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Date:      Wed, 20 Feb 2019 22:32:29 +0000 (UTC)
From:      Andrew Turner <andrew@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r344390 - head/sys/kern
Message-ID:  <201902202232.x1KMWTuD051794@repo.freebsd.org>
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Author: andrew
Date: Wed Feb 20 22:32:28 2019
New Revision: 344390
URL: https://svnweb.freebsd.org/changeset/base/344390

Log:
  Call pmap_qenter for each page when creating the kcov buffer.
  
  This removes the need to allocate a buffer to hold the vm_page_t objects
  at the cost of extra IPIs on some architectures.
  
  Reviewed by:	kib
  Sponsored by:	DARPA, AFRL
  Differential Revision:	https://reviews.freebsd.org/D19252

Modified:
  head/sys/kern/kern_kcov.c

Modified: head/sys/kern/kern_kcov.c
==============================================================================
--- head/sys/kern/kern_kcov.c	Wed Feb 20 22:05:44 2019	(r344389)
+++ head/sys/kern/kern_kcov.c	Wed Feb 20 22:32:28 2019	(r344390)
@@ -357,7 +357,7 @@ static int
 kcov_alloc(struct kcov_info *info, size_t entries)
 {
 	size_t n, pages;
-	vm_page_t *m;
+	vm_page_t m;
 
 	KASSERT(info->kvaddr == 0, ("kcov_alloc: Already have a buffer"));
 	KASSERT(info->state == KCOV_STATE_OPEN,
@@ -376,16 +376,14 @@ kcov_alloc(struct kcov_info *info, size_t entries)
 	info->bufobj = vm_pager_allocate(OBJT_PHYS, 0, info->bufsize,
 	    PROT_READ | PROT_WRITE, 0, curthread->td_ucred);
 
-	m = malloc(sizeof(*m) * pages, M_TEMP, M_WAITOK);
 	VM_OBJECT_WLOCK(info->bufobj);
 	for (n = 0; n < pages; n++) {
-		m[n] = vm_page_grab(info->bufobj, n,
+		m = vm_page_grab(info->bufobj, n,
 		    VM_ALLOC_NOBUSY | VM_ALLOC_ZERO | VM_ALLOC_WIRED);
-		m[n]->valid = VM_PAGE_BITS_ALL;
+		m->valid = VM_PAGE_BITS_ALL;
+		pmap_qenter(info->kvaddr + n * PAGE_SIZE, &m, 1);
 	}
 	VM_OBJECT_WUNLOCK(info->bufobj);
-	pmap_qenter(info->kvaddr, m, pages);
-	free(m, M_TEMP);
 
 	info->entries = entries;

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