Author: brooks
Date: Wed Oct 21 16:00:15 2020
New Revision: 366911
URL: https://svnweb.freebsd.org/changeset/base/366911

Log:
  vmapbuf: don't smuggle address or length in buf
  
  Instead, add arguments to vmapbuf.  Since this argument is
  always a pointer use a type of void * and cast to vm_offset_t in
  vmapbuf.  (In CheriBSD we've altered vm_fault_quick_hold_pages to
  take a pointer and check its bounds.)
  
  In no other situtation does b_data contain a user pointer and vmapbuf
  replaces b_data with the actual mapping.
  
  Suggested by: jhb
  Reviewed by:  imp, jhb
  Obtained from:        CheriBSD
  MFC after:    1 week
  Sponsored by: DARPA
  Differential Revision:        https://reviews.freebsd.org/D26784

Modified:
  head/sys/cam/cam_periph.c
  head/sys/dev/nvme/nvme_ctrlr.c
  head/sys/kern/vfs_bio.c
  head/sys/sys/buf.h
  head/sys/ufs/ffs/ffs_rawread.c

Modified: head/sys/cam/cam_periph.c
==============================================================================
--- head/sys/cam/cam_periph.c   Wed Oct 21 15:06:44 2020        (r366910)
+++ head/sys/cam/cam_periph.c   Wed Oct 21 16:00:15 2020        (r366911)
@@ -955,18 +955,12 @@ cam_periph_mapmem(union ccb *ccb, struct cam_periph_ma
                 */
                mapinfo->bp[i] = uma_zalloc(pbuf_zone, M_WAITOK);
 
-               /* put our pointer in the data slot */
-               mapinfo->bp[i]->b_data = *data_ptrs[i];
-
-               /* set the transfer length, we know it's < MAXPHYS */
-               mapinfo->bp[i]->b_bufsize = lengths[i];
-
                /* set the direction */
                mapinfo->bp[i]->b_iocmd = (dirs[i] == CAM_DIR_OUT) ?
                    BIO_WRITE : BIO_READ;
 
                /* Map the buffer into kernel memory. */
-               if (vmapbuf(mapinfo->bp[i], 1) < 0) {
+               if (vmapbuf(mapinfo->bp[i], *data_ptrs[i], lengths[i], 1) < 0) {
                        uma_zfree(pbuf_zone, mapinfo->bp[i]);
                        goto fail;
                }

Modified: head/sys/dev/nvme/nvme_ctrlr.c
==============================================================================
--- head/sys/dev/nvme/nvme_ctrlr.c      Wed Oct 21 15:06:44 2020        
(r366910)
+++ head/sys/dev/nvme/nvme_ctrlr.c      Wed Oct 21 16:00:15 2020        
(r366911)
@@ -1268,10 +1268,8 @@ nvme_ctrlr_passthrough_cmd(struct nvme_controller *ctr
                         */
                        PHOLD(curproc);
                        buf = uma_zalloc(pbuf_zone, M_WAITOK);
-                       buf->b_data = pt->buf;
-                       buf->b_bufsize = pt->len;
                        buf->b_iocmd = pt->is_read ? BIO_READ : BIO_WRITE;
-                       if (vmapbuf(buf, 1) < 0) {
+                       if (vmapbuf(buf, pt->buf, pt->len, 1) < 0) {
                                ret = EFAULT;
                                goto err;
                        }

Modified: head/sys/kern/vfs_bio.c
==============================================================================
--- head/sys/kern/vfs_bio.c     Wed Oct 21 15:06:44 2020        (r366910)
+++ head/sys/kern/vfs_bio.c     Wed Oct 21 16:00:15 2020        (r366911)
@@ -4907,22 +4907,21 @@ vm_hold_free_pages(struct buf *bp, int newbsize)
  * This function only works with pager buffers.
  */
 int
-vmapbuf(struct buf *bp, int mapbuf)
+vmapbuf(struct buf *bp, void *uaddr, size_t len, int mapbuf)
 {
        vm_prot_t prot;
        int pidx;
 
-       if (bp->b_bufsize < 0)
-               return (-1);
        prot = VM_PROT_READ;
        if (bp->b_iocmd == BIO_READ)
                prot |= VM_PROT_WRITE;  /* Less backwards than it looks */
        if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
-           (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
+           (vm_offset_t)uaddr, len, prot, bp->b_pages,
            btoc(MAXPHYS))) < 0)
                return (-1);
+       bp->b_bufsize = len;
        bp->b_npages = pidx;
-       bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
+       bp->b_offset = ((vm_offset_t)uaddr) & PAGE_MASK;
        if (mapbuf || !unmapped_buf_allowed) {
                pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
                bp->b_data = bp->b_kvabase + bp->b_offset;

Modified: head/sys/sys/buf.h
==============================================================================
--- head/sys/sys/buf.h  Wed Oct 21 15:06:44 2020        (r366910)
+++ head/sys/sys/buf.h  Wed Oct 21 16:00:15 2020        (r366911)
@@ -575,7 +575,7 @@ void        vfs_bio_set_flags(struct buf *bp, int ioflags);
 void   vfs_bio_set_valid(struct buf *, int base, int size);
 void   vfs_busy_pages(struct buf *, int clear_modify);
 void   vfs_unbusy_pages(struct buf *);
-int    vmapbuf(struct buf *, int);
+int    vmapbuf(struct buf *, void *, size_t, int);
 void   vunmapbuf(struct buf *);
 void   brelvp(struct buf *);
 void   bgetvp(struct vnode *, struct buf *);

Modified: head/sys/ufs/ffs/ffs_rawread.c
==============================================================================
--- head/sys/ufs/ffs/ffs_rawread.c      Wed Oct 21 15:06:44 2020        
(r366910)
+++ head/sys/ufs/ffs/ffs_rawread.c      Wed Oct 21 16:00:15 2020        
(r366911)
@@ -216,7 +216,6 @@ ffs_rawread_readahead(struct vnode *vp,
        bp->b_flags = 0;        /* XXX necessary ? */
        bp->b_iocmd = BIO_READ;
        bp->b_iodone = bdone;
-       bp->b_data = udata;
        blockno = offset / bsize;
        blockoff = (offset % bsize) / DEV_BSIZE;
        if ((daddr_t) blockno != blockno) {
@@ -233,9 +232,8 @@ ffs_rawread_readahead(struct vnode *vp,
                
                if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
                        bp->b_bcount = bsize - blockoff * DEV_BSIZE;
-               bp->b_bufsize = bp->b_bcount;
                
-               if (vmapbuf(bp, 1) < 0)
+               if (vmapbuf(bp, udata, bp->b_bcount, 1) < 0)
                        return EFAULT;
                
                maybe_yield();
@@ -252,9 +250,8 @@ ffs_rawread_readahead(struct vnode *vp,
 
        if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
                bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
-       bp->b_bufsize = bp->b_bcount;
 
-       if (vmapbuf(bp, 1) < 0)
+       if (vmapbuf(bp, udata, bp->b_bcount, 1) < 0)
                return EFAULT;
 
        BO_STRATEGY(&dp->v_bufobj, bp);
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