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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
Notes: sideshowbarker 2024-07-18 11:25:19 +09:00 
Author: https://github.com/gunnarbeutner
Commit: https://github.com/SerenityOS/serenity/commit/32840dfa174
Pull-request: https://github.com/SerenityOS/serenity/pull/8290
Reviewed-by: https://github.com/Hendiadyoin1
8 changed files with 151 additions and 132 deletions
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71
Kernel/Arch/x86/common/Processor.cpp
View File

@ -40,9 +40,11 @@ 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.
// The compiler can't see the calls to these functions inside assembly.
// Declare them, to avoid dead code warnings.
extern "C" void context_first_init(Thread* from_thread, Thread* to_thread, TrapFrame* trap) __attribute__((used));
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));
UNMAP_AFTER_INIT static void sse_init()
{
@ -1165,4 +1167,69 @@ extern "C" void context_first_init([[maybe_unused]] Thread* from_thread, [[maybe
Scheduler::leave_on_first_switch(flags & ~0x200);
}
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()));
#if ARCH(I386)
from_regs.fs = get_fs();
from_regs.gs = get_gs();
set_fs(to_regs.fs);
set_gs(to_regs.gs);
#endif
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();
#if ARCH(I386)
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());
#endif
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();
#if ARCH(I386)
thread->regs().eflags = flags;
#else
thread->regs().rflags = flags;
#endif
return Processor::current().init_context(*thread, true);
}
}

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"

37
Kernel/Arch/x86/x86_64/CPU.cpp
View File

@ -1,37 +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)
{
(void)from_thread;
(void)to_thread;
TODO();
}
extern "C" u32 do_init_context(Thread* thread, u32 flags)
{
(void)thread;
(void)flags;
TODO();
}
}

71
Kernel/Arch/x86/x86_64/Processor.cpp
View File

@ -91,9 +91,8 @@ u32 Processor::init_context(Thread& thread, bool leave_crit)
auto& regs = thread.regs();
bool return_to_user = (regs.cs & 3) != 0;
stack_top -= 2 * sizeof(u64);
*reinterpret_cast<u64*>(kernel_stack_top - 2 * sizeof(u64)) = regs.rsp;
*reinterpret_cast<u64*>(kernel_stack_top - 3 * sizeof(u64)) = FlatPtr(&exit_kernel_thread);
stack_top -= 1 * sizeof(u64);
*reinterpret_cast<u64*>(kernel_stack_top - 2 * sizeof(u64)) = FlatPtr(&exit_kernel_thread);
stack_top -= sizeof(RegisterState);
@ -167,7 +166,71 @@ void Processor::switch_context(Thread*& from_thread, Thread*& to_thread)
dbgln_if(CONTEXT_SWITCH_DEBUG, "switch_context --> switching out of: {} {}", VirtualAddress(from_thread), *from_thread);
from_thread->save_critical(m_in_critical);
PANIC("Context switching not implemented.");
// clang-format off
// Switch to new thread context, passing from_thread and to_thread
// through to the new context using registers rdx and rax
asm volatile(
// NOTE: changing how much we push to the stack affects thread_context_first_enter()!
"pushfq \n"
"pushq %%rbx \n"
"pushq %%rcx \n"
"pushq %%rbp \n"
"pushq %%rsi \n"
"pushq %%rdi \n"
"pushq %%r8 \n"
"pushq %%r9 \n"
"pushq %%r10 \n"
"pushq %%r11 \n"
"pushq %%r12 \n"
"pushq %%r13 \n"
"pushq %%r14 \n"
"pushq %%r15 \n"
"movq %%rsp, %[from_rsp] \n"
"movabs $1f, %%rbx \n"
"movq %%rbx, %[from_rip] \n"
"movq %[to_rsp0], %%rbx \n"
"movl %%ebx, %[tss_rsp0l] \n"
"shrq $32, %%rbx \n"
"movl %%ebx, %[tss_rsp0h] \n"
"movq %[to_rsp], %%rsp \n"
"pushq %[to_thread] \n"
"pushq %[from_thread] \n"
"pushq %[to_rip] \n"
"cld \n"
"movq 16(%%rsp), %%rsi \n"
"movq 8(%%rsp), %%rdi \n"
"jmp enter_thread_context \n"
"1: \n"
"popq %%rdx \n"
"popq %%rax \n"
"popq %%r15 \n"
"popq %%r14 \n"
"popq %%r13 \n"
"popq %%r12 \n"
"popq %%r11 \n"
"popq %%r10 \n"
"popq %%r9 \n"
"popq %%r8 \n"
"popq %%rdi \n"
"popq %%rsi \n"
"popq %%rbp \n"
"popq %%rcx \n"
"popq %%rbx \n"
"popfq \n"
: [from_rsp] "=m" (from_thread->regs().rsp),
[from_rip] "=m" (from_thread->regs().rip),
[tss_rsp0l] "=m" (m_tss.rsp0l),
[tss_rsp0h] "=m" (m_tss.rsp0h),
"=d" (from_thread), // needed so that from_thread retains the correct value
"=a" (to_thread) // needed so that to_thread retains the correct value
: [to_rsp] "g" (to_thread->regs().rsp),
[to_rsp0] "g" (to_thread->regs().rsp0),
[to_rip] "c" (to_thread->regs().rip),
[from_thread] "d" (from_thread),
[to_thread] "a" (to_thread)
: "memory", "rbx"
);
// clang-format on
dbgln_if(CONTEXT_SWITCH_DEBUG, "switch_context <-- from {} {} to {} {}", VirtualAddress(from_thread), *from_thread, VirtualAddress(to_thread), *to_thread);

1
Kernel/CMakeLists.txt
View File

@ -277,7 +277,6 @@ set(KERNEL_SOURCES
${KERNEL_SOURCES}
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/ASM_wrapper.cpp
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/Boot/boot.S
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/CPU.cpp
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/InterruptEntry.cpp
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/Processor.cpp
)

2
Kernel/Process.cpp
View File

@ -185,7 +185,7 @@ RefPtr<Process> Process::create_kernel_process(RefPtr<Thread>& first_thread, Str
first_thread->regs().esp = FlatPtr(entry_data); // entry function argument is expected to be in regs.esp
#else
first_thread->regs().rip = (FlatPtr)entry;
first_thread->regs().rsp = FlatPtr(entry_data); // entry function argument is expected to be in regs.rsp
first_thread->regs().rdi = FlatPtr(entry_data); // entry function argument is expected to be in regs.rdi
#endif
if (process->pid() != 0) {

16
Kernel/Scheduler.cpp
View File

@ -354,8 +354,13 @@ bool Scheduler::context_switch(Thread* thread)
from_thread->set_state(Thread::Runnable);
#ifdef LOG_EVERY_CONTEXT_SWITCH
# if ARCH(I386)
dbgln("Scheduler[{}]: {} -> {} [prio={}] {:04x}:{:08x}", Processor::id(), from_thread->tid().value(),
thread->tid().value(), thread->priority(), thread->regs().cs, thread->regs().eip);
# else
dbgln("Scheduler[{}]: {} -> {} [prio={}] {:04x}:{:16x}", Processor::id(), from_thread->tid().value(),
thread->tid().value(), thread->priority(), thread->regs().cs, thread->regs().rip);
# endif
#endif
}
@ -375,14 +380,19 @@ bool Scheduler::context_switch(Thread* thread)
enter_current(*from_thread, false);
VERIFY(thread == Thread::current());
#if ARCH(I386)
if (thread->process().is_user_process()) {
auto iopl = get_iopl_from_eflags(Thread::current()->get_register_dump_from_stack().eflags);
FlatPtr flags;
auto& regs = Thread::current()->get_register_dump_from_stack();
#if ARCH(I386)
flags = regs.eflags;
#else
flags = regs.rflags;
#endif
auto iopl = get_iopl_from_eflags(flags);
if (iopl != 0) {
PANIC("Switched to thread {} with non-zero IOPL={}", Thread::current()->tid().value(), iopl);
}
}
#endif
return true;
}