diff options
| -rw-r--r-- | Kernel/Arch/i386/CPU.cpp | 29 |
1 files changed, 23 insertions, 6 deletions
diff --git a/Kernel/Arch/i386/CPU.cpp b/Kernel/Arch/i386/CPU.cpp index 24bf137685..4cb3533fd0 100644 --- a/Kernel/Arch/i386/CPU.cpp +++ b/Kernel/Arch/i386/CPU.cpp @@ -1049,8 +1049,12 @@ UNMAP_AFTER_INIT void Processor::cpu_setup() // initialized yet! cpu_detect(); - if (has_feature(CPUFeature::SSE)) + if (has_feature(CPUFeature::SSE)) { + // enter_thread_context() assumes that if a x86 CPU supports SSE then it also supports FXSR. + // SSE support without FXSR is an extremely unlikely scenario, so let's be pragmatic about it. + VERIFY(has_feature(CPUFeature::FXSR)); sse_init(); + } write_cr0(read_cr0() | 0x00010000); @@ -1233,8 +1237,12 @@ UNMAP_AFTER_INIT void Processor::initialize(u32 cpu) if (cpu == 0) { VERIFY((FlatPtr(&s_clean_fpu_state) & 0xF) == 0); asm volatile("fninit"); - asm volatile("fxsave %0" - : "=m"(s_clean_fpu_state)); + if (has_feature(CPUFeature::FXSR)) + asm volatile("fxsave %0" + : "=m"(s_clean_fpu_state)); + else + asm volatile("fnsave %0" + : "=m"(s_clean_fpu_state)); } m_info = new ProcessorInfo(*this); @@ -1412,12 +1420,18 @@ extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread) VERIFY(from_thread == to_thread || from_thread->state() != Thread::Running); VERIFY(to_thread->state() == Thread::Running); + bool has_fxsr = Processor::current().has_feature(CPUFeature::FXSR); Processor::set_current_thread(*to_thread); auto& from_tss = from_thread->tss(); auto& to_tss = to_thread->tss(); - asm volatile("fxsave %0" - : "=m"(from_thread->fpu_state())); + + if (has_fxsr) + asm volatile("fxsave %0" + : "=m"(from_thread->fpu_state())); + else + asm volatile("fnsave %0" + : "=m"(from_thread->fpu_state())); from_tss.fs = get_fs(); from_tss.gs = get_gs(); @@ -1444,7 +1458,10 @@ extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread) to_thread->set_cpu(processor.get_id()); processor.restore_in_critical(to_thread->saved_critical()); - asm volatile("fxrstor %0" ::"m"(to_thread->fpu_state())); + if (has_fxsr) + asm volatile("fxrstor %0" ::"m"(to_thread->fpu_state())); + else + asm volatile("frstor %0" ::"m"(to_thread->fpu_state())); // TODO: ioperm? } |