aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/staging/android/uapi/vsoc_shm.h
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/staging/android/uapi/vsoc_shm.h')
-rw-r--r--drivers/staging/android/uapi/vsoc_shm.h295
1 files changed, 0 insertions, 295 deletions
diff --git a/drivers/staging/android/uapi/vsoc_shm.h b/drivers/staging/android/uapi/vsoc_shm.h
deleted file mode 100644
index 6291fb24efb2..000000000000
--- a/drivers/staging/android/uapi/vsoc_shm.h
+++ /dev/null
@@ -1,295 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Copyright (C) 2017 Google, Inc.
- *
- */
-
-#ifndef _UAPI_LINUX_VSOC_SHM_H
-#define _UAPI_LINUX_VSOC_SHM_H
-
-#include <linux/types.h>
-
-/**
- * A permission is a token that permits a receiver to read and/or write an area
- * of memory within a Vsoc region.
- *
- * An fd_scoped permission grants both read and write access, and can be
- * attached to a file description (see open(2)).
- * Ownership of the area can then be shared by passing a file descriptor
- * among processes.
- *
- * begin_offset and end_offset define the area of memory that is controlled by
- * the permission. owner_offset points to a word, also in shared memory, that
- * controls ownership of the area.
- *
- * ownership of the region expires when the associated file description is
- * released.
- *
- * At most one permission can be attached to each file description.
- *
- * This is useful when implementing HALs like gralloc that scope and pass
- * ownership of shared resources via file descriptors.
- *
- * The caller is responsibe for doing any fencing.
- *
- * The calling process will normally identify a currently free area of
- * memory. It will construct a proposed fd_scoped_permission_arg structure:
- *
- * begin_offset and end_offset describe the area being claimed
- *
- * owner_offset points to the location in shared memory that indicates the
- * owner of the area.
- *
- * owned_value is the value that will be stored in owner_offset iff the
- * permission can be granted. It must be different than VSOC_REGION_FREE.
- *
- * Two fd_scoped_permission structures are compatible if they vary only by
- * their owned_value fields.
- *
- * The driver ensures that, for any group of simultaneous callers proposing
- * compatible fd_scoped_permissions, it will accept exactly one of the
- * propopsals. The other callers will get a failure with errno of EAGAIN.
- *
- * A process receiving a file descriptor can identify the region being
- * granted using the VSOC_GET_FD_SCOPED_PERMISSION ioctl.
- */
-struct fd_scoped_permission {
- __u32 begin_offset;
- __u32 end_offset;
- __u32 owner_offset;
- __u32 owned_value;
-};
-
-/*
- * This value represents a free area of memory. The driver expects to see this
- * value at owner_offset when creating a permission otherwise it will not do it,
- * and will write this value back once the permission is no longer needed.
- */
-#define VSOC_REGION_FREE ((__u32)0)
-
-/**
- * ioctl argument for VSOC_CREATE_FD_SCOPE_PERMISSION
- */
-struct fd_scoped_permission_arg {
- struct fd_scoped_permission perm;
- __s32 managed_region_fd;
-};
-
-#define VSOC_NODE_FREE ((__u32)0)
-
-/*
- * Describes a signal table in shared memory. Each non-zero entry in the
- * table indicates that the receiver should signal the futex at the given
- * offset. Offsets are relative to the region, not the shared memory window.
- *
- * interrupt_signalled_offset is used to reliably signal interrupts across the
- * vmm boundary. There are two roles: transmitter and receiver. For example,
- * in the host_to_guest_signal_table the host is the transmitter and the
- * guest is the receiver. The protocol is as follows:
- *
- * 1. The transmitter should convert the offset of the futex to an offset
- * in the signal table [0, (1 << num_nodes_lg2))
- * The transmitter can choose any appropriate hashing algorithm, including
- * hash = futex_offset & ((1 << num_nodes_lg2) - 1)
- *
- * 3. The transmitter should atomically compare and swap futex_offset with 0
- * at hash. There are 3 possible outcomes
- * a. The swap fails because the futex_offset is already in the table.
- * The transmitter should stop.
- * b. Some other offset is in the table. This is a hash collision. The
- * transmitter should move to another table slot and try again. One
- * possible algorithm:
- * hash = (hash + 1) & ((1 << num_nodes_lg2) - 1)
- * c. The swap worked. Continue below.
- *
- * 3. The transmitter atomically swaps 1 with the value at the
- * interrupt_signalled_offset. There are two outcomes:
- * a. The prior value was 1. In this case an interrupt has already been
- * posted. The transmitter is done.
- * b. The prior value was 0, indicating that the receiver may be sleeping.
- * The transmitter will issue an interrupt.
- *
- * 4. On waking the receiver immediately exchanges a 0 with the
- * interrupt_signalled_offset. If it receives a 0 then this a spurious
- * interrupt. That may occasionally happen in the current protocol, but
- * should be rare.
- *
- * 5. The receiver scans the signal table by atomicaly exchanging 0 at each
- * location. If a non-zero offset is returned from the exchange the
- * receiver wakes all sleepers at the given offset:
- * futex((int*)(region_base + old_value), FUTEX_WAKE, MAX_INT);
- *
- * 6. The receiver thread then does a conditional wait, waking immediately
- * if the value at interrupt_signalled_offset is non-zero. This catches cases
- * here additional signals were posted while the table was being scanned.
- * On the guest the wait is handled via the VSOC_WAIT_FOR_INCOMING_INTERRUPT
- * ioctl.
- */
-struct vsoc_signal_table_layout {
- /* log_2(Number of signal table entries) */
- __u32 num_nodes_lg2;
- /*
- * Offset to the first signal table entry relative to the start of the
- * region
- */
- __u32 futex_uaddr_table_offset;
- /*
- * Offset to an atomic_t / atomic uint32_t. A non-zero value indicates
- * that one or more offsets are currently posted in the table.
- * semi-unique access to an entry in the table
- */
- __u32 interrupt_signalled_offset;
-};
-
-#define VSOC_REGION_WHOLE ((__s32)0)
-#define VSOC_DEVICE_NAME_SZ 16
-
-/**
- * Each HAL would (usually) talk to a single device region
- * Mulitple entities care about these regions:
- * - The ivshmem_server will populate the regions in shared memory
- * - The guest kernel will read the region, create minor device nodes, and
- * allow interested parties to register for FUTEX_WAKE events in the region
- * - HALs will access via the minor device nodes published by the guest kernel
- * - Host side processes will access the region via the ivshmem_server:
- * 1. Pass name to ivshmem_server at a UNIX socket
- * 2. ivshmemserver will reply with 2 fds:
- * - host->guest doorbell fd
- * - guest->host doorbell fd
- * - fd for the shared memory region
- * - region offset
- * 3. Start a futex receiver thread on the doorbell fd pointed at the
- * signal_nodes
- */
-struct vsoc_device_region {
- __u16 current_version;
- __u16 min_compatible_version;
- __u32 region_begin_offset;
- __u32 region_end_offset;
- __u32 offset_of_region_data;
- struct vsoc_signal_table_layout guest_to_host_signal_table;
- struct vsoc_signal_table_layout host_to_guest_signal_table;
- /* Name of the device. Must always be terminated with a '\0', so
- * the longest supported device name is 15 characters.
- */
- char device_name[VSOC_DEVICE_NAME_SZ];
- /* There are two ways that permissions to access regions are handled:
- * - When subdivided_by is VSOC_REGION_WHOLE, any process that can
- * open the device node for the region gains complete access to it.
- * - When subdivided is set processes that open the region cannot
- * access it. Access to a sub-region must be established by invoking
- * the VSOC_CREATE_FD_SCOPE_PERMISSION ioctl on the region
- * referenced in subdivided_by, providing a fileinstance
- * (represented by a fd) opened on this region.
- */
- __u32 managed_by;
-};
-
-/*
- * The vsoc layout descriptor.
- * The first 4K should be reserved for the shm header and region descriptors.
- * The regions should be page aligned.
- */
-
-struct vsoc_shm_layout_descriptor {
- __u16 major_version;
- __u16 minor_version;
-
- /* size of the shm. This may be redundant but nice to have */
- __u32 size;
-
- /* number of shared memory regions */
- __u32 region_count;
-
- /* The offset to the start of region descriptors */
- __u32 vsoc_region_desc_offset;
-};
-
-/*
- * This specifies the current version that should be stored in
- * vsoc_shm_layout_descriptor.major_version and
- * vsoc_shm_layout_descriptor.minor_version.
- * It should be updated only if the vsoc_device_region and
- * vsoc_shm_layout_descriptor structures have changed.
- * Versioning within each region is transferred
- * via the min_compatible_version and current_version fields in
- * vsoc_device_region. The driver does not consult these fields: they are left
- * for the HALs and host processes and will change independently of the layout
- * version.
- */
-#define CURRENT_VSOC_LAYOUT_MAJOR_VERSION 2
-#define CURRENT_VSOC_LAYOUT_MINOR_VERSION 0
-
-#define VSOC_CREATE_FD_SCOPED_PERMISSION \
- _IOW(0xF5, 0, struct fd_scoped_permission)
-#define VSOC_GET_FD_SCOPED_PERMISSION _IOR(0xF5, 1, struct fd_scoped_permission)
-
-/*
- * This is used to signal the host to scan the guest_to_host_signal_table
- * for new futexes to wake. This sends an interrupt if one is not already
- * in flight.
- */
-#define VSOC_MAYBE_SEND_INTERRUPT_TO_HOST _IO(0xF5, 2)
-
-/*
- * When this returns the guest will scan host_to_guest_signal_table to
- * check for new futexes to wake.
- */
-/* TODO(ghartman): Consider moving this to the bottom half */
-#define VSOC_WAIT_FOR_INCOMING_INTERRUPT _IO(0xF5, 3)
-
-/*
- * Guest HALs will use this to retrieve the region description after
- * opening their device node.
- */
-#define VSOC_DESCRIBE_REGION _IOR(0xF5, 4, struct vsoc_device_region)
-
-/*
- * Wake any threads that may be waiting for a host interrupt on this region.
- * This is mostly used during shutdown.
- */
-#define VSOC_SELF_INTERRUPT _IO(0xF5, 5)
-
-/*
- * This is used to signal the host to scan the guest_to_host_signal_table
- * for new futexes to wake. This sends an interrupt unconditionally.
- */
-#define VSOC_SEND_INTERRUPT_TO_HOST _IO(0xF5, 6)
-
-enum wait_types {
- VSOC_WAIT_UNDEFINED = 0,
- VSOC_WAIT_IF_EQUAL = 1,
- VSOC_WAIT_IF_EQUAL_TIMEOUT = 2
-};
-
-/*
- * Wait for a condition to be true
- *
- * Note, this is sized and aligned so the 32 bit and 64 bit layouts are
- * identical.
- */
-struct vsoc_cond_wait {
- /* Input: Offset of the 32 bit word to check */
- __u32 offset;
- /* Input: Value that will be compared with the offset */
- __u32 value;
- /* Monotonic time to wake at in seconds */
- __u64 wake_time_sec;
- /* Input: Monotonic time to wait in nanoseconds */
- __u32 wake_time_nsec;
- /* Input: Type of wait */
- __u32 wait_type;
- /* Output: Number of times the thread woke before returning. */
- __u32 wakes;
- /* Ensure that we're 8-byte aligned and 8 byte length for 32/64 bit
- * compatibility.
- */
- __u32 reserved_1;
-};
-
-#define VSOC_COND_WAIT _IOWR(0xF5, 7, struct vsoc_cond_wait)
-
-/* Wake any local threads waiting at the offset given in arg */
-#define VSOC_COND_WAKE _IO(0xF5, 8)
-
-#endif /* _UAPI_LINUX_VSOC_SHM_H */