+/*
+ * Copyright (c) 2007 Apple Inc. All rights reserved.
+ */
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License, Version 1.0 only
+ * (the "License"). You may not use this file except in compliance
+ * with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
+ * Use is subject to license terms.
+ */
+
+/*
+ * #pragma ident "@(#)dtrace_subr.c 1.12 05/06/08 SMI"
+ */
+
+#include <sys/dtrace.h>
+#include <sys/dtrace_glue.h>
+#include <sys/dtrace_impl.h>
+#include <sys/fasttrap.h>
+#include <sys/vm.h>
+#include <sys/user.h>
+#include <sys/kauth.h>
+#include <kern/debug.h>
+#include <arm/proc_reg.h>
+
+int (*dtrace_pid_probe_ptr) (arm_saved_state_t *);
+int (*dtrace_return_probe_ptr) (arm_saved_state_t *);
+
+kern_return_t
+dtrace_user_probe(arm_saved_state_t *, unsigned int);
+
+kern_return_t
+dtrace_user_probe(arm_saved_state_t *regs, unsigned int instr)
+{
+ /*
+ * FIXME
+ *
+ * The only call path into this method is always a user trap.
+ * We don't need to test for user trap, but should assert it.
+ */
+
+ lck_rw_t *rwp;
+ struct proc *p = current_proc();
+
+ uthread_t uthread = (uthread_t)get_bsdthread_info(current_thread());
+
+ kauth_cred_uthread_update(uthread, p);
+
+ if (((regs->cpsr & PSR_TF) && ((uint16_t) instr) == FASTTRAP_THUMB_RET_INSTR) ||
+ ((uint32_t) instr == FASTTRAP_ARM_RET_INSTR)) {
+ uint8_t step = uthread->t_dtrace_step;
+ uint8_t ret = uthread->t_dtrace_ret;
+ user_addr_t npc = uthread->t_dtrace_npc;
+
+ if (uthread->t_dtrace_ast) {
+ printf("dtrace_user_probe() should be calling aston()\n");
+ // aston(thread);
+ // uthread->t_sig_check = 1;
+ }
+
+ /*
+ * Clear all user tracing flags.
+ */
+ uthread->t_dtrace_ft = 0;
+
+ /*
+ * If we weren't expecting to take a return probe trap, kill
+ * the process as though it had just executed an unassigned
+ * trap instruction.
+ */
+ if (step == 0) {
+ /*
+ * APPLE NOTE: We're returning KERN_FAILURE, which causes
+ * the generic signal handling code to take over, which will effectively
+ * deliver a EXC_BAD_INSTRUCTION to the user process.
+ */
+ return KERN_FAILURE;
+ }
+
+ /*
+ * If we hit this trap unrelated to a return probe, we're
+ * just here to reset the AST flag since we deferred a signal
+ * until after we logically single-stepped the instruction we
+ * copied out.
+ */
+ if (ret == 0) {
+ regs->pc = npc;
+ return KERN_SUCCESS;
+ }
+
+ /*
+ * We need to wait until after we've called the
+ * dtrace_return_probe_ptr function pointer to step the pc.
+ */
+ rwp = &CPU->cpu_ft_lock;
+ lck_rw_lock_shared(rwp);
+
+ if (dtrace_return_probe_ptr != NULL)
+ (void) (*dtrace_return_probe_ptr)(regs);
+ lck_rw_unlock_shared(rwp);
+
+ regs->pc = npc;
+
+ return KERN_SUCCESS;
+ } else {
+ rwp = &CPU->cpu_ft_lock;
+
+ /*
+ * The DTrace fasttrap provider uses a trap,
+ * FASTTRAP_{ARM,THUMB}_INSTR. We let
+ * DTrace take the first crack at handling
+ * this trap; if it's not a probe that DTrace knows about,
+ * we call into the trap() routine to handle it like a
+ * breakpoint placed by a conventional debugger.
+ */
+
+ /*
+ * APPLE NOTE: I believe the purpose of the reader/writers lock
+ * is thus: There are times which dtrace needs to prevent calling
+ * dtrace_pid_probe_ptr(). Sun's original impl grabbed a plain
+ * mutex here. However, that serialized all probe calls, and
+ * destroyed MP behavior. So now they use a RW lock, with probes
+ * as readers, and the top level synchronization as a writer.
+ */
+ lck_rw_lock_shared(rwp);
+ if (dtrace_pid_probe_ptr != NULL &&
+ (*dtrace_pid_probe_ptr)(regs) == 0) {
+ lck_rw_unlock_shared(rwp);
+ return KERN_SUCCESS;
+ }
+ lck_rw_unlock_shared(rwp);
+
+ /*
+ * If the instruction that caused the breakpoint trap doesn't
+ * look like our trap anymore, it may be that this tracepoint
+ * was removed just after the user thread executed it. In
+ * that case, return to user land to retry the instuction.
+ *
+ * Note that the PC points to the instruction that caused the fault.
+ */
+ if (regs->cpsr & PSR_TF) {
+ uint16_t instr_check;
+ if (fuword16(regs->pc, &instr_check) == 0 && instr_check != FASTTRAP_THUMB_INSTR) {
+ return KERN_SUCCESS;
+ }
+ } else {
+ uint32_t instr_check;
+ if (fuword32(regs->pc, &instr_check) == 0 && instr_check != FASTTRAP_ARM_INSTR) {
+ return KERN_SUCCESS;
+ }
+ }
+ }
+
+ return KERN_FAILURE;
+}
+
+void
+dtrace_safe_synchronous_signal(void)
+{
+ /* Not implemented */
+}
+
+int
+dtrace_safe_defer_signal(void)
+{
+ /* Not implemented */
+ return 0;
+}
projects / apple / xnu.git / blobdiff