path: root/drivers/usb/mon/mon_bin.c

/*
 * The USB Monitor, inspired by Dave Harding's USBMon.
 *
 * This is a binary format reader.
 *
 * Copyright (C) 2006 Paolo Abeni (paolo.abeni@email.it)
 * Copyright (C) 2006 Pete Zaitcev (zaitcev@redhat.com)
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/usb.h>
#include <linux/poll.h>
#include <linux/compat.h>
#include <linux/mm.h>

#include <asm/uaccess.h>

#include "usb_mon.h"

/*
 * Defined by USB 2.0 clause 9.3, table 9.2.
 */
#define SETUP_LEN  8

/* ioctl macros */
#define MON_IOC_MAGIC 0x92

#define MON_IOCQ_URB_LEN _IO(MON_IOC_MAGIC, 1)
/* #2 used to be MON_IOCX_URB, removed before it got into Linus tree */
#define MON_IOCG_STATS _IOR(MON_IOC_MAGIC, 3, struct mon_bin_stats)
#define MON_IOCT_RING_SIZE _IO(MON_IOC_MAGIC, 4)
#define MON_IOCQ_RING_SIZE _IO(MON_IOC_MAGIC, 5)
#define MON_IOCX_GET   _IOW(MON_IOC_MAGIC, 6, struct mon_bin_get)
#define MON_IOCX_MFETCH _IOWR(MON_IOC_MAGIC, 7, struct mon_bin_mfetch)
#define MON_IOCH_MFLUSH _IO(MON_IOC_MAGIC, 8)
#ifdef CONFIG_COMPAT
#define MON_IOCX_GET32 _IOW(MON_IOC_MAGIC, 6, struct mon_bin_get32)
#define MON_IOCX_MFETCH32 _IOWR(MON_IOC_MAGIC, 7, struct mon_bin_mfetch32)
#endif

/*
 * Some architectures have enormous basic pages (16KB for ia64, 64KB for ppc).
 * But it's all right. Just use a simple way to make sure the chunk is never
 * smaller than a page.
 *
 * N.B. An application does not know our chunk size.
 *
 * Woops, get_zeroed_page() returns a single page. I guess we're stuck with
 * page-sized chunks for the time being.
 */
#define CHUNK_SIZE   PAGE_SIZE
#define CHUNK_ALIGN(x)   (((x)+CHUNK_SIZE-1) & ~(CHUNK_SIZE-1))

/*
 * The magic limit was calculated so that it allows the monitoring
 * application to pick data once in two ticks. This way, another application,
 * which presumably drives the bus, gets to hog CPU, yet we collect our data.
 * If HZ is 100, a 480 mbit/s bus drives 614 KB every jiffy. USB has an
 * enormous overhead built into the bus protocol, so we need about 1000 KB.
 *
 * This is still too much for most cases, where we just snoop a few
 * descriptor fetches for enumeration. So, the default is a "reasonable"
 * amount for systems with HZ=250 and incomplete bus saturation.
 *
 * XXX What about multi-megabyte URBs which take minutes to transfer?
 */
#define BUFF_MAX  CHUNK_ALIGN(1200*1024)
#define BUFF_DFL   CHUNK_ALIGN(300*1024)
#define BUFF_MIN     CHUNK_ALIGN(8*1024)

/*
 * The per-event API header (2 per URB).
 *
 * This structure is seen in userland as defined by the documentation.
 */
struct mon_bin_hdr {
	u64 id;			/* URB ID - from submission to callback */
	unsigned char type;	/* Same as in text API; extensible. */
	unsigned char xfer_type;	/* ISO, Intr, Control, Bulk */
	unsigned char epnum;	/* Endpoint number and transfer direction */
	unsigned char devnum;	/* Device address */
	unsigned short busnum;	/* Bus number */
	char flag_setup;
	char flag_data;
	s64 ts_sec;		/* gettimeofday */
	s32 ts_usec;		/* gettimeofday */
	int status;
	unsigned int len_urb;	/* Length of data (submitted or actual) */
	unsigned int len_cap;	/* Delivered length */
	unsigned char setup[SETUP_LEN];	/* Only for Control S-type */
};

/* per file statistic */
struct mon_bin_stats {
	u32 queued;
	u32 dropped;
};

struct mon_bin_get {
	struct mon_bin_hdr __user *hdr;	/* Only 48 bytes, not 64. */
	void __user *data;
	size_t alloc;		/* Length of data (can be zero) */
};

struct mon_bin_mfetch {
	u32 __user *offvec;	/* Vector of events fetched */
	u32 nfetch;		/* Number of events to fetch (out: fetched) */
	u32 nflush;		/* Number of events to flush */
};

#ifdef CONFIG_COMPAT
struct mon_bin_get32 {
	u32 hdr32;
	u32 data32;
	u32 alloc32;
};

struct mon_bin_mfetch32 {
        u32 offvec32;
        u32 nfetch32;
        u32 nflush32;
};
#endif

/* Having these two values same prevents wrapping of the mon_bin_hdr */
#define PKT_ALIGN   64
#define PKT_SIZE    64

/* max number of USB bus supported */
#define MON_BIN_MAX_MINOR 128

/*
 * The buffer: map of used pages.
 */
struct mon_pgmap {
	struct page *pg;
	unsigned char *ptr;	/* XXX just use page_to_virt everywhere? */
};

/*
 * This gets associated with an open file struct.
 */
struct mon_reader_bin {
	/* The buffer: one per open. */
	spinlock_t b_lock;		/* Protect b_cnt, b_in */
	unsigned int b_size;		/* Current size of the buffer - bytes */
	unsigned int b_cnt;		/* Bytes used */
	unsigned int b_in, b_out;	/* Offsets into buffer - bytes */
	unsigned int b_read;		/* Amount of read data in curr. pkt. */
	struct mon_pgmap *b_vec;	/* The map array */
	wait_queue_head_t b_wait;	/* Wait for data here */

	struct mutex fetch_lock;	/* Protect b_read, b_out */
	int mmap_active;

	/* A list of these is needed for "bus 0". Some time later. */
	struct mon_reader r;

	/* Stats */
	unsigned int cnt_lost;
};

static inline struct mon_bin_hdr *MON_OFF2HDR(const struct mon_reader_bin *rp,
    unsigned int offset)
{
	return