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| author |   matthew <matthew@openbsd.org> | 2014-06-13 01:48:51 +0000 |
|---|---|---|
| committer | matthew <matthew@openbsd.org> | 2014-06-13 01:48:51 +0000 |
| commit | 7c15f335b2e8baba31f059cf0102f4d0564433b9 (patch) | |
| tree | 858aa614e7f7293dfd72d33534465dae68dac9fc /lib/libc | |
| parent | Fix ptrace() hanging hppa MP systems (diff) | |
| download | wireguard-openbsd-7c15f335b2e8baba31f059cf0102f4d0564433b9.tar.xz wireguard-openbsd-7c15f335b2e8baba31f059cf0102f4d0564433b9.zip | |
Add support for MAP_INHERIT_ZERO.
This provides a way for a process to designate pages in its address
space that should be replaced by fresh, zero-initialized anonymous
memory in forked child processes, rather than being copied or shared.
ok jmc, kettenis, tedu, deraadt; positive feedback from many more
Diffstat (limited to 'lib/libc')
| -rw-r--r-- | lib/libc/sys/minherit.2 | 40 |
1 files changed, 24 insertions, 16 deletions
diff --git a/lib/libc/sys/minherit.2 b/lib/libc/sys/minherit.2 index 05ea31c61a4..d6d0784e60c 100644 --- a/lib/libc/sys/minherit.2 +++ b/lib/libc/sys/minherit.2 @@ -1,4 +1,4 @@ -.\" $OpenBSD: minherit.2,v 1.13 2007/05/31 19:19:33 jmc Exp $ +.\" $OpenBSD: minherit.2,v 1.14 2014/06/13 01:48:51 matthew Exp $ .\" .\" Copyright (c) 1991, 1993 .\" The Regents of the University of California. All rights reserved. @@ -29,7 +29,7 @@ .\" .\" @(#)minherit.2 8.1 (Berkeley) 6/9/93 .\" -.Dd $Mdocdate: May 31 2007 $ +.Dd $Mdocdate: June 13 2014 $ .Dt MINHERIT 2 .Os .Sh NAME @@ -45,12 +45,25 @@ The .Fn minherit system call changes the specified pages to have the inheritance characteristic -.Fa inherit , -which can be set to -.Dv MAP_INHERIT_NONE , -.Dv MAP_INHERIT_COPY , -or -.Dv MAP_INHERIT_SHARE . +.Fa inherit . +A page's inheritance characteristic controls how it will be mapped +in child processes as created by +.Xr fork 2 . +.Pp +The possible inheritance characteristics are: +.Pp +.Bl -tag -width MAP_INHERIT_SHARE -offset indent -compact +.It Dv MAP_INHERIT_NONE +Pages are not mapped in the child process. +.It Dv MAP_INHERIT_COPY +Private copy of pages are mapped in the child process. +.It Dv MAP_INHERIT_SHARE +Mapped pages are shared between the parent and child processes. +.It Dv MAP_INHERIT_ZERO +New anonymous pages (initialized to all zero bytes) +are mapped in the child process. +.El +.Pp Not all implementations will guarantee that the inheritance characteristic can be set on a page basis; the granularity of changes may be as large as an entire region. @@ -72,15 +85,10 @@ The virtual address range specified by the and .Fa len arguments is not valid. -.It Bq Er EACCES -The flags specified by the +.It Bq Er EINVAL +The .Fa inherit -argument were not valid for the pages specified -by the -.Fa addr -and -.Fa len -arguments. +argument is invalid. .El .Sh SEE ALSO .Xr madvise 2 , |