Commit-ID: a352a3b7b7920212ee4c45a41500c66826318e92 Gitweb: https://git.kernel.org/tip/a352a3b7b7920212ee4c45a41500c66826318e92 Author: Rik van Riel <[email protected]> AuthorDate: Wed, 3 Apr 2019 18:41:47 +0200 Committer: Borislav Petkov <[email protected]> CommitDate: Thu, 11 Apr 2019 18:20:04 +0200
x86/fpu: Prepare copy_fpstate_to_sigframe() for TIF_NEED_FPU_LOAD The FPU registers need only to be saved if TIF_NEED_FPU_LOAD is not set. Otherwise this has been already done and can be skipped. [ bp: Massage a bit. ] Signed-off-by: Rik van Riel <[email protected]> Signed-off-by: Sebastian Andrzej Siewior <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Dave Hansen <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Jann Horn <[email protected]> Cc: "Jason A. Donenfeld" <[email protected]> Cc: kvm ML <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Radim Krčmář <[email protected]> Cc: Rik van Riel <[email protected]> Cc: x86-ml <[email protected]> Link: https://lkml.kernel.org/r/[email protected] --- arch/x86/kernel/fpu/signal.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 8f23f5237218..9b9dfdc96285 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -171,7 +171,17 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) sizeof(struct user_i387_ia32_struct), NULL, (struct _fpstate_32 __user *) buf) ? -1 : 1; - copy_fpregs_to_fpstate(fpu); + /* + * If we do not need to load the FPU registers at return to userspace + * then the CPU has the current state and we need to save it. Otherwise, + * it has already been done and we can skip it. + */ + fpregs_lock(); + if (!test_thread_flag(TIF_NEED_FPU_LOAD)) { + copy_fpregs_to_fpstate(fpu); + set_thread_flag(TIF_NEED_FPU_LOAD); + } + fpregs_unlock(); if (using_compacted_format()) { if (copy_xstate_to_user(buf_fx, xsave, 0, size))
