From 45fa45a9ccc39ab51aa7429912b55d8c7556bcf5 Mon Sep 17 00:00:00 2001
From: gonzo <gonzo@FreeBSD.org>
Date: Sat, 24 Mar 2012 05:17:38 +0000
Subject: Add DTrace-related part to machine-dependent code:

- DTrace trap handler
- invop-related variables (unused on MIPS but still referenced from dtrace)
---
 sys/mips/mips/exception.S | 21 ++++++++++++++++++
 sys/mips/mips/trap.c      | 54 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+)

(limited to 'sys/mips')

diff --git a/sys/mips/mips/exception.S b/sys/mips/mips/exception.S
index 34cf564..50da30b 100644
--- a/sys/mips/mips/exception.S
+++ b/sys/mips/mips/exception.S
@@ -55,6 +55,7 @@
  */
 
 #include "opt_ddb.h"
+#include "opt_kdtrace.h"
 #include <machine/asm.h>
 #include <machine/cpu.h>
 #include <machine/regnum.h>
@@ -65,6 +66,26 @@
 
 	.set	noreorder		# Noreorder is default style!
 
+#ifdef KDTRACE_HOOKS
+	.data
+	.globl	dtrace_invop_jump_addr
+	.align	4
+	.type	dtrace_invop_jump_addr, @object
+        .size	dtrace_invop_jump_addr, 8
+dtrace_invop_jump_addr:
+	.word	0
+	.word	0
+	.globl	dtrace_invop_calltrap_addr
+	.align	4
+	.type	dtrace_invop_calltrap_addr, @object
+        .size	dtrace_invop_calltrap_addr, 8
+dtrace_invop_calltrap_addr:
+	.word	0
+	.word	0
+
+	.text
+#endif
+
 /*
  * Reasonable limit
  */
diff --git a/sys/mips/mips/trap.c b/sys/mips/mips/trap.c
index bfffd8b..f2b343a 100644
--- a/sys/mips/mips/trap.c
+++ b/sys/mips/mips/trap.c
@@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$");
 #include "opt_ddb.h"
 #include "opt_global.h"
 #include "opt_ktrace.h"
+#include "opt_kdtrace.h"
 
 #define	NO_REG_DEFS	1	/* Prevent asm.h from including regdef.h */
 #include <sys/param.h>
@@ -93,6 +94,33 @@ __FBSDID("$FreeBSD$");
 #include <sys/kdb.h>
 #endif
 
+#ifdef KDTRACE_HOOKS
+#include <sys/dtrace_bsd.h>
+
+/*
+ * This is a hook which is initialised by the dtrace module
+ * to handle traps which might occur during DTrace probe
+ * execution.
+ */
+dtrace_trap_func_t	dtrace_trap_func;
+
+dtrace_doubletrap_func_t	dtrace_doubletrap_func;
+
+/*
+ * This is a hook which is initialised by the systrace module
+ * when it is loaded. This keeps the DTrace syscall provider
+ * implementation opaque. 
+ */
+systrace_probe_func_t	systrace_probe_func;
+
+/*
+ * These hooks are necessary for the pid, usdt and fasttrap providers.
+ */
+dtrace_fasttrap_probe_ptr_t	dtrace_fasttrap_probe_ptr;
+dtrace_pid_probe_ptr_t		dtrace_pid_probe_ptr;
+dtrace_return_probe_ptr_t	dtrace_return_probe_ptr;
+#endif
+
 #ifdef TRAP_DEBUG
 int trap_debug = 0;
 SYSCTL_INT(_machdep, OID_AUTO, trap_debug, CTLFLAG_RW,
@@ -529,6 +557,29 @@ trap(struct trapframe *trapframe)
 		}
 	}
 #endif
+
+#ifdef KDTRACE_HOOKS
+	/*
+	 * A trap can occur while DTrace executes a probe. Before
+	 * executing the probe, DTrace blocks re-scheduling and sets
+	 * a flag in it's per-cpu flags to indicate that it doesn't
+	 * want to fault. On returning from the probe, the no-fault
+	 * flag is cleared and finally re-scheduling is enabled.
+	 *
+	 * If the DTrace kernel module has registered a trap handler,
+	 * call it and if it returns non-zero, assume that it has
+	 * handled the trap and modified the trap frame so that this
+	 * function can return normally.
+	 */
+	/*
+	 * XXXDTRACE: add fasttrap and pid  probes handlers here (if ever)
+	 */
+	if (!usermode) {
+		if (dtrace_trap_func != NULL && (*dtrace_trap_func)(trapframe, type))
+			return (trapframe->pc);
+	}
+#endif
+
 	switch (type) {
 	case T_MCHECK:
 #ifdef DDB
@@ -633,6 +684,9 @@ dofault:
 			PROC_LOCK(p);
 			--p->p_lock;
 			PROC_UNLOCK(p);
+			/*
+			 * XXXDTRACE: add dtrace_doubletrap_func here?
+			 */
 #ifdef VMFAULT_TRACE
 			printf("vm_fault(%p (pmap %p), %p (%p), %x, %d) -> %x at pc %p\n",
 			    map, &vm->vm_pmap, (void *)va, (void *)(intptr_t)trapframe->badvaddr,
-- 
cgit v1.1