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Introduce kcov_silence_enter() and kcov_silence_leave(), to allow to 

temporarily disable KCOV on the current lwp. Should be used in the rare
but problematic cases where extreme noise is introduced by an
uninteresting subsystem.

Use this capability to silence KCOV during the LOCKDEBUG lookups. This
divides the size of the KCOV output by more than two in my KCOV+vHCI
tests.
This commit is contained in:
maxv 2020-05-15 13:09:02 +00:00
parent 5e7beab597
commit 69ffbd327c
3 changed files with 43 additions and 4 deletions
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28
sys/kern/subr_kcov.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: subr_kcov.c,v 1.13 2020/05/15 12:34:52 maxv Exp $ */
/* $NetBSD: subr_kcov.c,v 1.14 2020/05/15 13:09:02 maxv Exp $ */
/*
* Copyright (c) 2019-2020 The NetBSD Foundation, Inc.
@ -108,6 +108,7 @@ typedef struct kcov_desc {
/* Local only */
kmutex_t lock;
bool lwpfree;
bool silenced;
/* Pointer to the end of the structure, if any */
struct kcov_desc *remote;
@ -423,6 +424,26 @@ kcov_disable(kcov_t *kd)
/* -------------------------------------------------------------------------- */
void
kcov_silence_enter(void)
{
kcov_t *kd = curlwp->l_kcov;
if (kd != NULL)
kd->silenced = true;
}
void
kcov_silence_leave(void)
{
kcov_t *kd = curlwp->l_kcov;
if (kd != NULL)
kd->silenced = false;
}
/* -------------------------------------------------------------------------- */
static int
kcov_open(dev_t dev, int flag, int mode, struct lwp *l)
{
@ -581,6 +602,11 @@ __sanitizer_cov_trace_pc(void)
return;
}
if (__predict_false(kd->silenced)) {
/* Silenced. */
return;
}
if (kd->mode != KCOV_MODE_TRACE_PC) {
/* PC tracing mode not enabled */
return;

13
sys/kern/subr_lockdebug.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: subr_lockdebug.c,v 1.76 2020/04/10 17:16:21 ad Exp $ */
/* $NetBSD: subr_lockdebug.c,v 1.77 2020/05/15 13:09:02 maxv Exp $ */
/*-
* Copyright (c) 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc.
@ -34,7 +34,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_lockdebug.c,v 1.76 2020/04/10 17:16:21 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: subr_lockdebug.c,v 1.77 2020/05/15 13:09:02 maxv Exp $");
#ifdef _KERNEL_OPT
#include "opt_ddb.h"
@ -52,6 +52,7 @@ __KERNEL_RCSID(0, "$NetBSD: subr_lockdebug.c,v 1.76 2020/04/10 17:16:21 ad Exp $
#include <sys/lock.h>
#include <sys/rbtree.h>
#include <sys/ksyms.h>
#include <sys/kcov.h>
#include <machine/lock.h>
@ -209,7 +210,10 @@ lockdebug_lookup(const char *func, size_t line, const volatile void *lock,
{
lockdebug_t *ld;
kcov_silence_enter();
ld = lockdebug_lookup1(lock);
kcov_silence_leave();
if (__predict_false(ld == NULL)) {
panic("%s,%zu: uninitialized lock (lock=%p, from=%08"
PRIxPTR ")", func, line, lock, where);
@ -675,6 +679,8 @@ lockdebug_mem_check(const char *func, size_t line, void *base, size_t sz)
if (__predict_false(panicstr != NULL || ld_panic))
return;
kcov_silence_enter();
s = splhigh();
ci = curcpu();
__cpu_simple_lock(&ci->ci_data.cpu_ld_lock);
@ -693,9 +699,12 @@ lockdebug_mem_check(const char *func, size_t line, void *base, size_t sz)
__cpu_simple_lock(&ld->ld_spinlock);
lockdebug_abort1(func, line, ld, s,
"allocation contains active lock", !cold);
kcov_silence_leave();
return;
}
splx(s);
kcov_silence_leave();
}
#endif /* _KERNEL */

6
sys/sys/kcov.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: kcov.h,v 1.8 2020/05/15 12:34:52 maxv Exp $ */
/* $NetBSD: kcov.h,v 1.9 2020/05/15 13:09:02 maxv Exp $ */
/*
* Copyright (c) 2019-2020 The NetBSD Foundation, Inc.
@ -66,11 +66,15 @@ typedef volatile uint64_t kcov_int_t;
void kcov_remote_register(uint64_t, uint64_t);
void kcov_remote_enter(uint64_t, uint64_t);
void kcov_remote_leave(uint64_t, uint64_t);
void kcov_silence_enter(void);
void kcov_silence_leave(void);
void kcov_lwp_free(struct lwp *);
#else
#define kcov_remote_register(s, i) __nothing
#define kcov_remote_enter(s, i) __nothing
#define kcov_remote_leave(s, i) __nothing
#define kcov_silence_enter() __nothing
#define kcov_silence_leave() __nothing
#define kcov_lwp_free(a) __nothing
#endif
#endif