Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6

[linux-2.6-omap-h63xx.git] / arch / x86 / kernel / xsave.c

diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 7415f3e38a5160a9fc9914345f1c1efcc8be0606..b13acb75e822e337aec4f8e8d6a094c24e30feb0 100644 (file)
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -82,8 +82,7 @@ int save_i387_xstate(void __user *buf)
        if (!access_ok(VERIFY_WRITE, buf, sig_xstate_size))
                return -EACCES;
 
-       BUILD_BUG_ON(sizeof(struct user_i387_struct) !=
-                       sizeof(tsk->thread.xstate->fxsave));
+       BUG_ON(sig_xstate_size < xstate_size);
 
        if ((unsigned long)buf % 64)
                printk("save_i387_xstate: bad fpstate %p\n", buf);
@@ -92,6 +91,14 @@ int save_i387_xstate(void __user *buf)
                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.
+                */
+               err = __clear_user(buf, sig_xstate_size);
+               if (err)
+                       return err;
+
                if (task_thread_info(tsk)->status & TS_XSAVE)
                        err = xsave_user(buf);
                else
@@ -109,6 +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));
@@ -116,6 +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;
@@ -214,7 +248,7 @@ 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;
@@ -267,7 +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;