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* memrar_handler 1.0: An Intel restricted access region handler device
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* Copyright (C) 2010 Intel Corporation. All rights reserved.
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General
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* Public License as published by the Free Software Foundation.
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* This program is distributed in the hope that it will be
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* useful, but WITHOUT ANY WARRANTY; without even the implied
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU General Public License for more details.
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the Free
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* Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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* The full GNU General Public License is included in this
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* distribution in the file called COPYING.
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* -------------------------------------------------------------------
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* Moorestown restricted access regions (RAR) provide isolated
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* areas of main memory that are only acceessible by authorized
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* The Intel Moorestown RAR handler module exposes a kernel space
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* RAR memory management mechanism. It is essentially a
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* RAR-specific allocator.
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* Besides providing RAR buffer management, the RAR handler also
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* behaves in many ways like an OS virtual memory manager. For
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* example, the RAR "handles" created by the RAR handler are
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* analogous to user space virtual addresses.
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* RAR memory itself is never accessed directly by the RAR
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#include <linux/miscdevice.h>
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#include <linux/slab.h>
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#include <linux/kref.h>
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#include <linux/mutex.h>
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#include <linux/kernel.h>
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#include <linux/uaccess.h>
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#include <linux/ioport.h>
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#include <linux/rar_register.h>
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#include "memrar_allocator.h"
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#define MEMRAR_VER "1.0"
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* Moorestown supports three restricted access regions.
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* We only care about the first two, video and audio. The third,
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* reserved for Chaabi and the P-unit, will be handled by their
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#define MRST_NUM_RAR 2
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/* ---------------- -------------------- ------------------- */
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* struct memrar_buffer_info - struct that keeps track of all RAR buffers
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* @list: Linked list of memrar_buffer_info objects.
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* @buffer: Core RAR buffer information.
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* @refcount: Reference count.
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* @owner: File handle corresponding to process that reserved the
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* block of memory in RAR. This will be zero for buffers
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* allocated by other drivers instead of by a user space
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* This structure encapsulates a link list of RAR buffers, as well as
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* other characteristics specific to a given list node, such as the
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* reference count on the corresponding RAR buffer.
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struct memrar_buffer_info {
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struct list_head list;
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struct RAR_buffer buffer;
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* struct memrar_rar_info - characteristics of a given RAR
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* @base: Base bus address of the RAR.
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* @length: Length of the RAR.
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* @iobase: Virtual address of RAR mapped into kernel.
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* @allocator: Allocator associated with the RAR. Note the allocator
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* "capacity" may be smaller than the RAR length if the
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* length is not a multiple of the configured allocator
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* @buffers: Table that keeps track of all reserved RAR buffers.
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* @lock: Lock used to synchronize access to RAR-specific data
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* Each RAR has an associated memrar_rar_info structure that describes
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* where in memory the RAR is located, how large it is, and a list of
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* reserved RAR buffers inside that RAR. Each RAR also has a mutex
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* associated with it to reduce lock contention when operations on
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* multiple RARs are performed in parallel.
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struct memrar_rar_info {
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unsigned long length;
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void __iomem *iobase;
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struct memrar_allocator *allocator;
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struct memrar_buffer_info buffers;
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int allocated; /* True if we own this RAR */
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* Array of RAR characteristics.
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static struct memrar_rar_info memrars[MRST_NUM_RAR];
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/* ---------------- -------------------- ------------------- */
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/* Validate RAR type. */
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static inline int memrar_is_valid_rar_type(u32 type)
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return type == RAR_TYPE_VIDEO || type == RAR_TYPE_AUDIO;
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/* Check if an address/handle falls with the given RAR memory range. */
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static inline int memrar_handle_in_range(struct memrar_rar_info *rar,
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unsigned long const iobase = (unsigned long) (rar->iobase);
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return (vaddr >= iobase && vaddr < iobase + rar->length);
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/* Retrieve RAR information associated with the given handle. */
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static struct memrar_rar_info *memrar_get_rar_info(u32 vaddr)
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for (i = 0; i < MRST_NUM_RAR; ++i) {
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struct memrar_rar_info * const rar = &memrars[i];
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if (memrar_handle_in_range(rar, vaddr))
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* memrar_get_bus address - handle to bus address
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* Retrieve bus address from given handle.
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* Returns address corresponding to given handle. Zero if handle is
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static dma_addr_t memrar_get_bus_address(
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struct memrar_rar_info *rar,
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unsigned long const iobase = (unsigned long) (rar->iobase);
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if (!memrar_handle_in_range(rar, vaddr))
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* An assumption is made that the virtual address offset is
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* the same as the bus address offset, at least based on the
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* way this driver is implemented. For example, vaddr + 2 ==
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* @todo Is that a valid assumption?
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return rar->base + (vaddr - iobase);
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* memrar_get_physical_address - handle to physical address
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* Retrieve physical address from given handle.
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* Returns address corresponding to given handle. Zero if handle is
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static dma_addr_t memrar_get_physical_address(
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struct memrar_rar_info *rar,
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* @todo This assumes that the bus address and physical
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* address are the same. That is true for Moorestown
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* but not necessarily on other platforms. This
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* deficiency should be addressed at some point.
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return memrar_get_bus_address(rar, vaddr);
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* memrar_release_block - release a block to the pool
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* @kref: kref of block
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* Core block release code. A node has hit zero references so can
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* be released and the lists must be updated.
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* Note: This code removes the node from a list. Make sure any list
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* iteration is performed using list_for_each_safe().
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static void memrar_release_block_i(struct kref *ref)
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* Last reference is being released. Remove from the table,
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* and reclaim resources.
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struct memrar_buffer_info * const node =
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container_of(ref, struct memrar_buffer_info, refcount);
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struct RAR_block_info * const user_info =
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struct memrar_allocator * const allocator =
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memrars[user_info->type].allocator;
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list_del(&node->list);
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memrar_allocator_free(allocator, user_info->handle);
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* memrar_init_rar_resources - configure a RAR
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* @rarnum: rar that has been allocated
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* @devname: name of our device
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* Initialize RAR parameters, such as bus addresses, etc and make
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* the resource accessible.
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static int memrar_init_rar_resources(int rarnum, char const *devname)
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/* ---- Sanity Checks ----
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* 1. RAR bus addresses in both Lincroft and Langwell RAR
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* registers should be the same.
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* a. There's no way we can do this through IA.
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* 2. Secure device ID in Langwell RAR registers should be set
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* appropriately, e.g. only LPE DMA for the audio RAR, and
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* security for the other Langwell based RAR registers.
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* a. There's no way we can do this through IA.
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* 3. Audio and video RAR registers and RAR access should be
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* locked down. If not, enable RAR access control. Except
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* for debugging purposes, there is no reason for them to
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* a. We can only do this for the Lincroft (IA) side.
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* @todo Should the RAR handler driver even be aware of audio
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* and video RAR settings?
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* RAR buffer block size.
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* We choose it to be the size of a page to simplify the
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* /dev/memrar mmap() implementation and usage. Otherwise
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* paging is not involved once an RAR is locked down.
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static size_t const RAR_BLOCK_SIZE = PAGE_SIZE;
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dma_addr_t low, high;
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struct memrar_rar_info * const rar = &memrars[rarnum];
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BUG_ON(MRST_NUM_RAR != ARRAY_SIZE(memrars));
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BUG_ON(!memrar_is_valid_rar_type(rarnum));
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BUG_ON(rar->allocated);
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if (rar_get_address(rarnum, &low, &high) != 0)
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/* No RAR is available. */
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if (low == 0 || high == 0) {
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rar->allocator = NULL;
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* @todo Verify that LNC and LNW RAR register contents
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* addresses, security, etc are compatible and
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rar->length = high - low + 1;
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/* Claim RAR memory as our own. */
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if (request_mem_region(low, rar->length, devname) == NULL) {
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pr_err("%s: Unable to claim RAR[%d] memory.\n",
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pr_err("%s: RAR[%d] disabled.\n", devname, rarnum);
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* Now map it into the kernel address space.
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* Note that the RAR memory may only be accessed by IA
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* when debugging. Otherwise attempts to access the
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* RAR memory when it is locked down will result in
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* behavior similar to writing to /dev/null and
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* reading from /dev/zero. This behavior is enforced
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* by the hardware. Even if we don't access the
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* memory, mapping it into the kernel provides us with
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* a convenient RAR handle to bus address mapping.
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rar->iobase = ioremap_nocache(rar->base, rar->length);
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if (rar->iobase == NULL) {
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pr_err("%s: Unable to map RAR memory.\n", devname);
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release_mem_region(low, rar->length);
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/* Initialize corresponding memory allocator. */
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rar->allocator = memrar_create_allocator((unsigned long) rar->iobase,
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rar->length, RAR_BLOCK_SIZE);
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if (rar->allocator == NULL) {
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iounmap(rar->iobase);
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release_mem_region(low, rar->length);
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pr_info("%s: BRAR[%d] bus address range = [0x%lx, 0x%lx]\n",
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devname, rarnum, (unsigned long) low, (unsigned long) high);
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pr_info("%s: BRAR[%d] size = %zu KiB\n",
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devname, rarnum, rar->allocator->capacity / 1024);
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* memrar_fini_rar_resources - free up RAR resources
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* Finalize RAR resources. Free up the resource tables, hand the memory
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* back to the kernel, unmap the device and release the address space.
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static void memrar_fini_rar_resources(void)
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struct memrar_buffer_info *pos;
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struct memrar_buffer_info *tmp;
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* @todo Do we need to hold a lock at this point in time?
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* (module initialization failure or exit?)
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for (z = MRST_NUM_RAR; z-- != 0; ) {
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struct memrar_rar_info * const rar = &memrars[z];
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/* Clean up remaining resources. */
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list_for_each_entry_safe(pos,
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kref_put(&pos->refcount, memrar_release_block_i);
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memrar_destroy_allocator(rar->allocator);
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rar->allocator = NULL;
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iounmap(rar->iobase);
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release_mem_region(rar->base, rar->length);
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* memrar_reserve_block - handle an allocation request
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* @request: block being requested
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* @filp: owner it is tied to
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* Allocate a block of the requested RAR. If successful return the
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* request object filled in and zero, if not report an error code
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static long memrar_reserve_block(struct RAR_buffer *request,
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struct RAR_block_info * const rinfo = &request->info;
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struct RAR_buffer *buffer;
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struct memrar_buffer_info *buffer_info;
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struct memrar_rar_info *rar = NULL;
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/* Prevent array overflow. */
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if (!memrar_is_valid_rar_type(rinfo->type))
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rar = &memrars[rinfo->type];
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/* Reserve memory in RAR. */
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handle = memrar_allocator_alloc(rar->allocator, rinfo->size);
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buffer_info = kmalloc(sizeof(*buffer_info), GFP_KERNEL);
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if (buffer_info == NULL) {
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memrar_allocator_free(rar->allocator, handle);
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buffer = &buffer_info->buffer;
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buffer->info.type = rinfo->type;
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buffer->info.size = rinfo->size;
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/* Memory handle corresponding to the bus address. */
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buffer->info.handle = handle;
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buffer->bus_address = memrar_get_bus_address(rar, handle);
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* Keep track of owner so that we can later cleanup if
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buffer_info->owner = filp;
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kref_init(&buffer_info->refcount);
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mutex_lock(&rar->lock);
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list_add(&buffer_info->list, &rar->buffers.list);
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mutex_unlock(&rar->lock);
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rinfo->handle = buffer->info.handle;
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request->bus_address = buffer->bus_address;
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* memrar_release_block - release a RAR block
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* @addr: address in RAR space
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* Release a previously allocated block. Releases act on complete
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* blocks, partially freeing a block is not supported
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static long memrar_release_block(u32 addr)
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struct memrar_buffer_info *pos;
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struct memrar_buffer_info *tmp;
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struct memrar_rar_info * const rar = memrar_get_rar_info(addr);
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long result = -EINVAL;
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mutex_lock(&rar->lock);
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* Iterate through the buffer list to find the corresponding
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* buffer to be released.
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list_for_each_entry_safe(pos,
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struct RAR_block_info * const info =
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* Take into account handle offsets that may have been
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* added to the base handle, such as in the following
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* u32 handle = base + offset;
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* rar_handle_to_bus(handle);
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* rar_release(handle);
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if (addr >= info->handle
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&& addr < (info->handle + info->size)
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&& memrar_is_valid_rar_type(info->type)) {
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kref_put(&pos->refcount, memrar_release_block_i);
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mutex_unlock(&rar->lock);
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* memrar_get_stats - read statistics for a RAR
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* @r: statistics to be filled in
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* Returns the statistics data for the RAR, or an error code if
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* the request cannot be completed
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static long memrar_get_stat(struct RAR_stat *r)
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struct memrar_allocator *allocator;
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if (!memrar_is_valid_rar_type(r->type))
528
if (!memrars[r->type].allocated)
531
allocator = memrars[r->type].allocator;
533
BUG_ON(allocator == NULL);
536
* Allocator capacity doesn't change over time. No
537
* need to synchronize.
539
r->capacity = allocator->capacity;
541
mutex_lock(&allocator->lock);
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r->largest_block_size = allocator->largest_free_area;
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mutex_unlock(&allocator->lock);
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* memrar_ioctl - ioctl callback
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* @filp: file issuing the request
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* @arg: pointer to control information
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* Perform one of the ioctls supported by the memrar device
556
static long memrar_ioctl(struct file *filp,
560
void __user *argp = (void __user *)arg;
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struct RAR_buffer buffer;
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struct RAR_block_info * const request = &buffer.info;
565
struct RAR_stat rar_info;
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case RAR_HANDLER_RESERVE:
570
if (copy_from_user(request,
575
result = memrar_reserve_block(&buffer, filp);
579
return copy_to_user(argp, request, sizeof(*request));
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case RAR_HANDLER_RELEASE:
582
if (copy_from_user(&rar_handle,
587
return memrar_release_block(rar_handle);
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case RAR_HANDLER_STAT:
590
if (copy_from_user(&rar_info,
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* Populate the RAR_stat structure based on the RAR
597
* type given by the user
599
if (memrar_get_stat(&rar_info) != 0)
603
* @todo Do we need to verify destination pointer
604
* "argp" is non-zero? Is that already done by
607
return copy_to_user(argp,
609
sizeof(rar_info)) ? -EFAULT : 0;
619
* memrar_mmap - mmap helper for deubgging
620
* @filp: handle doing the mapping
623
* Support the mmap operation on the RAR space for debugging systems
624
* when the memory is not locked down.
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static int memrar_mmap(struct file *filp, struct vm_area_struct *vma)
630
* This mmap() implementation is predominantly useful for
631
* debugging since the CPU will be prevented from accessing
632
* RAR memory by the hardware when RAR is properly locked
635
* In order for this implementation to be useful RAR memory
636
* must be not be locked down. However, we only want to do
637
* that when debugging. DO NOT leave RAR memory unlocked in a
638
* deployed device that utilizes RAR.
641
size_t const size = vma->vm_end - vma->vm_start;
643
/* Users pass the RAR handle as the mmap() offset parameter. */
644
unsigned long const handle = vma->vm_pgoff << PAGE_SHIFT;
646
struct memrar_rar_info * const rar = memrar_get_rar_info(handle);
649
/* Only allow priviledged apps to go poking around this way */
650
if (!capable(CAP_SYS_RAWIO))
653
/* Invalid RAR handle or size passed to mmap(). */
656
|| size > (handle - (unsigned long) rar->iobase))
660
* Retrieve physical address corresponding to the RAR handle,
661
* and convert it to a page frame.
663
pfn = memrar_get_physical_address(rar, handle) >> PAGE_SHIFT;
666
pr_debug("memrar: mapping RAR range [0x%lx, 0x%lx) into user space.\n",
671
* Map RAR memory into user space. This is really only useful
672
* for debugging purposes since the memory won't be
673
* accessible, i.e. reads return zero and writes are ignored,
674
* when RAR access control is enabled.
676
if (remap_pfn_range(vma,
683
/* vma->vm_ops = &memrar_mem_ops; */
689
* memrar_open - device open method
690
* @inode: inode to open
693
* As we support multiple arbitary opens there is no work to be done
697
static int memrar_open(struct inode *inode, struct file *filp)
699
nonseekable_open(inode, filp);
704
* memrar_release - close method for miscev
705
* @inode: inode of device
706
* @filp: handle that is going away
708
* Free up all the regions that belong to this file handle. We use
709
* the handle as a natural Linux style 'lifetime' indicator and to
710
* ensure resources are not leaked when their owner explodes in an
714
static int memrar_release(struct inode *inode, struct file *filp)
716
/* Free all regions associated with the given file handle. */
718
struct memrar_buffer_info *pos;
719
struct memrar_buffer_info *tmp;
722
for (z = 0; z != MRST_NUM_RAR; ++z) {
723
struct memrar_rar_info * const rar = &memrars[z];
725
mutex_lock(&rar->lock);
727
list_for_each_entry_safe(pos,
731
if (filp == pos->owner)
732
kref_put(&pos->refcount,
733
memrar_release_block_i);
736
mutex_unlock(&rar->lock);
743
* rar_reserve - reserve RAR memory
744
* @buffers: buffers to reserve
745
* @count: number wanted
747
* Reserve a series of buffers in the RAR space. Returns the number of
748
* buffers successfully allocated
751
size_t rar_reserve(struct RAR_buffer *buffers, size_t count)
753
struct RAR_buffer * const end =
754
(buffers == NULL ? buffers : buffers + count);
755
struct RAR_buffer *i;
757
size_t reserve_count = 0;
759
for (i = buffers; i != end; ++i) {
760
if (memrar_reserve_block(i, NULL) == 0)
766
return reserve_count;
768
EXPORT_SYMBOL(rar_reserve);
771
* rar_release - return RAR buffers
772
* @buffers: buffers to release
773
* @size: size of released block
775
* Return a set of buffers to the RAR pool
778
size_t rar_release(struct RAR_buffer *buffers, size_t count)
780
struct RAR_buffer * const end =
781
(buffers == NULL ? buffers : buffers + count);
782
struct RAR_buffer *i;
784
size_t release_count = 0;
786
for (i = buffers; i != end; ++i) {
787
u32 * const handle = &i->info.handle;
788
if (memrar_release_block(*handle) == 0) {
790
* @todo We assume we should do this each time
791
* the ref count is decremented. Should
792
* we instead only do this when the ref
793
* count has dropped to zero, and the
794
* buffer has been completely
802
return release_count;
804
EXPORT_SYMBOL(rar_release);
807
* rar_handle_to_bus - RAR to bus address
808
* @buffers: RAR buffer structure
809
* @count: number of buffers to convert
811
* Turn a list of RAR handle mappings into actual bus addresses. Note
812
* that when the device is locked down the bus addresses in question
813
* are not CPU accessible.
816
size_t rar_handle_to_bus(struct RAR_buffer *buffers, size_t count)
818
struct RAR_buffer * const end =
819
(buffers == NULL ? buffers : buffers + count);
820
struct RAR_buffer *i;
821
struct memrar_buffer_info *pos;
823
size_t conversion_count = 0;
826
* Find all bus addresses corresponding to the given handles.
828
* @todo Not liking this nested loop. Optimize.
830
for (i = buffers; i != end; ++i) {
831
struct memrar_rar_info * const rar =
832
memrar_get_rar_info(i->info.handle);
835
* Check if we have a bogus handle, and then continue
836
* with remaining buffers.
843
mutex_lock(&rar->lock);
845
list_for_each_entry(pos, &rar->buffers.list, list) {
846
struct RAR_block_info * const user_info =
850
* Take into account handle offsets that may
851
* have been added to the base handle, such as
852
* in the following scenario:
854
* u32 handle = base + offset;
855
* rar_handle_to_bus(handle);
858
if (i->info.handle >= user_info->handle
859
&& i->info.handle < (user_info->handle
860
+ user_info->size)) {
862
i->info.handle - user_info->handle;
864
i->info.type = user_info->type;
865
i->info.size = user_info->size - offset;
867
pos->buffer.bus_address
870
/* Increment the reference count. */
871
kref_get(&pos->refcount);
880
mutex_unlock(&rar->lock);
883
return conversion_count;
885
EXPORT_SYMBOL(rar_handle_to_bus);
887
static const struct file_operations memrar_fops = {
888
.owner = THIS_MODULE,
889
.unlocked_ioctl = memrar_ioctl,
892
.release = memrar_release,
896
static struct miscdevice memrar_miscdev = {
897
.minor = MISC_DYNAMIC_MINOR, /* dynamic allocation */
898
.name = "memrar", /* /dev/memrar */
902
static char const banner[] __initdata =
904
"Intel RAR Handler: " MEMRAR_VER " initialized.\n";
907
* memrar_registration_callback - RAR obtained
910
* We have been granted ownership of the RAR. Add it to our memory
914
static int memrar_registration_callback(unsigned long rar)
917
* We initialize the RAR parameters early on so that we can
918
* discontinue memrar device initialization and registration
919
* if suitably configured RARs are not available.
921
return memrar_init_rar_resources(rar, memrar_miscdev.name);
925
* memrar_init - initialise RAR support
927
* Initialise support for RAR handlers. This may get loaded before
928
* the RAR support is activated, but the callbacks on the registration
929
* will handle that situation for us anyway.
932
static int __init memrar_init(void)
940
* Some delayed initialization is performed in this driver.
941
* Make sure resources that are used during driver clean-up
942
* (e.g. during driver's release() function) are fully
943
* initialized before first use. This is particularly
944
* important for the case when the delayed initialization
945
* isn't completed, leaving behind a partially initialized
948
* Such a scenario can occur when RAR is not available on the
949
* platform, and the driver is release()d.
951
for (i = 0; i != ARRAY_SIZE(memrars); ++i) {
952
struct memrar_rar_info * const rar = &memrars[i];
953
mutex_init(&rar->lock);
954
INIT_LIST_HEAD(&rar->buffers.list);
957
err = misc_register(&memrar_miscdev);
961
/* Now claim the two RARs we want */
962
err = register_rar(0, memrar_registration_callback, 0);
966
err = register_rar(1, memrar_registration_callback, 1);
970
/* It is possible rar 0 registered and allocated resources then rar 1
971
failed so do a full resource free */
972
memrar_fini_rar_resources();
974
misc_deregister(&memrar_miscdev);
979
* memrar_exit - unregister and unload
981
* Unregister the device and then unload any mappings and release
985
static void __exit memrar_exit(void)
987
misc_deregister(&memrar_miscdev);
988
memrar_fini_rar_resources();
992
module_init(memrar_init);
993
module_exit(memrar_exit);
996
MODULE_AUTHOR("Ossama Othman <ossama.othman@intel.com>");
997
MODULE_DESCRIPTION("Intel Restricted Access Region Handler");
998
MODULE_LICENSE("GPL");
999
MODULE_VERSION(MEMRAR_VER);
1005
c-file-style: "linux"
added
removed
drivers/staging/memrar/memrar_handler.c
