The Apple DART has a nifty feature that allows us protection of subranges

of a page with a granularity of 32-bit words.  Use this to expose just
those parts of memory to devices that we want the device to see.  This
means that handing down a small mbuf to a network card driver no longer
gives the hardware access to other mbufs in the same page.

It turns out that bge(4) always does aligned 64-bit access to memory though.
So round up/down to the nearest 64-bit boundary to prevent triggering an
IOMMU fault.

ok patrick@

diff --git a/sys/arch/arm64/dev/apldart.c b/sys/arch/arm64/dev/apldart.c
index 3999406..d6df9f4 100644 (file)
--- a/sys/arch/arm64/dev/apldart.c
+++ b/sys/arch/arm64/dev/apldart.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: apldart.c,v 1.7 2021/11/01 20:04:11 kettenis Exp $    */
+/*     $OpenBSD: apldart.c,v 1.8 2021/11/11 18:43:05 kettenis Exp $    */
 /*
  * Copyright (c) 2021 Mark Kettenis <kettenis@openbsd.org>
  *
@@ -31,11 +31,6 @@
 #include <dev/ofw/fdt.h>
 
 /*
- * This driver is based on preliminary device tree bindings and will
- * almost certainly need changes once the official bindings land in
- * mainline Linux.  Support for these preliminary bindings will be
- * dropped as soon as official bindings are available.
- *
  * This driver largely ignores stream IDs and simply uses a single
  * translation table for all the devices that it serves.  This is good
  * enough for the PCIe host bridge that serves the on-board devices on
@@ -49,6 +44,9 @@
 #define  DART_TLB_OP_FLUSH             (1 << 20)
 #define  DART_TLB_OP_BUSY              (1 << 2)
 #define DART_TLB_OP_SIDMASK    0x0034
+#define DART_ERROR             0x0040
+#define DART_ERROR_ADDR_LO     0x0050
+#define DART_ERROR_ADDR_HI     0x0054
 #define DART_TCR(sid)          (0x0100 + 4 *(sid))
 #define  DART_TCR_TRANSLATE_ENABLE     (1 << 7)
 #define  DART_TCR_BYPASS_DART          (1 << 8)
@@ -63,9 +61,19 @@
 #define DART_PAGE_SIZE         16384
 #define DART_PAGE_MASK         (DART_PAGE_SIZE - 1)
 
+/*
+ * Some hardware (e.g. bge(4)) will always use (aligned) 64-bit memory
+ * access.  To make sure this doesn't fault, round the subpage limits
+ * down and up accordingly.
+ */
+#define DART_OFFSET_MASK       7
+
 #define DART_L1_TABLE          0xb
-#define DART_L2_INVAL          0x0
-#define DART_L2_PAGE           0x3
+#define DART_L2_INVAL          0
+#define DART_L2_VALID          (1 << 0)
+#define DART_L2_FULL_PAGE      (1 << 1)
+#define DART_L2_START(addr)    ((((addr) & DART_PAGE_MASK) >> 2) << 52)
+#define DART_L2_END(addr)      ((((addr) & DART_PAGE_MASK) >> 2) << 40)
 
 static inline paddr_t
 apldart_round_page(paddr_t pa)
@@ -73,12 +81,24 @@ apldart_round_page(paddr_t pa)
        return ((pa + DART_PAGE_MASK) & ~DART_PAGE_MASK);
 }
 
-inline paddr_t
-static apldart_trunc_page(paddr_t pa)
+static inline paddr_t
+apldart_trunc_page(paddr_t pa)
 {
        return (pa & ~DART_PAGE_MASK);
 }
 
+static inline psize_t
+apldart_round_offset(psize_t off)
+{
+       return ((off + DART_OFFSET_MASK) & ~DART_OFFSET_MASK);
+}
+
+static inline psize_t
+apldart_trunc_offset(psize_t off)
+{
+       return (off & ~DART_OFFSET_MASK);
+}
+
 #define HREAD4(sc, reg)                                                        \
        (bus_space_read_4((sc)->sc_iot, (sc)->sc_ioh, (reg)))
 #define HWRITE4(sc, reg, val)                                          \
@@ -303,7 +323,9 @@ apldart_intr(void *arg)
 {
        struct apldart_softc *sc = arg;
 
-       panic("%s: %s", sc->sc_dev.dv_xname, __func__);
+       panic("%s: error 0x%08x addr 0x%08x%08x\n", sc->sc_dev.dv_xname,
+           HREAD4(sc, DART_ERROR), HREAD4(sc, DART_ERROR_ADDR_HI),
+           HREAD4(sc, DART_ERROR_ADDR_LO));
 }
 
 void
@@ -340,6 +362,7 @@ apldart_load_map(struct apldart_softc *sc, bus_dmamap_t map)
        for (seg = 0; seg < map->dm_nsegs; seg++) {
                paddr_t pa = map->dm_segs[seg]._ds_paddr;
                psize_t off = pa - apldart_trunc_page(pa);
+               psize_t start, end;
                u_long len, dva;
 
                len = apldart_round_page(map->dm_segs[seg].ds_len + off);
@@ -359,13 +382,20 @@ apldart_load_map(struct apldart_softc *sc, bus_dmamap_t map)
                map->dm_segs[seg].ds_addr = dva + off;
 
                pa = apldart_trunc_page(pa);
+               start = apldart_trunc_offset(off);
+               end = DART_PAGE_MASK;
                while (len > 0) {
+                       if (len < DART_PAGE_SIZE)
+                               end = apldart_round_offset(len) - 1;
+
                        tte = apldart_lookup_tte(sc, dva);
-                       *tte = pa | DART_L2_PAGE;
+                       *tte = pa | DART_L2_VALID |
+                           DART_L2_START(start) | DART_L2_END(end);
 
                        pa += DART_PAGE_SIZE;
                        dva += DART_PAGE_SIZE;
                        len -= DART_PAGE_SIZE;
+                       start = 0;
                }
        }