PERFORCE change 143185 for review

[John Birrell]

http://perforce.freebsd.org/chv.cgi?CH=143185

Change 143185 by jb at freebsd3 on 2008/06/09 07:00:10

	Add the syscall hooks for DTrace.

Affected files ...

.. //depot/projects/dtrace6/src/sys/amd64/amd64/trap.c#3 edit

Differences ...

==== //depot/projects/dtrace6/src/sys/amd64/amd64/trap.c#3 (text+ko) ====

@@ -49,6 +49,7 @@
 #include "opt_hwpmc_hooks.h"
 #include "opt_isa.h"
 #include "opt_kdb.h"
+#include "opt_kdtrace.h"
 #include "opt_ktrace.h"
 
 #include <sys/param.h>
@@ -101,6 +102,26 @@
 static int trap_pfault(struct trapframe *, int);
 static void trap_fatal(struct trapframe *, vm_offset_t);
 
+#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;
+#endif
+
 #define MAX_TRAP_MSG		30
 static char *trap_msg[] = {
 	"",					/*  0 unused */
@@ -196,6 +217,25 @@
 		goto out;
 #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 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.
+	 */
+	if ((type == T_PROTFLT || type == T_PAGEFLT) &&
+	    dtrace_trap_func != NULL)
+		if ((*dtrace_trap_func)(&frame, type))
+			goto out;
+#endif
+
 	if ((frame.tf_rflags & PSL_I) == 0) {
 		/*
 		 * Buggy application or kernel code has disabled
@@ -680,6 +720,10 @@
 void
 dblfault_handler(struct trapframe frame)
 {
+#ifdef KDTRACE_HOOKS
+	if (dtrace_doubletrap_func != NULL)
+		(*dtrace_doubletrap_func)();
+#endif
 	printf("\nFatal double fault\n");
 	printf("rip = 0x%lx\n", frame.tf_rip);
 	printf("rsp = 0x%lx\n", frame.tf_rsp);
@@ -798,14 +842,62 @@
 
 		if ((callp->sy_narg & SYF_MPSAFE) == 0) {
 			mtx_lock(&Giant);
+
+#if defined(KDTRACE_HOOKS) && defined(BREAK_SYSENT_ABI)
+			/*
+			 * If the systrace module has registered it's probe
+			 * callback and if there is a probe active for the
+			 * syscall 'entry', process the probe.
+			 */
+			if (systrace_probe_func != NULL && callp->sy_entry != 0)
+				(*systrace_probe_func)(callp->sy_entry, code, callp,
+				    args);
+#endif
+
 			AUDIT_SYSCALL_ENTER(code, td);
 			error = (*callp->sy_call)(td, argp);
 			AUDIT_SYSCALL_EXIT(error, td);
+
+#if defined(KDTRACE_HOOKS) && defined(BREAK_SYSENT_ABI)
+			/*
+			 * If the systrace module has registered it's probe
+			 * callback and if there is a probe active for the
+			 * syscall 'return', process the probe.
+			 */
+			if (systrace_probe_func != NULL && callp->sy_return != 0)
+				(*systrace_probe_func)(callp->sy_return, code, callp,
+				    args);
+#endif
 			mtx_unlock(&Giant);
 		} else {
+#if defined(KDTRACE_HOOKS) && defined(BREAK_SYSENT_ABI)
+			/*
+			 * If the systrace module has registered it's probe
+			 * callback and if there is a probe active for the
+			 * syscall 'entry', process the probe.
+			 */
+			if (systrace_probe_func != NULL && callp->sy_entry != 0)
+				(*systrace_probe_func)(callp->sy_entry, code, callp,
+				    args);
+#endif
+
 			AUDIT_SYSCALL_ENTER(code, td);
 			error = (*callp->sy_call)(td, argp);
 			AUDIT_SYSCALL_EXIT(error, td);
+
+			/* Save the latest error return value. */
+			td->td_errno = error;
+
+#if defined(KDTRACE_HOOKS) && defined(BREAK_SYSENT_ABI)
+			/*
+			 * If the systrace module has registered it's probe
+			 * callback and if there is a probe active for the
+			 * syscall 'return', process the probe.
+			 */
+			if (systrace_probe_func != NULL && callp->sy_return != 0)
+				(*systrace_probe_func)(callp->sy_return, code, callp,
+				    args);
+#endif
 		}
 	}