change td_retval into a union w/ off_t, with defines to mask the

change...  This eliminates a cast, and also forces td_retval
(often 2 32-bit registers) to be aligned so that off_t's can be
stored there on arches with strict alignment requirements like
armeb (AVILA)...  On i386, this doesn't change alignment, and on
amd64 it doesn't either, as register_t is already 64bits...

This will also prevent future breakage due to people adding additional
fields to the struct...

This gets AVILA booting a bit farther...

Reviewed by:	bde

4 files changed, 8 insertions, 4 deletions

diff --git a/sys/compat/freebsd32/freebsd32_misc.c b/sys/compat/freebsd32/freebsd32_misc.c
index c7b677f703b8..749c91d587b8 100644
--- a/sys/compat/freebsd32/freebsd32_misc.c
+++ b/sys/compat/freebsd32/freebsd32_misc.c
@@ -1504,7 +1504,7 @@ freebsd32_lseek(struct thread *td, struct freebsd32_lseek_args *uap)
 	ap.whence = uap->whence;
 	error = sys_lseek(td, &ap);
 	/* Expand the quad return into two parts for eax and edx */
-	pos = *(off_t *)(td->td_retval);
+	pos = td->td_uretoff.tdu_off;
 	td->td_retval[RETVAL_LO] = pos & 0xffffffff;	/* %eax */
 	td->td_retval[RETVAL_HI] = pos >> 32;		/* %edx */
 	return error;
diff --git a/sys/kern/uipc_shm.c b/sys/kern/uipc_shm.c
index cf00ff480141..bb414e1f46cd 100644
--- a/sys/kern/uipc_shm.c
+++ b/sys/kern/uipc_shm.c
@@ -270,7 +270,7 @@ shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
 		if (offset < 0 || offset > shmfd->shm_size)
 			error = EINVAL;
 		else
-			*(off_t *)(td->td_retval) = offset;
+			td->td_uretoff.tdu_off = offset;
 	}
 	foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
 	return (error);
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index ec995c7e18a6..8cde4287f02b 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -2080,7 +2080,7 @@ vn_seek(struct file *fp, off_t offset, int whence, struct thread *td)
 	if (error != 0)
 		goto drop;
 	VFS_KNOTE_UNLOCKED(vp, 0);
-	*(off_t *)(td->td_retval) = offset;
+	td->td_uretoff.tdu_off = offset;
 drop:
 	foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
 	return (error);
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index fce1f8aa7692..bd2e10af60eb 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -300,7 +300,11 @@ struct thread {
 		TDS_RUNQ,
 		TDS_RUNNING
 	} td_state;			/* (t) thread state */
-	register_t	td_retval[2];	/* (k) Syscall aux returns. */
+	union {
+		register_t	tdu_retval[2];
+		off_t		tdu_off;	
+	} td_uretoff;			/* (k) Syscall aux returns. */
+#define td_retval	td_uretoff.tdu_retval
 	struct callout	td_slpcallout;	/* (h) Callout for sleep. */
 	struct trapframe *td_frame;	/* (k) */
 	struct vm_object *td_kstack_obj;/* (a) Kstack object. */