Save/restore interrupt state during context switch (#1036)

Previously, there were no guarantees about the value of the
interrupt flag when context switching.
If the context switch was voluntary, i.e. a task called `schedule()`
to yield the CPU, interrupts would most likely be enabled.
If a task was preempted, interrupts would be disabled.

This could result in a preempted task A switching to a
task B that voluntarily yielded, causing task B to return from
the call to `schedule()` with interrupts disabled, which
usually isn't desirable.

Now, this can no longer happen due to saving and restoring
the state of interrupts for a task when context switching
away from or to it, respectively.

* On aarch64, this corresponds to the DAIF+NZCV bitflags of `PSTATE`.
* On x86_64, this corresponds to the IF bit flag of the `RFLAGS` register.

Signed-off-by: Klimenty Tsoutsman <klim@tsoutsman.com>
Co-authored-by: Nathan Royer <nathan.royer.pro@gmail.com> 349adf8

doc/compositor/trait.CompositableRegion.html

@@ -31,16 +31,16 @@
 The <code>dest_coord</code> is the coordinate in the destination buffer (relative to its top-left corner)
 where the <code>src_fb</code> will be composited (starting at the <code>src_fb</code>’s top-left corner).
 <code>src_fb_row_range</code> is the index range of rows in the source framebuffer to blend.</p>
-</div></details></div><h2 id="foreign-impls" class="small-section-header">Implementations on Foreign Types<a href="#foreign-impls" class="anchor">§</a></h2><details class="toggle implementors-toggle"><summary><section id="impl-CompositableRegion-for-Coord" class="impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#94-118">source</a><a href="#impl-CompositableRegion-for-Coord" class="anchor">§</a><h3 class="code-header">impl <a class="trait" href="trait.CompositableRegion.html" title="trait compositor::CompositableRegion">CompositableRegion</a> for Coord</h3></section></summary><div class="impl-items"><section id="method.row_range" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#96-98">source</a><a href="#method.row_range" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.row_range" class="fn">row_range</a>(&amp;self) -&gt; <a class="struct" href="https://doc.rust-lang.org/nightly/core/ops/range/struct.Range.html" title="struct core::ops::range::Range">Range</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.isize.html">isize</a>&gt;</h4></section><section id="method.size" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#101-103">source</a><a href="#method.size" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.size" class="fn">size</a>(&amp;self) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.usize.html">usize</a></h4></section><section id="method.blend_buffers" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#105-117">source</a><a href="#method.blend_buffers" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.blend_buffers" class="fn">blend_buffers</a>&lt;P: Pixel&gt;(
+</div></details></div><h2 id="foreign-impls" class="small-section-header">Implementations on Foreign Types<a href="#foreign-impls" class="anchor">§</a></h2><details class="toggle implementors-toggle"><summary><section id="impl-CompositableRegion-for-Rectangle" class="impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#120-199">source</a><a href="#impl-CompositableRegion-for-Rectangle" class="anchor">§</a><h3 class="code-header">impl <a class="trait" href="trait.CompositableRegion.html" title="trait compositor::CompositableRegion">CompositableRegion</a> for Rectangle</h3></section></summary><div class="impl-items"><section id="method.row_range" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#122-124">source</a><a href="#method.row_range" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.row_range" class="fn">row_range</a>(&amp;self) -&gt; <a class="struct" href="https://doc.rust-lang.org/nightly/core/ops/range/struct.Range.html" title="struct core::ops::range::Range">Range</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.isize.html">isize</a>&gt;</h4></section><section id="method.size" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#127-129">source</a><a href="#method.size" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.size" class="fn">size</a>(&amp;self) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.usize.html">usize</a></h4></section><section id="method.blend_buffers" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#131-198">source</a><a href="#method.blend_buffers" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.blend_buffers" class="fn">blend_buffers</a>&lt;P: Pixel&gt;(
     &amp;self,
     src_fb: &amp;Framebuffer&lt;P&gt;,
     dest_fb: &amp;mut Framebuffer&lt;P&gt;,
     dest_coord: Coord,
-    _src_fb_row_range: <a class="struct" href="https://doc.rust-lang.org/nightly/core/ops/range/struct.Range.html" title="struct core::ops::range::Range">Range</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.usize.html">usize</a>&gt;
-) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.unit.html">()</a>, &amp;'static <a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.str.html">str</a>&gt;</h4></section></div></details><details class="toggle implementors-toggle"><summary><section id="impl-CompositableRegion-for-Rectangle" class="impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#120-199">source</a><a href="#impl-CompositableRegion-for-Rectangle" class="anchor">§</a><h3 class="code-header">impl <a class="trait" href="trait.CompositableRegion.html" title="trait compositor::CompositableRegion">CompositableRegion</a> for Rectangle</h3></section></summary><div class="impl-items"><section id="method.row_range-1" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#122-124">source</a><a href="#method.row_range-1" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.row_range" class="fn">row_range</a>(&amp;self) -&gt; <a class="struct" href="https://doc.rust-lang.org/nightly/core/ops/range/struct.Range.html" title="struct core::ops::range::Range">Range</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.isize.html">isize</a>&gt;</h4></section><section id="method.size-1" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#127-129">source</a><a href="#method.size-1" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.size" class="fn">size</a>(&amp;self) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.usize.html">usize</a></h4></section><section id="method.blend_buffers-1" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#131-198">source</a><a href="#method.blend_buffers-1" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.blend_buffers" class="fn">blend_buffers</a>&lt;P: Pixel&gt;(
+    src_fb_row_range: <a class="struct" href="https://doc.rust-lang.org/nightly/core/ops/range/struct.Range.html" title="struct core::ops::range::Range">Range</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.usize.html">usize</a>&gt;
+) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.unit.html">()</a>, &amp;'static <a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.str.html">str</a>&gt;</h4></section></div></details><details class="toggle implementors-toggle"><summary><section id="impl-CompositableRegion-for-Coord" class="impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#94-118">source</a><a href="#impl-CompositableRegion-for-Coord" class="anchor">§</a><h3 class="code-header">impl <a class="trait" href="trait.CompositableRegion.html" title="trait compositor::CompositableRegion">CompositableRegion</a> for Coord</h3></section></summary><div class="impl-items"><section id="method.row_range-1" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#96-98">source</a><a href="#method.row_range-1" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.row_range" class="fn">row_range</a>(&amp;self) -&gt; <a class="struct" href="https://doc.rust-lang.org/nightly/core/ops/range/struct.Range.html" title="struct core::ops::range::Range">Range</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.isize.html">isize</a>&gt;</h4></section><section id="method.size-1" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#101-103">source</a><a href="#method.size-1" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.size" class="fn">size</a>(&amp;self) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.usize.html">usize</a></h4></section><section id="method.blend_buffers-1" class="method trait-impl"><a class="srclink rightside" href="../src/compositor/lib.rs.html#105-117">source</a><a href="#method.blend_buffers-1" class="anchor">§</a><h4 class="code-header">fn <a href="#tymethod.blend_buffers" class="fn">blend_buffers</a>&lt;P: Pixel&gt;(
     &amp;self,
     src_fb: &amp;Framebuffer&lt;P&gt;,
     dest_fb: &amp;mut Framebuffer&lt;P&gt;,
     dest_coord: Coord,
-    src_fb_row_range: <a class="struct" href="https://doc.rust-lang.org/nightly/core/ops/range/struct.Range.html" title="struct core::ops::range::Range">Range</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.usize.html">usize</a>&gt;
+    _src_fb_row_range: <a class="struct" href="https://doc.rust-lang.org/nightly/core/ops/range/struct.Range.html" title="struct core::ops::range::Range">Range</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.usize.html">usize</a>&gt;
 ) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.unit.html">()</a>, &amp;'static <a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.str.html">str</a>&gt;</h4></section></div></details><h2 id="implementors" class="small-section-header">Implementors<a href="#implementors" class="anchor">§</a></h2><div id="implementors-list"></div><script src="../implementors/compositor/trait.CompositableRegion.js" data-ignore-extern-crates="shapes" async></script></section></div></main></body></html>

doc/context_switch_regular/fn.context_switch_regular.html

@@ -1,4 +1,4 @@
-<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Switches context from a regular Task to another regular Task."><title>context_switch_regular in context_switch_regular - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceSerif4-Bold-a2c9cd1067f8b328.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../static.files/rustdoc-f40c346f39d9abc1.css" id="mainThemeStyle"><div id="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="context_switch_regular" data-themes="" data-resource-suffix="" data-rustdoc-version="1.72.0-nightly (065a1f5df 2023-06-21)" data-search-js="search-95c92dd01058facf.js" data-settings-js="settings-de11bff964e9d4e5.js" data-settings-css="settings-8c76f75bfb6bd192.css" data-theme-light-css="light-0f8c037637f9eb3e.css" data-theme-dark-css="dark-1097f8e92a01e3cf.css" data-theme-ayu-css="ayu-614652228113ac93.css" ></div><script src="../static.files/storage-62ce34ea385b278a.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-190c35055d2a8300.js"></script><noscript><link rel="stylesheet" media="(prefers-color-scheme:light)" href="../static.files/light-0f8c037637f9eb3e.css"><link rel="stylesheet" media="(prefers-color-scheme:dark)" href="../static.files/dark-1097f8e92a01e3cf.css"><link rel="stylesheet" href="../static.files/noscript-13285aec31fa243e.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc fn"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">&#9776;</button><a class="logo-container" href="../context_switch_regular/index.html"><img class="rust-logo" src="../static.files/rust-logo-151179464ae7ed46.svg" alt="logo"></a><h2></h2></nav><nav class="sidebar"><a class="logo-container" href="../context_switch_regular/index.html"><img class="rust-logo" src="../static.files/rust-logo-151179464ae7ed46.svg" alt="logo"></a><div class="sidebar-elems"><h2><a href="index.html">In context_switch_regular</a></h2></div></nav><main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Function <a href="index.html">context_switch_regular</a>::<wbr><a class="fn" href="#">context_switch_regular</a><button id="copy-path" title="Copy item path to clipboard"><img src="../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../src/context_switch_regular/x86_64.rs.html#146-156">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>&#x2212;</span>]</button></span></div><pre class="rust item-decl"><code>pub unsafe extern &quot;C&quot; fn context_switch_regular(
+<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Switches context from a regular Task to another regular Task."><title>context_switch_regular in context_switch_regular - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceSerif4-Bold-a2c9cd1067f8b328.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../static.files/rustdoc-f40c346f39d9abc1.css" id="mainThemeStyle"><div id="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="context_switch_regular" data-themes="" data-resource-suffix="" data-rustdoc-version="1.72.0-nightly (065a1f5df 2023-06-21)" data-search-js="search-95c92dd01058facf.js" data-settings-js="settings-de11bff964e9d4e5.js" data-settings-css="settings-8c76f75bfb6bd192.css" data-theme-light-css="light-0f8c037637f9eb3e.css" data-theme-dark-css="dark-1097f8e92a01e3cf.css" data-theme-ayu-css="ayu-614652228113ac93.css" ></div><script src="../static.files/storage-62ce34ea385b278a.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-190c35055d2a8300.js"></script><noscript><link rel="stylesheet" media="(prefers-color-scheme:light)" href="../static.files/light-0f8c037637f9eb3e.css"><link rel="stylesheet" media="(prefers-color-scheme:dark)" href="../static.files/dark-1097f8e92a01e3cf.css"><link rel="stylesheet" href="../static.files/noscript-13285aec31fa243e.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc fn"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">&#9776;</button><a class="logo-container" href="../context_switch_regular/index.html"><img class="rust-logo" src="../static.files/rust-logo-151179464ae7ed46.svg" alt="logo"></a><h2></h2></nav><nav class="sidebar"><a class="logo-container" href="../context_switch_regular/index.html"><img class="rust-logo" src="../static.files/rust-logo-151179464ae7ed46.svg" alt="logo"></a><div class="sidebar-elems"><h2><a href="index.html">In context_switch_regular</a></h2></div></nav><main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Function <a href="index.html">context_switch_regular</a>::<wbr><a class="fn" href="#">context_switch_regular</a><button id="copy-path" title="Copy item path to clipboard"><img src="../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../src/context_switch_regular/x86_64.rs.html#152-162">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>&#x2212;</span>]</button></span></div><pre class="rust item-decl"><code>pub unsafe extern &quot;C&quot; fn context_switch_regular(
     _prev_stack_pointer: <a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.pointer.html">*mut </a><a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.usize.html">usize</a>,
     _next_stack_pointer_value: <a class="primitive" href="https://doc.rust-lang.org/nightly/core/primitive.usize.html">usize</a>
 )</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Switches context from a regular Task to another regular Task.</p>