Hi Marc,

On 12/6/20 5:48 pm, Marc Kleine-Budde wrote:
the k-build robot found this sparse problem, triggered by building a CAN driver
for m68k. Is this a problem in our CAN driver or in the m68k headers?

I suspect a problem with the m68k (specifically non-mmu) headers.


On 6/12/20 7:28 AM, kernel test robot wrote:
tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
master
head:   b791d1bdf9212d944d749a5c7ff6febdba241771
commit: 26ad340e582d3d5958ed8456a1911d79cfb567b4 can: kvaser_pciefd: Add driver 
for Kvaser PCIEcan devices
date:   11 months ago
config: m68k-randconfig-s032-20200612 (attached as .config)
compiler: m68k-linux-gcc (GCC) 9.3.0
reproduce:
         # apt-get install sparse
         # sparse version: v0.6.1-250-g42323db3-dirty
         git checkout 26ad340e582d3d5958ed8456a1911d79cfb567b4
         # save the attached .config to linux build tree
         make W=1 C=1 ARCH=m68k CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <l...@intel.com>


sparse warnings: (new ones prefixed by >>)

drivers/net/can/kvaser_pciefd.c:801:17: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    drivers/net/can/kvaser_pciefd.c:805:17: sparse: sparse: cast removes address 
space '<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:77:24: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression

I think this one is due to not forcing the volatile cast in __raw_write().
So this change will fix that:

diff --git a/arch/m68k/include/asm/io_no.h b/arch/m68k/include/asm/io_no.h
index 0498192e1d98..1bc739f1f1ad 100644
--- a/arch/m68k/include/asm/io_no.h
+++ b/arch/m68k/include/asm/io_no.h
@@ -14,15 +14,15 @@
  * that behavior here first before we include asm-generic/io.h.
  */
 #define __raw_readb(addr) \
-    ({ unsigned char __v = (*(volatile unsigned char *) (addr)); __v; })
+    ({ u8 __v = (*(__force volatile u8 *) (addr)); __v; })
 #define __raw_readw(addr) \
-    ({ unsigned short __v = (*(volatile unsigned short *) (addr)); __v; })
+    ({ u16 __v = (*(__force volatile u16 *) (addr)); __v; })
 #define __raw_readl(addr) \
-    ({ unsigned int __v = (*(volatile unsigned int *) (addr)); __v; })
+    ({ u32 __v = (*(__force volatile u32 *) (addr)); __v; })
-#define __raw_writeb(b, addr) (void)((*(volatile unsigned char *) (addr)) = (b))
-#define __raw_writew(b, addr) (void)((*(volatile unsigned short *) (addr)) = 
(b))
-#define __raw_writel(b, addr) (void)((*(volatile unsigned int *) (addr)) = (b))
+#define __raw_writeb(b, addr) (void)((*(__force volatile u8 *) (addr)) = (b))
+#define __raw_writew(b, addr) (void)((*(__force volatile u16 *) (addr)) = (b))
+#define __raw_writel(b, addr) (void)((*(__force volatile u32 *) (addr)) = (b))
#if defined(CONFIG_COLDFIRE)
 /*


    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32

This one I am not sure about yet.
Still investigating.

Regards
Greg


    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:77:24: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:77:24: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:77:24: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast removes address space 
'<asn:2>' of expression
    arch/m68k/include/asm/io_no.h:78:16: sparse: sparse: cast to restricted 
__le32

vim +801 drivers/net/can/kvaser_pciefd.c

    764 
    765 static netdev_tx_t kvaser_pciefd_start_xmit(struct sk_buff *skb,
    766                                             struct net_device *netdev)
    767 {
    768         struct kvaser_pciefd_can *can = netdev_priv(netdev);
    769         unsigned long irq_flags;
    770         struct kvaser_pciefd_tx_packet packet;
    771         int nwords;
    772         u8 count;
    773 
    774         if (can_dropped_invalid_skb(netdev, skb))
    775                 return NETDEV_TX_OK;
    776 
    777         nwords = kvaser_pciefd_prepare_tx_packet(&packet, can, skb);
    778 
    779         spin_lock_irqsave(&can->echo_lock, irq_flags);
    780 
    781         /* Prepare and save echo skb in internal slot */
    782         can_put_echo_skb(skb, netdev, can->echo_idx);
    783 
    784         /* Move echo index to the next slot */
    785         can->echo_idx = (can->echo_idx + 1) % can->can.echo_skb_max;
    786 
    787         /* Write header to fifo */
    788         iowrite32(packet.header[0],
    789                   can->reg_base + KVASER_PCIEFD_KCAN_FIFO_REG);
    790         iowrite32(packet.header[1],
    791                   can->reg_base + KVASER_PCIEFD_KCAN_FIFO_REG);
    792 
    793         if (nwords) {
    794                 u32 data_last = ((u32 *)packet.data)[nwords - 1];
    795 
    796                 /* Write data to fifo, except last word */
    797                 iowrite32_rep(can->reg_base +
    798                               KVASER_PCIEFD_KCAN_FIFO_REG, packet.data,
    799                               nwords - 1);
    800                 /* Write last word to end of fifo */
  > 801                      __raw_writel(data_last, can->reg_base +
    802                              KVASER_PCIEFD_KCAN_FIFO_LAST_REG);
    803         } else {
    804                 /* Complete write to fifo */
    805                 __raw_writel(0, can->reg_base +
    806                              KVASER_PCIEFD_KCAN_FIFO_LAST_REG);
    807         }
    808 
    809         count = ioread32(can->reg_base + 
KVASER_PCIEFD_KCAN_TX_NPACKETS_REG);
    810         /* No room for a new message, stop the queue until at least one
    811          * successful transmit
    812          */
    813         if (count >= KVASER_PCIEFD_CAN_TX_MAX_COUNT ||
    814             can->can.echo_skb[can->echo_idx])
    815                 netif_stop_queue(netdev);
    816 
    817         spin_unlock_irqrestore(&can->echo_lock, irq_flags);
    818 
    819         return NETDEV_TX_OK;
    820 }
    821 

---
0-DAY CI Kernel Test Service, Intel Corporation
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