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Kernel: Implement initializing threads on x86_64

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Gunnar Beutner 2021-06-27 13:59:41 +02:00 committed by Andreas Kling
parent f285241cb8
commit 9ed051fe25
Notes: sideshowbarker 2024-07-18 11:27:03 +09:00 
Author: https://github.com/gunnarbeutner
Commit: https://github.com/SerenityOS/serenity/commit/9ed051fe258
Pull-request: https://github.com/SerenityOS/serenity/pull/8269
Reviewed-by: https://github.com/Hendiadyoin1
Reviewed-by: https://github.com/IdanHo
5 changed files with 59 additions and 44 deletions
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31
Kernel/Arch/x86/common/Processor.cpp
View file

@ -40,6 +40,10 @@ Atomic<u32> Processor::s_idle_cpu_mask { 0 };
extern "C" void thread_context_first_enter(void);
extern "C" void exit_kernel_thread(void);
// The compiler can't see the calls to this function inside assembly.
// Declare it, to avoid dead code warnings.
extern "C" void context_first_init(Thread* from_thread, Thread* to_thread, TrapFrame* trap) __attribute__((used));
UNMAP_AFTER_INIT static void sse_init()
{
write_cr0((read_cr0() & 0xfffffffbu) | 0x2);
@ -1134,4 +1138,31 @@ UNMAP_AFTER_INIT void Processor::gdt_init()
// clang-format on
#endif
}
extern "C" void context_first_init([[maybe_unused]] Thread* from_thread, [[maybe_unused]] Thread* to_thread, [[maybe_unused]] TrapFrame* trap)
{
VERIFY(!are_interrupts_enabled());
VERIFY(is_kernel_mode());
dbgln_if(CONTEXT_SWITCH_DEBUG, "switch_context <-- from {} {} to {} {} (context_first_init)", VirtualAddress(from_thread), *from_thread, VirtualAddress(to_thread), *to_thread);
VERIFY(to_thread == Thread::current());
Scheduler::enter_current(*from_thread, true);
// Since we got here and don't have Scheduler::context_switch in the
// call stack (because this is the first time we switched into this
// context), we need to notify the scheduler so that it can release
// the scheduler lock. We don't want to enable interrupts at this point
// as we're still in the middle of a context switch. Doing so could
// trigger a context switch within a context switch, leading to a crash.
FlatPtr flags;
#if ARCH(I386)
flags = trap->regs->eflags;
#else
flags = trap->regs->rflags;
#endif
Scheduler::leave_on_first_switch(flags & ~0x200);
}
}

21
Kernel/Arch/x86/i386/CPU.cpp
View file

@ -19,7 +19,6 @@ namespace Kernel {
// The compiler can't see the calls to these functions inside assembly.
// Declare them, to avoid dead code warnings.
extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread) __attribute__((used));
extern "C" void context_first_init(Thread* from_thread, Thread* to_thread, TrapFrame* trap) __attribute__((used));
extern "C" u32 do_init_context(Thread* thread, u32 flags) __attribute__((used));
extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread)
@ -73,26 +72,6 @@ extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread)
// TODO: ioperm?
}
extern "C" void context_first_init([[maybe_unused]] Thread* from_thread, [[maybe_unused]] Thread* to_thread, [[maybe_unused]] TrapFrame* trap)
{
VERIFY(!are_interrupts_enabled());
VERIFY(is_kernel_mode());
dbgln_if(CONTEXT_SWITCH_DEBUG, "switch_context <-- from {} {} to {} {} (context_first_init)", VirtualAddress(from_thread), *from_thread, VirtualAddress(to_thread), *to_thread);
VERIFY(to_thread == Thread::current());
Scheduler::enter_current(*from_thread, true);
// Since we got here and don't have Scheduler::context_switch in the
// call stack (because this is the first time we switched into this
// context), we need to notify the scheduler so that it can release
// the scheduler lock. We don't want to enable interrupts at this point
// as we're still in the middle of a context switch. Doing so could
// trigger a context switch within a context switch, leading to a crash.
Scheduler::leave_on_first_switch(trap->regs->eflags & ~0x200);
}
extern "C" u32 do_init_context(Thread* thread, u32 flags)
{
VERIFY_INTERRUPTS_DISABLED();

6
Kernel/Arch/x86/x86_64/CPU.cpp
View file

@ -19,7 +19,6 @@ namespace Kernel {
// The compiler can't see the calls to these functions inside assembly.
// Declare them, to avoid dead code warnings.
extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread) __attribute__((used));
extern "C" void context_first_init(Thread* from_thread, Thread* to_thread, TrapFrame* trap) __attribute__((used));
extern "C" u32 do_init_context(Thread* thread, u32 flags) __attribute__((used));
extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread)
@ -29,11 +28,6 @@ extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread)
TODO();
}
extern "C" void context_first_init([[maybe_unused]] Thread* from_thread, [[maybe_unused]] Thread* to_thread, [[maybe_unused]] TrapFrame* trap)
{
TODO();
}
extern "C" u32 do_init_context(Thread* thread, u32 flags)
{
(void)thread;

39
Kernel/Arch/x86/x86_64/Processor.cpp
View file

@ -15,7 +15,6 @@
namespace Kernel {
#define ENTER_THREAD_CONTEXT_ARGS_SIZE (2 * 4) // to_thread, from_thread
extern "C" void thread_context_first_enter(void);
extern "C" void do_assume_context(Thread* thread, u32 flags);
extern "C" void exit_kernel_thread(void);
@ -28,11 +27,11 @@ asm(
// switch_context will have pushed from_thread and to_thread to our new
// stack prior to thread_context_first_enter() being called, and the
// pointer to TrapFrame was the top of the stack before that
" movl 8(%esp), %ebx \n" // save pointer to TrapFrame
" popq %rdi \n" // from_thread (argument 0)
" popq %rsi \n" // to_thread (argument 1)
" popq %rdx \n" // pointer to TrapFrame (argument 2)
" cld \n"
" call context_first_init \n"
" addl $" __STRINGIFY(ENTER_THREAD_CONTEXT_ARGS_SIZE) ", %esp \n"
" movl %ebx, 0(%esp) \n" // push pointer to TrapFrame
" jmp common_trap_exit \n"
);
// clang-format on
@ -79,12 +78,12 @@ u32 Processor::init_context(Thread& thread, bool leave_crit)
VERIFY(in_critical() == 1);
}
u32 kernel_stack_top = thread.kernel_stack_top();
u64 kernel_stack_top = thread.kernel_stack_top();
// Add a random offset between 0-256 (16-byte aligned)
kernel_stack_top -= round_up_to_power_of_two(get_fast_random<u8>(), 16);
u32 stack_top = kernel_stack_top;
u64 stack_top = kernel_stack_top;
// TODO: handle NT?
VERIFY((cpu_flags() & 0x24000) == 0); // Assume !(NT | VM)
@ -102,13 +101,13 @@ u32 Processor::init_context(Thread& thread, bool leave_crit)
// which should be in regs.rsp and exit_kernel_thread as return
// address.
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);
*reinterpret_cast<u64*>(kernel_stack_top - 2 * sizeof(u64)) = regs.rsp;
*reinterpret_cast<u64*>(kernel_stack_top - 3 * sizeof(u64)) = FlatPtr(&exit_kernel_thread);
} else {
stack_top -= sizeof(RegisterState);
}
// we want to end up 16-byte aligned, %esp + 4 should be aligned
// we want to end up 16-byte aligned, %rsp + 8 should be aligned
stack_top -= sizeof(u64);
*reinterpret_cast<u64*>(kernel_stack_top - sizeof(u64)) = 0;
@ -116,7 +115,19 @@ u32 Processor::init_context(Thread& thread, bool leave_crit)
// we will end up either in kernel mode or user mode, depending on how the thread is set up
// However, the first step is to always start in kernel mode with thread_context_first_enter
RegisterState& iretframe = *reinterpret_cast<RegisterState*>(stack_top);
// FIXME: copy state to be recovered through TSS
iretframe.rdi = regs.rdi;
iretframe.rsi = regs.rsi;
iretframe.rbp = regs.rbp;
iretframe.rsp = 0;
iretframe.rbx = regs.rbx;
iretframe.rdx = regs.rdx;
iretframe.rcx = regs.rcx;
iretframe.rax = regs.rax;
iretframe.rflags = regs.rflags;
iretframe.rip = regs.rip;
iretframe.cs = regs.cs;
if (return_to_user)
iretframe.userspace_rsp = regs.rsp;
// make space for a trap frame
stack_top -= sizeof(TrapFrame);
@ -205,21 +216,15 @@ UNMAP_AFTER_INIT void Processor::initialize_context_switching(Thread& initial_th
"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
"movq 24(%%rsp), %%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),

6
Kernel/Thread.cpp
View file

@ -105,7 +105,13 @@ Thread::Thread(NonnullRefPtr<Process> process, NonnullOwnPtr<Region> kernel_stac
m_regs.gs = GDT_SELECTOR_TLS | 3;
}
#else
// Only IF is set when a process boots.
m_regs.rflags = 0x0202;
if (m_process->is_kernel_process())
m_regs.cs = GDT_SELECTOR_CODE0;
else
m_regs.cs = GDT_SELECTOR_CODE3 | 3;
#endif
m_regs.cr3 = m_process->space().page_directory().cr3();