From da4e4a2411b9fbf39978f96211ad9b2e0505ca52 Mon Sep 17 00:00:00 2001
From: pumnflqv2 <ggdxz77@163.com>
Date: Sun, 26 Jun 2022 22:37:19 +0800
Subject: [PATCH] ADD file via upload

---
 kernel/printk.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 kernel/printk.c

diff --git a/kernel/printk.c b/kernel/printk.c
new file mode 100644
index 0000000..0daa097
--- /dev/null
+++ b/kernel/printk.c
@@ -0,0 +1,41 @@
+/*
+ *  linux/kernel/printk.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+/*
+ * When in kernel-mode, we cannot use printf, as fs is liable to
+ * point to 'interesting' things. Make a printf with fs-saving, and
+ * all is well.
+ */
+#include <stdarg.h>
+#include <stddef.h>
+
+#include <linux/kernel.h>
+
+static char buf[1024];
+
+extern int vsprintf(char * buf, const char * fmt, va_list args);
+
+int printk(const char *fmt, ...)
+{
+	va_list args;
+	int i;
+
+	va_start(args, fmt);
+	i=vsprintf(buf,fmt,args);
+	va_end(args);
+	__asm__("push %%fs\n\t"
+		"push %%ds\n\t"
+		"pop %%fs\n\t"
+		"pushl %0\n\t"
+		"pushl $buf\n\t"
+		"pushl $0\n\t"
+		"call tty_write\n\t"
+		"addl $8,%%esp\n\t"
+		"popl %0\n\t"
+		"pop %%fs"
+		::"r" (i):"ax","cx","dx");
+	return i;
+}