From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Thu, 8 Dec 2011 02:51:52 +0000 (-0800)
Subject: kernel - Add TDF_RUNNING assertions
X-Git-Tag: v3.0.0~451
X-Git-Url: http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/121f93bc96d950e7ad625952a6de5b189863e3b7

kernel - Add TDF_RUNNING assertions

* Assert that the target lwkt thread being switched to is not flagged as
  running.

* Assert that the originating lwkt thread being switched from is flagged as
  running.

* Fix the running flag initial condition for the idle thread.
---

diff --git a/sys/kern/lwkt_thread.c b/sys/kern/lwkt_thread.c
index ddc782c..244df96 100644
--- a/sys/kern/lwkt_thread.c
+++ b/sys/kern/lwkt_thread.c
@@ -594,6 +594,7 @@ lwkt_switch(void)
     int spinning = 0;
 
     KKASSERT(gd->gd_processing_ipiq == 0);
+    KKASSERT(td->td_flags & TDF_RUNNING);
 
     /*
      * Switching from within a 'fast' (non thread switched) interrupt or IPI
@@ -922,6 +923,7 @@ haveidle:
 	 *
 	 * We are responsible for marking ntd as TDF_RUNNING.
 	 */
+	KKASSERT((ntd->td_flags & TDF_RUNNING) == 0);
 	++switch_count;
 	KTR_LOG(ctxsw_sw, gd->gd_cpuid, ntd);
 	ntd->td_flags |= TDF_RUNNING;
@@ -1032,6 +1034,10 @@ lwkt_preempt(thread_t ntd, int critcount)
 	return;
     }
 #ifdef SMP
+    if (td->td_cscount) {
+	++preempt_miss;
+	return;
+    }
     if (ntd->td_gd != gd) {
 	++preempt_miss;
 	return;
@@ -1078,6 +1084,8 @@ lwkt_preempt(thread_t ntd, int critcount)
     KTR_LOG(ctxsw_pre, gd->gd_cpuid, ntd);
     save_gd_intr_nesting_level = gd->gd_intr_nesting_level;
     gd->gd_intr_nesting_level = 0;
+
+    KKASSERT((ntd->td_flags & TDF_RUNNING) == 0);
     ntd->td_flags |= TDF_RUNNING;
     xtd = td->td_switch(ntd);
     KKASSERT(xtd == ntd);
diff --git a/sys/platform/pc32/i386/swtch.s b/sys/platform/pc32/i386/swtch.s
index 29dac4c..0a6d4ad 100644
--- a/sys/platform/pc32/i386/swtch.s
+++ b/sys/platform/pc32/i386/swtch.s
@@ -558,9 +558,7 @@ ENTRY(cpu_idle_restore)
 	pushl	$0
 	movl	%ecx,%cr3
 	andl	$~TDF_RUNNING,TD_FLAGS(%ebx)
-#if 0
-	orl	$TDF_RUNNING,TD_FLAGS(%eax)
-#endif
+	orl	$TDF_RUNNING,TD_FLAGS(%eax)	/* manual, no switch_return */
 #ifdef SMP
 	cmpl	$0,PCPU(cpuid)
 	je	1f
diff --git a/sys/platform/pc64/x86_64/support.s b/sys/platform/pc64/x86_64/support.s
index ddd0a38..d814b7a 100644
--- a/sys/platform/pc64/x86_64/support.s
+++ b/sys/platform/pc64/x86_64/support.s
@@ -44,7 +44,7 @@
 
 /*
  * bcopy family
- * void bzero(void *buf, u_int len)
+ * void bzero(void *buf, size_t len)
  */
 
 /* done */
diff --git a/sys/platform/pc64/x86_64/swtch.s b/sys/platform/pc64/x86_64/swtch.s
index 48a0eae..14b543c 100644
--- a/sys/platform/pc64/x86_64/swtch.s
+++ b/sys/platform/pc64/x86_64/swtch.s
@@ -298,6 +298,8 @@ ENTRY(cpu_exit_switch)
  */
 
 ENTRY(cpu_heavy_restore)
+	movq	TD_PCB(%rax),%rdx		/* RDX = PCB */
+	movq	%rdx, PCPU(common_tss) + TSS_RSP0
 	popfq
 
 #if defined(SWTCH_OPTIM_STATS)
@@ -337,6 +339,13 @@ ENTRY(cpu_heavy_restore)
 	 */
 	btq	$CPUMASK_BIT,%rax	/* test interlock */
 	jnc	1f
+
+#if 0
+	movq	TD_PCB(%r12),%rdx	/* XXX debugging unconditional */
+	movq	PCB_CR3(%rdx),%rdx	/*     reloading of %cr3 */
+	movq	%rdx,%cr3
+#endif
+
 	movq	%rcx,%rdi		/* (found to be set) */
 	call	pmap_interlock_wait	/* pmap_interlock_wait(%rdi:vm) */
 
@@ -621,9 +630,7 @@ ENTRY(cpu_idle_restore)
 	pushq	$0
 	movq	%rcx,%cr3
 	andl	$~TDF_RUNNING,TD_FLAGS(%rbx)
-#if 0
-	orl	$TDF_RUNNING,TD_FLAGS(%rax)
-#endif
+	orl	$TDF_RUNNING,TD_FLAGS(%rax)	/* manual, no switch_return */
 #ifdef SMP
 	cmpl	$0,PCPU(cpuid)
 	je	1f
@@ -750,6 +757,15 @@ ENTRY(cpu_lwkt_restore)
 	movq	%rcx,%cr3
 1:
 	/*
+	 * Safety, clear RSP0 in the tss so it isn't pointing at the
+	 * previous thread's kstack (if a heavy weight user thread).
+	 * RSP0 should only be used in ring 3 transitions and kernel
+	 * threads run in ring 0 so there should be none.
+	 */
+	xorq	%rdx,%rdx
+	movq	%rdx, PCPU(common_tss) + TSS_RSP0
+
+	/*
 	 * NOTE: %rbx is the previous thread and %rax is the new thread.
 	 *	 %rbx is retained throughout so we can return it.
 	 *
diff --git a/sys/platform/vkernel/i386/swtch.s b/sys/platform/vkernel/i386/swtch.s
index 174b830..edb9b39 100644
--- a/sys/platform/vkernel/i386/swtch.s
+++ b/sys/platform/vkernel/i386/swtch.s
@@ -502,9 +502,7 @@ ENTRY(cpu_idle_restore)
 	movl	$0,%ebp
 	pushl	$0
 	andl	$~TDF_RUNNING,TD_FLAGS(%ebx)
-#if 0
-	orl	$TDF_RUNNING,TD_FLAGS(%eax)
-#endif
+	orl	$TDF_RUNNING,TD_FLAGS(%eax)	/* manual, no switch_return */
 #ifdef SMP
 	cmpl	$0,PCPU(cpuid)
 	je	1f
diff --git a/sys/platform/vkernel64/x86_64/swtch.s b/sys/platform/vkernel64/x86_64/swtch.s
index 88e57ec..2f32e21 100644
--- a/sys/platform/vkernel64/x86_64/swtch.s
+++ b/sys/platform/vkernel64/x86_64/swtch.s
@@ -561,9 +561,7 @@ ENTRY(cpu_idle_restore)
 	/* JG push RBP? */
 	pushq	$0
 	andl	$~TDF_RUNNING,TD_FLAGS(%rbx)
-#if 0
-	orl	$TDF_RUNNING,TD_FLAGS(%rax)
-#endif
+	orl	$TDF_RUNNING,TD_FLAGS(%rax)	/* manual, no switch_return */
 #ifdef SMP
 	cmpl	$0,PCPU(cpuid)
 	je	1f