panic: move to separate file, add KASSERT macro

CMakeLists.txt

@@ -28,6 +28,9 @@ configure_file(
 
 include("arch/${ARCH}/config/toolchain.cmake")
 
+# Used by the KASSERT macro for printing the filename relative to the source root
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D__FILENAME__='\"$(subst ${CMAKE_SOURCE_DIR}/,,$(abspath $<))\"'")
+
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -pipe -nostdinc -ffreestanding -fno-stack-protector")
 set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -pipe -D_ASM_SOURCE")
 if(DEBUG)

include/gay/cdefs.h

@@ -55,6 +55,9 @@
  */
 #define __packed __attribute__(( packed ))
 
+#define __printflike(fmt_argn, firstva_argn) \
+	__attribute__(( format(printf, fmt_argn, firstva_argn) ))
+
 /**
  * @brief Function does not have any side effects or internal state.
  * Subsequent calls with the same parameters always return the same result.

include/gay/kprintf.h

@@ -18,8 +18,7 @@
  * @returns The amount of bytes written,
  *	or a negative number from `errno.h` on failure
  */
-__attribute__(( format(printf, 1, 2) ))
-int kprintf(const char *__restrict fmt, ...);
+int kprintf(const char *__restrict fmt, ...) __printflike(1, 2);
 
 /**
  * @brief Print to the kernel log.
@@ -29,7 +28,7 @@ int kprintf(const char *__restrict fmt, ...);
  * @returns The amount of bytes written,
  *	or a negative number from `errno.h` on failure
  */
-int kvprintf(const char *__restrict fmt, va_list args);
+int kvprintf(const char *__restrict fmt, va_list args) __printflike(1, 0);
 
 /**
  * @brief Printing functions that `kprintf()` and friends call for writing.

include/gay/sched.h

@@ -25,6 +25,11 @@ struct task {
 	tcb_t tcb;
 	struct task *parent;
 	pid_t pid;
+	/**
+	 * @brief 0 = interruptable, > 0 = uninterruptible, < 0 = we messed up.
+	 * Increment/decrement using `critical_enter()`/`critical_leave()`.
+	 */
+	volatile int critnest;
 	enum task_state state;
 };
 

include/gay/systm.h

@@ -0,0 +1,64 @@
+/* See the end of this file for copyright and license terms. */
+
+#pragma once
+
+#include <gay/cdefs.h>
+#include <gay/sched.h>
+#include <gay/types.h>
+
+/**
+ * @brief Print an error message and halt the system immediately.
+ *
+ * @param fmt printf style format string
+ */
+void panic(const char *fmt, ...) __noreturn __printflike(1, 2);
+
+#ifdef DEBUG
+/**
+ * @brief Assert that statement `x` is true.
+ * If it is not and debugging is enabled, the kernel panics.
+ */
+#define KASSERT(x) do {						\
+	if ( __predict_false(!(x)) ) {				\
+		panic("Assertion \"%s\" failed!\n"		\
+		      "  in function %s()\n"			\
+		      "  in file %s, line %u\n",		\
+		      #x, __func__, __FILENAME__, __LINE__);	\
+	}							\
+} while (0)
+#else
+#define KASSERT(x) do { } while (0)
+#endif
+
+static inline void critical_enter(void)
+{
+	struct task *tsk = current;
+	tsk->critnest++;
+}
+
+static inline void critical_leave(void)
+{
+	struct task *tsk = current;
+	tsk->critnest--;
+
+	KASSERT(tsk->critnest >= 0);
+}
+
+static inline bool in_critical(void)
+{
+	return current->critnest > 0;
+}
+
+/*
+ * This file is part of GayBSD.
+ * Copyright (c) 2021 fef <owo@fef.moe>.
+ *
+ * GayBSD is nonviolent software: you may only use, redistribute, and/or
+ * modify it under the terms of the Cooperative Nonviolent Public License
+ * (CNPL) as found in the LICENSE file in the source code root directory
+ * or at <https://git.pixie.town/thufie/npl-builder>; either version 7
+ * of the license, or (at your option) any later version.
+ *
+ * GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
+ * permitted by applicable law.  See the CNPL for details.
+ */

include/gay/util.h

@@ -5,8 +5,6 @@
 #include <gay/cdefs.h>
 #include <gay/types.h>
 
-void panic(const char *fmt, ...) __noreturn;
-
 /**
  * @brief Get the number of elements in a statically allocated array.
  *
@@ -49,20 +47,20 @@ static __always_inline bool sus_nil(const void *ptr)
 	return ptr < (void *)0x1000;
 }
 
-/**
- * @brief Align `ptr` such that `ptr % n == 0`.
- *
- * @param ptr Pointer to align
- * @param log The log2 of the alignment.  If negative, the pointer will be
- *	aligned to the next lower address, otherwise to the next higher one.
- * @returns The aligned pointer
- */
-void *ptr_align(void *ptr, int log);
+static __always_inline uintptr_t _align_floor(uintptr_t ptr, usize size)
+{
+	return ptr - ptr % size;
+}
+#define align_floor(ptr, size) ( (typeof(ptr))_align_floor((uintptr_t)(ptr), size) )
 
-static __always_inline uintptr_t uintptr_align(uintptr_t ptr, int log)
+static __always_inline uintptr_t _align_ceil(uintptr_t ptr, usize size)
 {
-	return (uintptr_t)ptr_align((void *)ptr, log);
+	uintptr_t aligned = ptr - ptr % size;
+	if (aligned < ptr)
+		aligned += size;
+	return aligned;
 }
+#define align_ceil(ptr, size) ( (typeof(ptr))_align_ceil((uintptr_t)(ptr), size) )
 
 /*
  * This file is part of GayBSD.

kernel/CMakeLists.txt

@@ -13,8 +13,8 @@ target_sources(gay_kernel PRIVATE
     kprintf.c
     main.c
     mutex.c
+    panic.c
     sched.c
-    util.c
 )
 
 add_subdirectory(mm)

kernel/mm/kmalloc.c

@@ -38,7 +38,7 @@ int kmalloc_init(uintptr_t _phys_start, uintptr_t _phys_end)
 			phys_start = image_end_phys;
 	}
 
-	phys_start = uintptr_align(phys_start, +HUGEPAGE_SHIFT);
+	phys_start = align_ceil(phys_start, HUGEPAGE_SIZE);
 	/*
 	 * This is intentionally not aligned to hugepages, because __early_get_page()
 	 * shrinks it in single PAGE_SIZE steps whenever it is called anyway.
@@ -48,7 +48,7 @@ int kmalloc_init(uintptr_t _phys_start, uintptr_t _phys_end)
 	 * be able to allocate pages before the page frame allocator is set up
 	 * in the first place).
 	 */
-	phys_end = uintptr_align(phys_end, -PAGE_SHIFT);
+	phys_end = align_floor(phys_end, PAGE_SIZE);
 
 	int err = pages_init();
 	if (err)

kernel/panic.c

@@ -2,12 +2,13 @@
 
 #include <arch/cpufunc.h>
 
+#include <gay/cdefs.h>
+#include <gay/config.h>
 #include <gay/kprintf.h>
-#include <gay/types.h>
-#include <gay/util.h>
 
 #include <stdarg.h>
 
+__noreturn
 void panic(const char *fmt, ...)
 {
 	va_list args;
@@ -21,7 +22,7 @@ void panic(const char *fmt, ...)
 	else
 		kvprintf(fmt, args);
 
-	kprintf("\nSystem halted");
+	kprintf("\nKernel version: %s\nSystem halted", GAY_VERSION_STR);
 
 	/* no need for va_end() here i guess */
 	while (1) {
@@ -30,17 +31,6 @@ void panic(const char *fmt, ...)
 	}
 }
 
-void *ptr_align(void *ptr, int log)
-{
-	uintptr_t shifted = 1 << abs(log);
-	uintptr_t aligned = (uintptr_t)ptr & ~(shifted - 1);
-
-	if (log > 0 && aligned != (uintptr_t)ptr)
-		aligned += shifted;
-
-	return (void *)aligned;
-}
-
 /*
  * This file is part of GayBSD.
  * Copyright (c) 2021 fef <owo@fef.moe>.

kernel/sched.c

@@ -11,6 +11,7 @@ struct task kernel_task = {
 	.parent = nil,
 	.pid = 0,
 	.state = TASK_READY,
+	.critnest = 0,
 };
 
 struct task *current_array[CFG_MAX_CPU] = {
@@ -40,6 +41,9 @@ void schedule(void)
 	struct task *old = current;
 	struct task *new = nil;
 
+	if (old->critnest)
+		return;
+
 	clist_add(inactive_queue, &old->run_queue);
 
 /* Dijkstra would be so mad if he saw this */