1 files changed, 31 insertions, 2 deletions

diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 07713d64debe..9abac8a9d823 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -95,7 +95,9 @@ int save_i387_xstate(void __user *buf)
                  * Start with clearing the user buffer. This will present a
                  * clean context for the bytes not touched by the fxsave/xsave.
                  */
-                __clear_user(buf, sig_xstate_size);
+                err = __clear_user(buf, sig_xstate_size);
+                if (err)
+                        return err;
 
                 if (task_thread_info(tsk)->status & TS_XSAVE)
                         err = xsave_user(buf);
@@ -114,6 +116,8 @@ int save_i387_xstate(void __user *buf)
 
         if (task_thread_info(tsk)->status & TS_XSAVE) {
                 struct _fpstate __user *fx = buf;
+                struct _xstate __user *x = buf;
+                u64 xstate_bv;
 
                 err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved,
                                      sizeof(struct _fpx_sw_bytes));
@@ -121,6 +125,31 @@ int save_i387_xstate(void __user *buf)
                 err |= __put_user(FP_XSTATE_MAGIC2,
                                   (__u32 __user *) (buf + sig_xstate_size
                                                     - FP_XSTATE_MAGIC2_SIZE));
+
+                /*
+                 * Read the xstate_bv which we copied (directly from the cpu or
+                 * from the state in task struct) to the user buffers and
+                 * set the FP/SSE bits.
+                 */
+                err |= __get_user(xstate_bv, &x->xstate_hdr.xstate_bv);
+
+                /*
+                 * For legacy compatible, we always set FP/SSE bits in the bit
+                 * vector while saving the state to the user context. This will
+                 * enable us capturing any changes(during sigreturn) to
+                 * the FP/SSE bits by the legacy applications which don't touch
+                 * xstate_bv in the xsave header.
+                 *
+                 * xsave aware apps can change the xstate_bv in the xsave
+                 * header as well as change any contents in the memory layout.
+                 * xrestore as part of sigreturn will capture all the changes.
+                 */
+                xstate_bv |= XSTATE_FPSSE;
+
+                err |= __put_user(xstate_bv, &x->xstate_hdr.xstate_bv);
+
+                if (err)
+                        return err;
         }
 
         return 1;
@@ -272,7 +301,7 @@ void __cpuinit xsave_init(void)
 /*
  * setup the xstate image representing the init state
  */
-void setup_xstate_init(void)
+static void __init setup_xstate_init(void)
 {
         init_xstate_buf = alloc_bootmem(xstate_size);
         init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;