4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: James Hogan <[email protected]> commit 2e6c7747730296a6d4fd700894286db1132598c4 upstream. When a 32-bit kernel is configured to support MIPS64r6 (CPU_MIPS64_R6), MIPS_O32_FP64_SUPPORT won't be selected as it should be because MIPS32_O32 is disabled (o32 is already the default ABI available on 32-bit kernels). This results in userland FP breakage as CP0_Status.FR is read-only 1 since r6 (when an FPU is present) so __enable_fpu() will fail to clear FR. This causes the FPU emulator to get used which will incorrectly emulate 32-bit FPU registers. Force o32 fp64 support in this case by also selecting MIPS_O32_FP64_SUPPORT from CPU_MIPS64_R6 if 32BIT. Fixes: 4e9d324d4288 ("MIPS: Require O32 FP64 support for MIPS64 with O32 compat") Signed-off-by: James Hogan <[email protected]> Reviewed-by: Paul Burton <[email protected]> Cc: Ralf Baechle <[email protected]> Cc: [email protected] Patchwork: https://patchwork.linux-mips.org/patch/15310/ Signed-off-by: James Hogan <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/mips/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -1412,7 +1412,7 @@ config CPU_MIPS32_R6 select CPU_SUPPORTS_MSA select GENERIC_CSUM select HAVE_KVM - select MIPS_O32_FP64_SUPPORT + select MIPS_O32_FP64_SUPPORT if 32BIT help Choose this option to build a kernel for release 6 or later of the MIPS32 architecture. New MIPS processors, starting with the Warrior
