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Kernel: Rename Thread::tss to Thread::regs and add x86_64 support

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We're using software context switches so calling this struct tss is
somewhat misleading.
This commit is contained in:
Gunnar Beutner 2021-06-26 19:57:16 +02:00 • committed by Andreas Kling
parent eba33f82b8
commit f285241cb8
14 changed files with 246 additions and 204 deletions
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97
Kernel/Arch/x86/x86_64/Processor.cpp
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@ -67,6 +67,7 @@ String Processor::platform_string() const
return "x86_64";
}
// FIXME: For the most part this is a copy of the i386-specific function, get rid of the code duplication
u32 Processor::init_context(Thread& thread, bool leave_crit)
{
VERIFY(is_kernel_mode());
@ -88,29 +89,28 @@ u32 Processor::init_context(Thread& thread, bool leave_crit)
// TODO: handle NT?
VERIFY((cpu_flags() & 0x24000) == 0); // Assume !(NT | VM)
#if 0
auto& tss = thread.tss();
bool return_to_user = (tss.cs & 3) != 0;
auto& regs = thread.regs();
bool return_to_user = (regs.cs & 3) != 0;
// make room for an interrupt frame
if (!return_to_user) {
// userspace_esp and userspace_ss are not popped off by iret
// userspace_rsp is not popped off by iretq
// unless we're switching back to user mode
stack_top -= sizeof(RegisterState) - 2 * sizeof(u32);
stack_top -= sizeof(RegisterState) - 2 * sizeof(FlatPtr);
// For kernel threads we'll push the thread function argument
// which should be in tss.esp and exit_kernel_thread as return
// which should be in regs.rsp and exit_kernel_thread as return
// address.
stack_top -= 2 * sizeof(u32);
*reinterpret_cast<u32*>(kernel_stack_top - 2 * sizeof(u32)) = tss.esp;
stack_top -= 2 * sizeof(u64);
*reinterpret_cast<u64*>(kernel_stack_top - 2 * sizeof(u32)) = regs.rsp;
*reinterpret_cast<u32*>(kernel_stack_top - 3 * sizeof(u32)) = FlatPtr(&exit_kernel_thread);
} else {
stack_top -= sizeof(RegisterState);
}
// we want to end up 16-byte aligned, %esp + 4 should be aligned
stack_top -= sizeof(u32);
*reinterpret_cast<u32*>(kernel_stack_top - sizeof(u32)) = 0;
stack_top -= sizeof(u64);
*reinterpret_cast<u64*>(kernel_stack_top - sizeof(u64)) = 0;
// set up the stack so that after returning from thread_context_first_enter()
// we will end up either in kernel mode or user mode, depending on how the thread is set up
@ -125,25 +125,24 @@ u32 Processor::init_context(Thread& thread, bool leave_crit)
trap.prev_irq_level = 0;
trap.next_trap = nullptr;
stack_top -= sizeof(u32); // pointer to TrapFrame
*reinterpret_cast<u32*>(stack_top) = stack_top + 4;
stack_top -= sizeof(u64); // pointer to TrapFrame
*reinterpret_cast<u64*>(stack_top) = stack_top + 8;
if constexpr (CONTEXT_SWITCH_DEBUG) {
if (return_to_user) {
dbgln("init_context {} ({}) set up to execute at eip={}:{}, esp={}, stack_top={}, user_top={}:{}",
dbgln("init_context {} ({}) set up to execute at rip={}:{}, rsp={}, stack_top={}, user_top={}",
thread,
VirtualAddress(&thread),
iretframe.cs, tss.eip,
VirtualAddress(tss.esp),
iretframe.cs, regs.rip,
VirtualAddress(regs.rsp),
VirtualAddress(stack_top),
iretframe.userspace_ss,
iretframe.userspace_esp);
iretframe.userspace_rsp);
} else {
dbgln("init_context {} ({}) set up to execute at eip={}:{}, esp={}, stack_top={}",
dbgln("init_context {} ({}) set up to execute at rip={}:{}, rsp={}, stack_top={}",
thread,
VirtualAddress(&thread),
iretframe.cs, tss.eip,
VirtualAddress(tss.esp),
iretframe.cs, regs.rip,
VirtualAddress(regs.rsp),
VirtualAddress(stack_top));
}
}
@ -152,18 +151,9 @@ u32 Processor::init_context(Thread& thread, bool leave_crit)
// in kernel mode, so set up these values so that we end up popping iretframe
// off the stack right after the context switch completed, at which point
// control is transferred to what iretframe is pointing to.
tss.eip = FlatPtr(&thread_context_first_enter);
tss.esp0 = kernel_stack_top;
tss.esp = stack_top;
tss.cs = GDT_SELECTOR_CODE0;
tss.ds = GDT_SELECTOR_DATA0;
tss.es = GDT_SELECTOR_DATA0;
tss.gs = GDT_SELECTOR_DATA0;
tss.ss = GDT_SELECTOR_DATA0;
tss.fs = GDT_SELECTOR_PROC;
#else
TODO();
#endif
regs.rip = FlatPtr(&thread_context_first_enter);
regs.rsp0 = kernel_stack_top;
regs.rsp = stack_top;
return stack_top;
}
@ -203,21 +193,40 @@ UNMAP_AFTER_INIT void Processor::initialize_context_switching(Thread& initial_th
{
VERIFY(initial_thread.process().is_kernel_process());
auto& tss = initial_thread.tss();
m_tss = tss;
#if 0
m_tss.esp0 = tss.esp0;
m_tss.ss0 = GDT_SELECTOR_DATA0;
// user mode needs to be able to switch to kernel mode:
m_tss.cs = m_tss.ds = m_tss.es = m_tss.gs = m_tss.ss = GDT_SELECTOR_CODE0 | 3;
m_tss.fs = GDT_SELECTOR_PROC | 3;
#else
TODO();
#endif
auto& regs = initial_thread.regs();
m_tss.iomapbase = sizeof(m_tss);
m_tss.rsp0l = regs.rsp0 & 0xffffffff;
m_tss.rsp0h = regs.rsp0 >> 32;
m_scheduler_initialized = true;
// FIXME: Context switching (see i386 impl)
// clang-format off
asm volatile(
"movq %[new_rsp], %%rsp \n" // switch to new stack
"pushq %[from_to_thread] \n" // to_thread
"pushq %[from_to_thread] \n" // from_thread
"pushq $" __STRINGIFY(GDT_SELECTOR_CODE0) " \n"
"pushq %[new_rip] \n" // save the entry rip to the stack
"movq %%rsp, %%rbx \n"
"addq $40, %%rbx \n" // calculate pointer to TrapFrame
"pushq %%rbx \n"
"cld \n"
"pushq %[cpu] \n" // push argument for init_finished before register is clobbered
"call pre_init_finished \n"
"pop %%rdi \n" // move argument for init_finished into place
"call init_finished \n"
"addq $8, %%rsp \n"
"call post_init_finished \n"
"pop %%rdi \n" // move pointer to TrapFrame into place
"call enter_trap_no_irq \n"
"addq $8, %%rsp \n"
"retq \n"
:: [new_rsp] "g" (regs.rsp),
[new_rip] "a" (regs.rip),
[from_to_thread] "b" (&initial_thread),
[cpu] "c" ((u64)id())
);
// clang-format on
VERIFY_NOT_REACHED();
}