MFC r272536:

Add kernel option KSTACK_USAGE_PROF.

5 files changed, 58 insertions, 0 deletions

diff --git a/sys/conf/NOTES b/sys/conf/NOTES
index 3e5f806..ca77e3f 100644
--- a/sys/conf/NOTES
+++ b/sys/conf/NOTES
@@ -2950,6 +2950,7 @@ options 	SC_RENDER_DEBUG	# syscons rendering debugging
 options 	VFS_BIO_DEBUG	# VFS buffer I/O debugging
 
 options 	KSTACK_MAX_PAGES=32 # Maximum pages to give the kernel stack
+options 	KSTACK_USAGE_PROF
 
 # Adaptec Array Controller driver options
 options 	AAC_DEBUG	# Debugging levels:
diff --git a/sys/conf/options b/sys/conf/options
index a613612..2d68b75 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -132,6 +132,7 @@ GEOM_ZERO	opt_geom.h
 KDTRACE_HOOKS	opt_kdtrace.h
 KSTACK_MAX_PAGES
 KSTACK_PAGES
+KSTACK_USAGE_PROF
 KTRACE
 KTRACE_REQUEST_POOL	opt_ktrace.h
 LIBICONV
diff --git a/sys/kern/kern_intr.c b/sys/kern/kern_intr.c
index e4f1c82..fa466ed 100644
--- a/sys/kern/kern_intr.c
+++ b/sys/kern/kern_intr.c
@@ -28,6 +28,7 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_ddb.h"
+#include "opt_kstack_usage_prof.h"
 
 #include <sys/param.h>
 #include <sys/bus.h>
@@ -1407,6 +1408,10 @@ intr_event_handle(struct intr_event *ie, struct trapframe *frame)
 
 	td = curthread;
 
+#ifdef KSTACK_USAGE_PROF
+	intr_prof_stack_use(td, frame);
+#endif
+
 	/* An interrupt with no event or handlers is a stray interrupt. */
 	if (ie == NULL || TAILQ_EMPTY(&ie->ie_handlers))
 		return (EINVAL);
diff --git a/sys/sys/systm.h b/sys/sys/systm.h
index 0f2732c..c484b7b 100644
--- a/sys/sys/systm.h
+++ b/sys/sys/systm.h
@@ -443,4 +443,6 @@ bitcount16(uint32_t x)
 	return (x);
 }
 
+void	intr_prof_stack_use(struct thread *td, struct trapframe *frame);
+
 #endif /* !_SYS_SYSTM_H_ */
diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c
index 9e8995f..de2dff2 100644
--- a/sys/vm/vm_glue.c
+++ b/sys/vm/vm_glue.c
@@ -62,6 +62,7 @@ __FBSDID("$FreeBSD$");
 #include "opt_vm.h"
 #include "opt_kstack_pages.h"
 #include "opt_kstack_max_pages.h"
+#include "opt_kstack_usage_prof.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -98,6 +99,8 @@ __FBSDID("$FreeBSD$");
 #include <vm/vm_pager.h>
 #include <vm/swap_pager.h>
 
+#include <machine/cpu.h>
+
 #ifndef NO_SWAPPING
 static int swapout(struct proc *);
 static void swapclear(struct proc *);
@@ -486,6 +489,52 @@ kstack_cache_init(void *nulll)
 
 SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL);
 
+#ifdef KSTACK_USAGE_PROF
+/*
+ * Track maximum stack used by a thread in kernel.
+ */
+static int max_kstack_used;
+
+SYSCTL_INT(_debug, OID_AUTO, max_kstack_used, CTLFLAG_RD,
+    &max_kstack_used, 0,
+    "Maxiumum stack depth used by a thread in kernel");
+
+void
+intr_prof_stack_use(struct thread *td, struct trapframe *frame)
+{
+	vm_offset_t stack_top;
+	vm_offset_t current;
+	int used, prev_used;
+
+	/*
+	 * Testing for interrupted kernel mode isn't strictly
+	 * needed. It optimizes the execution, since interrupts from
+	 * usermode will have only the trap frame on the stack.
+	 */
+	if (TRAPF_USERMODE(frame))
+		return;
+
+	stack_top = td->td_kstack + td->td_kstack_pages * PAGE_SIZE;
+	current = (vm_offset_t)(uintptr_t)&stack_top;
+
+	/*
+	 * Try to detect if interrupt is using kernel thread stack.
+	 * Hardware could use a dedicated stack for interrupt handling.
+	 */
+	if (stack_top <= current || current < td->td_kstack)
+		return;
+
+	used = stack_top - current;
+	for (;;) {
+		prev_used = max_kstack_used;
+		if (prev_used >= used)
+			break;
+		if (atomic_cmpset_int(&max_kstack_used, prev_used, used))
+			break;
+	}
+}
+#endif /* KSTACK_USAGE_PROF */
+
 #ifndef NO_SWAPPING
 /*
  * Allow a thread's kernel stack to be paged out.