diff options
Diffstat (limited to 'arch/x86/kernel/fpu/core.c')
| -rw-r--r-- | arch/x86/kernel/fpu/core.c | 35 |
1 files changed, 25 insertions, 10 deletions
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 4018083c5b36..1ff6b83094a1 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -423,8 +423,20 @@ void fpstate_reset(struct fpu *fpu) fpu->perm.__user_state_size = fpu_user_cfg.default_size; } +static inline void fpu_inherit_perms(struct fpu *dst_fpu) +{ + if (fpu_state_size_dynamic()) { + struct fpu *src_fpu = ¤t->group_leader->thread.fpu; + + spin_lock_irq(¤t->sighand->siglock); + /* Fork also inherits the permissions of the parent */ + dst_fpu->perm = src_fpu->perm; + spin_unlock_irq(¤t->sighand->siglock); + } +} + /* Clone current's FPU state on fork */ -int fpu_clone(struct task_struct *dst) +int fpu_clone(struct task_struct *dst, unsigned long clone_flags) { struct fpu *src_fpu = ¤t->thread.fpu; struct fpu *dst_fpu = &dst->thread.fpu; @@ -455,17 +467,20 @@ int fpu_clone(struct task_struct *dst) } /* - * If the FPU registers are not owned by current just memcpy() the - * state. Otherwise save the FPU registers directly into the - * child's FPU context, without any memory-to-memory copying. + * Save the default portion of the current FPU state into the + * clone. Assume all dynamic features to be defined as caller- + * saved, which enables skipping both the expansion of fpstate + * and the copying of any dynamic state. + * + * Do not use memcpy() when TIF_NEED_FPU_LOAD is set because + * copying is not valid when current uses non-default states. */ fpregs_lock(); - if (test_thread_flag(TIF_NEED_FPU_LOAD)) { - memcpy(&dst_fpu->fpstate->regs, &src_fpu->fpstate->regs, - dst_fpu->fpstate->size); - } else { - save_fpregs_to_fpstate(dst_fpu); - } + if (test_thread_flag(TIF_NEED_FPU_LOAD)) + fpregs_restore_userregs(); + save_fpregs_to_fpstate(dst_fpu); + if (!(clone_flags & CLONE_THREAD)) + fpu_inherit_perms(dst_fpu); fpregs_unlock(); trace_x86_fpu_copy_src(src_fpu); |