MIPS: Fix inline asm input/output type mismatch in checksum.h used with Clang

Fix the following build error when make M=samples/bpf used with Clang:

  CLANG-bpf  samples/bpf/sockex2_kern.o
In file included from samples/bpf/sockex2_kern.c:7:
In file included from ./include/uapi/linux/if_tunnel.h:7:
In file included from ./include/linux/ip.h:16:
In file included from ./include/linux/skbuff.h:28:
In file included from ./include/net/checksum.h:22:
./arch/mips/include/asm/checksum.h:161:9: error: unsupported inline asm: input with type 'unsigned long' matching output with type '__wsum' (aka 'unsigned int')
        : "0" ((__force unsigned long)daddr),
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

This is a known issue on MIPS [1], the changed code can be compiled
successfully by both GCC and Clang.

[1] https://lore.kernel.org/linux-mips/CAG_fn=W0JHf8QyUX==+rQMp8PoULHrsQCa9Htffws31ga8k-iw@mail.gmail.com/

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

diff --git a/arch/mips/include/asm/checksum.h b/arch/mips/include/asm/checksum.h
index 5f80c28..1e6c135 100644 (file)
--- a/arch/mips/include/asm/checksum.h
+++ b/arch/mips/include/asm/checksum.h
@@ -130,6 +130,8 @@ static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
                                        __u32 len, __u8 proto,
                                        __wsum sum)
 {
+       unsigned long tmp = (__force unsigned long)sum;
+
        __asm__(
        "       .set    push            # csum_tcpudp_nofold\n"
        "       .set    noat            \n"
@@ -157,7 +159,7 @@ static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
        "       addu    %0, $1          \n"
 #endif
        "       .set    pop"
-       : "=r" (sum)
+       : "=r" (tmp)
        : "0" ((__force unsigned long)daddr),
          "r" ((__force unsigned long)saddr),
 #ifdef __MIPSEL__
@@ -167,7 +169,7 @@ static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 #endif
          "r" ((__force unsigned long)sum));
 
-       return sum;
+       return (__force __wsum)tmp;
 }
 #define csum_tcpudp_nofold csum_tcpudp_nofold