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binder: Add support for scatter-gather

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Previously all data passed over binder needed
to be serialized, with the exception of Binder
objects and file descriptors.

This patchs adds support for scatter-gathering raw
memory buffers into a binder transaction, avoiding
the need to first serialize them into a Parcel.

To remain backwards compatibile with existing
binder clients, it introduces two new command
ioctls for this purpose - BC_TRANSACTION_SG and
BC_REPLY_SG. These commands may only be used with
the new binder_transaction_data_sg structure,
which adds a field for the total size of the
buffers we are scatter-gathering.

Because memory buffers may contain pointers to
other buffers, we allow callers to specify
a parent buffer and an offset into it, to indicate
this is a location pointing to the buffer that
we are fixing up. The kernel will then take care
of fixing up the pointer to that buffer as well.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Martijn Coenen <maco@google.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Amit Pundir <amit.pundir@linaro.org>
Cc: Serban Constantinescu <serban.constantinescu@arm.com>
Cc: Dmitry Shmidt <dimitrysh@google.com>
Cc: Rom Lemarchand <romlem@google.com>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Martijn Coenen <maco@google.com>
[jstultz: Fold in small fix from Amit Pundir <amit.pundir@linaro.org>]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Martijn Coenen 2017-02-03 14:40:51 -08:00 • committed by Greg Kroah-Hartman
parent 4bfac80af3
commit 7980240b6d
2 changed files with 275 additions and 12 deletions
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45
include/uapi/linux/android/binder.h
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@ -33,6 +33,7 @@ enum {
BINDER_TYPE_HANDLE = B_PACK_CHARS('s', 'h', '*', B_TYPE_LARGE),
BINDER_TYPE_WEAK_HANDLE = B_PACK_CHARS('w', 'h', '*', B_TYPE_LARGE),
BINDER_TYPE_FD = B_PACK_CHARS('f', 'd', '*', B_TYPE_LARGE),
BINDER_TYPE_PTR = B_PACK_CHARS('p', 't', '*', B_TYPE_LARGE),
};
enum {
@ -95,6 +96,39 @@ struct binder_fd_object {
binder_uintptr_t cookie;
};
/* struct binder_buffer_object - object describing a userspace buffer
* @hdr: common header structure
* @flags: one or more BINDER_BUFFER_* flags
* @buffer: address of the buffer
* @length: length of the buffer
* @parent: index in offset array pointing to parent buffer
* @parent_offset: offset in @parent pointing to this buffer
*
* A binder_buffer object represents an object that the
* binder kernel driver can copy verbatim to the target
* address space. A buffer itself may be pointed to from
* within another buffer, meaning that the pointer inside
* that other buffer needs to be fixed up as well. This
* can be done by setting the BINDER_BUFFER_FLAG_HAS_PARENT
* flag in @flags, by setting @parent buffer to the index
* in the offset array pointing to the parent binder_buffer_object,
* and by setting @parent_offset to the offset in the parent buffer
* at which the pointer to this buffer is located.
*/
struct binder_buffer_object {
struct binder_object_header hdr;
__u32 flags;
binder_uintptr_t buffer;
binder_size_t length;
binder_size_t parent;
binder_size_t parent_offset;
};
enum {
BINDER_BUFFER_FLAG_HAS_PARENT = 0x01,
};
/*
* On 64-bit platforms where user code may run in 32-bits the driver must
* translate the buffer (and local binder) addresses appropriately.
@ -187,6 +221,11 @@ struct binder_transaction_data {
} data;
};
struct binder_transaction_data_sg {
struct binder_transaction_data transaction_data;
binder_size_t buffers_size;
};
struct binder_ptr_cookie {
binder_uintptr_t ptr;
binder_uintptr_t cookie;
@ -371,6 +410,12 @@ enum binder_driver_command_protocol {
/*
* void *: cookie
*/
BC_TRANSACTION_SG = _IOW('c', 17, struct binder_transaction_data_sg),
BC_REPLY_SG = _IOW('c', 18, struct binder_transaction_data_sg),
/*
* binder_transaction_data_sg: the sent command.
*/
};
#endif /* _UAPI_LINUX_BINDER_H */