up for now */ 148 wakeup_domain(waddr, PDOMAIN_UMTX); 149 } 150 return(0); 151 } 152 153