1 files changed, 21 insertions, 1 deletions

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 05872d92fca2..bc683b8219b5 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -564,6 +564,21 @@ int vfp_preserve_user_clear_hwstate(struct user_vfp __user *ufp,
 
         if (err)
                 return -EFAULT;
+
+        /* Ensure that VFP is disabled. */
+        vfp_flush_hwstate(thread);
+
+        /*
+         * As per the PCS, clear the length and stride bits for function
+         * entry.
+         */
+        hwstate->fpscr &= ~(FPSCR_LENGTH_MASK | FPSCR_STRIDE_MASK);
+
+        /*
+         * Disable VFP in the hwstate so that we can detect if it gets
+         * used.
+         */
+        hwstate->fpexc &= ~FPEXC_EN;
         return 0;
 }
 
@@ -576,7 +591,12 @@ int vfp_restore_user_hwstate(struct user_vfp __user *ufp,
         unsigned long fpexc;
         int err = 0;
 
-        vfp_flush_hwstate(thread);
+        /*
+         * If VFP has been used, then disable it to avoid corrupting
+         * the new thread state.
+         */
+        if (hwstate->fpexc & FPEXC_EN)
+                vfp_flush_hwstate(thread);
 
         /*
          * Copy the floating point registers. There can be unused