Add an option to EXA for the DDX to request that EXA hide the pixmap's

devPrivate.ptr when pointing at offscreen memory, outside of
    exaPrepare/FinishAccess(). This was used with fakexa to find (by NULL
    dereference) many instances of un-Prepared CPU access to the
    framebuffer:
- GC tiles used in several ops when fillStyle == FillTiled were never
    Prepared.
- Migration could lead to un-Prepared access to mask data in render's
    Trapezoids and Triangles
- PutImage's UploadToScreen failure fallback failed to Prepare.

ChangeLog

@@ -1,3 +1,34 @@
+2006-03-31  Eric Anholt  <anholt@FreeBSD.org>
+
+	* exa/exa.c: (exaGetPixmapOffset), (exaPixmapIsOffscreen),
+	(exaPrepareAccess), (exaFinishAccess), (exaDriverInit):
+	* exa/exa_accel.c: (exaPutImage):
+	* exa/exa_migration.c: (exaPixmapSave), (exaMoveInPixmap),
+	(exaMoveOutPixmap):
+	* exa/exa_priv.h:
+	* exa/exa_render.c: (exaRasterizeTrapezoid), (exaAddTriangles):
+	* exa/exa_unaccel.c: (exaPrepareAccessGC), (exaFinishAccessGC),
+	(ExaCheckFillSpans), (ExaCheckPolylines), (ExaCheckPolySegment),
+	(ExaCheckPolyArc), (ExaCheckPolyFillRect), (ExaCheckImageGlyphBlt),
+	(ExaCheckPolyGlyphBlt), (ExaCheckPushPixels):
+	* hw/kdrive/ephyr/ephyr.h:
+	* hw/kdrive/ephyr/ephyr_draw.c: (ephyrPreparePipelinedAccess),
+	(ephyrFinishPipelinedAccess), (ephyrPrepareSolid),
+	(ephyrDoneSolid), (ephyrPrepareCopy), (ephyrDoneCopy),
+	(ephyrPrepareComposite), (ephyrDoneComposite),
+	(ephyrDownloadFromScreen), (ephyrUploadToScreen),
+	(ephyrPrepareAccess), (ephyrDrawInit), (exaDDXDriverInit):
+	Add an option to EXA for the DDX to request that EXA hide the pixmap's
+	devPrivate.ptr when pointing at offscreen memory, outside of
+	exaPrepare/FinishAccess().  This was used with fakexa to find (by NULL
+	dereference) many instances of un-Prepared CPU access to the
+	framebuffer:
+	- GC tiles used in several ops when fillStyle == FillTiled were never
+	  Prepared.
+	- Migration could lead to un-Prepared access to mask data in render's
+	  Trapezoids and Triangles
+	- PutImage's UploadToScreen failure fallback failed to Prepare.
+
 2006-03-31  Eric Anholt  <anholt@FreeBSD.org>
 
 	* exa/exa_offscreen.c: (ExaOffscreenValidate):

exa/exa.c

@@ -58,9 +58,16 @@ unsigned long
 exaGetPixmapOffset(PixmapPtr pPix)
 {
     ExaScreenPriv (pPix->drawable.pScreen);
+    ExaPixmapPriv (pPix);
+    void *ptr;
 
-    return ((unsigned long)pPix->devPrivate.ptr -
+    /* Return the offscreen pointer if we've hidden the data. */
-	(unsigned long)pExaScr->info->memoryBase);
+    if (pPix->devPrivate.ptr == NULL)
+	ptr = pExaPixmap->fb_ptr;
+    else
+	ptr = pPix->devPrivate.ptr;
+
+    return ((unsigned long)ptr - (unsigned long)pExaScr->info->memoryBase);
 }
 
 /**
@@ -232,6 +239,11 @@ exaPixmapIsOffscreen(PixmapPtr p)
     ScreenPtr	pScreen = p->drawable.pScreen;
     ExaScreenPriv(pScreen);
 
+    /* If the devPrivate.ptr is NULL, it's offscreen but we've hidden the data.
+     */
+    if (p->devPrivate.ptr == NULL)
+	return TRUE;
+
     return ((unsigned long) ((CARD8 *) p->devPrivate.ptr -
 			     (CARD8 *) pExaScr->info->memoryBase) <
 	    pExaScr->info->memorySize);
@@ -301,6 +313,13 @@ exaPrepareAccess(DrawablePtr pDrawable, int index)
     else
 	return;
 
+    /* Unhide pixmap pointer */
+    if (pPixmap->devPrivate.ptr == NULL) {
+	ExaPixmapPriv (pPixmap);
+
+	pPixmap->devPrivate.ptr = pExaPixmap->fb_ptr;
+    }
+
     if (pExaScr->info->PrepareAccess == NULL)
 	return;
 
@@ -324,14 +343,25 @@ exaFinishAccess(DrawablePtr pDrawable, int index)
     ScreenPtr	    pScreen = pDrawable->pScreen;
     ExaScreenPriv  (pScreen);
     PixmapPtr	    pPixmap;
+    ExaPixmapPrivPtr pExaPixmap;
 
     if (index == EXA_PREPARE_DEST)
 	exaDrawableDirty (pDrawable);
 
+    pPixmap = exaGetDrawablePixmap (pDrawable);
+
+    pExaPixmap = ExaGetPixmapPriv(pPixmap);
+
+    /* Rehide pixmap pointer if we're doing that. */
+    if (pExaPixmap != NULL && pExaScr->hideOffscreenPixmapData &&
+	pExaPixmap->fb_ptr == pPixmap->devPrivate.ptr)
+    {
+	pPixmap->devPrivate.ptr = pExaPixmap->fb_ptr;
+    }
+
     if (pExaScr->info->FinishAccess == NULL)
 	return;
 
-    pPixmap = exaGetDrawablePixmap (pDrawable);
     if (!exaPixmapIsOffscreen (pPixmap))
 	return;
 
@@ -508,6 +538,12 @@ exaDriverInit (ScreenPtr		pScreen,
         pExaScr->SavedComposite = ps->Composite;
 	ps->Composite = exaComposite;
 
+	pExaScr->SavedRasterizeTrapezoid = ps->RasterizeTrapezoid;
+	ps->RasterizeTrapezoid = exaRasterizeTrapezoid;
+
+	pExaScr->SavedAddTriangles = ps->AddTriangles;
+	ps->AddTriangles = exaAddTriangles;
+
 	pExaScr->SavedGlyphs = ps->Glyphs;
 	ps->Glyphs = exaGlyphs;
     }

exa/exa_accel.c

@@ -165,6 +165,9 @@ exaPutImage (DrawablePtr pDrawable, GCPtr pGC, int depth, int x, int y,
     if (pPix == NULL)
 	goto fallback;
 
+    x += pDrawable->x;
+    y += pDrawable->y;
+
     pClip = fbGetCompositeClip(pGC);
     src_stride = PixmapBytePad(w, pDrawable->depth);
     for (nbox = REGION_NUM_RECTS(pClip),
@@ -190,7 +193,7 @@ exaPutImage (DrawablePtr pDrawable, GCPtr pGC, int depth, int x, int y,
 	if (x1 >= x2 || y1 >= y2)
 	    continue;
 
-	src = bits + (y1 - y + yoff) * src_stride + (x1 - x + xoff) * (bpp / 8);
+	src = bits + (y1 - y) * src_stride + (x1 - x) * (bpp / 8);
 	ok = pExaScr->info->UploadToScreen(pPix, x1 + xoff, y1 + yoff,
 					   x2 - x1, y2 - y1, src, src_stride);
 	/* If we fail to accelerate the upload, fall back to using unaccelerated
@@ -202,6 +205,8 @@ exaPutImage (DrawablePtr pDrawable, GCPtr pGC, int depth, int x, int y,
 	    int	dstBpp;
 	    int	dstXoff, dstYoff;
 
+	    exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
+
 	    fbGetStipDrawable(pDrawable, dst, dst_stride, dstBpp,
 			      dstXoff, dstYoff);
 
@@ -214,6 +219,8 @@ exaPutImage (DrawablePtr pDrawable, GCPtr pGC, int depth, int x, int y,
 		      (x2 - x1) * bpp,
 		      y2 - y1,
 		      GXcopy, FB_ALLONES, bpp);
+
+	    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
 	}
     }
 

exa/exa_migration.c

@@ -190,7 +190,7 @@ exaPixmapSave (ScreenPtr pScreen, ExaOffscreenArea *area)
 		  pPixmap->drawable.width,
 		  pPixmap->drawable.height));
 
-    if (pPixmap->devPrivate.ptr == pExaPixmap->fb_ptr) {
+    if (exaPixmapIsOffscreen(pPixmap)) {
 	exaCopyDirtyToSys (pPixmap);
 	pPixmap->devPrivate.ptr = pExaPixmap->sys_ptr;
 	pPixmap->devKind = pExaPixmap->sys_pitch;
@@ -233,7 +233,7 @@ exaMoveInPixmap (PixmapPtr pPixmap)
 	return;
 
     /* If we're already in FB, our work is done. */
-    if (pPixmap->devPrivate.ptr == pExaPixmap->fb_ptr)
+    if (exaPixmapIsOffscreen(pPixmap))
 	return;
 
     /* If we're not allowed to move, then fail. */
@@ -267,7 +267,10 @@ exaMoveInPixmap (PixmapPtr pPixmap)
 
     exaCopyDirtyToFb (pPixmap);
 
-    pPixmap->devPrivate.ptr = (pointer) pExaPixmap->fb_ptr;
+    if (pExaScr->hideOffscreenPixmapData)
+	pPixmap->devPrivate.ptr = NULL;
+    else
+	pPixmap->devPrivate.ptr = pExaPixmap->fb_ptr;
     pPixmap->devKind = pExaPixmap->fb_pitch;
     pPixmap->drawable.serialNumber = NEXT_SERIAL_NUMBER;
 }
@@ -291,7 +294,7 @@ exaMoveOutPixmap (PixmapPtr pPixmap)
 		  pPixmap->drawable.width,
 		  pPixmap->drawable.height));
 
-    if (pPixmap->devPrivate.ptr == pExaPixmap->fb_ptr) {
+    if (exaPixmapIsOffscreen(pPixmap)) {
 	exaCopyDirtyToSys (pPixmap);
 
 	pPixmap->devPrivate.ptr = pExaPixmap->sys_ptr;

exa/exa_priv.h

@@ -100,10 +100,13 @@ typedef struct {
     CopyWindowProcPtr 		 SavedCopyWindow;
 #ifdef RENDER
     CompositeProcPtr             SavedComposite;
+    RasterizeTrapezoidProcPtr	 SavedRasterizeTrapezoid;
+    AddTrianglesProcPtr		 SavedAddTriangles;
     GlyphsProcPtr                SavedGlyphs;
 #endif
     Bool			 swappedOut;
     enum ExaMigrationHeuristic	 migration;
+    Bool			 hideOffscreenPixmapData;
 } ExaScreenPrivRec, *ExaScreenPrivPtr;
 
 /*
@@ -219,24 +222,14 @@ void
 ExaCheckPolySegment (DrawablePtr pDrawable, GCPtr pGC,
 		    int nsegInit, xSegment *pSegInit);
 
-void
-ExaCheckPolyRectangle (DrawablePtr pDrawable, GCPtr pGC,
-		      int nrects, xRectangle *prect);
-
 void
 ExaCheckPolyArc (DrawablePtr pDrawable, GCPtr pGC,
 		int narcs, xArc *pArcs);
 
-#define ExaCheckFillPolygon	miFillPolygon
-
 void
 ExaCheckPolyFillRect (DrawablePtr pDrawable, GCPtr pGC,
 		     int nrect, xRectangle *prect);
 
-void
-ExaCheckPolyFillArc (DrawablePtr pDrawable, GCPtr pGC,
-		    int narcs, xArc *pArcs);
-
 void
 ExaCheckImageGlyphBlt (DrawablePtr pDrawable, GCPtr pGC,
 		      int x, int y, unsigned int nglyph,
@@ -374,6 +367,7 @@ exaCopyNtoN (DrawablePtr    pSrcDrawable,
 	     Pixel	    bitplane,
 	     void	    *closure);
 
+/* exa_render.c */
 void
 exaComposite(CARD8	op,
 	     PicturePtr pSrc,
@@ -388,6 +382,14 @@ exaComposite(CARD8	op,
 	     CARD16	width,
 	     CARD16	height);
 
+void
+exaRasterizeTrapezoid (PicturePtr pPicture, xTrapezoid  *trap,
+		       int x_off, int y_off);
+
+void
+exaAddTriangles (PicturePtr pPicture, INT16 x_off, INT16 y_off, int ntri,
+		 xTriangle *tris);
+
 void
 exaGlyphs (CARD8	op,
 	  PicturePtr	pSrc,

exa/exa_render.c

@@ -576,6 +576,49 @@ exaComposite(CARD8	op,
 
 #define NeedsComponent(f) (PICT_FORMAT_A(f) != 0 && PICT_FORMAT_RGB(f) != 0)
 
+/**
+ * exaRasterizeTrapezoid is just a wrapper around the software implementation.
+ *
+ * The trapezoid specification is basically too hard to be done in hardware (at
+ * the very least, without programmability), so we just do the appropriate
+ * Prepare/FinishAccess for it before using fbtrap.c.
+ */
+void
+exaRasterizeTrapezoid (PicturePtr pPicture, xTrapezoid  *trap,
+		       int x_off, int y_off)
+{
+    ExaMigrationRec pixmaps[1];
+
+    pixmaps[0].as_dst = TRUE;
+    pixmaps[0].as_src = TRUE;
+    pixmaps[0].pPix = exaGetDrawablePixmap (pPicture->pDrawable);
+    exaDoMigration(pixmaps, 1, FALSE);
+
+    exaPrepareAccess(pPicture->pDrawable, EXA_PREPARE_DEST);
+    fbRasterizeTrapezoid(pPicture, trap, x_off, y_off);
+    exaFinishAccess(pPicture->pDrawable, EXA_PREPARE_DEST);
+}
+
+/**
+ * exaAddTriangles does migration and syncing before dumping down to the
+ * software implementation.
+ */
+void
+exaAddTriangles (PicturePtr pPicture, INT16 x_off, INT16 y_off, int ntri,
+		 xTriangle *tris)
+{
+    ExaMigrationRec pixmaps[1];
+
+    pixmaps[0].as_dst = TRUE;
+    pixmaps[0].as_src = TRUE;
+    pixmaps[0].pPix = exaGetDrawablePixmap (pPicture->pDrawable);
+    exaDoMigration(pixmaps, 1, FALSE);
+
+    exaPrepareAccess(pPicture->pDrawable, EXA_PREPARE_DEST);
+    fbAddTriangles(pPicture, x_off, y_off, ntri, tris);
+    exaFinishAccess(pPicture->pDrawable, EXA_PREPARE_DEST);
+}
+
 /* exaGlyphs is a slight variation on miGlyphs, to support acceleration.  The
  * issue is that miGlyphs' use of ModifyPixmapHeader makes it impossible to
  * migrate these pixmaps.  So, instead we create a pixmap at the beginning of

exa/exa_unaccel.c

@@ -29,13 +29,39 @@
  * the accelerator is idle
  */
 
+/**
+ * Calls exaPrepareAccess with EXA_PREPARE_SRC for the tile, if that is the
+ * current fill style.
+ *
+ * Solid doesn't use an extra pixmap source, and Stippled/OpaqueStippled are
+ * 1bpp and never in fb, so we don't worry about them.
+ */
+static void
+exaPrepareAccessGC(GCPtr pGC)
+{
+    if (pGC->fillStyle == FillTiled)
+	exaPrepareAccess(&pGC->tile.pixmap->drawable, EXA_PREPARE_SRC);
+}
+
+/**
+ * Finishes access to the tile in the GC, if used.
+ */
+static void
+exaFinishAccessGC(GCPtr pGC)
+{
+    if (pGC->fillStyle == FillTiled)
+	exaFinishAccess(&pGC->tile.pixmap->drawable, EXA_PREPARE_SRC);
+}
+
 void
 ExaCheckFillSpans  (DrawablePtr pDrawable, GCPtr pGC, int nspans,
 		   DDXPointPtr ppt, int *pwidth, int fSorted)
 {
     EXA_FALLBACK(("to 0x%lx\n", (long)pDrawable));
     exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
+    exaPrepareAccessGC (pGC);
     fbFillSpans (pDrawable, pGC, nspans, ppt, pwidth, fSorted);
+    exaFinishAccessGC (pGC);
     exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
 }
 
@@ -112,10 +138,13 @@ ExaCheckPolylines (DrawablePtr pDrawable, GCPtr pGC,
 
     if (pGC->lineWidth == 0) {
 	exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
+	exaPrepareAccessGC (pGC);
 	fbPolyLine (pDrawable, pGC, mode, npt, ppt);
+	exaFinishAccessGC (pGC);
 	exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
 	return;
     }
+    /* fb calls mi functions in the lineWidth != 0 case. */
     fbPolyLine (pDrawable, pGC, mode, npt, ppt);
 }
 
@@ -126,27 +155,16 @@ ExaCheckPolySegment (DrawablePtr pDrawable, GCPtr pGC,
     EXA_FALLBACK(("to 0x%lx\n", (long)pDrawable));
     if (pGC->lineWidth == 0) {
 	exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
+	exaPrepareAccessGC (pGC);
 	fbPolySegment (pDrawable, pGC, nsegInit, pSegInit);
+	exaFinishAccessGC (pGC);
 	exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
 	return;
     }
+    /* fb calls mi functions in the lineWidth != 0 case. */
     fbPolySegment (pDrawable, pGC, nsegInit, pSegInit);
 }
 
-void
-ExaCheckPolyRectangle (DrawablePtr pDrawable, GCPtr pGC,
-		      int nrects, xRectangle *prect)
-{
-    EXA_FALLBACK(("to 0x%lx\n", (long)pDrawable));
-    if (pGC->lineWidth == 0) {
-	exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
-	fbPolyRectangle (pDrawable, pGC, nrects, prect);
-	exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
-	return;
-    }
-    fbPolyRectangle (pDrawable, pGC, nrects, prect);
-}
-
 void
 ExaCheckPolyArc (DrawablePtr pDrawable, GCPtr pGC,
 		int narcs, xArc *pArcs)
@@ -155,42 +173,24 @@ ExaCheckPolyArc (DrawablePtr pDrawable, GCPtr pGC,
     if (pGC->lineWidth == 0)
     {
 	exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
+	exaPrepareAccessGC (pGC);
 	fbPolyArc (pDrawable, pGC, narcs, pArcs);
+	exaFinishAccessGC (pGC);
 	exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
 	return;
     }
     miPolyArc (pDrawable, pGC, narcs, pArcs);
 }
 
-#if 0
-void
-ExaCheckFillPolygon (DrawablePtr pDrawable, GCPtr pGC,
-		    int shape, int mode, int count, DDXPointPtr pPts)
-{
-    EXA_FALLBACK(("to 0x%lx\n", (long)pDrawable));
-    exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
-    fbFillPolygon (pDrawable, pGC, mode, count, pPts);
-    exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
-}
-#endif
-
 void
 ExaCheckPolyFillRect (DrawablePtr pDrawable, GCPtr pGC,
 		     int nrect, xRectangle *prect)
 {
     EXA_FALLBACK(("to 0x%lx\n", (long)pDrawable));
     exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
+    exaPrepareAccessGC (pGC);
     fbPolyFillRect (pDrawable, pGC, nrect, prect);
-    exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
+    exaFinishAccessGC (pGC);
-}
-
-void
-ExaCheckPolyFillArc (DrawablePtr pDrawable, GCPtr pGC,
-		    int narcs, xArc *pArcs)
-{
-    EXA_FALLBACK(("to 0x%lx\n", (long)pDrawable));
-    exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
-    fbPolyFillArc (pDrawable, pGC, narcs, pArcs);
     exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
 }
 
@@ -201,7 +201,9 @@ ExaCheckImageGlyphBlt (DrawablePtr pDrawable, GCPtr pGC,
 {
     EXA_FALLBACK(("to 0x%lx\n", (long)pDrawable));
     exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
+    exaPrepareAccessGC (pGC);
     fbImageGlyphBlt (pDrawable, pGC, x, y, nglyph, ppci, pglyphBase);
+    exaFinishAccessGC (pGC);
     exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
 }
 
@@ -212,7 +214,9 @@ ExaCheckPolyGlyphBlt (DrawablePtr pDrawable, GCPtr pGC,
 {
     EXA_FALLBACK(("to 0x%lx\n", (long)pDrawable));
     exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
+    exaPrepareAccessGC (pGC);
     fbPolyGlyphBlt (pDrawable, pGC, x, y, nglyph, ppci, pglyphBase);
+    exaFinishAccessGC (pGC);
     exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
 }
 
@@ -223,7 +227,9 @@ ExaCheckPushPixels (GCPtr pGC, PixmapPtr pBitmap,
 {
     EXA_FALLBACK(("from 0x%lx to 0x%lx\n", (long)pBitmap, (long)pDrawable));
     exaPrepareAccess (pDrawable, EXA_PREPARE_DEST);
+    exaPrepareAccessGC (pGC);
     fbPushPixels (pGC, pBitmap, pDrawable, w, h, x, y);
+    exaFinishAccessGC (pGC);
     exaFinishAccess (pDrawable, EXA_PREPARE_DEST);
 }
 

hw/kdrive/ephyr/ephyr.h

@@ -55,7 +55,8 @@ typedef struct _ephyrFakexaPriv {
      */
     int op;
     PicturePtr pSrcPicture, pMaskPicture, pDstPicture;
-    PixmapPtr pSrc, pDst;
+    void *saved_ptrs[3];
+    PixmapPtr pDst, pSrc, pMask;
     GCPtr pGC;
 } EphyrFakexaPriv;
 

hw/kdrive/ephyr/ephyr_draw.c

@@ -28,6 +28,7 @@
 #ifdef HAVE_CONFIG_H
 #include <kdrive-config.h>
 #endif
+#undef NDEBUG	/* No, really.  The whole point of this module is to crash. */
 
 #include "ephyr.h"
 #include "exa_priv.h"
@@ -48,6 +49,44 @@
 #define EPHYR_OFFSCREEN_SIZE	(16 * 1024 * 1024)
 #define EPHYR_OFFSCREEN_BASE	(1 * 1024 * 1024)
 
+/**
+ * Forces a real devPrivate.ptr for hidden pixmaps, so that we can call down to
+ * fb functions.
+ */
+static void
+ephyrPreparePipelinedAccess(PixmapPtr pPix, int index)
+{
+    KdScreenPriv(pPix->drawable.pScreen);
+    KdScreenInfo *screen = pScreenPriv->screen;
+    EphyrScrPriv *scrpriv = screen->driver;
+    EphyrFakexaPriv *fakexa = scrpriv->fakexa;
+
+    assert(fakexa->saved_ptrs[index] == NULL);
+    fakexa->saved_ptrs[index] = pPix->devPrivate.ptr;
+
+    if (pPix->devPrivate.ptr != NULL)
+	return;
+
+    pPix->devPrivate.ptr = fakexa->exa->memoryBase + exaGetPixmapOffset(pPix);
+}
+
+/**
+ * Restores the original devPrivate.ptr of the pixmap from before we messed with
+ * it.
+ */
+static void
+ephyrFinishPipelinedAccess(PixmapPtr pPix, int index)
+{
+    KdScreenPriv(pPix->drawable.pScreen);
+    KdScreenInfo *screen = pScreenPriv->screen;
+    EphyrScrPriv *scrpriv = screen->driver;
+    EphyrFakexaPriv *fakexa = scrpriv->fakexa;
+    void *offscreen_begin, *offscreen_end;
+
+    pPix->devPrivate.ptr = fakexa->saved_ptrs[index];
+    fakexa->saved_ptrs[index] = NULL;
+}
+
 /**
  * Sets up a scratch GC for fbFill, and saves other parameters for the
  * ephyrSolid implementation.
@@ -62,6 +101,8 @@ ephyrPrepareSolid(PixmapPtr pPix, int alu, Pixel pm, Pixel fg)
     EphyrFakexaPriv *fakexa = scrpriv->fakexa;
     CARD32 tmpval[3];
 
+    ephyrPreparePipelinedAccess(pPix, EXA_PREPARE_DEST);
+
     fakexa->pDst = pPix;
     fakexa->pGC = GetScratchGC(pPix->drawable.depth, pScreen);
 
@@ -106,6 +147,8 @@ ephyrDoneSolid(PixmapPtr pPix)
     EphyrFakexaPriv *fakexa = scrpriv->fakexa;
 
     FreeScratchGC(fakexa->pGC);
+
+    ephyrFinishPipelinedAccess(pPix, EXA_PREPARE_DEST);
 }
 
 /**
@@ -123,6 +166,9 @@ ephyrPrepareCopy(PixmapPtr pSrc, PixmapPtr pDst, int dx, int dy, int alu,
     EphyrFakexaPriv *fakexa = scrpriv->fakexa;
     CARD32 tmpval[2];
 
+    ephyrPreparePipelinedAccess(pDst, EXA_PREPARE_DEST);
+    ephyrPreparePipelinedAccess(pSrc, EXA_PREPARE_SRC);
+
     fakexa->pSrc = pSrc;
     fakexa->pDst = pDst;
     fakexa->pGC = GetScratchGC(pDst->drawable.depth, pScreen);
@@ -167,6 +213,9 @@ ephyrDoneCopy(PixmapPtr pDst)
     EphyrFakexaPriv *fakexa = scrpriv->fakexa;
 
     FreeScratchGC (fakexa->pGC);
+
+    ephyrFinishPipelinedAccess(fakexa->pSrc, EXA_PREPARE_SRC);
+    ephyrFinishPipelinedAccess(fakexa->pDst, EXA_PREPARE_DEST);
 }
 
 /**
@@ -194,10 +243,18 @@ ephyrPrepareComposite(int op, PicturePtr pSrcPicture, PicturePtr pMaskPicture,
     EphyrScrPriv *scrpriv = screen->driver;
     EphyrFakexaPriv *fakexa = scrpriv->fakexa;
 
+    ephyrPreparePipelinedAccess(pDst, EXA_PREPARE_DEST);
+    ephyrPreparePipelinedAccess(pSrc, EXA_PREPARE_SRC);
+    if (pMask != NULL)
+	ephyrPreparePipelinedAccess(pMask, EXA_PREPARE_MASK);
+
     fakexa->op = op;
     fakexa->pSrcPicture = pSrcPicture;
     fakexa->pMaskPicture = pMaskPicture;
     fakexa->pDstPicture = pDstPicture;
+    fakexa->pSrc = pSrc;
+    fakexa->pMask = pMask;
+    fakexa->pDst = pDst;
 
     TRACE_DRAW();
 
@@ -224,6 +281,15 @@ ephyrComposite(PixmapPtr pDst, int srcX, int srcY, int maskX, int maskY,
 static void
 ephyrDoneComposite(PixmapPtr pDst)
 {
+    KdScreenPriv(pDst->drawable.pScreen);
+    KdScreenInfo *screen = pScreenPriv->screen;
+    EphyrScrPriv *scrpriv = screen->driver;
+    EphyrFakexaPriv *fakexa = scrpriv->fakexa;
+
+    if (fakexa->pMask != NULL)
+	ephyrFinishPipelinedAccess(fakexa->pMask, EXA_PREPARE_MASK);
+    ephyrFinishPipelinedAccess(fakexa->pSrc, EXA_PREPARE_SRC);
+    ephyrFinishPipelinedAccess(fakexa->pDst, EXA_PREPARE_DEST);
 }
 
 /**
@@ -243,6 +309,8 @@ ephyrDownloadFromScreen(PixmapPtr pSrc, int x, int y, int w, int h, char *dst,
     if (pSrc->drawable.bitsPerPixel < 8)
 	return FALSE;
 
+    ephyrPreparePipelinedAccess(pSrc, EXA_PREPARE_SRC);
+
     cpp = pSrc->drawable.bitsPerPixel / 8;
     src_pitch = exaGetPixmapPitch(pSrc);
     src = fakexa->exa->memoryBase + exaGetPixmapOffset(pSrc);
@@ -256,6 +324,8 @@ ephyrDownloadFromScreen(PixmapPtr pSrc, int x, int y, int w, int h, char *dst,
 
     exaMarkSync(pSrc->drawable.pScreen);
 
+    ephyrFinishPipelinedAccess(pSrc, EXA_PREPARE_SRC);
+
     return TRUE;
 }
 
@@ -276,11 +346,13 @@ ephyrUploadToScreen(PixmapPtr pDst, int x, int y, int w, int h, char *src,
     if (pDst->drawable.bitsPerPixel < 8)
 	return FALSE;
 
+    ephyrPreparePipelinedAccess(pDst, EXA_PREPARE_DEST);
+
     cpp = pDst->drawable.bitsPerPixel / 8;
     dst_pitch = exaGetPixmapPitch(pDst);
     dst = fakexa->exa->memoryBase + exaGetPixmapOffset(pDst);
     dst += y * dst_pitch + x * cpp;
-
+    ErrorF("uts %d,%d, %dx%d, %dbpp %p/%x\n", x, y, w, h, pDst->drawable.bitsPerPixel, dst, dst_pitch);
     for (; h > 0; h--) {
 	memcpy(dst, src, w * cpp);
 	dst += dst_pitch;
@@ -289,14 +361,26 @@ ephyrUploadToScreen(PixmapPtr pDst, int x, int y, int w, int h, char *src,
 
     exaMarkSync(pDst->drawable.pScreen);
 
+    ephyrFinishPipelinedAccess(pDst, EXA_PREPARE_DEST);
+
+    return TRUE;
+}
+
+static Bool
+ephyrPrepareAccess(PixmapPtr pPix, int index)
+{
+    /* Make sure we don't somehow end up with a pointer that is in framebuffer
+     * and hasn't been readied for us.
+     */
+    assert(pPix->devPrivate.ptr != NULL);
+
     return TRUE;
 }
 
 /**
  * In fakexa, we currently only track whether we have synced to the latest
- * "accelerated" drawing that has happened or not.  This will be used by an
+ * "accelerated" drawing that has happened or not.  It's not used for anything
- * ephyrPrepareAccess for the purpose of reliably providing garbage when
+ * yet.
- * reading/writing when we haven't synced.
  */
 static int
 ephyrMarkSync(ScreenPtr pScreen)
@@ -382,6 +466,8 @@ ephyrDrawInit(ScreenPtr pScreen)
     fakexa->exa->MarkSync = ephyrMarkSync;
     fakexa->exa->WaitMarker = ephyrWaitMarker;
 
+    fakexa->exa->PrepareAccess = ephyrPrepareAccess;
+
     fakexa->exa->pixmapOffsetAlign = EPHYR_OFFSET_ALIGN;
     fakexa->exa->pixmapPitchAlign = EPHYR_PITCH_ALIGN;
 
@@ -429,4 +515,5 @@ exaDDXDriverInit(ScreenPtr pScreen)
     ExaScreenPriv(pScreen);
 
     pExaScr->migration = ExaMigrationAlways;
+    pExaScr->hideOffscreenPixmapData = TRUE;
 }