Implement DTrace for PowerPC. This includes both 32-bit and 64-bit.

There is one known issue:  Some probes will display an error message along the
lines of:  "Invalid address (0)"

I tested this with both a simple dtrace probe and dtruss on a few different
binaries on 32-bit.  I only compiled 64-bit, did not run it, but I don't expect
problems without the modules loaded.  Volunteers are welcome.

MFC after:	1 month

5 files changed, 97 insertions, 0 deletions

diff --git a/sys/powerpc/aim/locore32.S b/sys/powerpc/aim/locore32.S
index 80c3c08..f039db9 100644
--- a/sys/powerpc/aim/locore32.S
+++ b/sys/powerpc/aim/locore32.S
@@ -65,6 +65,8 @@
 #include <machine/spr.h>
 #include <machine/asm.h>
 
+#include "opt_kdtrace.h"
+
 /* Locate the per-CPU data structure */
 #define GET_CPUINFO(r)  \
         mfsprg0  r
diff --git a/sys/powerpc/aim/locore64.S b/sys/powerpc/aim/locore64.S
index 65c4999..3b3c8f3 100644
--- a/sys/powerpc/aim/locore64.S
+++ b/sys/powerpc/aim/locore64.S
@@ -65,6 +65,8 @@
 #include <machine/spr.h>
 #include <machine/asm.h>
 
+#include "opt_kdtrace.h"
+
 /* Locate the per-CPU data structure */
 #define GET_CPUINFO(r)  \
         mfsprg0  r
diff --git a/sys/powerpc/aim/trap.c b/sys/powerpc/aim/trap.c
index b55d34b..d30aded 100644
--- a/sys/powerpc/aim/trap.c
+++ b/sys/powerpc/aim/trap.c
@@ -35,6 +35,7 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_hwpmc_hooks.h"
+#include "opt_kdtrace.h"
 
 #include <sys/param.h>
 #include <sys/kdb.h>
@@ -104,6 +105,33 @@ struct powerpc_exception {
 	char	*name;
 };
 
+#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
+
 static struct powerpc_exception powerpc_exceptions[] = {
 	{ 0x0100, "system reset" },
 	{ 0x0200, "machine check" },
@@ -176,6 +204,28 @@ trap(struct trapframe *frame)
 	}
 	else
 #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 (!user) {
+		if (dtrace_trap_func != NULL && (*dtrace_trap_func)(frame, type))
+			return;
+	}
+#endif
+
 	if (user) {
 		td->td_pticks = 0;
 		td->td_frame = frame;
@@ -617,6 +667,9 @@ trap_pfault(struct trapframe *frame, int user)
 		PROC_LOCK(p);
 		--p->p_lock;
 		PROC_UNLOCK(p);
+		/*
+		 * XXXDTRACE: add dtrace_doubletrap_func here?
+		 */
 	} else {
 		/*
 		 * Don't have to worry about process locking or stacks in the
diff --git a/sys/powerpc/aim/trap_subr32.S b/sys/powerpc/aim/trap_subr32.S
index cf8d03a..a00cc3d 100644
--- a/sys/powerpc/aim/trap_subr32.S
+++ b/sys/powerpc/aim/trap_subr32.S
@@ -240,6 +240,26 @@
 	mfsprg2	%r2;			/* restore r2 & r3 */		\
 	mfsprg3	%r3
 
+#ifdef KDTRACE_HOOKS
+	.data
+	.globl	dtrace_invop_jump_addr
+	.align	4
+	.type	dtrace_invop_jump_addr, @object
+        .size	dtrace_invop_jump_addr, 4
+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, 4
+dtrace_invop_calltrap_addr:
+	.word	0
+	.word	0
+
+	.text
+#endif
+
 /*
  * The next two routines are 64-bit glue code. The first is used to test if
  * we are on a 64-bit system. By copying it to the illegal instruction
diff --git a/sys/powerpc/aim/trap_subr64.S b/sys/powerpc/aim/trap_subr64.S
index 8243dc7..0a12753 100644
--- a/sys/powerpc/aim/trap_subr64.S
+++ b/sys/powerpc/aim/trap_subr64.S
@@ -274,6 +274,26 @@ restore_kernsrs:
 	mtsrr1	%r3;							\
 	mfsprg3	%r3			/* restore r3 */
 
+#ifdef KDTRACE_HOOKS
+	.data
+	.globl	dtrace_invop_jump_addr
+	.align	8
+	.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	8
+	.type	dtrace_invop_calltrap_addr, @object
+        .size	dtrace_invop_calltrap_addr, 8
+dtrace_invop_calltrap_addr:
+	.word	0
+	.word	0
+
+	.text
+#endif
+
 #ifdef SMP
 /*
  * Processor reset exception handler. These are typically