/* * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ #include <sys/types.h> #include <sys/proc.h> #include <sys/proc_internal.h> #include <sys/systm.h> #include <sys/user.h> #include <sys/dtrace_ptss.h> #include <mach/vm_param.h> #include <mach/mach_vm.h> #include <kern/task.h> #include <vm/vm_map.h> /* * This function requires the sprlock to be held * * In general, it will not block. If it needs to allocate a new * page of memory, the underlying kernel _MALLOC may block. */ struct dtrace_ptss_page_entry* dtrace_ptss_claim_entry_locked(struct proc* p) { lck_mtx_assert(&p->p_dtrace_sprlock, LCK_MTX_ASSERT_OWNED); struct dtrace_ptss_page_entry* entry = NULL; while (TRUE) { struct dtrace_ptss_page_entry* temp = p->p_dtrace_ptss_free_list; if (temp == NULL) { // Nothing on the free list. Allocate a new page, its okay if multiple threads race here. struct dtrace_ptss_page* page = dtrace_ptss_allocate_page(p); // Make sure we actually got a page if (page == NULL) return NULL; // Add the page to the page list page->next = p->p_dtrace_ptss_pages; p->p_dtrace_ptss_pages = page; // CAS the entries onto the free list. do { page->entries[DTRACE_PTSS_ENTRIES_PER_PAGE-1].next = p->p_dtrace_ptss_free_list; } while (!OSCompareAndSwapPtr((void *)page->entries[DTRACE_PTSS_ENTRIES_PER_PAGE-1].next, (void *)&page->entries[0], (void * volatile *)&p->p_dtrace_ptss_free_list)); // Now that we've added to the free list, try again. continue; } // Claim temp if (!OSCompareAndSwapPtr((void *)temp, (void *)temp->next, (void * volatile *)&p->p_dtrace_ptss_free_list)) continue; // At this point, we own temp. entry = temp; break; } return entry; } /* * This function does not require any locks to be held on entry. */ struct dtrace_ptss_page_entry* dtrace_ptss_claim_entry(struct proc* p) { // Verify no locks held on entry lck_mtx_assert(&p->p_dtrace_sprlock, LCK_MTX_ASSERT_NOTOWNED); lck_mtx_assert(&p->p_mlock, LCK_MTX_ASSERT_NOTOWNED); struct dtrace_ptss_page_entry* entry = NULL; while (TRUE) { struct dtrace_ptss_page_entry* temp = p->p_dtrace_ptss_free_list; if (temp == NULL) { lck_mtx_lock(&p->p_dtrace_sprlock); temp = dtrace_ptss_claim_entry_locked(p); lck_mtx_unlock(&p->p_dtrace_sprlock); return temp; } // Claim temp if (!OSCompareAndSwapPtr((void *)temp, (void *)temp->next, (void * volatile *)&p->p_dtrace_ptss_free_list)) continue; // At this point, we own temp. entry = temp; break; } return entry; } /* * This function does not require any locks to be held on entry. * * (PR-11138709) A NULL p->p_dtrace_ptss_pages means the entry can * no longer be referenced safely. When found in this state, the chore * of releasing an entry to the free list is ignored. */ void dtrace_ptss_release_entry(struct proc* p, struct dtrace_ptss_page_entry* e) { if (p && p->p_dtrace_ptss_pages && e) { do { e->next = p->p_dtrace_ptss_free_list; } while (!OSCompareAndSwapPtr((void *)e->next, (void *)e, (void * volatile *)&p->p_dtrace_ptss_free_list)); } } /* * This function allocates a new page in the target process's address space. * * It returns a dtrace_ptss_page that has its entries chained, with the last * entries next field set to NULL. It does not add the page or the entries to * the process's page/entry lists. * * This function does not require that any locks be held when it is invoked. */ struct dtrace_ptss_page* dtrace_ptss_allocate_page(struct proc* p) { // Allocate the kernel side data struct dtrace_ptss_page* ptss_page = _MALLOC(sizeof(struct dtrace_ptss_page), M_TEMP, M_ZERO | M_WAITOK); if (ptss_page == NULL) return NULL; // Now allocate a page in user space and set its protections to allow execute. task_t task = p->task; vm_map_t map = get_task_map_reference(task); mach_vm_address_t addr = 0LL; mach_vm_size_t size = PAGE_SIZE; // We need some way to assert that this matches vm_map_round_page() !!! #if CONFIG_EMBEDDED /* The embedded OS has extra permissions for writable and executable pages. We can't pass in the flags * we need for the correct permissions from mach_vm_allocate, so need to call mach_vm_map directly. */ mach_vm_offset_t map_addr = 0; kern_return_t kr = mach_vm_map(map, &map_addr, size, 0, VM_FLAGS_ANYWHERE, IPC_PORT_NULL, 0, FALSE, VM_PROT_READ|VM_PROT_EXECUTE, VM_PROT_READ|VM_PROT_EXECUTE, VM_INHERIT_DEFAULT); if (kr != KERN_SUCCESS) { goto err; } addr = map_addr; #else kern_return_t kr = mach_vm_allocate(map, &addr, size, VM_FLAGS_ANYWHERE); if (kr != KERN_SUCCESS) { goto err; } kr = mach_vm_protect(map, addr, size, 0, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE); if (kr != KERN_SUCCESS) { mach_vm_deallocate(map, addr, size); goto err; } #endif // Chain the page entries. int i; for (i=0; i<DTRACE_PTSS_ENTRIES_PER_PAGE; i++) { ptss_page->entries[i].addr = addr + (i * DTRACE_PTSS_SCRATCH_SPACE_PER_THREAD); ptss_page->entries[i].next = &ptss_page->entries[i+1]; } // The last entry should point to NULL ptss_page->entries[DTRACE_PTSS_ENTRIES_PER_PAGE-1].next = NULL; vm_map_deallocate(map); return ptss_page; err: _FREE(ptss_page, M_TEMP); vm_map_deallocate(map); return NULL; } /* * This function frees an existing page in the target process's address space. * * It does not alter any of the process's page/entry lists. * * TODO: Inline in dtrace_ptrace_exec_exit? */ void dtrace_ptss_free_page(struct proc* p, struct dtrace_ptss_page* ptss_page) { // Grab the task and get a reference to its vm_map task_t task = p->task; vm_map_t map = get_task_map_reference(task); mach_vm_address_t addr = ptss_page->entries[0].addr; mach_vm_size_t size = PAGE_SIZE; // We need some way to assert that this matches vm_map_round_page() !!! // Silent failures, no point in checking return code. mach_vm_deallocate(map, addr, size); vm_map_deallocate(map); } /* * This function assumes that the target process has been * suspended, and the proc_lock & sprlock is held */ void dtrace_ptss_enable(struct proc* p) { lck_mtx_assert(&p->p_dtrace_sprlock, LCK_MTX_ASSERT_OWNED); lck_mtx_assert(&p->p_mlock, LCK_MTX_ASSERT_OWNED); struct uthread* uth; /* * XXX There has been a concern raised about holding the proc_lock * while calling dtrace_ptss_claim_entry(), due to the fact * that dtrace_ptss_claim_entry() can potentially malloc. */ TAILQ_FOREACH(uth, &p->p_uthlist, uu_list) { uth->t_dtrace_scratch = dtrace_ptss_claim_entry_locked(p); } } /* * This function is not thread safe. * * It assumes the sprlock is held, and the proc_lock is not. */ void dtrace_ptss_exec_exit(struct proc* p) { /* * Should hold sprlock to touch the pages list. Must not * hold the proc lock to avoid deadlock. */ lck_mtx_assert(&p->p_dtrace_sprlock, LCK_MTX_ASSERT_OWNED); lck_mtx_assert(&p->p_mlock, LCK_MTX_ASSERT_NOTOWNED); p->p_dtrace_ptss_free_list = NULL; struct dtrace_ptss_page* temp = p->p_dtrace_ptss_pages; p->p_dtrace_ptss_pages = NULL; while (temp != NULL) { struct dtrace_ptss_page* next = temp->next; // Do we need to specifically mach_vm_deallocate the user pages? // This can be called when the process is exiting, I believe the proc's // vm_map_t may already be toast. // Must be certain to free the kernel memory! _FREE(temp, M_TEMP); temp = next; } } /* * This function is not thread safe. It is not used for vfork. * * The child proc ptss fields are initialized to NULL at fork time. * Pages allocated in the parent are copied as part of the vm_map copy, though. * We need to deallocate those pages. * * Parent and child sprlock should be held, and proc_lock must NOT be held. */ void dtrace_ptss_fork(struct proc* parent, struct proc* child) { // The child should not have any pages/entries allocated at this point. // ASSERT(child->p_dtrace_ptss_pages == NULL); // ASSERT(child->p_dtrace_ptss_free_list == NULL); /* * The parent's sprlock should be held, to protect its pages list * from changing while the child references it. The child's sprlock * must also be held, because we are modifying its pages list. * Finally, to prevent a deadlock with the fasttrap cleanup code, * neither the parent or child proc_lock should be held. */ lck_mtx_assert(&parent->p_dtrace_sprlock, LCK_MTX_ASSERT_OWNED); lck_mtx_assert(&parent->p_mlock, LCK_MTX_ASSERT_NOTOWNED); lck_mtx_assert(&child->p_dtrace_sprlock, LCK_MTX_ASSERT_OWNED); lck_mtx_assert(&child->p_mlock, LCK_MTX_ASSERT_NOTOWNED); // Get page list from *PARENT* struct dtrace_ptss_page* temp = parent->p_dtrace_ptss_pages; while (temp != NULL) { // Freeing the page in the *CHILD* dtrace_ptss_free_page(child, temp); // Do not free the kernel memory, it belong to the parent. temp = temp->next; } }