Kernel+LibC: Clean up how assertions work in the kernel and LibC

This also brings LibC's abort() function closer to the spec.

Kernel/API/Syscall.h

@@ -189,7 +189,6 @@ namespace Kernel {
     S(prctl)                  \
     S(mremap)                 \
     S(set_coredump_metadata)  \
-    S(abort)                  \
     S(anon_create)            \
     S(msyscall)               \
     S(readv)                  \

Kernel/Arch/i386/CPU.cpp

@@ -33,6 +33,7 @@
 #include <Kernel/Arch/x86/ISRStubs.h>
 #include <Kernel/Arch/x86/ProcessorInfo.h>
 #include <Kernel/Arch/x86/SafeMem.h>
+#include <Kernel/Assertions.h>
 #include <Kernel/Debug.h>
 #include <Kernel/IO.h>
 #include <Kernel/Interrupts/APIC.h>
@@ -2419,6 +2420,13 @@ void __assertion_failed(const char* msg, const char* file, unsigned line, const
     dmesgln("ASSERTION FAILED: {}", msg);
     dmesgln("{}:{} in {}", file, line, func);
 
+    abort();
+}
+#endif
+
+[[noreturn]] void abort()
+{
+#ifdef DEBUG
     // Switch back to the current process's page tables if there are any.
     // Otherwise stack walking will be a disaster.
     auto process = Process::current();
@@ -2427,9 +2435,17 @@ void __assertion_failed(const char* msg, const char* file, unsigned line, const
 
     Kernel::dump_backtrace();
     Processor::halt();
-}
 #endif
 
+    abort();
+}
+
+[[noreturn]] void _abort()
+{
+    asm volatile("ud2");
+    __builtin_unreachable();
+}
+
 NonMaskableInterruptDisabler::NonMaskableInterruptDisabler()
 {
     IO::out8(0x70, IO::in8(0x70) | 0x80);

Kernel/Assertions.h

@@ -35,12 +35,13 @@
 #    define VERIFY_NOT_REACHED() VERIFY(false)
 #else
 #    define VERIFY(expr)
-#    define VERIFY_NOT_REACHED() CRASH()
+#    define VERIFY_NOT_REACHED() _abort()
 #endif
-#define CRASH()              \
-    do {                     \
-        asm volatile("ud2"); \
-    } while (0)
+
+extern "C" {
+[[noreturn]] void _abort();
+[[noreturn]] void abort();
+}
 
 #define VERIFY_INTERRUPTS_DISABLED() VERIFY(!(cpu_flags() & 0x200))
 #define VERIFY_INTERRUPTS_ENABLED() VERIFY(cpu_flags() & 0x200)

Kernel/CMakeLists.txt

@@ -131,7 +131,6 @@ set(KERNEL_SOURCES
     StdLib.cpp
     Syscall.cpp
     Syscalls/anon_create.cpp
-    Syscalls/abort.cpp
     Syscalls/access.cpp
     Syscalls/alarm.cpp
     Syscalls/beep.cpp

Kernel/Process.h

@@ -408,7 +408,6 @@ public:
     KResultOr<FlatPtr> sys$allocate_tls(size_t);
     KResultOr<int> sys$prctl(int option, FlatPtr arg1, FlatPtr arg2);
     KResultOr<int> sys$set_coredump_metadata(Userspace<const Syscall::SC_set_coredump_metadata_params*>);
-    [[noreturn]] void sys$abort();
     KResultOr<int> sys$anon_create(size_t, int options);
 
     template<bool sockname, typename Params>

Kernel/Syscall.cpp

@@ -99,7 +99,7 @@ KResultOr<FlatPtr> handle(RegisterState& regs, FlatPtr function, FlatPtr arg1, F
     auto& process = current_thread->process();
     current_thread->did_syscall();
 
-    if (function == SC_abort || function == SC_exit || function == SC_exit_thread) {
+    if (function == SC_exit || function == SC_exit_thread) {
         // These syscalls need special handling since they never return to the caller.
 
         if (auto* tracer = process.tracer(); tracer && tracer->is_tracing_syscalls()) {
@@ -109,9 +109,6 @@ KResultOr<FlatPtr> handle(RegisterState& regs, FlatPtr function, FlatPtr arg1, F
         }
 
         switch (function) {
-        case SC_abort:
-            process.sys$abort();
-            break;
         case SC_exit:
             process.sys$exit(arg1);
             break;

Kernel/Syscalls/abort.cpp

@@ -1,38 +0,0 @@
-/*
- * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice, this
- *    list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <AK/StringView.h>
-#include <Kernel/FileSystem/VirtualFileSystem.h>
-#include <Kernel/Process.h>
-
-namespace Kernel {
-
-void Process::sys$abort()
-{
-    crash(SIGABRT, 0);
-}
-
-}