diff options
Diffstat (limited to 'arch/x86/kernel/fpu/signal.c')
| -rw-r--r-- | arch/x86/kernel/fpu/signal.c | 44 |
1 files changed, 39 insertions, 5 deletions
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 6184fe70a9e1..9393a445d73c 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -347,6 +347,23 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) ret = copy_user_to_fpregs_zeroing(buf_fx, user_xfeatures, fx_only); pagefault_enable(); if (!ret) { + + /* + * Restore supervisor states: previous context switch + * etc has done XSAVES and saved the supervisor states + * in the kernel buffer from which they can be restored + * now. + * + * We cannot do a single XRSTORS here - which would + * be nice - because the rest of the FPU registers are + * being restored from a user buffer directly. The + * single XRSTORS happens below, when the user buffer + * has been copied to the kernel one. + */ + if (test_thread_flag(TIF_NEED_FPU_LOAD) && + xfeatures_mask_supervisor()) + copy_kernel_to_xregs(&fpu->state.xsave, + xfeatures_mask_supervisor()); fpregs_mark_activate(); fpregs_unlock(); return 0; @@ -364,14 +381,25 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) } /* - * The current state of the FPU registers does not matter. By setting - * TIF_NEED_FPU_LOAD unconditionally it is ensured that the our xstate - * is not modified on context switch and that the xstate is considered + * By setting TIF_NEED_FPU_LOAD it is ensured that our xstate is + * not modified on context switch and that the xstate is considered * to be loaded again on return to userland (overriding last_cpu avoids * the optimisation). */ - set_thread_flag(TIF_NEED_FPU_LOAD); + fpregs_lock(); + + if (!test_thread_flag(TIF_NEED_FPU_LOAD)) { + + /* + * Supervisor states are not modified by user space input. Save + * current supervisor states first and invalidate the FPU regs. + */ + if (xfeatures_mask_supervisor()) + copy_supervisor_to_kernel(&fpu->state.xsave); + set_thread_flag(TIF_NEED_FPU_LOAD); + } __fpu_invalidate_fpregs_state(fpu); + fpregs_unlock(); if (use_xsave() && !fx_only) { u64 init_bv = xfeatures_mask_user() & ~user_xfeatures; @@ -393,7 +421,13 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) fpregs_lock(); if (unlikely(init_bv)) copy_kernel_to_xregs(&init_fpstate.xsave, init_bv); - ret = copy_kernel_to_xregs_err(&fpu->state.xsave, user_xfeatures); + + /* + * Restore previously saved supervisor xstates along with + * copied-in user xstates. + */ + ret = copy_kernel_to_xregs_err(&fpu->state.xsave, + user_xfeatures | xfeatures_mask_supervisor()); } else if (use_fxsr()) { ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size); |