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<ol class="chapter"><li class="chapter-item expanded affix "><a href="index.html">简明 zCore 教程</a></li><li class="chapter-item expanded affix "><a href="zcore-intro.html">🚧 zCore 整体结构和设计模式</a></li><li class="chapter-item expanded affix "><a href="fuchsia.html">🚧 Fuchsia OS 和 Zircon 微内核</a></li><li class="chapter-item expanded "><a href="ch01-00-object.html"><strong aria-hidden="true">1.</strong> 内核对象</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch01-01-kernel-object.html"><strong aria-hidden="true">1.1.</strong> ✅ 初识内核对象</a></li><li class="chapter-item expanded "><a href="ch01-02-process-object.html"><strong aria-hidden="true">1.2.</strong> 🚧 对象管理器：Process 对象</a></li><li class="chapter-item expanded "><a href="ch01-03-channel-object.html"><strong aria-hidden="true">1.3.</strong> 🚧 对象传送器：Channel 对象</a></li></ol></li><li class="chapter-item expanded "><a href="ch02-00-task.html"><strong aria-hidden="true">2.</strong> 任务管理</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch02-01-zircon-task.html"><strong aria-hidden="true">2.1.</strong> 🚧 Zircon 任务管理体系</a></li><li class="chapter-item expanded "><a href="ch02-02-process-job-object.html"><strong aria-hidden="true">2.2.</strong> 🚧 进程管理：Process 与 Job 对象</a></li><li class="chapter-item expanded "><a href="ch02-03-thread-object.html"><strong aria-hidden="true">2.3.</strong> 🚧 线程管理：Thread 对象</a></li></ol></li><li class="chapter-item expanded "><a href="ch03-00-memory.html"><strong aria-hidden="true">3.</strong> 内存管理</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch03-01-zircon-memory.html"><strong aria-hidden="true">3.1.</strong> 🚧 Zircon 内存管理模型</a></li><li class="chapter-item expanded "><a href="ch03-02-vmo.html"><strong aria-hidden="true">3.2.</strong> 🚧 物理内存：VMO 对象</a></li><li class="chapter-item expanded "><a href="ch03-03-vmo-paged.html"><strong aria-hidden="true">3.3.</strong> 🚧 物理内存：按页分配的 VMO</a></li><li class="chapter-item expanded "><a href="ch03-04-vmar.html"><strong aria-hidden="true">3.4.</strong> 🚧 虚拟内存：VMAR 对象</a></li></ol></li><li class="chapter-item expanded "><a href="ch04-00-userspace.html"><strong aria-hidden="true">4.</strong> 用户程序</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch04-01-user-program.html"><strong aria-hidden="true">4.1.</strong> 🚧 Zircon 用户程序</a></li><li class="chapter-item expanded "><a href="ch04-02-context-switch.html"><strong aria-hidden="true">4.2.</strong> 🚧 上下文切换</a></li><li class="chapter-item expanded "><a href="ch04-03-syscall.html" class="active"><strong aria-hidden="true">4.3.</strong> 🚧 系统调用</a></li></ol></li><li class="chapter-item expanded "><a href="ch05-00-signal-and-waiting.html"><strong aria-hidden="true">5.</strong> 信号和等待</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch05-01-wait-signal.html"><strong aria-hidden="true">5.1.</strong> 🚧 等待内核对象的信号</a></li><li class="chapter-item expanded "><a href="ch05-02-port-object.html"><strong aria-hidden="true">5.2.</strong> 🚧 同时等待多个信号：Port 对象</a></li><li class="chapter-item expanded "><a href="ch05-03-more-signal-objects.html"><strong aria-hidden="true">5.3.</strong> 🚧 实现更多：EventPair, Timer 对象</a></li><li class="chapter-item expanded "><a href="ch05-04-futex-object.html"><strong aria-hidden="true">5.4.</strong> 🚧 用户态同步互斥：Futex 对象</a></li></ol></li><li class="chapter-item expanded "><a href="ch06-00-hal.html"><strong aria-hidden="true">6.</strong> 硬件抽象层</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="ch06-01-zcore-hal-unix.html"><strong aria-hidden="true">6.1.</strong> ✅ UNIX硬件抽象层</a></li></ol></li></ol> </div>
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<main>
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<h1 id="zircon-系统调用"><a class="header" href="#zircon-系统调用">Zircon 系统调用</a></h1>
|
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|
<blockquote>
|
|
|
<p>目录位于<code>zCore/zircon-syscall</code></p>
|
|
|
</blockquote>
|
|
|
<p>从userboot运行起来到实现调用syscall的简要函数调用流程如下：</p>
|
|
|
<ol>
|
|
|
<li>run_userboot -></li>
|
|
|
<li>proc.start -></li>
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|
|
<li>thread_fn -></li>
|
|
|
<li>new_thread -> </li>
|
|
|
<li>handle_syscall -> </li>
|
|
|
<li>syscall -></li>
|
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|
<li>sys_handle_close() (举例某一具体的syscall运行，该syscall可用于实现<code>close a handle</code>的功能)</li>
|
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</ol>
|
|
|
<h2 id="获取系统调用参数"><a class="header" href="#获取系统调用参数">获取系统调用参数</a></h2>
|
|
|
<p>从寄存器中获取参数</p>
|
|
|
<blockquote>
|
|
|
<p>不同的计算机体系结构获得参数的方式不同</p>
|
|
|
<p>以下区分<code>x86_64</code>以及<code>aarch64</code></p>
|
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|
</blockquote>
|
|
|
<p>调用syscall需要从寄存器收集两种参数：<br />
|
|
|
+ <code>num</code> : 系统调用号<br />
|
|
|
+ <code>args</code> : 具体某一系统调用的参数</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2018">
|
|
|
<span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>async fn handle_syscall(thread: &CurrentThread, regs: &mut GeneralRegs) {
|
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#[cfg(target_arch = "x86_64")]
|
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|
let num = regs.rax as u32;
|
|
|
#[cfg(target_arch = "aarch64")]
|
|
|
let num = regs.x16 as u32;
|
|
|
// LibOS: Function call ABI
|
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|
#[cfg(feature = "std")]
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#[cfg(target_arch = "x86_64")]
|
|
|
let args = unsafe {
|
|
|
let a6 = (regs.rsp as *const usize).read();
|
|
|
let a7 = (regs.rsp as *const usize).add(1).read();
|
|
|
[
|
|
|
regs.rdi, regs.rsi, regs.rdx, regs.rcx, regs.r8, regs.r9, a6, a7,
|
|
|
]
|
|
|
};
|
|
|
// RealOS: Zircon syscall ABI
|
|
|
#[cfg(not(feature = "std"))]
|
|
|
#[cfg(target_arch = "x86_64")]
|
|
|
let args = [
|
|
|
regs.rdi, regs.rsi, regs.rdx, regs.r10, regs.r8, regs.r9, regs.r12, regs.r13,
|
|
|
];
|
|
|
// ARM64
|
|
|
#[cfg(target_arch = "aarch64")]
|
|
|
let args = [
|
|
|
regs.x0, regs.x1, regs.x2, regs.x3, regs.x4, regs.x5, regs.x6, regs.x7,
|
|
|
];
|
|
|
let mut syscall = Syscall {
|
|
|
regs,
|
|
|
thread,
|
|
|
thread_fn,
|
|
|
};
|
|
|
let ret = syscall.syscall(num, args).await as usize;
|
|
|
#[cfg(target_arch = "x86_64")]
|
|
|
{
|
|
|
syscall.regs.rax = ret;
|
|
|
}
|
|
|
#[cfg(target_arch = "aarch64")]
|
|
|
{
|
|
|
syscall.regs.x0 = ret;
|
|
|
}
|
|
|
}
|
|
|
|
|
|
<span class="boring">}
|
|
|
</span></code></pre></pre>
|
|
|
<h2 id="系统调用上下文与处理函数"><a class="header" href="#系统调用上下文与处理函数">系统调用上下文与处理函数</a></h2>
|
|
|
<h3 id="定义-syscall-结构体"><a class="header" href="#定义-syscall-结构体">定义 Syscall 结构体</a></h3>
|
|
|
<p>保存上下文信息</p>
|
|
|
<blockquote>
|
|
|
<p>zCore/zircon-syscall/src/lib.rs#L52</p>
|
|
|
</blockquote>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2018">
|
|
|
<span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>/// 系统调用的结构(存储关于创建系统调用的信息)
|
|
|
pub struct Syscall<'a> {
|
|
|
/// store the regs statues
|
|
|
pub regs: &'a mut GeneralRegs,
|
|
|
/// the thread making a syscall
|
|
|
pub thread: &'a CurrentThread,
|
|
|
/// new thread function
|
|
|
pub thread_fn: ThreadFn,
|
|
|
}
|
|
|
<span class="boring">}
|
|
|
</span></code></pre></pre>
|
|
|
<h3 id="实现-syscall-函数"><a class="header" href="#实现-syscall-函数">实现 syscall 函数</a></h3>
|
|
|
<blockquote>
|
|
|
<p>zCore/zircon-syscall/src/lib.rs#L59</p>
|
|
|
</blockquote>
|
|
|
<ol>
|
|
|
<li>检查系统调用号<code>sys_type</code>是否合法</li>
|
|
|
<li>获取传递给具体某一系统调用的参数<code>args</code></li>
|
|
|
<li>若syscall函数输入的系统调用号合法，则进一步根据系统调用号匹配具体系统调用处理函数</li>
|
|
|
<li>传入对应系统调用所需的参数，并运行之</li>
|
|
|
<li>检查系统调用的返回值<code>ret</code>是否符合预期 </li>
|
|
|
</ol>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2018">
|
|
|
<span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span> pub async fn syscall(&mut self, num: u32, args: [usize; 8]) -> isize {
|
|
|
|
|
|
...
|
|
|
|
|
|
// 1. 检查系统调用号`sys_type`是否合法
|
|
|
let sys_type = match Sys::try_from(num) {
|
|
|
Ok(t) => t,
|
|
|
Err(_) => {
|
|
|
error!("invalid syscall number: {}", num);
|
|
|
return ZxError::INVALID_ARGS as _;
|
|
|
}
|
|
|
};
|
|
|
|
|
|
...
|
|
|
|
|
|
// 2. 获取传递给具体系统调用参数
|
|
|
let [a0, a1, a2, a3, a4, a5, a6, a7] = args;
|
|
|
|
|
|
// 3. 若syscall函数输入的系统调用号合法
|
|
|
// 则进一步根据系统调用号匹配具体系统调用处理函数
|
|
|
|
|
|
let ret = match sys_type {
|
|
|
|
|
|
// 4. 传入对应系统调用所需的参数，并运行之
|
|
|
Sys::HANDLE_CLOSE => self.sys_handle_close(a0 as _),
|
|
|
Sys::HANDLE_CLOSE_MANY => self.sys_handle_close_many(a0.into(), a1 as _),
|
|
|
Sys::HANDLE_DUPLICATE => self.sys_handle_duplicate(a0 as _, a1 as _, a2.into()),
|
|
|
Sys::HANDLE_REPLACE => self.sys_handle_replace(a0 as _, a1 as _, a2.into()),
|
|
|
|
|
|
...
|
|
|
// 更多系统调用匹配的分支
|
|
|
Sys::CLOCK_GET => self.sys_clock_get(a0 as _, a1.into()),
|
|
|
Sys::CLOCK_READ => self.sys_clock_read(a0 as _, a1.into()),
|
|
|
Sys::CLOCK_ADJUST => self.sys_clock_adjust(a0 as _, a1 as _, a2 as _),
|
|
|
Sys::CLOCK_UPDATE => self.sys_clock_update(a0 as _, a1 as _, a2.into()),
|
|
|
Sys::TIMER_CREATE => self.sys_timer_create(a0 as _, a1 as _, a2.into()),
|
|
|
|
|
|
...
|
|
|
};
|
|
|
|
|
|
...
|
|
|
|
|
|
// 5. 检查系统调用的返回值`ret`是否符合预期
|
|
|
match ret {
|
|
|
Ok(_) => 0,
|
|
|
Err(err) => err as isize,
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}
|
|
|
</span></code></pre></pre>
|
|
|
<p>系统调用号匹配信息位于</p>
|
|
|
<blockquote>
|
|
|
<p>zCore/zircon-syscall/src/consts.rs#L8</p>
|
|
|
</blockquote>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2018">
|
|
|
<span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>pub enum SyscallType {
|
|
|
BTI_CREATE = 0,
|
|
|
BTI_PIN = 1,
|
|
|
BTI_RELEASE_QUARANTINE = 2,
|
|
|
CHANNEL_CREATE = 3,
|
|
|
CHANNEL_READ = 4,
|
|
|
CHANNEL_READ_ETC = 5,
|
|
|
CHANNEL_WRITE = 6,
|
|
|
CHANNEL_WRITE_ETC = 7,
|
|
|
CHANNEL_CALL_NORETRY = 8,
|
|
|
CHANNEL_CALL_FINISH = 9,
|
|
|
CLOCK_GET = 10,
|
|
|
CLOCK_ADJUST = 11,
|
|
|
CLOCK_GET_MONOTONIC_VIA_KERNEL = 12,
|
|
|
|
|
|
...
|
|
|
|
|
|
VMO_CREATE_CONTIGUOUS = 165,
|
|
|
VMO_CREATE_PHYSICAL = 166,
|
|
|
COUNT = 167,
|
|
|
FUTEX_WAKE_HANDLE_CLOSE_THREAD_EXIT = 200,
|
|
|
VMAR_UNMAP_HANDLE_CLOSE_THREAD_EXIT = 201,
|
|
|
}
|
|
|
<span class="boring">}
|
|
|
</span></code></pre></pre>
|
|
|
<h3 id="简单实现一个系统调用处理函数sys_clock_adjust为例"><a class="header" href="#简单实现一个系统调用处理函数sys_clock_adjust为例">简单实现一个系统调用处理函数（<code>sys_clock_adjust</code>为例）</a></h3>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2018">
|
|
|
<span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span> pub fn sys_clock_adjust(&self, resource: HandleValue, clock_id: u32, offset: u64) -> ZxResult {
|
|
|
|
|
|
// 1. 记录log信息：info!()
|
|
|
info!(
|
|
|
"clock.adjust: resource={:#x?}, id={:#x}, offset={:#x}",
|
|
|
resource, clock_id, offset
|
|
|
);
|
|
|
|
|
|
// 2. 检查参数合法性（需要归纳出每个系统调用的参数值的范围）
|
|
|
// missing now
|
|
|
|
|
|
// 3. 获取当前进程对象
|
|
|
let proc = self.thread.proc();
|
|
|
|
|
|
// 4. 根据句柄从进程中获取对象
|
|
|
proc.get_object::<Resource>(resource)?
|
|
|
.validate(ResourceKind::ROOT)?;
|
|
|
match clock_id {
|
|
|
ZX_CLOCK_MONOTONIC => Err(ZxError::ACCESS_DENIED),
|
|
|
|
|
|
// 5. 调用内河对象API执行具体功能
|
|
|
ZX_CLOCK_UTC => {
|
|
|
UTC_OFFSET.store(offset, Ordering::Relaxed);
|
|
|
Ok(())
|
|
|
}
|
|
|
_ => Err(ZxError::INVALID_ARGS),
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}
|
|
|
</span></code></pre></pre>
|
|
|
<blockquote>
|
|
|
<p>一个现有不完全的系统调用实现<code>sys_clock_get</code></p>
|
|
|
</blockquote>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2018">
|
|
|
<span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span> /// Acquire the current time.
|
|
|
///
|
|
|
/// + Returns the current time of clock_id via `time`.
|
|
|
/// + Returns whether `clock_id` was valid.
|
|
|
pub fn sys_clock_get(&self, clock_id: u32, mut time: UserOutPtr<u64>) -> ZxResult {
|
|
|
// 记录log信息：info!()
|
|
|
info!("clock.get: id={}", clock_id);
|
|
|
// 检查参数合法性
|
|
|
// miss
|
|
|
|
|
|
match clock_id {
|
|
|
ZX_CLOCK_MONOTONIC => {
|
|
|
time.write(timer_now().as_nanos() as u64)?;
|
|
|
Ok(())
|
|
|
}
|
|
|
ZX_CLOCK_UTC => {
|
|
|
time.write(timer_now().as_nanos() as u64 + UTC_OFFSET.load(Ordering::Relaxed))?;
|
|
|
Ok(())
|
|
|
}
|
|
|
ZX_CLOCK_THREAD => {
|
|
|
time.write(self.thread.get_time())?;
|
|
|
Ok(())
|
|
|
}
|
|
|
_ => Err(ZxError::NOT_SUPPORTED),
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}
|
|
|
</span></code></pre></pre>
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