1 files changed, 6 insertions, 4 deletions

diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index a61f33d06ea3..cd2d5d5514fe 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -803,15 +803,17 @@ void math_error(void __user *eip)
          */
         cwd = get_fpu_cwd(task);
         swd = get_fpu_swd(task);
-        switch (((~cwd) & swd & 0x3f) | (swd & 0x240)) {
+        switch (swd & ~cwd & 0x3f) {
                 case 0x000:
                 default:
                         break;
                 case 0x001: /* Invalid Op */
-                case 0x041: /* Stack Fault */
-                case 0x241: /* Stack Fault | Direction */
+                        /*
+                         * swd & 0x240 == 0x040: Stack Underflow
+                         * swd & 0x240 == 0x240: Stack Overflow
+                         * User must clear the SF bit (0x40) if set
+                         */
                         info.si_code = FPE_FLTINV;
-                        /* Should we clear the SF or let user space do it ???? */
                         break;
                 case 0x002: /* Denormalize */
                 case 0x010: /* Underflow */