atl2: prevent compiler memory access misordering

While no problems have been observed in practice yet, modern compilers
may reorder memory access operations, and that could lead to problems
with memory-mapped I/O typically done by drivers. This patch prevents
any potentially problematic reordering by the compiler in the ATL2
driver.

In addition, this patch removes a number of gcc/clang warnings.

diff --git a/drivers/atl2/atl2.c b/drivers/atl2/atl2.c
index 30af19469d4aac2f4b801a3fc1eb3c9114c8f816..70adec6ec555c7d9455c486cd079e8dd162bd029 100644 (file)
--- a/drivers/atl2/atl2.c
+++ b/drivers/atl2/atl2.c
@@ -37,7 +37,7 @@ PRIVATE struct {
        int irq;                /* IRQ number */
        int hook_id;            /* IRQ hook ID */
        int mode;               /* datalink mode */
-       char *base;             /* base address of memory-mapped registers */
+       volatile u8_t *base;    /* base address of memory-mapped registers */
        u32_t size;             /* size of memory-mapped area */
        u32_t hwaddr[2];        /* MAC address, in register representation */
 
@@ -628,25 +628,27 @@ PRIVATE int atl2_tx_advance(void)
                 */
                size = stat & ATL2_TXS_SIZE_MASK;
 
-               assert(state.txd_tail <= ATL2_TXD_BUFSIZE - sizeof(u32_t));
+               assert((u32_t) state.txd_tail <=
+                       ATL2_TXD_BUFSIZE - sizeof(u32_t));
                dsize = * (u32_t *) (state.txd_base + state.txd_tail);
                if (size != dsize)
-                       printf("ATL2: TxD/TxS size mismatch (%lx vs %lx)\n",
+                       printf("ATL2: TxD/TxS size mismatch (%x vs %x)\n",
                                size, dsize);
 
                /* Advance tails accordingly. */
                size = sizeof(u32_t) + ATL2_ALIGN_32(dsize);
-               assert(state.txd_num >= size);
+               assert((u32_t) state.txd_num >= size);
                state.txd_tail = (state.txd_tail + size) % ATL2_TXD_BUFSIZE;
                state.txd_num -= size;
 
                state.txs_tail = (state.txs_tail + 1) % ATL2_TXS_COUNT;
                state.txs_num--;
 
-               if (stat & ATL2_TXS_SUCCESS)
+               if (stat & ATL2_TXS_SUCCESS) {
                        ATL2_DEBUG(("ATL2: successfully sent packet\n"));
-               else
+               } else {
                        ATL2_DEBUG(("ATL2: failed to send packet\n"));
+               }
 
                /* Update statistics. */
                atl2_tx_stat(stat);
@@ -718,8 +720,11 @@ PRIVATE void atl2_rx_advance(int next)
        }
 
        /* If new RxD descriptors are now up for reuse, tell the device. */
-       if (update_tail)
+       if (update_tail) {
+               __insn_barrier();
+
                ATL2_WRITE_U32(ATL2_RXD_IDX_REG, state.rxd_tail);
+       }
 }
 
 /*===========================================================================*
@@ -935,13 +940,16 @@ PRIVATE void atl2_writev(const message *m, int from_int)
        /* Update the TxD head. */
        state.txd_num += sizeof(u32_t) + ATL2_ALIGN_32(count);
        pos = ATL2_ALIGN_32(pos) % ATL2_TXD_BUFSIZE;
-       assert(pos == (state.txd_tail + state.txd_num) % ATL2_TXD_BUFSIZE);
+       assert((int) pos ==
+               (state.txd_tail + state.txd_num) % ATL2_TXD_BUFSIZE);
 
        /* Initialize and update the TxS head. */
        state.txs_base[(state.txs_tail + state.txs_num) % ATL2_TXS_COUNT] = 0;
        state.txs_num++;
 
        /* Tell the device about our new position. */
+       __insn_barrier();
+
        ATL2_WRITE_U32(ATL2_TXD_IDX_REG, pos / sizeof(u32_t));
 
        /* We have now successfully set up the transmission of a packet. */
@@ -971,7 +979,7 @@ suspend:
 /*===========================================================================*
  *                             atl2_intr                                    *
  *===========================================================================*/
-PRIVATE void atl2_intr(const message *m)
+PRIVATE void atl2_intr(const message *UNUSED(m))
 {
        /* Interrupt received.
         */
@@ -1030,21 +1038,21 @@ PRIVATE void atl2_conf(message *m)
 {
        /* Configure the mode of the card.
         */
-       ether_addr_t *addr;
+       ether_addr_t addr;
        int r;
 
        state.mode = m->DL_MODE;
 
        atl2_set_mode();
 
-       addr = (ether_addr_t *) m->DL_HWADDR;
+       addr.ea_addr[0] = state.hwaddr[1] >> 8;
+       addr.ea_addr[1] = state.hwaddr[1] & 0xff;
+       addr.ea_addr[2] = state.hwaddr[0] >> 24;
+       addr.ea_addr[3] = (state.hwaddr[0] >> 16) & 0xff;
+       addr.ea_addr[4] = (state.hwaddr[0] >> 8) & 0xff;
+       addr.ea_addr[5] = state.hwaddr[0] & 0xff;
 
-       addr->ea_addr[0] = state.hwaddr[1] >> 8;
-       addr->ea_addr[1] = state.hwaddr[1] & 0xff;
-       addr->ea_addr[2] = state.hwaddr[0] >> 24;
-       addr->ea_addr[3] = (state.hwaddr[0] >> 16) & 0xff;
-       addr->ea_addr[4] = (state.hwaddr[0] >> 8) & 0xff;
-       addr->ea_addr[5] = state.hwaddr[0] & 0xff;
+       memcpy(m->DL_HWADDR, &addr, sizeof(addr));
 
        m->m_type = DL_CONF_REPLY;
        m->DL_STAT = OK;
@@ -1155,7 +1163,7 @@ PRIVATE void atl2_dump(void)
 /*===========================================================================*
  *                         sef_cb_init_fresh                                *
  *===========================================================================*/
-PRIVATE int sef_cb_init_fresh(int type, sef_init_info_t *UNUSED(info))
+PRIVATE int sef_cb_init_fresh(int UNUSED(type), sef_init_info_t *UNUSED(info))
 {
        /* Initialize the atl2 driver.
         */
@@ -1216,7 +1224,7 @@ PRIVATE void sef_cb_signal_handler(int signo)
        free_contig(state.rxd_base_u,
                state.rxd_align + ATL2_RXD_COUNT * ATL2_RXD_SIZE);
 
-       vm_unmap_phys(SELF, state.base, state.size);
+       vm_unmap_phys(SELF, (void *) state.base, state.size);
 
        /* We cannot free the PCI device at this time. */