When using tcmu it might happen, that userspace application cannot
be built as 64 bit program even on a 64 bit host due to existing
32 bit libraries that must be used, e.g. for compression, encryption,
deduplication, ...
Currently this only works with manual changes in userspace include
file target_core_user.h due to a missing padding field in
struct tcmu_cmd_entry. Additionally one has to change uio.h because
32-bit userspace interprets struct iovec to have 8 byte size while
64-bit kernel creates it with 16 byte size.
This patch adds CONFIG_COMPAT support for X86_64 in tcmu to avoid
header file editing.
During mmap() of the command ring and data area of tcmu_dev's
uio device, tcmu checks and saves the value returned from
in_compat_syscall(). That way it allows multiple tasks to mmap()
only if they are of same type (32-/64-bit).
During SCSI command processing tcmu now creates tcmu_cmd_entry
records according to the saved type of the userspace program.
Offset and size of data fields in tcmu_cmd_entry differ between
32-bit and 64-bit only in the req part.
The field cdb_off (__u64) is on a 4-byte boundary in 32-bit, while
in 64-bit it is on the next 8-byte boundary.
The same is true for the start of the "struct iovec iov[]" array.
It also contains 8 vs. 16 byte per array entry in 32-bit vs 64-bit
mode.
Since differences are not too many, I mostly inserted changes into
existing code where necessary instead of writing a full set of
compat_* functions.
This patch is tested on x86_64.
Signed-off-by: Bodo Stroesser <bstroesser@xxxxxxxxxxxxxx>
---
This patch is made on top of Martin's 5.10/scsi-queue tree
History:
- First attempt was a PATCH RFC that didn't compile correctly in
32-bit kernel, but in 64bit kernel only.
- The first PATCH was fixed to compile in 32bit kernel and in
64bit kernel with and without CONFIG_COMPAT.
Additionally I changed it to support CONFIG_COMPAT for X86_64
only, since I wasn't able to find out what field sizes and
offsets if struct tcmu_cmd_entry userspace programs on other
archs would expect in compat mode.
- V2:
Meanwhile I found out, that the compat handling in the patch
should be fine for all ARCHes:
* see iovec vs. compat_iovec handling in fs/io_uring.c
* see usage of "__attribute__ ((__packed__))" in
struct btrfs_ioctl_send_args_32 in fs/btrfs/ioctl.c
vs. struct btrfs_ioctl_send_args in include/uapi/linux/btrfs.h
So I re-allowed COMPAT support for all ARCHes.
---
drivers/target/target_core_user.c | 170 +++++++++++++++++++++++++++++++++-----
1 file changed, 149 insertions(+), 21 deletions(-)
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 9b7592350502..5fe73e5ab5a7 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -24,6 +24,15 @@
#include <net/genetlink.h>
#include <scsi/scsi_common.h>
#include <scsi/scsi_proto.h>
+
+#if defined(CONFIG_COMPAT) && defined(CONFIG_64BIT)
+#define TCMU_COMPAT
+#endif
+
+#ifdef TCMU_COMPAT
+#include <linux/compat.h>
+#endif
+
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <target/target_core_backend.h>
@@ -136,6 +145,11 @@ struct tcmu_dev {
uint32_t max_blocks;
size_t ring_size;
+#ifdef TCMU_COMPAT
+ bool compat;
+ bool new_open;
+#endif
+
struct mutex cmdr_lock;
struct list_head qfull_queue;
struct list_head tmr_queue;
@@ -193,6 +207,30 @@ struct tcmu_tmr {
uint32_t tmr_cmd_cnt;
int16_t tmr_cmd_ids[0];
};
+#ifdef TCMU_COMPAT
+struct tcmu_compat_cmd_entry {
+ struct tcmu_cmd_entry_hdr hdr;
+
+ union {
+ struct {
+ __u32 iov_cnt;
+ __u32 iov_bidi_cnt;
+ __u32 iov_dif_cnt;
+ __u64 cdb_off;
+ __u64 __pad1;
+ __u64 __pad2;
+ struct compat_iovec iov[0];
+ } __packed req;
+ struct {
+ __u8 scsi_status;
+ __u8 __pad1;
+ __u16 __pad2;
+ __u32 read_len;
+ char sense_buffer[TCMU_SENSE_BUFFERSIZE];
+ } rsp;
+ };
+} __packed;
+#endif
/*
* To avoid dead lock the mutex lock order should always be:
@@ -671,6 +709,26 @@ static inline size_t iov_tail(struct iovec *iov)
return (size_t)iov->iov_base + iov->iov_len;
}
+#ifdef TCMU_COMPAT
+static inline void compat_new_iov(struct iovec **iov, int *iov_cnt)
+{
+ struct compat_iovec **c_iov = (struct compat_iovec **)iov;
+
+ if (*iov_cnt != 0)
+ (*c_iov)++;
+ (*iov_cnt)++;
+
+ memset(*c_iov, 0, sizeof(struct compat_iovec));
+}
+
+static inline size_t compat_iov_tail(struct iovec *iov)
+{
+ struct compat_iovec *c_iov = (struct compat_iovec *)iov;
+
+ return (size_t)c_iov->iov_base + c_iov->iov_len;
+}
+#endif
+
static void scatter_data_area(struct tcmu_dev *udev,
struct tcmu_cmd *tcmu_cmd, struct scatterlist *data_sg,
unsigned int data_nents, struct iovec **iov,
@@ -705,13 +763,41 @@ static void scatter_data_area(struct tcmu_dev *udev,
to_offset = get_block_offset_user(udev, dbi,
block_remaining);
+ copy_bytes = min_t(size_t, sg_remaining,
+ block_remaining);
+ if (copy_data) {
+ offset = DATA_BLOCK_SIZE - block_remaining;
+ memcpy(to + offset,
+ from + sg->length - sg_remaining,
+ copy_bytes);
+ }
+ sg_remaining -= copy_bytes;
+ block_remaining -= copy_bytes;
+
/*
* The following code will gather and map the blocks
* to the same iovec when the blocks are all next to
* each other.
*/
- copy_bytes = min_t(size_t, sg_remaining,
- block_remaining);
+#ifdef TCMU_COMPAT
+ if (udev->compat) {
+ struct compat_iovec *c_iov;
+
+ if (*iov_cnt != 0 &&
+ to_offset == compat_iov_tail(*iov)) {
+ c_iov = (struct compat_iovec *)*iov;
+ c_iov->iov_len += copy_bytes;
+ } else {
+ compat_new_iov(iov, iov_cnt);
+ c_iov = (struct compat_iovec *)*iov;
+ c_iov->iov_base =
+ (compat_uptr_t)to_offset;
+ c_iov->iov_len = copy_bytes;
+ }
+ continue;
+ }
+#endif
+
if (*iov_cnt != 0 &&
to_offset == iov_tail(*iov)) {
/*
@@ -730,16 +816,6 @@ static void scatter_data_area(struct tcmu_dev *udev,
(*iov)->iov_base = (void __user *)to_offset;
(*iov)->iov_len = copy_bytes;
}
-
- if (copy_data) {
- offset = DATA_BLOCK_SIZE - block_remaining;
- memcpy(to + offset,
- from + sg->length - sg_remaining,
- copy_bytes);
- }
-
- sg_remaining -= copy_bytes;
- block_remaining -= copy_bytes;
}
kunmap_atomic(from - sg->offset);
}
@@ -879,8 +955,15 @@ static bool is_ring_space_avail(struct tcmu_dev *udev, struct tcmu_cmd *cmd,
return tcmu_get_empty_blocks(udev, cmd);
}
-static inline size_t tcmu_cmd_get_base_cmd_size(size_t iov_cnt)
+static inline size_t tcmu_cmd_get_base_cmd_size(struct tcmu_dev *tcmu_dev,
+ size_t iov_cnt)
{
+#ifdef TCMU_COMPAT
+ if (tcmu_dev->compat) {
+ return max(offsetof(struct tcmu_compat_cmd_entry, req.iov[iov_cnt]),
+ sizeof(struct tcmu_compat_cmd_entry));
+ }
+#endif
return max(offsetof(struct tcmu_cmd_entry, req.iov[iov_cnt]),
sizeof(struct tcmu_cmd_entry));
}
@@ -1016,7 +1099,7 @@ static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err)
* The size will be recalculated later as actually needed to save
* cmd area memories.
*/
- base_command_size = tcmu_cmd_get_base_cmd_size(tcmu_cmd->dbi_cnt);
+ base_command_size = tcmu_cmd_get_base_cmd_size(udev, tcmu_cmd->dbi_cnt);
command_size = tcmu_cmd_get_cmd_size(tcmu_cmd, base_command_size);
if (!list_empty(&udev->qfull_queue))
@@ -1049,7 +1132,15 @@ static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err)
/* Handle allocating space from the data area */
tcmu_cmd_reset_dbi_cur(tcmu_cmd);
- iov = &entry->req.iov[0];
+#ifdef TCMU_COMPAT
+ if (udev->compat) {
+ struct compat_iovec *c_iov;
+
+ c_iov = &((struct tcmu_compat_cmd_entry *)entry)->req.iov[0];
+ iov = (struct iovec *)c_iov;
+ } else
+#endif
+ iov = &entry->req.iov[0];
iov_cnt = 0;
copy_to_data_area = (se_cmd->data_direction == DMA_TO_DEVICE
|| se_cmd->se_cmd_flags & SCF_BIDI);
@@ -1061,7 +1152,12 @@ static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err)
/* Handle BIDI commands */
iov_cnt = 0;
if (se_cmd->se_cmd_flags & SCF_BIDI) {
- iov++;
+#ifdef TCMU_COMPAT
+ if (udev->compat)
+ iov = (struct iovec *)((struct compat_iovec *)iov + 1);
+ else
+#endif
+ iov++;
scatter_data_area(udev, tcmu_cmd, se_cmd->t_bidi_data_sg,
se_cmd->t_bidi_data_nents, &iov, &iov_cnt,
false);
@@ -1089,7 +1185,7 @@ static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err)
* Recalaulate the command's base size and size according
* to the actual needs
*/
- base_command_size = tcmu_cmd_get_base_cmd_size(entry->req.iov_cnt +
+ base_command_size = tcmu_cmd_get_base_cmd_size(udev, entry->req.iov_cnt +
entry->req.iov_bidi_cnt);
command_size = tcmu_cmd_get_cmd_size(tcmu_cmd, base_command_size);
@@ -1098,7 +1194,14 @@ static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err)
/* All offsets relative to mb_addr, not start of entry! */
cdb_off = CMDR_OFF + cmd_head + base_command_size;
memcpy((void *) mb + cdb_off, se_cmd->t_task_cdb, scsi_command_size(se_cmd->t_task_cdb));
- entry->req.cdb_off = cdb_off;
+
+#ifdef TCMU_COMPAT
+ if (udev->compat)
+ ((struct tcmu_compat_cmd_entry *)entry)->req.cdb_off = cdb_off;
+ else
+#endif
+ entry->req.cdb_off = cdb_off;
+
tcmu_flush_dcache_range(entry, command_size);
UPDATE_HEAD(mb->cmd_head, command_size, udev->cmdr_size);
@@ -1729,6 +1832,8 @@ static const struct vm_operations_struct tcmu_vm_ops = {
.fault = tcmu_vma_fault,
};
+static void __tcmu_reset_ring(struct tcmu_dev *, u8);
+
static int tcmu_mmap(struct uio_info *info, struct vm_area_struct *vma)
{
struct tcmu_dev *udev = container_of(info, struct tcmu_dev, uio_info);
@@ -1742,6 +1847,23 @@ static int tcmu_mmap(struct uio_info *info, struct vm_area_struct *vma)
if (vma_pages(vma) != (udev->ring_size >> PAGE_SHIFT))
return -EINVAL;
+#ifdef TCMU_COMPAT
+ mutex_lock(&udev->cmdr_lock);
+ if (udev->new_open) {
+ if (in_compat_syscall() != udev->compat) {
+ udev->compat = !udev->compat;
+ __tcmu_reset_ring(udev, 1);
+ }
+ udev->new_open = false;
+ } else if (in_compat_syscall() != udev->compat) {
+ mutex_unlock(&udev->cmdr_lock);
+ return -EINVAL;
+ }
+ mutex_unlock(&udev->cmdr_lock);
+
+ pr_debug("mmap() successful on %s, compat = %d\n", udev->name, udev->compat);
+#endif
+
return 0;
}
@@ -1752,6 +1874,9 @@ static int tcmu_open(struct uio_info *info, struct inode *inode)
/* O_EXCL not supported for char devs, so fake it? */
if (test_and_set_bit(TCMU_DEV_BIT_OPEN, &udev->flags))
return -EBUSY;
+#ifdef TCMU_COMPAT
+ udev->new_open = true;
+#endif
udev->inode = inode;
kref_get(&udev->kref);
@@ -2209,14 +2334,12 @@ static void tcmu_block_dev(struct tcmu_dev *udev)
mutex_unlock(&udev->cmdr_lock);
}
-static void tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level)
+static void __tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level)
{
struct tcmu_mailbox *mb;
struct tcmu_cmd *cmd;
int i;
- mutex_lock(&udev->cmdr_lock);
-
idr_for_each_entry(&udev->commands, cmd, i) {
pr_debug("removing cmd %u on dev %s from ring (is expired %d)\n",
cmd->cmd_id, udev->name,
@@ -2265,7 +2388,12 @@ static void tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level)
tcmu_remove_all_queued_tmr(udev);
run_qfull_queue(udev, false);
+}
+static void tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level)
+{
+ mutex_lock(&udev->cmdr_lock);
+ __tcmu_reset_ring(udev, err_level);
mutex_unlock(&udev->cmdr_lock);
}
--
2.12.3
