[src/trunk]: src/sys/arch/amd64/amd64 dtrace kernel hooks

[cegger <cegger%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/eec99d0cdabf
branches:  trunk
changeset: 752324:eec99d0cdabf
user:      cegger <cegger%NetBSD.org@localhost>
date:      Tue Feb 23 06:27:40 2010 +0000

description:
dtrace kernel hooks

ok darran@

diffstat:

 sys/arch/amd64/amd64/trap.c   |  39 +++++++++++++++++++++++++++++++++++++--
 sys/arch/amd64/amd64/vector.S |  42 +++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 78 insertions(+), 3 deletions(-)

diffs (141 lines):

diff -r 1649148a30df -r eec99d0cdabf sys/arch/amd64/amd64/trap.c
--- a/sys/arch/amd64/amd64/trap.c       Tue Feb 23 05:32:08 2010 +0000
+++ b/sys/arch/amd64/amd64/trap.c       Tue Feb 23 06:27:40 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: trap.c,v 1.60 2009/11/21 03:11:01 rmind Exp $  */
+/*     $NetBSD: trap.c,v 1.61 2010/02/23 06:27:40 cegger Exp $ */
 
 /*-
  * Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
@@ -68,11 +68,12 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.60 2009/11/21 03:11:01 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.61 2010/02/23 06:27:40 cegger Exp $");
 
 #include "opt_ddb.h"
 #include "opt_kgdb.h"
 #include "opt_xen.h"
+#include "opt_dtrace.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -111,6 +112,19 @@
 #include <sys/kgdb.h>
 #endif
 
+#ifdef KDTRACE_HOOKS
+#include <sys/dtrace_bsd.h>
+
+/*
+ * This is a hook which is initialized by the dtrace module
+ * to handle traps which might occur during DTrace probe
+ * execution.
+ */
+dtrace_trap_func_t     dtrace_trap_func = NULL;
+
+dtrace_doubletrap_func_t       dtrace_doubletrap_func = NULL;
+#endif
+
 void trap(struct trapframe *);
 
 const char * const trap_type[] = {
@@ -232,6 +246,27 @@
                LWP_CACHE_CREDS(l, p);
        }
 
+#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)) {
+                       return;
+               }
+       }
+#endif
+
        switch (type) {
 
        default:
diff -r 1649148a30df -r eec99d0cdabf sys/arch/amd64/amd64/vector.S
--- a/sys/arch/amd64/amd64/vector.S     Tue Feb 23 05:32:08 2010 +0000
+++ b/sys/arch/amd64/amd64/vector.S     Tue Feb 23 06:27:40 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vector.S,v 1.32 2010/02/23 00:23:36 cegger Exp $       */
+/*     $NetBSD: vector.S,v 1.33 2010/02/23 06:27:40 cegger Exp $       */
 
 /*-
  * Copyright (c) 1998, 2007, 2008 The NetBSD Foundation, Inc.
@@ -69,6 +69,7 @@
 #include "opt_ddb.h"
 #include "opt_multiprocessor.h"
 #include "opt_xen.h"
+#include "opt_dtrace.h"
 
 #define ALIGN_TEXT     .align 16,0x90
 
@@ -112,6 +113,21 @@
 
 #define        BPTTRAP(a)      ZTRAP(a)
 
+#ifdef KDTRACE_HOOKS
+       .bss
+       .globl  dtrace_invop_jump_addr
+       .align  8
+       .type   dtrace_invop_jump_addr, @object
+       .size   dtrace_invop_jump_addr, 8
+dtrace_invop_jump_addr:
+       .zero   8
+       .globl  dtrace_invop_calltrap_addr
+       .align  8
+       .type   dtrace_invop_calltrap_addr, @object
+       .size   dtrace_invop_calltrap_addr, 8
+dtrace_invop_calltrap_addr:
+       .zero   8
+#endif
        .text
 
 IDTVEC(trap00)
@@ -283,6 +299,30 @@
 NENTRY(alltraps)
        INTRENTRY
        STI(si)
+#ifdef KDTRACE_HOOKS
+       /*
+        * DTrace Function Boundary Trace (fbt) probes are triggered
+        * by int3 (0xcc) which causes the #BP (T_BPTFLT) breakpoint
+        * interrupt. For all other trap types, just handle them in
+        * the usual way.
+        */
+       cmpl    $T_BPTFLT,TF_TRAPNO(%rsp)
+       jne     calltrap
+
+       /* Check if there is no DTrace hook registered. */
+       cmpq    $0,dtrace_invop_jump_addr
+       je      calltrap
+
+       /*
+        * Set our jump address for the jump back in the event that
+        * the exception wasn't caused by DTrace at all.
+        */
+       movq    $calltrap, dtrace_invop_calltrap_addr(%rip)
+
+       /* Jump to the code hooked in by DTrace. */
+       movq    dtrace_invop_jump_addr, %rax
+       jmpq    *dtrace_invop_jump_addr
+#endif
 calltrap:
 #ifdef DIAGNOSTIC
        movl    CPUVAR(ILEVEL),%ebx