1 files changed, 11 insertions, 4 deletions

diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
index 8f2f8e9d8b21..f2338d1c0b48 100644
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -78,6 +78,9 @@ DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
 #define FPCREG_RID      0       /* $0  = revision id */
 #define FPCREG_CSR      31      /* $31 = csr */
 
+/* Determine rounding mode from the RM bits of the FCSR */
+#define modeindex(v) ((v) & FPU_CSR_RM)
+
 /* Convert Mips rounding mode (0..3) to IEEE library modes. */
 static const unsigned char ieee_rm[4] = {
         [FPU_CSR_RN] = IEEE754_RN,
@@ -384,10 +387,14 @@ static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx)
                                         (void *) (xcp->cp0_epc),
                                         MIPSInst_RT(ir), value);
 #endif
-                                value &= (FPU_CSR_FLUSH | FPU_CSR_ALL_E | FPU_CSR_ALL_S | 0x03);
-                                ctx->fcr31 &= ~(FPU_CSR_FLUSH | FPU_CSR_ALL_E | FPU_CSR_ALL_S | 0x03);
-                                /* convert to ieee library modes */
-                                ctx->fcr31 |= (value & ~0x3) | ieee_rm[value & 0x3];
+
+                                /*
+                                 * Don't write reserved bits,
+                                 * and convert to ieee library modes
+                                 */
+                                ctx->fcr31 = (value &
+                                                ~(FPU_CSR_RSVD | FPU_CSR_RM)) |
+                                                ieee_rm[modeindex(value)];
                         }
                         if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
                                 return SIGFPE;