releases/4.4.61/mips-force-o32-fp64-support-on-32bit-mips64r6-kernels.patch

   1 From 2e6c7747730296a6d4fd700894286db1132598c4 Mon Sep 17 00:00:00 2001
   2 From: James Hogan <james.hogan@imgtec.com>
   3 Date: Thu, 16 Feb 2017 12:39:01 +0000
   4 Subject: MIPS: Force o32 fp64 support on 32bit MIPS64r6 kernels
   5
   6 From: James Hogan <james.hogan@imgtec.com>
   7
   8 commit 2e6c7747730296a6d4fd700894286db1132598c4 upstream.
   9
  10 When a 32-bit kernel is configured to support MIPS64r6 (CPU_MIPS64_R6),
  11 MIPS_O32_FP64_SUPPORT won't be selected as it should be because
  12 MIPS32_O32 is disabled (o32 is already the default ABI available on
  13 32-bit kernels).
  14
  15 This results in userland FP breakage as CP0_Status.FR is read-only 1
  16 since r6 (when an FPU is present) so __enable_fpu() will fail to clear
  17 FR. This causes the FPU emulator to get used which will incorrectly
  18 emulate 32-bit FPU registers.
  19
  20 Force o32 fp64 support in this case by also selecting
  21 MIPS_O32_FP64_SUPPORT from CPU_MIPS64_R6 if 32BIT.
  22
  23 Fixes: 4e9d324d4288 ("MIPS: Require O32 FP64 support for MIPS64 with O32 compat")
  24 Signed-off-by: James Hogan <james.hogan@imgtec.com>
  25 Reviewed-by: Paul Burton <paul.burton@imgtec.com>
  26 Cc: Ralf Baechle <ralf@linux-mips.org>
  27 Cc: linux-mips@linux-mips.org
  28 Patchwork: https://patchwork.linux-mips.org/patch/15310/
  29 Signed-off-by: James Hogan <james.hogan@imgtec.com>
  30 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  31
  32 ---
  33  arch/mips/Kconfig |    2 +-
  34  1 file changed, 1 insertion(+), 1 deletion(-)
  35
  36 --- a/arch/mips/Kconfig
  37 +++ b/arch/mips/Kconfig
  38 @@ -1412,7 +1412,7 @@ config CPU_MIPS32_R6
  39         select CPU_SUPPORTS_MSA
  40         select GENERIC_CSUM
  41         select HAVE_KVM
  42 -       select MIPS_O32_FP64_SUPPORT
  43 +       select MIPS_O32_FP64_SUPPORT if 32BIT
  44         help
  45           Choose this option to build a kernel for release 6 or later of the
  46           MIPS32 architecture.  New MIPS processors, starting with the Warrior