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?
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)
