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Kernel: Implement more x86_64 context switching functionality

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Gunnar Beutner 2021-06-27 19:49:19 +02:00 • committed by Andreas Kling
parent 076692b1ef
commit 32840dfa17
8 changed files with 151 additions and 132 deletions
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82
Kernel/Arch/x86/i386/CPU.cpp
View file

@ -1,82 +0,0 @@
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Assertions.h>
#include <AK/Types.h>
#include <Kernel/Arch/x86/CPU.h>
#include <Kernel/Arch/x86/Processor.h>
#include <Kernel/Arch/x86/TrapFrame.h>
#include <Kernel/KSyms.h>
#include <Kernel/Process.h>
#include <Kernel/Thread.h>
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" u32 do_init_context(Thread* thread, u32 flags) __attribute__((used));
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_regs = from_thread->regs();
auto& to_regs = to_thread->regs();
if (has_fxsr)
asm volatile("fxsave %0"
: "=m"(from_thread->fpu_state()));
else
asm volatile("fnsave %0"
: "=m"(from_thread->fpu_state()));
from_regs.fs = get_fs();
from_regs.gs = get_gs();
set_fs(to_regs.fs);
set_gs(to_regs.gs);
if (from_thread->process().is_traced())
read_debug_registers_into(from_thread->debug_register_state());
if (to_thread->process().is_traced()) {
write_debug_registers_from(to_thread->debug_register_state());
} else {
clear_debug_registers();
}
auto& processor = Processor::current();
auto& tls_descriptor = processor.get_gdt_entry(GDT_SELECTOR_TLS);
tls_descriptor.set_base(to_thread->thread_specific_data());
tls_descriptor.set_limit(to_thread->thread_specific_region_size());
if (from_regs.cr3 != to_regs.cr3)
write_cr3(to_regs.cr3);
to_thread->set_cpu(processor.get_id());
processor.restore_in_critical(to_thread->saved_critical());
if (has_fxsr)
asm volatile("fxrstor %0" ::"m"(to_thread->fpu_state()));
else
asm volatile("frstor %0" ::"m"(to_thread->fpu_state()));
// TODO: ioperm?
}
extern "C" u32 do_init_context(Thread* thread, u32 flags)
{
VERIFY_INTERRUPTS_DISABLED();
thread->regs().eflags = flags;
return Processor::current().init_context(*thread, true);
}
}

3
Kernel/Arch/x86/i386/Processor.cpp
View file

@ -193,8 +193,7 @@ void Processor::switch_context(Thread*& from_thread, Thread*& to_thread)
// Switch to new thread context, passing from_thread and to_thread
// through to the new context using registers edx and eax
asm volatile(
// NOTE: changing how much we push to the stack affects
// SWITCH_CONTEXT_TO_STACK_SIZE and thread_context_first_enter()!
// NOTE: changing how much we push to the stack affects thread_context_first_enter()!
"pushfl \n"
"pushl %%ebx \n"
"pushl %%esi \n"