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authordelphij <delphij@FreeBSD.org>2017-05-31 05:10:03 +0000
committerdelphij <delphij@FreeBSD.org>2017-05-31 05:10:03 +0000
commitbfde52da67b17e680ca5da34f553788ce1cbf7ef (patch)
tree4c8a0d1953b02c05a68b3ea408e34c0d4ca31aa5 /lib/libc/sys
parent7ce24dc81f292794ddadd8289ff9cd494aa96852 (diff)
downloadFreeBSD-src-bfde52da67b17e680ca5da34f553788ce1cbf7ef.zip
FreeBSD-src-bfde52da67b17e680ca5da34f553788ce1cbf7ef.tar.gz
MFC r315272, r315370
r315272: Implement INHERIT_ZERO for minherit(2). INHERIT_ZERO is an OpenBSD feature. When a page is marked as such, it would be zeroed upon fork(). This would be used in new arc4random(3) functions. PR: 182610 Reviewed by: kib (earlier version) Differential Revision: https://reviews.freebsd.org/D427 r315370: The adj_free and max_free values of new_entry will be calculated and assigned by subsequent vm_map_entry_link(), therefore, remove the pointless copying. Submitted by: alc
Diffstat (limited to 'lib/libc/sys')
-rw-r--r--lib/libc/sys/minherit.214
1 files changed, 13 insertions, 1 deletions
diff --git a/lib/libc/sys/minherit.2 b/lib/libc/sys/minherit.2
index dc85d09..f2d437d 100644
--- a/lib/libc/sys/minherit.2
+++ b/lib/libc/sys/minherit.2
@@ -29,7 +29,7 @@
.\"
.\" @(#)minherit.2 8.1 (Berkeley) 6/9/93
.\"
-.Dd October 30, 2007
+.Dd March 15, 2017
.Dt MINHERIT 2
.Os
.Sh NAME
@@ -91,6 +91,11 @@ it will no longer be shared in the parent
after the parent forks and there is no way to get the previous
shared-backing-store mapping without unmapping and remapping the address
space in the parent.
+.It Dv INHERIT_ZERO
+This option causes the address space in question to be mapped as new
+anonymous pages,
+which would be initialized to all zero bytes,
+in the child process.
.El
.Sh RETURN VALUES
.Rv -std minherit
@@ -130,6 +135,13 @@ system call first appeared in
.Ox
and then in
.Fx 2.2 .
+.Pp
+The
+.Dv INHERIT_ZERO
+support first appeared in
+.Ox 5.6
+and then in
+.Fx 12.0 .
.Sh BUGS
Once you set inheritance to
.Dv MAP_PRIVATE
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