Add fueword(9) and casueword(9) functions. They are like fuword(9)

and casuword(9), but do not mix value read and indication of fault.

I know (or remember) enough assembly to handle x86 and powerpc.  For
arm, mips and sparc64, implement fueword() and casueword() as wrappers
around fuword() and casuword(), which means that the functions cannot
distinguish between -1 and fault.

On architectures where fueword() and casueword() are native, implement
fuword() and casuword() using fueword() and casuword(), to reduce
assembly code duplication.

Sponsored by:	The FreeBSD Foundation
Tested by:	pho
MFC after:	2 weeks (ia64 needs treating)

1 files changed, 55 insertions, 7 deletions

diff --git a/share/man/man9/fetch.9 b/share/man/man9/fetch.9
index ccf68668d3d8..7e13cbc51c45 100644
--- a/share/man/man9/fetch.9
+++ b/share/man/man9/fetch.9
@@ -34,7 +34,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October 5, 2009
+.Dd October 21, 2014
 .Dt FETCH 9
 .Os
 .Sh NAME
@@ -44,11 +44,13 @@
 .Nm fuword ,
 .Nm fuword16 ,
 .Nm fuword32 ,
-.Nm fuword64
+.Nm fuword64 ,
+.Nm fueword ,
+.Nm fueword32 ,
+.Nm fueword64
 .Nd fetch data from user-space
 .Sh SYNOPSIS
 .In sys/types.h
-.In sys/time.h
 .In sys/systm.h
 .Ft int
 .Fn fubyte "const void *base"
@@ -60,27 +62,38 @@
 .Fn fuword32 "const void *base"
 .Ft int64_t
 .Fn fuword64 "const void *base"
+.Ft long
+.Fn fueword "const void *base" "long *val"
+.Ft int32_t
+.Fn fueword32 "const void *base" "int32_t *val"
+.Ft int64_t
+.Fn fueword64 "const void *base" "int64_t *val"
 .In sys/resourcevar.h
 .Ft int
 .Fn fuswintr "void *base"
 .Sh DESCRIPTION
 The
 .Nm
-functions are designed to copy small amounts of data from user-space.
+functions are designed to copy small amounts of data from user-space
+of the current process.
+If read is successful, it is performed atomically.
+The data read must be naturally aligned.
 .Pp
 The
 .Nm
 routines provide the following functionality:
-.Bl -tag -width "fuswintr()"
+.Bl -tag -width "fueword32()"
 .It Fn fubyte
 Fetches a byte of data from the user-space address
 .Pa base .
+The byte read is zero-extended into the results variable.
 .It Fn fuword
-Fetches a word of data from the user-space address
+Fetches a word of data (long) from the user-space address
 .Pa base .
 .It Fn fuword16
 Fetches 16 bits of data from the user-space address
 .Pa base .
+The half-word read is zero-extended into the results variable.
 .It Fn fuword32
 Fetches 32 bits of data from the user-space address
 .Pa base .
@@ -91,11 +104,46 @@ Fetches 64 bits of data from the user-space address
 Fetches a short word of data from the user-space address
 .Pa base .
 This function is safe to call during an interrupt context.
+.It Fn fueword
+Fetches a word of data (long) from the user-space address
+.Pa base
+and stores the result in the variable pointed by
+.Pa val .
+.It Fn fueword32
+Fetches 32 bits of data from the user-space address
+.Pa base
+and stores the result in the variable pointed by
+.Pa val .
+.It Fn fueword64
+Fetches 64 bits of data from the user-space address
+.Pa base
+and stores the result in the variable pointed by
+.Pa val .
 .El
+.Pp
+The callers of
+.Fn fuword ,
+.Fn fuword32
+and
+.Fn fuword64
+functions cannot distinguish between -1 read from
+userspace and function failure.
 .Sh RETURN VALUES
 The
-.Nm
+.Fn fubyte ,
+.Fn fuword ,
+.Fn fuword16 ,
+.Fn fuword32 ,
+.Fn fuword64 ,
+and
+.Fn fuswintr
 functions return the data fetched or -1 on failure.
+The
+.Fn fueword ,
+.Fn fueword32
+and
+.Fn fueword64
+functions return 0 on success and -1 on failure.
 .Sh SEE ALSO
 .Xr copy 9 ,
 .Xr store 9