Commit-ID: a352a3b7b7920212ee4c45a41500c66826318e92 Gitweb: https://git.kernel.org/tip/a352a3b7b7920212ee4c45a41500c66826318e92 Author: Rik van Riel <r...@surriel.com> AuthorDate: Wed, 3 Apr 2019 18:41:47 +0200 Committer: Borislav Petkov <b...@suse.de> 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 <r...@surriel.com> Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de> Signed-off-by: Borislav Petkov <b...@suse.de> Reviewed-by: Dave Hansen <dave.han...@intel.com> Reviewed-by: Thomas Gleixner <t...@linutronix.de> Cc: Andy Lutomirski <l...@kernel.org> Cc: "H. Peter Anvin" <h...@zytor.com> Cc: Ingo Molnar <mi...@redhat.com> Cc: Jann Horn <ja...@google.com> Cc: "Jason A. Donenfeld" <ja...@zx2c4.com> Cc: kvm ML <k...@vger.kernel.org> Cc: Paolo Bonzini <pbonz...@redhat.com> Cc: Radim Krčmář <rkrc...@redhat.com> Cc: Rik van Riel <r...@surriel.com> Cc: x86-ml <x...@kernel.org> Link: https://lkml.kernel.org/r/20190403164156.19645-19-bige...@linutronix.de --- 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))
