Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[safe/jmp/linux-2.6] / arch / x86 / kernel / xsave.c

diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 448fde9..c5ee17e 100644 (file)
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -89,13 +89,15 @@ int save_i387_xstate(void __user *buf)
 
        if (!used_math())
                return 0;
-       clear_used_math(); /* trigger finit */
+
        if (task_thread_info(tsk)->status & TS_USEDFPU) {
                /*
                 * 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);
@@ -112,8 +114,12 @@ int save_i387_xstate(void __user *buf)
                        return -1;
        }
 
+       clear_used_math(); /* trigger finit */
+
        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 +127,29 @@ 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;
        }
@@ -132,7 +161,7 @@ int save_i387_xstate(void __user *buf)
  * Restore the extended state if present. Otherwise, restore the FP/SSE
  * state.
  */
-int restore_user_xstate(void __user *buf)
+static int restore_user_xstate(void __user *buf)
 {
        struct _fpx_sw_bytes fx_sw_user;
        u64 mask;
@@ -221,7 +250,7 @@ clear:
  * This will be saved when ever the FP and extended state context is
  * saved on the user stack during the signal handler delivery to the user.
  */
-void prepare_fx_sw_frame(void)
+static void prepare_fx_sw_frame(void)
 {
        int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) +
                             FP_XSTATE_MAGIC2_SIZE;
@@ -283,7 +312,7 @@ static void __init setup_xstate_init(void)
 /*
  * Enable and initialize the xsave feature.
  */
-void __init xsave_cntxt_init(void)
+void __ref xsave_cntxt_init(void)
 {
        unsigned int eax, ebx, ecx, edx;
 
@@ -297,7 +326,7 @@ void __init xsave_cntxt_init(void)
        }
 
        /*
-        * for now OS knows only about FP/SSE
+        * Support only the state known to OS.
         */
        pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
        xsave_init();