MIPS: Fix FCSR Cause bit handling for correct SIGFPE issue

[sfrench/cifs-2.6.git] / arch / mips / include / asm / switch_to.h

diff --git a/arch/mips/include/asm/switch_to.h b/arch/mips/include/asm/switch_to.h
index ebb5c0f2f90daef7b2bcca348fb90df2b7530037..c0ae27971e3108093fdc3952969d15bb3bfd5f30 100644 (file)
--- a/arch/mips/include/asm/switch_to.h
+++ b/arch/mips/include/asm/switch_to.h
@@ -75,6 +75,22 @@ do { if (cpu_has_rw_llb) {                                           \
        }                                                               \
 } while (0)
 
+/*
+ * Check FCSR for any unmasked exceptions pending set with `ptrace',
+ * clear them and send a signal.
+ */
+#define __sanitize_fcr31(next)                                         \
+do {                                                                   \
+       unsigned long fcr31 = mask_fcr31_x(next->thread.fpu.fcr31);     \
+       void __user *pc;                                                \
+                                                                       \
+       if (unlikely(fcr31)) {                                          \
+               pc = (void __user *)task_pt_regs(next)->cp0_epc;        \
+               next->thread.fpu.fcr31 &= ~fcr31;                       \
+               force_fcr31_sig(fcr31, pc, next);                       \
+       }                                                               \
+} while (0)
+
 /*
  * For newly created kernel threads switch_to() will return to
  * ret_from_kernel_thread, newly created user threads to ret_from_fork.
@@ -85,6 +101,8 @@ do { if (cpu_has_rw_llb) {                                           \
 do {                                                                   \
        __mips_mt_fpaff_switch_to(prev);                                \
        lose_fpu_inatomic(1, prev);                                     \
+       if (tsk_used_math(next))                                        \
+               __sanitize_fcr31(next);                                 \
        if (cpu_has_dsp) {                                              \
                __save_dsp(prev);                                       \
                __restore_dsp(next);                                    \