Entering a signal handler, the kernel saves XSAVE area. The dynamic user
state is better to be saved only when used. fpu->state_mask can help to
exclude unused states.
Returning from signal handler, XRSTOR re-initializes the excluded state
components.
No functional change until the kernel actually supports the dynamic user
states.
Signed-off-by: Chang S. Bae <chang.seok....@intel.com>
Reviewed-by: Len Brown <len.br...@intel.com>
Cc: x...@kernel.org
Cc: linux-kernel@vger.kernel.org
---
arch/x86/include/asm/fpu/internal.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/fpu/internal.h
b/arch/x86/include/asm/fpu/internal.h
index f5dbbaa060fb..fd044b31ce40 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -368,7 +368,7 @@ static inline void copy_kernel_to_xregs(struct xregs_state
*xstate, u64 mask)
*/
static inline int copy_xregs_to_user(struct xregs_state __user *buf)
{
- u64 mask = xfeatures_mask_user();
+ u64 mask = current->thread.fpu.state_mask;
u32 lmask = mask;
u32 hmask = mask >> 32;
int err;
--
2.17.1
