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linux-next/include/uapi/linux/blkpg.h
Brian Norris 53bb724f94 mtd: provide proper 32/64-bit compat_ioctl() support for BLKPG
After a bit of poking around wondering why my 32-bit user-space can't
seem to send a proper ioctl(BLKPG) to an MTD on my 64-bit kernel
(ARM64), I noticed that struct blkpg_ioctl_arg is actually pretty
unsuitable for use in the ioctl() ABI, due to its use of raw pointers,
and its lack of alignment/packing restrictions (32-bit arch'es tend to
pack the 4 fields into 4 32-bit words, whereas 64-bit arch'es would add
padding after the third int, and make this 6 32-bit words).

Anyway, this means BLKPG deserves some special compat_ioctl handling. Do
the conversion in a small shim for MTD.

block/compat_ioctl.c already has compat support for the block subsystem,
but it does so by a re-marshalling data to/from user-space (see
compat_blkpg_ioctl()). Personally, I think this approach is cleaner.

Tested only on MTD, with an ARM32 user space on an ARM64 kernel.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
2015-09-29 13:37:04 -07:00

60 lines
1.6 KiB
C

#ifndef _UAPI__LINUX_BLKPG_H
#define _UAPI__LINUX_BLKPG_H
/*
* Partition table and disk geometry handling
*
* A single ioctl with lots of subfunctions:
*
* Device number stuff:
* get_whole_disk() (given the device number of a partition,
* find the device number of the encompassing disk)
* get_all_partitions() (given the device number of a disk, return the
* device numbers of all its known partitions)
*
* Partition stuff:
* add_partition()
* delete_partition()
* test_partition_in_use() (also for test_disk_in_use)
*
* Geometry stuff:
* get_geometry()
* set_geometry()
* get_bios_drivedata()
*
* For today, only the partition stuff - aeb, 990515
*/
#include <linux/compiler.h>
#include <linux/ioctl.h>
#define BLKPG _IO(0x12,105)
/* The argument structure */
struct blkpg_ioctl_arg {
int op;
int flags;
int datalen;
void __user *data;
};
/* The subfunctions (for the op field) */
#define BLKPG_ADD_PARTITION 1
#define BLKPG_DEL_PARTITION 2
#define BLKPG_RESIZE_PARTITION 3
/* Sizes of name fields. Unused at present. */
#define BLKPG_DEVNAMELTH 64
#define BLKPG_VOLNAMELTH 64
/* The data structure for ADD_PARTITION and DEL_PARTITION */
struct blkpg_partition {
long long start; /* starting offset in bytes */
long long length; /* length in bytes */
int pno; /* partition number */
char devname[BLKPG_DEVNAMELTH]; /* partition name, like sda5 or c0d1p2,
to be used in kernel messages */
char volname[BLKPG_VOLNAMELTH]; /* volume label */
};
#endif /* _UAPI__LINUX_BLKPG_H */