mirror of
https://github.com/LadybirdBrowser/ladybird.git
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cf16b2c8e6
This forces anyone who wants to look into and/or manipulate an address space to lock it. And this replaces the previous, more flimsy, manual spinlock use. Note that pointers *into* the address space are not safe to use after you unlock the space. We've got many issues like this, and we'll have to track those down as wlel.
251 lines
8.1 KiB
C++
251 lines
8.1 KiB
C++
/*
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* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2022, the SerenityOS developers.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/API/Syscall.h>
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#include <Kernel/Arch/x86/Interrupts.h>
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#include <Kernel/Arch/x86/TrapFrame.h>
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#include <Kernel/Memory/MemoryManager.h>
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#include <Kernel/Panic.h>
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#include <Kernel/PerformanceManager.h>
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#include <Kernel/Process.h>
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#include <Kernel/Scheduler.h>
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#include <Kernel/Sections.h>
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#include <Kernel/ThreadTracer.h>
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namespace Kernel {
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extern "C" void syscall_handler(TrapFrame*) __attribute__((used));
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extern "C" void syscall_asm_entry();
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NEVER_INLINE NAKED void syscall_asm_entry()
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{
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// clang-format off
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#if ARCH(I386)
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asm(
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" pushl $0x0\n"
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" pusha\n"
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" pushl %ds\n"
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" pushl %es\n"
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" pushl %fs\n"
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" pushl %gs\n"
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" pushl %ss\n"
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" mov $" __STRINGIFY(GDT_SELECTOR_DATA0) ", %ax\n"
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" mov %ax, %ds\n"
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" mov %ax, %es\n"
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" mov $" __STRINGIFY(GDT_SELECTOR_PROC) ", %ax\n"
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" mov %ax, %gs\n"
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" cld\n"
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" xor %esi, %esi\n"
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" xor %edi, %edi\n"
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" pushl %esp \n" // set TrapFrame::regs
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" subl $" __STRINGIFY(TRAP_FRAME_SIZE - 4) ", %esp \n"
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" movl %esp, %ebx \n"
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" pushl %ebx \n" // push pointer to TrapFrame
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" call enter_trap_no_irq \n"
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" movl %ebx, 0(%esp) \n" // push pointer to TrapFrame
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" call syscall_handler \n"
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" movl %ebx, 0(%esp) \n" // push pointer to TrapFrame
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" jmp common_trap_exit \n");
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#elif ARCH(X86_64)
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asm(
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" pushq $0x0\n"
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" pushq %r15\n"
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" pushq %r14\n"
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" pushq %r13\n"
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" pushq %r12\n"
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" pushq %r11\n"
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" pushq %r10\n"
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" pushq %r9\n"
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" pushq %r8\n"
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" pushq %rax\n"
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" pushq %rcx\n"
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" pushq %rdx\n"
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" pushq %rbx\n"
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" pushq %rsp\n"
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" pushq %rbp\n"
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" pushq %rsi\n"
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" pushq %rdi\n"
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" pushq %rsp \n" /* set TrapFrame::regs */
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" subq $" __STRINGIFY(TRAP_FRAME_SIZE - 8) ", %rsp \n"
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" movq %rsp, %rdi \n"
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" cld\n"
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" call enter_trap_no_irq \n"
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" movq %rsp, %rdi \n"
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" call syscall_handler\n"
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" jmp common_trap_exit \n");
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#endif
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// clang-format on
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}
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namespace Syscall {
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static ErrorOr<FlatPtr> handle(RegisterState&, FlatPtr function, FlatPtr arg1, FlatPtr arg2, FlatPtr arg3, FlatPtr arg4);
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UNMAP_AFTER_INIT void initialize()
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{
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register_user_callable_interrupt_handler(syscall_vector, syscall_asm_entry);
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}
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using Handler = auto(Process::*)(FlatPtr, FlatPtr, FlatPtr, FlatPtr) -> ErrorOr<FlatPtr>;
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using HandlerWithRegisterState = auto(Process::*)(RegisterState&) -> ErrorOr<FlatPtr>;
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struct HandlerMetadata {
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Handler handler;
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NeedsBigProcessLock needs_lock;
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};
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#define __ENUMERATE_SYSCALL(sys_call, needs_lock) { bit_cast<Handler>(&Process::sys$##sys_call), needs_lock },
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static const HandlerMetadata s_syscall_table[] = {
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ENUMERATE_SYSCALLS(__ENUMERATE_SYSCALL)
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};
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#undef __ENUMERATE_SYSCALL
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ErrorOr<FlatPtr> handle(RegisterState& regs, FlatPtr function, FlatPtr arg1, FlatPtr arg2, FlatPtr arg3, FlatPtr arg4)
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{
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VERIFY_INTERRUPTS_ENABLED();
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auto* current_thread = Thread::current();
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auto& process = current_thread->process();
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current_thread->did_syscall();
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PerformanceManager::add_syscall_event(*current_thread, regs);
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if (function >= Function::__Count) {
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dbgln("Unknown syscall {} requested ({:p}, {:p}, {:p}, {:p})", function, arg1, arg2, arg3, arg4);
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return ENOSYS;
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}
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auto const syscall_metadata = s_syscall_table[function];
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if (syscall_metadata.handler == nullptr) {
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dbgln("Null syscall {} requested, you probably need to rebuild this program!", function);
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return ENOSYS;
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}
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MutexLocker mutex_locker;
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auto const needs_big_lock = syscall_metadata.needs_lock == NeedsBigProcessLock::Yes;
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if (needs_big_lock) {
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mutex_locker.attach_and_lock(process.big_lock());
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};
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if (function == SC_exit || function == SC_exit_thread) {
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// These syscalls need special handling since they never return to the caller.
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// In these cases the process big lock will get released on the exit of the thread.
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if (auto* tracer = process.tracer(); tracer && tracer->is_tracing_syscalls()) {
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regs.set_return_reg(0);
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tracer->set_trace_syscalls(false);
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process.tracer_trap(*current_thread, regs); // this triggers SIGTRAP and stops the thread!
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}
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switch (function) {
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case SC_exit:
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process.sys$exit(arg1);
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case SC_exit_thread:
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process.sys$exit_thread(arg1, arg2, arg3);
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default:
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VERIFY_NOT_REACHED();
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}
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}
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ErrorOr<FlatPtr> result { FlatPtr(nullptr) };
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if (function == SC_fork || function == SC_sigreturn) {
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// These syscalls want the RegisterState& rather than individual parameters.
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auto handler = bit_cast<HandlerWithRegisterState>(syscall_metadata.handler);
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result = (process.*(handler))(regs);
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} else {
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result = (process.*(syscall_metadata.handler))(arg1, arg2, arg3, arg4);
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}
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return result;
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}
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}
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NEVER_INLINE void syscall_handler(TrapFrame* trap)
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{
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// Make sure SMAP protection is enabled on syscall entry.
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clac();
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auto& regs = *trap->regs;
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auto* current_thread = Thread::current();
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VERIFY(current_thread->previous_mode() == Thread::PreviousMode::UserMode);
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auto& process = current_thread->process();
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if (process.is_dying()) {
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// It's possible this thread is just about to make a syscall while another is
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// is killing our process.
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current_thread->die_if_needed();
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return;
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}
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if (auto* tracer = process.tracer(); tracer && tracer->is_tracing_syscalls()) {
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tracer->set_trace_syscalls(false);
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process.tracer_trap(*current_thread, regs); // this triggers SIGTRAP and stops the thread!
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}
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current_thread->yield_if_stopped();
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// Apply a random offset in the range 0-255 to the stack pointer,
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// to make kernel stacks a bit less deterministic.
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u32 lsw;
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u32 msw;
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read_tsc(lsw, msw);
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auto* ptr = (char*)__builtin_alloca(lsw & 0xff);
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asm volatile(""
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: "=m"(*ptr));
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constexpr FlatPtr iopl_mask = 3u << 12;
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FlatPtr flags = regs.flags();
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if ((flags & (iopl_mask)) != 0) {
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PANIC("Syscall from process with IOPL != 0");
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}
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Memory::MemoryManager::validate_syscall_preconditions(process, regs);
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FlatPtr function;
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FlatPtr arg1;
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FlatPtr arg2;
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FlatPtr arg3;
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FlatPtr arg4;
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regs.capture_syscall_params(function, arg1, arg2, arg3, arg4);
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auto result = Syscall::handle(regs, function, arg1, arg2, arg3, arg4);
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if (result.is_error()) {
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regs.set_return_reg(-result.error().code());
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} else {
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regs.set_return_reg(result.value());
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}
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if (auto* tracer = process.tracer(); tracer && tracer->is_tracing_syscalls()) {
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tracer->set_trace_syscalls(false);
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process.tracer_trap(*current_thread, regs); // this triggers SIGTRAP and stops the thread!
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}
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current_thread->yield_if_stopped();
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current_thread->check_dispatch_pending_signal();
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// If the previous mode somehow changed something is seriously messed up...
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VERIFY(current_thread->previous_mode() == Thread::PreviousMode::UserMode);
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// Check if we're supposed to return to userspace or just die.
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current_thread->die_if_needed();
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// Crash any processes which have commited a promise violation during syscall handling.
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if (result.is_error() && result.error().code() == EPROMISEVIOLATION) {
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VERIFY(current_thread->is_promise_violation_pending());
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current_thread->set_promise_violation_pending(false);
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process.crash(SIGABRT, 0);
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} else {
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VERIFY(!current_thread->is_promise_violation_pending());
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}
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VERIFY(!g_scheduler_lock.is_locked_by_current_processor());
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}
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}
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