refactor(kernel): use linux-style errno returns

arch/x86/kernel/irq.c

@@ -5,6 +5,7 @@
 
 #include <tianole/arch.h>
 #include <tianole/early_log.h>
+#include <tianole/errno.h>
 #include <tianole/irq.h>
 #include <tianole/timer.h>
 
@@ -102,14 +103,14 @@ int irq_register(uint8_t irq, irq_handler_t handler, void *data)
 	uint64_t flags;
 
 	if (irq >= IRQ_COUNT || handler == 0) {
-		return -1;
+		return -EINVAL;
 	}
 
 	flags = arch_irq_save();
 
 	if (irq_actions[irq].handler != 0) {
 		arch_irq_restore(flags);
-		return -1;
+		return -EBUSY;
 	}
 
 	irq_actions[irq].handler = handler;

arch/x86/mm/page_table.c

@@ -2,6 +2,7 @@
 
 #include <tianole/arch.h>
 #include <tianole/early_log.h>
+#include <tianole/errno.h>
 #include <tianole/mm.h>
 
 #include "page_table.h"
@@ -172,7 +173,7 @@ static int ensure_next_table(uint64_t *table, uint64_t index, uint64_t **next)
 
 	page = alloc_page();
 	if (page == 0) {
-		return -1;
+		return -ENOMEM;
 	}
 
 	clear_page(page);
@@ -193,24 +194,34 @@ static int page_entry(virt_addr_t virt, int create, uint64_t **entry)
 	uint64_t pt_index = table_index(virt, 12);
 
 	if (create != 0) {
-		if (ensure_next_table(pml4, pml4_index, &pdpt) != 0 ||
-			ensure_next_table(pdpt, pdpt_index, &pd) != 0 ||
-			ensure_next_table(pd, pd_index, &pt) != 0) {
-			return -1;
+		int ret = ensure_next_table(pml4, pml4_index, &pdpt);
+
+		if (ret != 0) {
+			return ret;
+		}
+
+		ret = ensure_next_table(pdpt, pdpt_index, &pd);
+		if (ret != 0) {
+			return ret;
+		}
+
+		ret = ensure_next_table(pd, pd_index, &pt);
+		if (ret != 0) {
+			return ret;
 		}
 	} else {
 		if ((pml4[pml4_index] & PAGE_PRESENT) == 0) {
-			return -1;
+			return -ENOENT;
 		}
 		pdpt = entry_table(pml4[pml4_index]);
 
 		if ((pdpt[pdpt_index] & PAGE_PRESENT) == 0) {
-			return -1;
+			return -ENOENT;
 		}
 		pd = entry_table(pdpt[pdpt_index]);
 
 		if ((pd[pd_index] & PAGE_PRESENT) == 0) {
-			return -1;
+			return -ENOENT;
 		}
 		pt = entry_table(pd[pd_index]);
 	}
@@ -222,17 +233,19 @@ static int page_entry(virt_addr_t virt, int create, uint64_t **entry)
 int map_page(virt_addr_t virt, phys_addr_t phys, uint64_t flags)
 {
 	uint64_t *entry;
+	int ret;
 
 	if ((virt & (PAGE_SIZE - 1)) != 0 || (phys & (PAGE_SIZE - 1)) != 0) {
-		return -1;
+		return -EINVAL;
 	}
 
-	if (page_entry(virt, 1, &entry) != 0) {
-		return -1;
+	ret = page_entry(virt, 1, &entry);
+	if (ret != 0) {
+		return ret;
 	}
 
 	if ((*entry & PAGE_PRESENT) != 0) {
-		return -1;
+		return -EEXIST;
 	}
 
 	*entry = (phys & PAGE_MASK) | flags | PAGE_PRESENT;
@@ -243,13 +256,15 @@ int map_page(virt_addr_t virt, phys_addr_t phys, uint64_t flags)
 int unmap_page(virt_addr_t virt)
 {
 	uint64_t *entry;
+	int ret;
 
 	if ((virt & (PAGE_SIZE - 1)) != 0) {
-		return -1;
+		return -EINVAL;
 	}
 
-	if (page_entry(virt, 0, &entry) != 0 || (*entry & PAGE_PRESENT) == 0) {
-		return -1;
+	ret = page_entry(virt, 0, &entry);
+	if (ret != 0 || (*entry & PAGE_PRESENT) == 0) {
+		return -ENOENT;
 	}
 
 	*entry = 0;
@@ -260,10 +275,15 @@ int unmap_page(virt_addr_t virt)
 int virt_to_phys(virt_addr_t virt, phys_addr_t *phys)
 {
 	uint64_t *entry;
+	int ret;
 
-	if (phys == 0 || page_entry(virt, 0, &entry) != 0 ||
-		(*entry & PAGE_PRESENT) == 0) {
-		return -1;
+	if (phys == 0) {
+		return -EINVAL;
+	}
+
+	ret = page_entry(virt, 0, &entry);
+	if (ret != 0 || (*entry & PAGE_PRESENT) == 0) {
+		return -ENOENT;
 	}
 
 	*phys = (*entry & PAGE_MASK) | (virt & (PAGE_SIZE - 1));

docs/agents/code-style.md

@@ -83,3 +83,11 @@
 - 新增或大改 C/H 文件后运行 `clang-format`。
 - 提交前至少运行 `scripts/check.sh`。
 - 如果只是文档修改，至少运行 `git diff --check`。
+
+## 错误码
+
+- 可恢复的内核内部错误优先返回 Linux 风格的负 errno，例如
+  `-EINVAL`、`-ENOMEM`、`-ENOENT`、`-EBUSY`、`-EEXIST`、`-ETIMEDOUT`。
+- 不要用裸 `-1` 表达多个失败原因；调用者需要能区分输入错误、资源耗尽、
+  对象已存在和超时。
+- errno 常量放在 `include/tianole/errno.h`，只增加当前内核实际使用的值。

include/tianole/errno.h

@@ -0,0 +1,34 @@
+#ifndef TIANOLE_ERRNO_H
+#define TIANOLE_ERRNO_H
+
+/**
+ * EINVAL - Invalid argument.
+ */
+#define EINVAL 22
+
+/**
+ * ENOENT - No such entry or mapping.
+ */
+#define ENOENT 2
+
+/**
+ * ENOMEM - Out of memory.
+ */
+#define ENOMEM 12
+
+/**
+ * EBUSY - Resource is already busy.
+ */
+#define EBUSY 16
+
+/**
+ * EEXIST - Object already exists.
+ */
+#define EEXIST 17
+
+/**
+ * ETIMEDOUT - Operation timed out.
+ */
+#define ETIMEDOUT 110
+
+#endif

include/tianole/irq.h

@@ -3,6 +3,11 @@
 
 #include <stdint.h>
 
+/**
+ * typedef irq_handler_t - External IRQ dispatch callback.
+ * @irq: IRQ line that triggered the callback.
+ * @data: Opaque pointer supplied at registration time.
+ */
 typedef void (*irq_handler_t)(uint8_t irq, void *data);
 
 /**
@@ -11,7 +16,7 @@ typedef void (*irq_handler_t)(uint8_t irq, void *data);
  * @handler: Function called when the IRQ is dispatched.
  * @data: Opaque handler data passed back during dispatch.
  *
- * Return: 0 on success, negative value on failure.
+ * Return: 0 on success, -EINVAL for bad input or -EBUSY if occupied.
  */
 int irq_register(uint8_t irq, irq_handler_t handler, void *data);
 

include/tianole/mm.h

@@ -85,7 +85,7 @@ void kfree(void *ptr);
  * @phys: Physical page address.
  * @flags: Generic page flags such as PAGE_WRITABLE.
  *
- * Return: 0 on success, negative value on failure.
+ * Return: 0 on success, -EINVAL, -ENOMEM or -EEXIST on failure.
  */
 int map_page(virt_addr_t virt, phys_addr_t phys, uint64_t flags);
 
@@ -93,7 +93,7 @@ int map_page(virt_addr_t virt, phys_addr_t phys, uint64_t flags);
  * unmap_page() - Remove one virtual page mapping.
  * @virt: Virtual page address to unmap.
  *
- * Return: 0 on success, negative value on failure.
+ * Return: 0 on success, -EINVAL or -ENOENT on failure.
  */
 int unmap_page(virt_addr_t virt);
 
@@ -102,7 +102,7 @@ int unmap_page(virt_addr_t virt);
  * @virt: Virtual address to query.
  * @phys: Output storage for the resolved physical address.
  *
- * Return: 0 when a mapping exists, negative value otherwise.
+ * Return: 0 when a mapping exists, -EINVAL or -ENOENT otherwise.
  */
 int virt_to_phys(virt_addr_t virt, phys_addr_t *phys);
 

include/tianole/sched.h

@@ -175,7 +175,7 @@ void wait_queue_sleep(struct wait_queue *queue);
  * @condition: Predicate checked before and after sleeping.
  * @arg: Opaque predicate argument.
  *
- * Return: 0 when the condition is true, negative value on invalid input.
+ * Return: 0 when the condition is true, -EINVAL on invalid input.
  */
 int wait_queue_wait(
 	struct wait_queue *queue, wait_condition_t condition, void *arg);
@@ -187,7 +187,7 @@ int wait_queue_wait(
  * @arg: Opaque predicate argument.
  * @ticks: Maximum number of timer ticks to wait.
  *
- * Return: 0 when the condition is true, negative value on timeout or error.
+ * Return: 0 when the condition is true, -EINVAL or -ETIMEDOUT otherwise.
  */
 int wait_queue_wait_timeout(struct wait_queue *queue,
 	wait_condition_t condition,

kernel/sched/idle.c

@@ -1,3 +1,4 @@
+#include <tianole/errno.h>
 #include <tianole/sched.h>
 
 #include "sched.h"
@@ -15,7 +16,7 @@ int sched_idle_create(void)
 {
 	idle_thread = kernel_thread_create("idle", idle_thread_entry, 0);
 	if (idle_thread == 0) {
-		return -1;
+		return -ENOMEM;
 	}
 
 	return 0;

kernel/sched/wait.c

@@ -1,3 +1,4 @@
+#include <tianole/errno.h>
 #include <tianole/sched.h>
 #include <tianole/timer.h>
 
@@ -96,7 +97,7 @@ int wait_queue_wait(
 	uint64_t flags;
 
 	if (queue == 0 || condition == 0 || current_thread == 0) {
-		return -1;
+		return -EINVAL;
 	}
 
 	for (;;) {
@@ -127,7 +128,7 @@ int wait_queue_wait_timeout(struct wait_queue *queue,
 	uint64_t flags;
 
 	if (queue == 0 || condition == 0 || current_thread == 0) {
-		return -1;
+		return -EINVAL;
 	}
 
 	if (condition(arg) != 0) {
@@ -135,7 +136,7 @@ int wait_queue_wait_timeout(struct wait_queue *queue,
 	}
 
 	if (ticks == 0) {
-		return -1;
+		return -ETIMEDOUT;
 	}
 
 	deadline = timer_ticks() + ticks;
@@ -152,7 +153,7 @@ int wait_queue_wait_timeout(struct wait_queue *queue,
 		if (now >= deadline) {
 			current_thread->wake_tick = 0;
 			spin_unlock_irqrestore(&queue->lock, flags);
-			return -1;
+			return -ETIMEDOUT;
 		}
 
 		thread_set_sleeping(current_thread, deadline);

kernel/selftest/sched.c

@@ -1,6 +1,7 @@
 #include <stdint.h>
 
 #include <tianole/early_log.h>
+#include <tianole/errno.h>
 #include <tianole/sched.h>
 #include <tianole/spinlock.h>
 
@@ -128,7 +129,7 @@ static void timeout_wait_demo_waiter(void *arg)
 	early_log_puts("timeout waiter sleeping\n");
 	if (wait_queue_wait_timeout(
 		    &timeout_wait_queue, condition_is_ready, &never_ready, 3) !=
-		-1) {
+		-ETIMEDOUT) {
 		panic("timeout wait did not time out");
 	}
 	early_log_puts("timeout waiter timed out\n");

mm/heap.c

@@ -2,6 +2,7 @@
 #include <stdint.h>
 
 #include <tianole/early_log.h>
+#include <tianole/errno.h>
 #include <tianole/mm.h>
 
 #define HEAP_BASE 0xffffff2000000000ull
@@ -85,12 +86,16 @@ static int map_heap_range(virt_addr_t start, size_t bytes)
 
 	for (current = start; current < end; current += PAGE_SIZE) {
 		phys_addr_t page = alloc_page();
+		int ret;
 
-		if (page == 0 ||
-			map_page(current,
-				page,
-				PAGE_WRITABLE | PAGE_NO_EXECUTE) != 0) {
-			return -1;
+		if (page == 0) {
+			return -ENOMEM;
+		}
+
+		ret = map_page(current, page, PAGE_WRITABLE | PAGE_NO_EXECUTE);
+		if (ret != 0) {
+			free_page(page);
+			return ret;
 		}
 	}
 
@@ -102,9 +107,11 @@ static int heap_extend(size_t min_size)
 	size_t bytes =
 		align_up_size(min_size + sizeof(struct heap_block), PAGE_SIZE);
 	struct heap_block *block = (struct heap_block *)(uintptr_t)heap_end;
+	int ret;
 
-	if (map_heap_range(heap_end, bytes) != 0) {
-		return -1;
+	ret = map_heap_range(heap_end, bytes);
+	if (ret != 0) {
+		return ret;
 	}
 
 	heap_end += bytes;