path: root/arch/s390/kernel/debug.c

// SPDX-License-Identifier: GPL-2.0
/*
 *   S/390 debug facility
 *
 *    Copyright IBM Corp. 1999, 2020
 *
 *    Author(s): Michael Holzheu (holzheu@de.ibm.com),
 *		 Holger Smolinski (Holger.Smolinski@de.ibm.com)
 *
 *    Bugreports to: <Linux390@de.ibm.com>
 */

#define KMSG_COMPONENT "s390dbf"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/sysctl.h>
#include <linux/uaccess.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/minmax.h>
#include <linux/debugfs.h>

#include <asm/debug.h>

#define DEBUG_PROLOG_ENTRY -1

#define ALL_AREAS 0 /* copy all debug areas */
#define NO_AREAS  1 /* copy no debug areas */

/* typedefs */

typedef struct file_private_info {
	loff_t offset;			/* offset of last read in file */
	int    act_area;		/* number of last formated area */
	int    act_page;		/* act page in given area */
	int    act_entry;		/* last formated entry (offset */
					/* relative to beginning of last */
					/* formated page) */
	size_t act_entry_offset;	/* up to this offset we copied */
					/* in last read the last formated */
					/* entry to userland */
	char   temp_buf[2048];		/* buffer for output */
	debug_info_t *debug_info_org;	/* original debug information */
	debug_info_t *debug_info_snap;	/* snapshot of debug information */
	struct debug_view *view;	/* used view of debug info */
} file_private_info_t;

typedef struct {
	char *string;
	/*
	 * This assumes that all args are converted into longs
	 * on L/390 this is the case for all types of parameter
	 * except of floats, and long long (32 bit)
	 *
	 */
	long args[0];
} debug_sprintf_entry_t;

/* internal function prototyes */

static int debug_init(void);
static ssize_t debug_output(struct file *file, char __user *user_buf,
			    size_t user_len, loff_t *offset);
static ssize_t debug_input(struct file *file, const char __user *user_buf,
			   size_t user_len, loff_t *offset);
static int debug_open(struct inode *inode, struct file *file);
static int debug_close(struct inode *inode, struct file *file);
static debug_info_t *debug_info_create(const char *name, int pages_per_area,
				       int nr_areas, int buf_size, umode_t mode);
static void debug_info_get(debug_info_t *);
static void debug_info_put(debug_info_t *);
static int debug_prolog_level_fn(debug_info_t *id,
				 struct debug_view *view, char *out_buf);
static int debug_input_level_fn(debug_info_t *id, struct debug_view *view,
				struct file *file, const char __user *user_buf,
				size_t user_buf_size, loff_t *offset);
static int debug_prolog_pages_fn(debug_info_t *id,
				 struct debug_view *view, char *out_buf);
static int debug_input_pages_fn(debug_info_t *id, struct debug_view *view,
				struct file *file, const char __user *user_buf,
				size_t user_buf_size, loff_t *offset);
static int debug_input_flush_fn(debug_info_t *id, struct debug_view *view,
				struct file *file, const char __user *user_buf,
				size_t user_buf_size, loff_t *offset);
static int debug_hex_ascii_format_fn(debug_info_t *id, struct debug_view *view,
				     char *out_buf, const char *in_buf);
static int debug_sprintf_format_fn(debug_info_t *id, struct debug_view *view,
				   char *out_buf, debug_sprintf_entry_t *curr_event);
static void debug_areas_swap(debug_info_t *a, debug_info_t *b);
static void debug_events_append(debug_info_t *dest, debug_info_t *src);

/* globals */

struct debug_view debug_hex_ascii_view = {
	"hex_ascii",
	NULL,
	&debug_dflt_header_fn,
	&debug_hex_ascii_format_fn,
	NULL,
	NULL
};
EXPORT_SYMBOL(debug_hex_ascii_view);

static struct debug_view debug_level_view = {
	"level",
	&debug_prolog_level_fn,
	NULL,
	NULL,
	&debug_input_level_fn,
	NULL
};

static struct debug_view debug_pages_view = {
	"pages",
	&debug_prolog_pages_fn,
	NULL,
	NULL,
	&debug_input_pages_fn,
	NULL
};

static struct debug_view debug_flush_view = {
	"flush",
	NULL,
	NULL,
	NULL,
	&debug_input_flush_fn,
	NULL
};

struct debug_view debug_sprintf_view = {
	"sprintf",
	NULL,
	&debug_dflt_header_fn,
	(debug_format_proc_t *)&debug_sprintf_format_fn,
	NULL,
	NULL
};
EXPORT_SYMBOL(debug_sprintf_view);

/* used by dump analysis tools to determine version of debug feature */
static unsigned int __used debug_feature_version = __DEBUG_FEATURE_VERSION;

/* static globals */

static debug_info_t *debug_area_first;
static debug_info_t *debug_area_last;
static DEFINE_MUTEX(debug_mutex);

static int initialized;
static int debug_critical;

static const struct file_operations debug_file_ops = {
	.owner	 = THIS_MODULE,
	.read	 = debug_output,
	.write	 = debug_input,
	.open	 = debug_open,
	.release = debug_close,
	.llseek  = no_llseek,
};

static struct dentry *debug_debugfs_root_entry;

/* functions */

/*
 * debug_areas_alloc
 * - Debug areas are implemented as a threedimensonal array:
 *   areas[areanumber][pagenumber][pageoffset]
 */

static debug_entry_t ***debug_areas_alloc(int pages_per_area, int nr_areas)
{
	debug_entry_t ***areas;
	int i, j;

	areas = kmalloc_array(nr_areas, sizeof(debug_entry_t **), GFP_KERNEL);
	if (!areas)
		goto fail_malloc_areas;
	for (i = 0; i < nr_areas; i++) {
		/* GFP_NOWARN to avoid user triggerable WARN, we handle fails */
		areas[i] = kmalloc_array(pages_per_area,
					 sizeof(debug_entry_t *),
					 GFP_KERNEL | __GFP_NOWARN);
		if (!areas[i])
			goto fail_malloc_areas2;
		for (j = 0; j < pages_per_area; j++) {
			areas[i][j] = kzalloc(PAGE_SIZE, GFP_KERNEL);
			if (!areas[i][j]) {
				for (j--; j >= 0 ; j--)
					kfree(areas[i][j]);
				kfree(areas[i]);
				goto fail_malloc_areas2;
			}
		}
	}
	return areas;

fail_malloc_areas2:
	for (i--; i >= 0; i--) {
		for (j = 0; j < pages_per_area; j++)
			kfree(areas[i][j]);
		kfree(areas[i]);
	}
	kfree(areas);
fail_malloc_areas:
	return