The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Link: https://lore.kernel.org/r/20200226212612.GA4663@embeddedor Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
53 lines
1.7 KiB
C
53 lines
1.7 KiB
C
/******************************************************************************
|
|
* tpmif.h
|
|
*
|
|
* TPM I/O interface for Xen guest OSes, v2
|
|
*
|
|
* This file is in the public domain.
|
|
*
|
|
*/
|
|
|
|
#ifndef __XEN_PUBLIC_IO_TPMIF_H__
|
|
#define __XEN_PUBLIC_IO_TPMIF_H__
|
|
|
|
/*
|
|
* Xenbus state machine
|
|
*
|
|
* Device open:
|
|
* 1. Both ends start in XenbusStateInitialising
|
|
* 2. Backend transitions to InitWait (frontend does not wait on this step)
|
|
* 3. Frontend populates ring-ref, event-channel, feature-protocol-v2
|
|
* 4. Frontend transitions to Initialised
|
|
* 5. Backend maps grant and event channel, verifies feature-protocol-v2
|
|
* 6. Backend transitions to Connected
|
|
* 7. Frontend verifies feature-protocol-v2, transitions to Connected
|
|
*
|
|
* Device close:
|
|
* 1. State is changed to XenbusStateClosing
|
|
* 2. Frontend transitions to Closed
|
|
* 3. Backend unmaps grant and event, changes state to InitWait
|
|
*/
|
|
|
|
enum vtpm_shared_page_state {
|
|
VTPM_STATE_IDLE, /* no contents / vTPM idle / cancel complete */
|
|
VTPM_STATE_SUBMIT, /* request ready / vTPM working */
|
|
VTPM_STATE_FINISH, /* response ready / vTPM idle */
|
|
VTPM_STATE_CANCEL, /* cancel requested / vTPM working */
|
|
};
|
|
/* The backend should only change state to IDLE or FINISH, while the
|
|
* frontend should only change to SUBMIT or CANCEL. */
|
|
|
|
|
|
struct vtpm_shared_page {
|
|
uint32_t length; /* request/response length in bytes */
|
|
|
|
uint8_t state; /* enum vtpm_shared_page_state */
|
|
uint8_t locality; /* for the current request */
|
|
uint8_t pad;
|
|
|
|
uint8_t nr_extra_pages; /* extra pages for long packets; may be zero */
|
|
uint32_t extra_pages[]; /* grant IDs; length in nr_extra_pages */
|
|
};
|
|
|
|
#endif
|