diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index 5e275d31802e728da6aeea0ef2173457efdf7d72..6eb6fcb83f6362c2126af95207971b5ff3620c80 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -51,6 +51,10 @@ static inline void kernel_fpu_end(void) preempt_enable(); } +/* Must be called with preempt disabled */ +extern void kernel_fpu_disable(void); +extern void kernel_fpu_enable(void); + /* * Some instructions like VIA's padlock instructions generate a spurious * DNA fault but don't modify SSE registers. And these instructions diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index 12088a3f459f7cc9ebd6fb27d365607b9b79156d..81049ffab2d601cf67ce6bdf455edb4d65abbc46 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -21,6 +21,17 @@ static DEFINE_PER_CPU(bool, in_kernel_fpu); +void kernel_fpu_disable(void) +{ + WARN_ON(this_cpu_read(in_kernel_fpu)); + this_cpu_write(in_kernel_fpu, true); +} + +void kernel_fpu_enable(void) +{ + this_cpu_write(in_kernel_fpu, false); +} + /* * Were we in an interrupt that interrupted kernel mode? * diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 88900e288021f23a2f22aebf739e25070f456971..fb4cb6adf2259b991796d2e88d72577790f140bd 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -788,18 +788,16 @@ void math_state_restore(void) local_irq_disable(); } + /* Avoid __kernel_fpu_begin() right after __thread_fpu_begin() */ + kernel_fpu_disable(); __thread_fpu_begin(tsk); - - /* - * Paranoid restore. send a SIGSEGV if we fail to restore the state. - */ if (unlikely(restore_fpu_checking(tsk))) { drop_init_fpu(tsk); force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk); - return; + } else { + tsk->thread.fpu_counter++; } - - tsk->thread.fpu_counter++; + kernel_fpu_enable(); } EXPORT_SYMBOL_GPL(math_state_restore);