linuxkpi: drm-kmod debugfs support

This diff extends LinuxKPI to support simple attribute files in debugfs.
These simple attributes are an essential component for compiling drm-kmod
with CONFIG_DEBUG_FS enabled.
This will allow for easier graphics driver debugging using
Intel's igt-gpu-tools.

Reviewed by:	hselasky
Differential Revision:	https://reviews.freebsd.org/D35883
Sponsored by:	Google, Inc. (GSoC 2022)

4 files changed, 123 insertions, 14 deletions

diff --git a/sys/compat/linuxkpi/common/include/linux/dcache.h b/sys/compat/linuxkpi/common/include/linux/dcache.h
index 9f9943a18dc6..512a29ec046a 100644
--- a/sys/compat/linuxkpi/common/include/linux/dcache.h
+++ b/sys/compat/linuxkpi/common/include/linux/dcache.h
@@ -29,8 +29,9 @@
 #ifndef _LINUXKPI_LINUX_DCACHE_H
 #define	_LINUXKPI_LINUX_DCACHE_H
 
-struct vnode;
-struct pfs_node;
+#include <sys/vnode.h>
+
+#include <fs/pseudofs/pseudofs.h>
 
 struct dentry {
 	struct vnode *d_inode;
diff --git a/sys/compat/linuxkpi/common/include/linux/debugfs.h b/sys/compat/linuxkpi/common/include/linux/debugfs.h
index 6a3273cbbf3c..ba1fa009dc62 100644
--- a/sys/compat/linuxkpi/common/include/linux/debugfs.h
+++ b/sys/compat/linuxkpi/common/include/linux/debugfs.h
@@ -31,21 +31,52 @@
 #define _LINUXKPI_LINUX_DEBUGFS_H_
 
 #include <linux/fs.h>
+#include <linux/module.h>
 #include <linux/seq_file.h>
-
 #include <linux/types.h>
 
-void debugfs_remove(struct dentry *dentry);
+MALLOC_DECLARE(M_DFSINT);
+
+struct debugfs_reg32 {
+	char *name;
+	unsigned long offset;
+};
+
+struct debugfs_regset32 {
+	const struct debugfs_reg32 *regs;
+	int nregs;
+};
 
 struct dentry *debugfs_create_file(const char *name, umode_t mode,
-				   struct dentry *parent, void *data,
-				   const struct file_operations *fops);
+    struct dentry *parent, void *data,
+    const struct file_operations *fops);
+
+struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode,
+    struct dentry *parent, void *data,
+    const struct file_operations *fops);
+
+struct dentry *debugfs_create_mode_unsafe(const char *name, umode_t mode,
+    struct dentry *parent, void *data,
+    const struct file_operations *fops,
+    const struct file_operations *fops_ro,
+    const struct file_operations *fops_wo);
 
 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent);
 
 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
-				      const char *dest);
+    const char *dest);
+
+void debugfs_remove(struct dentry *dentry);
 
 void debugfs_remove_recursive(struct dentry *dentry);
 
-#endif
+#define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \
+	DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)
+
+void debugfs_create_bool(const char *name, umode_t mode, struct dentry *parent,
+    bool *value);
+
+void debugfs_create_ulong(const char *name, umode_t mode, struct dentry *parent,
+    unsigned long *value);
+
+#endif /* _LINUXKPI_LINUX_DEBUGFS_H_ */
diff --git a/sys/compat/linuxkpi/common/include/linux/fs.h b/sys/compat/linuxkpi/common/include/linux/fs.h
index a21c140d5a9b..55c2ee3e00c6 100644
--- a/sys/compat/linuxkpi/common/include/linux/fs.h
+++ b/sys/compat/linuxkpi/common/include/linux/fs.h
@@ -45,6 +45,8 @@
 #include <linux/dcache.h>
 #include <linux/capability.h>
 #include <linux/wait_bit.h>
+#include <linux/kernel.h>
+#include <linux/mutex.h>
 
 struct module;
 struct kiocb;
@@ -250,6 +252,7 @@ nonseekable_open(struct inode *inode, struct file *filp)
 static inline int
 simple_open(struct inode *inode, struct file *filp)
 {
+	filp->private_data = inode->i_private;
 	return 0;
 }
 
@@ -298,6 +301,12 @@ no_llseek(struct file *file, loff_t offset, int whence)
 }
 
 static inline loff_t
+default_llseek(struct file *file, loff_t offset, int whence)
+{
+	return (no_llseek(file, offset, whence));
+}
+
+static inline loff_t
 noop_llseek(struct linux_file *file, loff_t offset, int whence)
 {
 
@@ -318,4 +327,73 @@ call_mmap(struct linux_file *file, struct vm_area_struct *vma)
 	return (file->f_op->mmap(file, vma));
 }
 
+static inline void
+i_size_write(struct inode *inode, loff_t i_size)
+{
+}
+
+/*
+ * simple_read_from_buffer: copy data from kernel-space origin
+ * buffer into user-space destination buffer
+ *
+ * @dest: destination buffer
+ * @read_size: number of bytes to be transferred
+ * @ppos: starting transfer position pointer
+ * @orig: origin buffer
+ * @buf_size: size of destination and origin buffers
+ *
+ * Return value:
+ * On success, total bytes copied with *ppos incremented accordingly.
+ * On failure, negative value.
+ */
+static inline ssize_t
+simple_read_from_buffer(void __user *dest, size_t read_size, loff_t *ppos,
+    void *orig, size_t buf_size)
+{
+	void *read_pos = ((char *) orig) + *ppos;
+	size_t buf_remain = buf_size - *ppos;
+	ssize_t num_read;
+
+	if (buf_remain < 0 || buf_remain > buf_size)
+		return -EINVAL;
+
+	if (read_size > buf_remain)
+		read_size = buf_remain;
+
+	/* copy_to_user returns number of bytes NOT read */
+	num_read = read_size - copy_to_user(dest, read_pos, read_size);
+	if (num_read == 0)
+		return -EFAULT;
+	*ppos += num_read;
+
+	return (num_read);
+}
+
+MALLOC_DECLARE(M_LSATTR);
+
+#define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)		\
+static inline int							\
+__fops ## _open(struct inode *inode, struct file *filp)			\
+{									\
+	return (simple_attr_open(inode, filp, __get, __set, __fmt));	\
+}									\
+static const struct file_operations __fops = {				\
+	.owner	 = THIS_MODULE,						\
+	.open	 = __fops ## _open,					\
+	.release = simple_attr_release,					\
+	.read	 = simple_attr_read,					\
+	.write	 = simple_attr_write,					\
+	.llseek	 = no_llseek						\
+}
+
+int simple_attr_open(struct inode *inode, struct file *filp,
+    int (*get)(void *, uint64_t *), int (*set)(void *, uint64_t),
+    const char *fmt);
+
+int simple_attr_release(struct inode *inode, struct file *filp);
+
+ssize_t simple_attr_read(struct file *filp, char *buf, size_t read_size, loff_t *ppos);
+
+ssize_t simple_attr_write(struct file *filp, const char *buf, size_t write_size, loff_t *ppos);
+
 #endif /* _LINUXKPI_LINUX_FS_H_ */
diff --git a/sys/compat/linuxkpi/common/include/linux/seq_file.h b/sys/compat/linuxkpi/common/include/linux/seq_file.h
index 9ab5ecce7768..f40b7984aa50 100644
--- a/sys/compat/linuxkpi/common/include/linux/seq_file.h
+++ b/sys/compat/linuxkpi/common/include/linux/seq_file.h
@@ -32,11 +32,12 @@
 
 #include <linux/types.h>
 #include <linux/fs.h>
-#include <sys/sbuf.h>
 
 #undef file
 #define inode vnode
 
+MALLOC_DECLARE(M_LSEQ);
+
 #define	DEFINE_SHOW_ATTRIBUTE(__name)					\
 static int __name ## _open(struct inode *inode, struct linux_file *file)	\
 {									\
@@ -51,11 +52,8 @@ static const struct file_operations __name ## _fops = {			\
 	.release	= single_release,				\
 }
 
-struct seq_operations;
-
 struct seq_file {
-	struct sbuf	*buf;
-
+	struct sbuf *buf;
 	const struct seq_operations *op;
 	const struct linux_file *file;
 	void *private;
@@ -78,7 +76,8 @@ off_t seq_lseek(struct linux_file *file, off_t offset, int whence);
 int single_open(struct linux_file *, int (*)(struct seq_file *, void *), void *);
 int single_release(struct inode *, struct linux_file *);
 
-#define seq_printf(m, fmt, ...) sbuf_printf((m)->buf, (fmt), ##__VA_ARGS__)
+void seq_vprintf(struct seq_file *m, const char *fmt, va_list args);
+void seq_printf(struct seq_file *m, const char *fmt, ...);
 
 #define seq_puts(m, str)	sbuf_printf((m)->buf, str)
 #define seq_putc(m, str)	sbuf_putc((m)->buf, str)