> Date: Thu, 26 Jun 2014 17:01:23 -0700 > From: Matthew Dempsky <matt...@dempsky.org> > > On Thu, Jun 26, 2014 at 12:28:18PM -0700, Matthew Dempsky wrote: > > I just reviewed our mmap(2) flags to compare them against Linux, > > FreeBSD, Solaris, and Darwin's flags. Of the flags listed below, none > > of them are specified by POSIX, and none of them do anything > > interesting on OpenBSD: MAP_COPY just gets rewritten to MAP_PRIVATE, > > and the rest are silently ignored by UVM. > > Feedback so far is the useless flags should go away. Diff below is a > first step towards this: > > 1. MAP_COPY is redefined as an alias for MAP_PRIVATE, and the other > useless MAP_* flags are redefined to 0. They're also hidden from the > kernel to make sure no kernel code accidentally depends on them still. > > 2. Adds COMPAT_O55_MAP_COPY so we can stay binary compatible with any > OpenBSD 5.5 programs that still use MAP_COPY (probably none, but it's > trivial to do), and COMPAT_O55_MAP_NOOPMASK just to keep track of > which bits were previously reserved for do-nothing flags. > > 3. Reshuffles the defines a little bit so the order makes more sense. > > Followup patch will add a deprecation warning for the MAP_* flags, but > I think that'll need some ports testing, whereas this should be safe > to commit now. > > ok?
Losing the descriptions of the "no-op" flags is a bit unfortunate. Can you add those back? > > Index: sys/mman.h > =================================================================== > RCS file: /home/matthew/cvs-mirror/cvs/src/sys/sys/mman.h,v > retrieving revision 1.24 > diff -u -p -r1.24 mman.h > --- sys/mman.h 13 Jun 2014 01:48:52 -0000 1.24 > +++ sys/mman.h 26 Jun 2014 23:54:28 -0000 > @@ -50,32 +50,43 @@ > */ > #define MAP_SHARED 0x0001 /* share changes */ > #define MAP_PRIVATE 0x0002 /* changes are private */ > -#define MAP_COPY 0x0004 /* "copy" region at mmap time */ > + > +/* > + * Mapping type > + */ > +#define MAP_FILE 0x0000 /* map from file (default) */ > +#define MAP_ANON 0x1000 /* allocated from memory, swap space */ > > /* > * Other flags > */ > -#define MAP_FIXED 0x0010 /* map addr must be exactly as > requested */ > -#define MAP_RENAME 0x0020 /* Sun: rename private pages to file */ > -#define MAP_NORESERVE 0x0040 /* Sun: don't reserve needed swap area > */ > -#define MAP_INHERIT 0x0080 /* region is retained after exec */ > -#define MAP_NOEXTEND 0x0100 /* for MAP_FILE, don't change file size > */ > -#define MAP_HASSEMAPHORE 0x0200 /* region may contain semaphores */ > -#define MAP_TRYFIXED 0x0400 /* attempt hint address, even within > heap */ > +#define MAP_FIXED 0x0010 /* map addr must be exactly as > requested */ > +#define __MAP_NOREPLACE 0x0800 /* fail if address not available */ > > -#define __MAP_NOREPLACE 0x0800 /* fail if address not available */ > +#ifdef _KERNEL > +#define COMPAT_O55_MAP_COPY 0x0004 /* alias for MAP_PRIVATE */ > +#define COMPAT_O55_MAP_NOOPMASK 0x07e0 /* formerly reserved flag bits > */ > +#endif > + > +#define MAP_FLAGMASK 0x1ff7 > > +#ifndef _KERNEL > /* > - * Error return from mmap() > + * Deprecated flags with no significant meaning on OpenBSD. > */ > -#define MAP_FAILED ((void *)-1) > +#define MAP_COPY MAP_PRIVATE > +#define MAP_HASSEMAPHORE 0 > +#define MAP_INHERIT 0 > +#define MAP_NOEXTEND 0 > +#define MAP_NORESERVE 0 > +#define MAP_RENAME 0 > +#define MAP_TRYFIXED 0 > +#endif > > /* > - * Mapping type > + * Error return from mmap() > */ > -#define MAP_FILE 0x0000 /* map from file (default) */ > -#define MAP_ANON 0x1000 /* allocated from memory, swap space */ > -#define MAP_FLAGMASK 0x1ff7 > +#define MAP_FAILED ((void *)-1) > > /* > * POSIX memory advisory values. > Index: uvm/uvm_mmap.c > =================================================================== > RCS file: /home/matthew/cvs-mirror/cvs/src/sys/uvm/uvm_mmap.c,v > retrieving revision 1.94 > diff -u -p -r1.94 uvm_mmap.c > --- uvm/uvm_mmap.c 13 Apr 2014 23:14:15 -0000 1.94 > +++ uvm/uvm_mmap.c 26 Jun 2014 23:49:39 -0000 > @@ -345,8 +345,8 @@ sys_mmap(struct proc *p, void *v, regist > return (EINVAL); > if ((flags & MAP_FLAGMASK) != flags) > return (EINVAL); > - if (flags & MAP_COPY) > - flags = (flags & ~MAP_COPY) | MAP_PRIVATE; > + if (flags & COMPAT_O55_MAP_COPY) > + flags = (flags & ~COMPAT_O55_MAP_COPY) | MAP_PRIVATE; > if ((flags & (MAP_SHARED|MAP_PRIVATE)) == (MAP_SHARED|MAP_PRIVATE)) > return (EINVAL); > if ((flags & (MAP_FIXED|__MAP_NOREPLACE)) == __MAP_NOREPLACE) > >
