From 84ab45b33858a87632e1f5e207e302bf48eaf52e Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Fri, 30 Jan 2015 12:09:37 +0000 Subject: [PATCH] MIPS: disable FPU if the mode is unsupported The expected semantics of __enable_fpu are for the FPU to be enabled in the given mode if possible, otherwise for the FPU to be left disabled and SIGFPE returned. The FPU was incorrectly being left enabled in cases where the desired value for FR was unavailable. Without ensuring the FPU is disabled in this case, it would be possible for userland to go on to execute further FP instructions natively in the incorrect mode, rather than those instructions being trapped & emulated as they need to be. Signed-off-by: Paul Burton Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9167/ Signed-off-by: Ralf Baechle --- arch/mips/include/asm/fpu.h | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/arch/mips/include/asm/fpu.h b/arch/mips/include/asm/fpu.h index 9f26b07..b104ad9 100644 --- a/arch/mips/include/asm/fpu.h +++ b/arch/mips/include/asm/fpu.h @@ -48,6 +48,12 @@ enum fpu_mode { #define FPU_FR_MASK 0x1 }; +#define __disable_fpu() \ +do { \ + clear_c0_status(ST0_CU1); \ + disable_fpu_hazard(); \ +} while (0) + static inline int __enable_fpu(enum fpu_mode mode) { int fr; @@ -86,7 +92,12 @@ fr_common: enable_fpu_hazard(); /* check FR has the desired value */ - return (!!(read_c0_status() & ST0_FR) == !!fr) ? 0 : SIGFPE; + if (!!(read_c0_status() & ST0_FR) == !!fr) + return 0; + + /* unsupported FR value */ + __disable_fpu(); + return SIGFPE; default: BUG(); @@ -95,12 +106,6 @@ fr_common: return SIGFPE; } -#define __disable_fpu() \ -do { \ - clear_c0_status(ST0_CU1); \ - disable_fpu_hazard(); \ -} while (0) - #define clear_fpu_owner() clear_thread_flag(TIF_USEDFPU) static inline int __is_fpu_owner(void) -- 2.7.4