1. 03 8月, 2017 1 次提交
    • H
      s390: use generic uapi/asm/swab.h · 3cb8f11c
      Heiko Carstens 提交于
      clang doesn't like s390 specific inline assembler constraints. These
      are present in our arch specific uapi/asm/swab.h which again is
      required by some ebpf test cases.
      
      For current compiler versions the generic swab.h already makes use of
      gcc's builtin functions. Therefore we can simply remove our own header
      file and use the generic one.
      
      This will generate worse code if used with compilers before gcc 4.8,
      which has no __builtin_bswap16(); or before gcc v4.4, which has no
      __builtin_bswap[32|64](). For these cases a C implementation fallback
      would be used which generates more code, but is still correct (170KB
      extra code for gcc 4.3 with performance_defconfig).
      
      However given that we need (and want) to get rid of the inline
      assemblies anyway in order to be able to use clang, the above is just
      a minor drawback if old gcc compilers are used.
      
      With current compilers there is close to zero difference, except for
      three btrfs bit functions which generate more out-of-line code. The
      generated code looks still correct and also uses the s390 specific
      byteswap instructions.
      Reported-and-tested-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
      Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
      3cb8f11c
  2. 02 8月, 2017 2 次提交
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