From 2079728a7455c7c2d852c2784f7b02bcf16f3583 Mon Sep 17 00:00:00 2001
From: Brian Gianforcaro <bgianf@serenityos.org>
Date: Sat, 15 Oct 2022 00:56:42 -0700
Subject: [PATCH] Kernel: Add formal Processor::verify_no_spinlocks_held() API

In a few places we check `!Processor::in_critical()` to validate
that the current processor doesn't hold any kernel spinlocks.

Instead lets provide it a first class name for readability.
I'll also be adding more of these, so I would rather add more
usages of a nice API instead of this implicit/assumed logic.
---
 Kernel/Arch/aarch64/Processor.h |  5 +++++
 Kernel/Arch/x86/Processor.h     |  5 +++++
 Kernel/Heap/kmalloc.cpp         | 20 ++++++++++----------
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/Kernel/Arch/aarch64/Processor.h b/Kernel/Arch/aarch64/Processor.h
index 163d5815ad..57a2b07c47 100644
--- a/Kernel/Arch/aarch64/Processor.h
+++ b/Kernel/Arch/aarch64/Processor.h
@@ -147,6 +147,11 @@ public:
         return current().m_in_critical;
     }
 
+    ALWAYS_INLINE static void verify_no_spinlocks_held()
+    {
+        VERIFY(!Processor::in_critical());
+    }
+
     // FIXME: Actually return the idle thread once aarch64 supports threading.
     ALWAYS_INLINE static Thread* idle_thread()
     {
diff --git a/Kernel/Arch/x86/Processor.h b/Kernel/Arch/x86/Processor.h
index 6cb8dffd69..64209ffbad 100644
--- a/Kernel/Arch/x86/Processor.h
+++ b/Kernel/Arch/x86/Processor.h
@@ -370,6 +370,11 @@ public:
         return read_gs_ptr(__builtin_offsetof(Processor, m_in_critical));
     }
 
+    ALWAYS_INLINE static void verify_no_spinlocks_held()
+    {
+        VERIFY(!Processor::in_critical());
+    }
+
     ALWAYS_INLINE static FPUState const& clean_fpu_state() { return s_clean_fpu_state; }
 
     static void smp_enable();
diff --git a/Kernel/Heap/kmalloc.cpp b/Kernel/Heap/kmalloc.cpp
index 5925566e9e..e158ca6fc5 100644
--- a/Kernel/Heap/kmalloc.cpp
+++ b/Kernel/Heap/kmalloc.cpp
@@ -410,14 +410,6 @@ void kmalloc_enable_expand()
     g_kmalloc_global->enable_expansion();
 }
 
-static inline void kmalloc_verify_nospinlock_held()
-{
-    // Catch bad callers allocating under spinlock.
-    if constexpr (KMALLOC_VERIFY_NO_SPINLOCK_HELD) {
-        VERIFY(!Processor::in_critical());
-    }
-}
-
 UNMAP_AFTER_INIT void kmalloc_init()
 {
     // Zero out heap since it's placed after end_of_kernel_bss.
@@ -429,7 +421,11 @@ UNMAP_AFTER_INIT void kmalloc_init()
 
 void* kmalloc(size_t size)
 {
-    kmalloc_verify_nospinlock_held();
+    // Catch bad callers allocating under spinlock.
+    if constexpr (KMALLOC_VERIFY_NO_SPINLOCK_HELD) {
+        Processor::verify_no_spinlocks_held();
+    }
+
     SpinlockLocker lock(s_lock);
     ++g_kmalloc_call_count;
 
@@ -472,7 +468,11 @@ void kfree_sized(void* ptr, size_t size)
 
     VERIFY(size > 0);
 
-    kmalloc_verify_nospinlock_held();
+    // Catch bad callers allocating under spinlock.
+    if constexpr (KMALLOC_VERIFY_NO_SPINLOCK_HELD) {
+        Processor::verify_no_spinlocks_held();
+    }
+
     SpinlockLocker lock(s_lock);
     ++g_kfree_call_count;
     ++g_nested_kfree_calls;