Author: kib
Date: Sat Oct 4 18:38:14 2014
New Revision: 272536
URL: https://svnweb.freebsd.org/changeset/base/272536
Log:
Add kernel option KSTACK_USAGE_PROF to sample the stack depth on
interrupts and report the largest value seen as sysctl
debug.max_kstack_used. Useful to estimate how close the kernel stack
size is to overflow.
In collaboration with: Larry Baird <l...@gta.com>
Sponsored by: The FreeBSD Foundation (kib)
MFC after: 1 week
Modified:
head/sys/conf/NOTES
head/sys/conf/options
head/sys/kern/kern_intr.c
head/sys/sys/systm.h
head/sys/vm/vm_glue.c
Modified: head/sys/conf/NOTES
==============================================================================
--- head/sys/conf/NOTES Sat Oct 4 18:35:00 2014 (r272535)
+++ head/sys/conf/NOTES Sat Oct 4 18:38:14 2014 (r272536)
@@ -2958,6 +2958,7 @@ options SC_RENDER_DEBUG # syscons rende
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:
Modified: head/sys/conf/options
==============================================================================
--- head/sys/conf/options Sat Oct 4 18:35:00 2014 (r272535)
+++ head/sys/conf/options Sat Oct 4 18:38:14 2014 (r272536)
@@ -136,6 +136,7 @@ KDTRACE_FRAME opt_kdtrace.h
KN_HASHSIZE opt_kqueue.h
KSTACK_MAX_PAGES
KSTACK_PAGES
+KSTACK_USAGE_PROF
KTRACE
KTRACE_REQUEST_POOL opt_ktrace.h
LIBICONV
Modified: head/sys/kern/kern_intr.c
==============================================================================
--- head/sys/kern/kern_intr.c Sat Oct 4 18:35:00 2014 (r272535)
+++ head/sys/kern/kern_intr.c Sat Oct 4 18:38:14 2014 (r272536)
@@ -28,6 +28,7 @@
__FBSDID("$FreeBSD$");
#include "opt_ddb.h"
+#include "opt_kstack_usage_prof.h"
#include <sys/param.h>
#include <sys/bus.h>
@@ -1396,6 +1397,10 @@ intr_event_handle(struct intr_event *ie,
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);
Modified: head/sys/sys/systm.h
==============================================================================
--- head/sys/sys/systm.h Sat Oct 4 18:35:00 2014 (r272535)
+++ head/sys/sys/systm.h Sat Oct 4 18:38:14 2014 (r272536)
@@ -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_ */
Modified: head/sys/vm/vm_glue.c
==============================================================================
--- head/sys/vm/vm_glue.c Sat Oct 4 18:35:00 2014 (r272535)
+++ head/sys/vm/vm_glue.c Sat Oct 4 18:38:14 2014 (r272536)
@@ -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.
_______________________________________________
svn-src-all@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
