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Kernel: Implement initializing threads on x86_64

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This commit is contained in:
Gunnar Beutner 2021-06-27 13:59:41 +02:00 • committed by Andreas Kling
parent f285241cb8
commit 9ed051fe25
5 changed files with 59 additions and 44 deletions
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39
Kernel/Arch/x86/x86_64/Processor.cpp
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@ -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),