target/linux/generic/patches-4.1/133-MIPS-UAPI-Ignore-__arch_swab-16-32-64-when-using-MIP.patch

   1 From 71a0a72456b48de972d7ed613b06a22a3aa9057f Mon Sep 17 00:00:00 2001
   2 From: Yousong Zhou <yszhou4tech@gmail.com>
   3 Date: Sat, 26 Sep 2015 13:41:43 +0800
   4 Subject: [PATCH] MIPS: UAPI: Ignore __arch_swab{16,32,64} when using MIPS16
   5
   6 Some GCC versions (e.g. 4.8.3) can incorrectly inline a function with
   7 MIPS32 instructions into another function with MIPS16 code [1], causing
   8 the assembler to genereate incorrect binary code or fail right away
   9 complaining about unrecognized opcode.
  10
  11 In the case of __arch_swab{16,32}, when inlined by the compiler with
  12 flags `-mips32r2 -mips16 -Os', the assembler can fail with the following
  13 error.
  14
  15     {standard input}:79: Error: unrecognized opcode `wsbh $2,$2'
  16
  17 For performance concerns and to workaround the issue already existing in
  18 older compilers, just ignore these 2 functions when compiling with
  19 mips16 enabled.
  20
  21  [1] Inlining nomips16 function into mips16 function can result in
  22      undefined builtins, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55777
  23
  24 Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
  25 Cc: Maciej W. Rozycki <macro@linux-mips.org>
  26 Cc: linux-mips@linux-mips.org
  27 Patchwork: https://patchwork.linux-mips.org/patch/11241/
  28 Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
  29 ---
  30  arch/mips/include/uapi/asm/swab.h |    7 ++++---
  31  1 file changed, 4 insertions(+), 3 deletions(-)
  32
  33 --- a/arch/mips/include/uapi/asm/swab.h
  34 +++ b/arch/mips/include/uapi/asm/swab.h
  35 @@ -13,8 +13,9 @@
  36
  37  #define __SWAB_64_THRU_32__
  38
  39 -#if (defined(__mips_isa_rev) && (__mips_isa_rev >= 2)) ||              \
  40 -    defined(_MIPS_ARCH_LOONGSON3A)
  41 +#if !defined(__mips16) &&                                      \
  42 +       ((defined(__mips_isa_rev) && (__mips_isa_rev >= 2)) ||  \
  43 +        defined(_MIPS_ARCH_LOONGSON3A))
  44
  45  static inline __attribute_const__ __u16 __arch_swab16(__u16 x)
  46  {
  47 @@ -65,5 +66,5 @@ static inline __attribute_const__ __u64
  48  }
  49  #define __arch_swab64 __arch_swab64
  50  #endif /* __mips64 */
  51 -#endif /* MIPS R2 or newer or Loongson 3A */
  52 +#endif /* (not __mips16) and (MIPS R2 or newer or Loongson 3A) */
  53  #endif /* _ASM_SWAB_H */