X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/0c530ab8987f0ae6a1a3d9284f40182b88852816..2d21ac55c334faf3a56e5634905ed6987fc787d4:/bsd/dev/i386/dtrace_subr_x86.c

diff --git a/bsd/dev/i386/dtrace_subr_x86.c b/bsd/dev/i386/dtrace_subr_x86.c
new file mode 100644
index 000000000..ae29f8416
--- /dev/null
+++ b/bsd/dev/i386/dtrace_subr_x86.c
@@ -0,0 +1,308 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (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 2006 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+/*
+ * #pragma ident	"@(#)dtrace_subr.c	1.13	06/06/12 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>
+
+int (*dtrace_pid_probe_ptr)(x86_saved_state_t *);
+int (*dtrace_return_probe_ptr)(x86_saved_state_t *);
+
+/*
+ * HACK! There doesn't seem to be an easy way to include trap.h from
+ * here. FIXME!
+ */
+#define	T_INT3			3		/* int 3 instruction */
+#define T_DTRACE_RET		0x7f		/* DTrace pid return */
+
+kern_return_t
+dtrace_user_probe(x86_saved_state_t *);
+
+kern_return_t
+dtrace_user_probe(x86_saved_state_t *regs)
+{
+	x86_saved_state64_t *regs64;
+	x86_saved_state32_t *regs32;
+        int trapno;
+
+	/*
+	 * 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.
+	 */
+	boolean_t user_mode = TRUE;
+
+        if (is_saved_state64(regs) == TRUE) {
+                regs64 = saved_state64(regs);
+		regs32 = NULL;
+                trapno = regs64->isf.trapno;
+                user_mode = TRUE; // By default, because xnu is 32 bit only
+        } else {
+		regs64 = NULL;
+                regs32 = saved_state32(regs);
+                if (regs32->cs & 0x03) user_mode = TRUE;
+                trapno = regs32->trapno;
+        }
+
+	lck_rw_t *rwp;
+	struct proc *p = current_proc();
+
+	uthread_t uthread = (uthread_t)get_bsdthread_info(current_thread());
+	if (user_mode /*|| (rp->r_ps & PS_VM)*/) {
+		/*
+		 * DTrace accesses t_cred in probe context.  t_cred
+		 * must always be either NULL, or point to a valid,
+		 * allocated cred structure.
+		 */
+		kauth_cred_uthread_update(uthread, p);
+	}
+
+	if (trapno == T_DTRACE_RET) {
+		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(uthread);
+			// 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) {
+			if (regs64) {
+				regs64->isf.rip = npc;
+			} else {
+				regs32->eip = npc;
+			}
+			return KERN_SUCCESS;
+		}
+
+		/*
+		 * We need to wait until after we've called the
+		 * dtrace_return_probe_ptr function pointer to set %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);
+
+		if (regs64) {
+			regs64->isf.rip = npc;
+		} else {
+			regs32->eip = npc;
+		}
+
+		return KERN_SUCCESS;
+	} else if (trapno == T_INT3) {
+		uint8_t instr;
+		rwp = &CPU->cpu_ft_lock;
+
+		/*
+		 * The DTrace fasttrap provider uses the breakpoint trap
+		 * (int 3). We let DTrace take the first crack at handling
+		 * this trap; if it's not a probe that DTrace knowns 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 an int 3 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.
+		 */
+		user_addr_t pc = (regs64) ? regs64->isf.rip : (user_addr_t)regs32->eip;
+		if (fuword8(pc - 1, &instr) == 0 && instr != FASTTRAP_INSTR) {
+			if (regs64) {
+				regs64->isf.rip--;
+			} else {
+				regs32->eip--;
+			}
+			return KERN_SUCCESS;
+		}
+
+	}
+
+	return KERN_FAILURE;
+}
+
+void
+dtrace_safe_synchronous_signal(void)
+{
+#if 0
+	kthread_t *t = curthread;
+	struct regs *rp = lwptoregs(ttolwp(t));
+	size_t isz = t->t_dtrace_npc - t->t_dtrace_pc;
+
+	ASSERT(t->t_dtrace_on);
+
+	/*
+	 * If we're not in the range of scratch addresses, we're not actually
+	 * tracing user instructions so turn off the flags. If the instruction
+	 * we copied out caused a synchonous trap, reset the pc back to its
+	 * original value and turn off the flags.
+	 */
+	if (rp->r_pc < t->t_dtrace_scrpc ||
+			rp->r_pc > t->t_dtrace_astpc + isz) {
+		t->t_dtrace_ft = 0;
+	} else if (rp->r_pc == t->t_dtrace_scrpc ||
+			rp->r_pc == t->t_dtrace_astpc) {
+		rp->r_pc = t->t_dtrace_pc;
+		t->t_dtrace_ft = 0;
+	}
+#endif /* 0 */
+}
+
+int
+dtrace_safe_defer_signal(void)
+{
+#if 0
+	kthread_t *t = curthread;
+	struct regs *rp = lwptoregs(ttolwp(t));
+	size_t isz = t->t_dtrace_npc - t->t_dtrace_pc;
+
+	ASSERT(t->t_dtrace_on);
+
+	/*
+	 * If we're not in the range of scratch addresses, we're not actually
+	 * tracing user instructions so turn off the flags.
+	 */
+	if (rp->r_pc < t->t_dtrace_scrpc ||
+			rp->r_pc > t->t_dtrace_astpc + isz) {
+		t->t_dtrace_ft = 0;
+		return (0);
+	}
+
+	/*
+	 * If we've executed the original instruction, but haven't performed
+	 * the jmp back to t->t_dtrace_npc or the clean up of any registers
+	 * used to emulate %rip-relative instructions in 64-bit mode, do that
+	 * here and take the signal right away. We detect this condition by
+	 * seeing if the program counter is the range [scrpc + isz, astpc).
+	 */
+	if (t->t_dtrace_astpc - rp->r_pc <
+			t->t_dtrace_astpc - t->t_dtrace_scrpc - isz) {
+#ifdef __sol64
+		/*
+		 * If there is a scratch register and we're on the
+		 * instruction immediately after the modified instruction,
+		 * restore the value of that scratch register.
+		 */
+		if (t->t_dtrace_reg != 0 &&
+				rp->r_pc == t->t_dtrace_scrpc + isz) {
+			switch (t->t_dtrace_reg) {
+				case REG_RAX:
+					rp->r_rax = t->t_dtrace_regv;
+					break;
+				case REG_RCX:
+					rp->r_rcx = t->t_dtrace_regv;
+					break;
+				case REG_R8:
+					rp->r_r8 = t->t_dtrace_regv;
+					break;
+				case REG_R9:
+					rp->r_r9 = t->t_dtrace_regv;
+					break;
+			}
+		}
+#endif
+		rp->r_pc = t->t_dtrace_npc;
+		t->t_dtrace_ft = 0;
+		return (0);
+	}
+
+	/*
+	 * Otherwise, make sure we'll return to the kernel after executing
+	 * the copied out instruction and defer the signal.
+	 */
+	if (!t->t_dtrace_step) {
+		ASSERT(rp->r_pc < t->t_dtrace_astpc);
+		rp->r_pc += t->t_dtrace_astpc - t->t_dtrace_scrpc;
+		t->t_dtrace_step = 1;
+	}
+
+	t->t_dtrace_ast = 1;
+
+	return (1);
+
+#endif /* 0 */
+
+	return 0;
+}