diff mbox series

[04/31] x86/fpu: Restrict xsaves()/xrstors() to independent states

Message ID 20211011223610.524176686@linutronix.de (mailing list archive)
State New, archived
Headers show
Series x86/fpu: Preparatory cleanups for AMX support (part 1) | expand

Commit Message

Thomas Gleixner Oct. 12, 2021, midnight UTC
These interfaces are really only valid for features which are independently
managed and not part of the task context state for various reasons.

Tighten the checks and adjust the misleading comments.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/fpu/xstate.c |   14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

Comments

Borislav Petkov Oct. 12, 2021, 2:24 p.m. UTC | #1
On Tue, Oct 12, 2021 at 02:00:04AM +0200, Thomas Gleixner wrote:
> These interfaces are really only valid for features which are independently
> managed and not part of the task context state for various reasons.
> 
> Tighten the checks and adjust the misleading comments.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
>  arch/x86/kernel/fpu/xstate.c |   14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> --- a/arch/x86/kernel/fpu/xstate.c
> +++ b/arch/x86/kernel/fpu/xstate.c
> @@ -1182,13 +1182,9 @@ static bool validate_xsaves_xrstors(u64

I guess then change the name too, to:

validate_indep_xstate_components()

or so?

Then you don't need the comment below.

>  	if (WARN_ON_FPU(!cpu_feature_enabled(X86_FEATURE_XSAVES)))
>  		return false;
>  	/*
> -	 * Validate that this is either a task->fpstate related component
> -	 * subset or an independent one.
> +	 * Validate that this is a independent compoment.

WARNING: 'compoment' may be misspelled - perhaps 'component'?
#78: FILE: arch/x86/kernel/fpu/xstate.c:1185:
+        * Validate that this is a independent compoment.
                                               ^^^^^^^^^
>  	 */
> -	if (mask & xfeatures_mask_independent())
> -		xchk = ~xfeatures_mask_independent();
> -	else
> -		xchk = ~xfeatures_mask_all;
> +	xchk = ~xfeatures_mask_independent();
>  
>  	if (WARN_ON_ONCE(!mask || mask & xchk))
>  		return false;
> @@ -1206,8 +1202,7 @@ static bool validate_xsaves_xrstors(u64
>   * buffer should be zeroed otherwise a consecutive XRSTORS from that buffer
>   * can #GP.
>   *
> - * The feature mask must either be a subset of the independent features or
> - * a subset of the task->fpstate related features.
> + * The feature mask must be a subset of the independent features

End with a fullstop.

>   */
>  void xsaves(struct xregs_state *xstate, u64 mask)
>  {
> @@ -1231,8 +1226,7 @@ void xsaves(struct xregs_state *xstate,
>   * Proper usage is to restore the state which was saved with
>   * xsaves() into @xstate.
>   *
> - * The feature mask must either be a subset of the independent features or
> - * a subset of the task->fpstate related features.
> + * The feature mask must be a subset of the independent features

Ditto.

>   */
>  void xrstors(struct xregs_state *xstate, u64 mask)
>  {
diff mbox series

Patch

--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1182,13 +1182,9 @@  static bool validate_xsaves_xrstors(u64
 	if (WARN_ON_FPU(!cpu_feature_enabled(X86_FEATURE_XSAVES)))
 		return false;
 	/*
-	 * Validate that this is either a task->fpstate related component
-	 * subset or an independent one.
+	 * Validate that this is a independent compoment.
 	 */
-	if (mask & xfeatures_mask_independent())
-		xchk = ~xfeatures_mask_independent();
-	else
-		xchk = ~xfeatures_mask_all;
+	xchk = ~xfeatures_mask_independent();
 
 	if (WARN_ON_ONCE(!mask || mask & xchk))
 		return false;
@@ -1206,8 +1202,7 @@  static bool validate_xsaves_xrstors(u64
  * buffer should be zeroed otherwise a consecutive XRSTORS from that buffer
  * can #GP.
  *
- * The feature mask must either be a subset of the independent features or
- * a subset of the task->fpstate related features.
+ * The feature mask must be a subset of the independent features
  */
 void xsaves(struct xregs_state *xstate, u64 mask)
 {
@@ -1231,8 +1226,7 @@  void xsaves(struct xregs_state *xstate,
  * Proper usage is to restore the state which was saved with
  * xsaves() into @xstate.
  *
- * The feature mask must either be a subset of the independent features or
- * a subset of the task->fpstate related features.
+ * The feature mask must be a subset of the independent features
  */
 void xrstors(struct xregs_state *xstate, u64 mask)
 {