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Kernel/LibC: Replace SYS_{GET,SET}_TLS with SYS_{SET,GET}_{FS,GS}BASE 

This allows userspace to use both registers
This commit is contained in:
Bananymous 2025-11-10 21:48:38 +02:00
parent 7a68ce7e94
commit 89c0ff1a9d
17 changed files with 165 additions and 46 deletions
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8
kernel/arch/i686/Thread.S
View File

@ -45,11 +45,11 @@ start_userspace_thread:
movw $(0x20 | 3), %bx
movw %bx, %ds
movw %bx, %es
# gs = thread local
# fs
movw $(0x30 | 3), %bx
movw %bx, %gs
# fs = 0
xorw %bx, %bx
movw %bx, %fs
# gs
movw $(0x38 | 3), %bx
movw %bx, %gs
iret

3
kernel/arch/x86_64/Syscall.S
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@ -2,6 +2,7 @@
// System V ABI: RDI, RSI, RDX, RCX, R8, R9
.global asm_syscall_handler
asm_syscall_handler:
swapgs
pushq %rbx
pushq %rcx
pushq %rdx
@ -42,9 +43,9 @@ asm_syscall_handler:
popq %rdx
popq %rcx
popq %rbx
swapgs
iretq
.global sys_fork_trampoline
sys_fork_trampoline:
pushq %rbx

2
kernel/arch/x86_64/Thread.S
View File

@ -32,4 +32,6 @@ start_userspace_thread:
call get_thread_start_sp
movq %rax, %rsp
swapgs
iretq

33
kernel/arch/x86_64/interrupts.S
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@ -1,4 +1,12 @@
.macro pushaq
.macro swapgs_if_necessary, n
cmpb $0x08, \n(%rsp)
je 1f
swapgs
1:
.endm
.macro pushaq, n
swapgs_if_necessary \n
pushq %rax
pushq %rcx
pushq %rdx
@ -16,7 +24,7 @@
pushq %r15
.endm
.macro popaq
.macro popaq, n
popq %r15
popq %r14
popq %r13
@ -32,10 +40,11 @@
popq %rdx
popq %rcx
popq %rax
swapgs_if_necessary \n
.endm
isr_stub:
pushaq
pushaq 24
cld
movq %cr0, %rax; pushq %rax
movq %cr2, %rax; pushq %rax
@ -49,43 +58,43 @@ isr_stub:
call cpp_isr_handler
addq $32, %rsp
popaq
popaq 24
addq $16, %rsp
iretq
irq_stub:
pushaq
pushaq 24
cld
movq 120(%rsp), %rdi # irq number
call cpp_irq_handler
popaq
popaq 24
addq $16, %rsp
iretq
.global asm_yield_handler
asm_yield_handler:
pushaq
pushaq 8
cld
leaq 120(%rsp), %rdi # interrupt stack ptr
movq %rsp, %rsi # interrupt register ptr
call cpp_yield_handler
popaq
popaq 8
iretq
.global asm_ipi_handler
asm_ipi_handler:
pushaq
pushaq 8
cld
call cpp_ipi_handler
popaq
popaq 8
iretq
.global asm_timer_handler
asm_timer_handler:
pushaq
pushaq 8
cld
call cpp_timer_handler
popaq
popaq 8
iretq
.macro isr n

7
kernel/include/kernel/GDT.h
View File

@ -129,7 +129,8 @@ namespace Kernel
}
#if ARCH(i686)
void set_tls(uintptr_t addr);
void set_fsbase(uintptr_t addr);
void set_gsbase(uintptr_t addr);
#endif
private:
@ -153,8 +154,8 @@ namespace Kernel
BAN::Array<SegmentDescriptor, 7> m_gdt; // null, kernel code, kernel data, user code, user data, tss low, tss high
static constexpr uint16_t m_tss_offset = 0x28;
#elif ARCH(i686)
BAN::Array<SegmentDescriptor, 8> m_gdt; // null, kernel code, kernel data, user code, user data, processor data, tls, tss
static constexpr uint16_t m_tss_offset = 0x38;
BAN::Array<SegmentDescriptor, 9> m_gdt; // null, kernel code, kernel data, user code, user data, processor data, fsbase, gsbase, tss
static constexpr uint16_t m_tss_offset = 0x40;
#endif
TaskStateSegment m_tss;
const GDTR m_gdtr {

8
kernel/include/kernel/Process.h
View File

@ -203,8 +203,12 @@ namespace Kernel
BAN::ErrorOr<long> sys_futex(int op, const uint32_t* addr, uint32_t val, const timespec* abstime);
BAN::ErrorOr<long> sys_yield();
BAN::ErrorOr<long> sys_set_tls(void*);
BAN::ErrorOr<long> sys_get_tls();
BAN::ErrorOr<long> sys_set_fsbase(void*);
BAN::ErrorOr<long> sys_get_fsbase();
BAN::ErrorOr<long> sys_set_gsbase(void*);
BAN::ErrorOr<long> sys_get_gsbase();
BAN::ErrorOr<long> sys_pthread_create(const pthread_attr_t* attr, void (*entry)(void*), void* arg);
BAN::ErrorOr<long> sys_pthread_exit(void* value);
BAN::ErrorOr<long> sys_pthread_join(pthread_t thread, void** value);

4
kernel/include/kernel/Processor.h
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@ -112,7 +112,9 @@ namespace Kernel
static void send_smp_message(ProcessorID, const SMPMessage&, bool send_ipi = true);
static void broadcast_smp_message(const SMPMessage&);
static void load_tls();
static void load_segments();
static void load_fsbase();
static void load_gsbase();
private:
Processor() = default;

9
kernel/include/kernel/Thread.h
View File

@ -122,8 +122,10 @@ namespace Kernel
void set_cpu_time_start();
void set_cpu_time_stop();
void set_tls(vaddr_t tls) { m_tls = tls; }
vaddr_t get_tls() const { return m_tls; }
void set_fsbase(vaddr_t base) { m_fsbase = base; }
vaddr_t get_fsbase() const { return m_fsbase; }
void set_gsbase(vaddr_t base) { m_gsbase = base; }
vaddr_t get_gsbase() const { return m_gsbase; }
size_t virtual_page_count() const { return (m_kernel_stack ? (m_kernel_stack->size() / PAGE_SIZE) : 0) + (m_userspace_stack ? (m_userspace_stack->size() / PAGE_SIZE) : 0); }
size_t physical_page_count() const { return virtual_page_count(); }
@ -164,7 +166,8 @@ namespace Kernel
bool m_is_userspace { false };
bool m_delete_process { false };
vaddr_t m_tls { 0 };
vaddr_t m_fsbase { 0 };
vaddr_t m_gsbase { 0 };
SchedulerQueue::Node* m_scheduler_node { nullptr };

9
kernel/kernel/GDT.cpp
View File

@ -29,7 +29,8 @@ namespace Kernel
gdt->write_entry(0x20, 0x00000000, 0xFFFFF, 0xF2, data_flags); // user data
#if ARCH(i686)
gdt->write_entry(0x28, reinterpret_cast<uint32_t>(processor), sizeof(Processor), 0x92, 0x4); // processor data
gdt->write_entry(0x30, 0x00000000, 0x00000, 0x00, 0x0); // tls
gdt->write_entry(0x30, 0x00000000, 0x00000, 0x00, 0x0); // fsbase
gdt->write_entry(0x38, 0x00000000, 0x00000, 0x00, 0x0); // gsbase
#endif
gdt->write_tss();
@ -37,10 +38,14 @@ namespace Kernel
}
#if ARCH(i686)
void GDT::set_tls(uintptr_t addr)
void GDT::set_fsbase(uintptr_t addr)
{
write_entry(0x30, addr, 0xFFFF, 0xF2, 0xC);
}
void GDT::set_gsbase(uintptr_t addr)
{
write_entry(0x38, addr, 0xFFFF, 0xF2, 0xC);
}
#endif
void GDT::write_entry(uint8_t offset, uint32_t base, uint32_t limit, uint8_t access, uint8_t flags)

40
kernel/kernel/Process.cpp
View File

@ -173,7 +173,15 @@ namespace Kernel
auxiliary_vector.span()
));
if (tls_addr.has_value())
thread->set_tls(*tls_addr);
{
#if ARCH(x86_64)
thread->set_fsbase(*tls_addr);
#elif ARCH(i686)
thread->set_gsbase(*tls_addr);
#else
#error
#endif
}
process->add_thread(thread);
process->register_to_scheduler();
@ -730,7 +738,13 @@ namespace Kernel
{
auto tls_result = TRY(initialize_thread_local_storage(*new_page_table, *executable.master_tls));
TRY(new_mapped_regions.emplace_back(BAN::move(tls_result.region)));
new_thread->set_tls(tls_result.addr);
#if ARCH(x86_64)
new_thread->set_fsbase(tls_result.addr);
#elif ARCH(i686)
new_thread->set_gsbase(tls_result.addr);
#else
#error
#endif
}
// NOTE: this is done before disabling interrupts and moving the threads as
@ -3016,16 +3030,28 @@ namespace Kernel
return 0;
}
BAN::ErrorOr<long> Process::sys_set_tls(void* addr)
BAN::ErrorOr<long> Process::sys_set_fsbase(void* addr)
{
Thread::current().set_tls(reinterpret_cast<vaddr_t>(addr));
Processor::load_tls();
Thread::current().set_fsbase(reinterpret_cast<vaddr_t>(addr));
Processor::load_fsbase();
return 0;
}
BAN::ErrorOr<long> Process::sys_get_tls()
BAN::ErrorOr<long> Process::sys_get_fsbase()
{
return Thread::current().get_tls();
return Thread::current().get_fsbase();
}
BAN::ErrorOr<long> Process::sys_set_gsbase(void* addr)
{
Thread::current().set_gsbase(reinterpret_cast<vaddr_t>(addr));
Processor::load_gsbase();
return 0;
}
BAN::ErrorOr<long> Process::sys_get_gsbase()
{
return Thread::current().get_gsbase();
}
BAN::ErrorOr<long> Process::sys_pthread_create(const pthread_attr_t* attr, void (*entry)(void*), void* arg)

44
kernel/kernel/Processor.cpp
View File

@ -12,6 +12,7 @@ namespace Kernel
#if ARCH(x86_64)
static constexpr uint32_t MSR_IA32_FS_BASE = 0xC0000100;
static constexpr uint32_t MSR_IA32_GS_BASE = 0xC0000101;
static constexpr uint32_t MSR_IA32_KERNEL_GS_BASE = 0xC0000102;
#endif
ProcessorID Processor::s_bsp_id { PROCESSOR_NONE };
@ -265,15 +266,52 @@ namespace Kernel
set_interrupt_state(state);
}
void Processor::load_tls()
void Processor::load_segments()
{
const auto addr = scheduler().current_thread().get_tls();
{
const auto addr = scheduler().current_thread().get_fsbase();
#if ARCH(x86_64)
uint32_t ptr_hi = addr >> 32;
uint32_t ptr_lo = addr & 0xFFFFFFFF;
asm volatile("wrmsr" :: "d"(ptr_hi), "a"(ptr_lo), "c"(MSR_IA32_FS_BASE));
#elif ARCH(i686)
gdt().set_tls(addr);
gdt().set_fsbase(addr);
#endif
}
{
const auto addr = scheduler().current_thread().get_gsbase();
#if ARCH(x86_64)
uint32_t ptr_hi = addr >> 32;
uint32_t ptr_lo = addr & 0xFFFFFFFF;
asm volatile("wrmsr" :: "d"(ptr_hi), "a"(ptr_lo), "c"(MSR_IA32_KERNEL_GS_BASE));
#elif ARCH(i686)
gdt().set_gsbase(addr);
#endif
}
}
void Processor::load_fsbase()
{
const auto addr = scheduler().current_thread().get_fsbase();
#if ARCH(x86_64)
uint32_t ptr_hi = addr >> 32;
uint32_t ptr_lo = addr & 0xFFFFFFFF;
asm volatile("wrmsr" :: "d"(ptr_hi), "a"(ptr_lo), "c"(MSR_IA32_FS_BASE));
#elif ARCH(i686)
gdt().set_fsbase(addr);
#endif
}
void Processor::load_gsbase()
{
const auto addr = scheduler().current_thread().get_gsbase();
#if ARCH(x86_64)
uint32_t ptr_hi = addr >> 32;
uint32_t ptr_lo = addr & 0xFFFFFFFF;
asm volatile("wrmsr" :: "d"(ptr_hi), "a"(ptr_lo), "c"(MSR_IA32_KERNEL_GS_BASE));
#elif ARCH(i686)
gdt().set_gsbase(addr);
#endif
}

3
kernel/kernel/Scheduler.cpp
View File

@ -282,7 +282,8 @@ namespace Kernel
}
Processor::gdt().set_tss_stack(thread->kernel_stack_top());
Processor::load_tls();
if (thread->is_userspace())
Processor::load_segments();
*interrupt_stack = thread->interrupt_stack();
*interrupt_registers = thread->interrupt_registers();

3
kernel/kernel/Thread.cpp
View File

@ -328,7 +328,8 @@ namespace Kernel
thread->m_kernel_stack = TRY(m_kernel_stack->clone(new_process->page_table()));
thread->m_userspace_stack = TRY(m_userspace_stack->clone(new_process->page_table()));
thread->m_tls = m_tls;
thread->m_fsbase = m_fsbase;
thread->m_gsbase = m_gsbase;
thread->m_state = State::NotStarted;

6
userspace/libraries/LibC/include/sys/syscall.h
View File

@ -101,8 +101,10 @@ __BEGIN_DECLS
O(SYS_HARDLINKAT, hardlinkat) \
O(SYS_UTIMENSAT, utimensat) \
O(SYS_YIELD, yield) \
O(SYS_SET_TLS, set_tls) \
O(SYS_GET_TLS, get_tls) \
O(SYS_SET_FSBASE, set_fsbase) \
O(SYS_GET_FSBASE, get_fsbase) \
O(SYS_SET_GSBASE, set_gsbase) \
O(SYS_GET_GSBASE, get_gsbase) \
O(SYS_PTHREAD_CREATE, pthread_create) \
O(SYS_PTHREAD_EXIT, pthread_exit) \
O(SYS_PTHREAD_JOIN, pthread_join) \

8
userspace/libraries/LibC/pthread.cpp
View File

@ -49,7 +49,13 @@ extern "C" void _pthread_trampoline_cpp(void* arg)
{
auto info = *reinterpret_cast<pthread_trampoline_info_t*>(arg);
info.uthread->id = syscall(SYS_PTHREAD_SELF);
syscall(SYS_SET_TLS, info.uthread);
#if defined(__x86_64__)
syscall(SYS_SET_FSBASE, info.uthread);
#elif defined(__i686__)
syscall(SYS_SET_GSBASE, info.uthread);
#else
#error
#endif
free(arg);
pthread_exit(info.start_routine(info.arg));
ASSERT_NOT_REACHED();

16
userspace/libraries/LibC/unistd.cpp
View File

@ -34,7 +34,13 @@ extern "C" void _init_libc(char** environ, init_funcs_t init_funcs, init_funcs_t
if (::environ == nullptr)
::environ = environ;
if (uthread* self = reinterpret_cast<uthread*>(syscall(SYS_GET_TLS)))
#if defined(__x86_64__)
if (uthread* self = reinterpret_cast<uthread*>(syscall(SYS_GET_FSBASE)))
#elif defined(__i686__)
if (uthread* self = reinterpret_cast<uthread*>(syscall(SYS_GET_GSBASE)))
#else
#error
#endif
{
self->cleanup_stack = nullptr;
self->id = syscall(SYS_PTHREAD_SELF);
@ -61,7 +67,13 @@ extern "C" void _init_libc(char** environ, init_funcs_t init_funcs, init_funcs_t
};
uthread.dtv[0] = 0;
syscall(SYS_SET_TLS, &uthread);
#if defined(__x86_64__)
syscall(SYS_SET_FSBASE, &uthread);
#elif defined(__i686__)
syscall(SYS_SET_GSBASE, &uthread);
#else
#error
#endif
}
// call global constructors

8
userspace/programs/DynamicLoader/main.cpp
View File

@ -1366,7 +1366,13 @@ static void initialize_tls(MasterTLS master_tls)
uthread.dtv[elf.tls_module] = reinterpret_cast<uintptr_t>(tls_addr) + uthread.master_tls_size - elf.tls_offset;
}
syscall(SYS_SET_TLS, &uthread);
#if defined(__x86_64__)
syscall(SYS_SET_FSBASE, &uthread);
#elif defined(__i686__)
syscall(SYS_SET_GSBASE, &uthread);
#else
#error
#endif
}
static void initialize_environ(char** envp)