Root/drivers/char/mspec.c

1/*
2 * Copyright (C) 2001-2006 Silicon Graphics, Inc. All rights
3 * reserved.
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of version 2 of the GNU General Public License
7 * as published by the Free Software Foundation.
8 */
9
10/*
11 * SN Platform Special Memory (mspec) Support
12 *
13 * This driver exports the SN special memory (mspec) facility to user
14 * processes.
15 * There are three types of memory made available thru this driver:
16 * fetchops, uncached and cached.
17 *
18 * Fetchops are atomic memory operations that are implemented in the
19 * memory controller on SGI SN hardware.
20 *
21 * Uncached are used for memory write combining feature of the ia64
22 * cpu.
23 *
24 * Cached are used for areas of memory that are used as cached addresses
25 * on our partition and used as uncached addresses from other partitions.
26 * Due to a design constraint of the SN2 Shub, you can not have processors
27 * on the same FSB perform both a cached and uncached reference to the
28 * same cache line. These special memory cached regions prevent the
29 * kernel from ever dropping in a TLB entry and therefore prevent the
30 * processor from ever speculating a cache line from this page.
31 */
32
33#include <linux/types.h>
34#include <linux/kernel.h>
35#include <linux/module.h>
36#include <linux/init.h>
37#include <linux/errno.h>
38#include <linux/miscdevice.h>
39#include <linux/spinlock.h>
40#include <linux/mm.h>
41#include <linux/fs.h>
42#include <linux/vmalloc.h>
43#include <linux/string.h>
44#include <linux/slab.h>
45#include <linux/numa.h>
46#include <asm/page.h>
47#include <asm/pgtable.h>
48#include <linux/atomic.h>
49#include <asm/tlbflush.h>
50#include <asm/uncached.h>
51#include <asm/sn/addrs.h>
52#include <asm/sn/arch.h>
53#include <asm/sn/mspec.h>
54#include <asm/sn/sn_cpuid.h>
55#include <asm/sn/io.h>
56#include <asm/sn/bte.h>
57#include <asm/sn/shubio.h>
58
59
60#define FETCHOP_ID "SGI Fetchop,"
61#define CACHED_ID "Cached,"
62#define UNCACHED_ID "Uncached"
63#define REVISION "4.0"
64#define MSPEC_BASENAME "mspec"
65
66/*
67 * Page types allocated by the device.
68 */
69enum mspec_page_type {
70    MSPEC_FETCHOP = 1,
71    MSPEC_CACHED,
72    MSPEC_UNCACHED
73};
74
75#ifdef CONFIG_SGI_SN
76static int is_sn2;
77#else
78#define is_sn2 0
79#endif
80
81/*
82 * One of these structures is allocated when an mspec region is mmaped. The
83 * structure is pointed to by the vma->vm_private_data field in the vma struct.
84 * This structure is used to record the addresses of the mspec pages.
85 * This structure is shared by all vma's that are split off from the
86 * original vma when split_vma()'s are done.
87 *
88 * The refcnt is incremented atomically because mm->mmap_sem does not
89 * protect in fork case where multiple tasks share the vma_data.
90 */
91struct vma_data {
92    atomic_t refcnt; /* Number of vmas sharing the data. */
93    spinlock_t lock; /* Serialize access to this structure. */
94    int count; /* Number of pages allocated. */
95    enum mspec_page_type type; /* Type of pages allocated. */
96    int flags; /* See VMD_xxx below. */
97    unsigned long vm_start; /* Original (unsplit) base. */
98    unsigned long vm_end; /* Original (unsplit) end. */
99    unsigned long maddr[0]; /* Array of MSPEC addresses. */
100};
101
102#define VMD_VMALLOCED 0x1 /* vmalloc'd rather than kmalloc'd */
103
104/* used on shub2 to clear FOP cache in the HUB */
105static unsigned long scratch_page[MAX_NUMNODES];
106#define SH2_AMO_CACHE_ENTRIES 4
107
108static inline int
109mspec_zero_block(unsigned long addr, int len)
110{
111    int status;
112
113    if (is_sn2) {
114        if (is_shub2()) {
115            int nid;
116            void *p;
117            int i;
118
119            nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
120            p = (void *)TO_AMO(scratch_page[nid]);
121
122            for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
123                FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
124                p += FETCHOP_VAR_SIZE;
125            }
126        }
127
128        status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
129                  BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
130    } else {
131        memset((char *) addr, 0, len);
132        status = 0;
133    }
134    return status;
135}
136
137/*
138 * mspec_open
139 *
140 * Called when a device mapping is created by a means other than mmap
141 * (via fork, munmap, etc.). Increments the reference count on the
142 * underlying mspec data so it is not freed prematurely.
143 */
144static void
145mspec_open(struct vm_area_struct *vma)
146{
147    struct vma_data *vdata;
148
149    vdata = vma->vm_private_data;
150    atomic_inc(&vdata->refcnt);
151}
152
153/*
154 * mspec_close
155 *
156 * Called when unmapping a device mapping. Frees all mspec pages
157 * belonging to all the vma's sharing this vma_data structure.
158 */
159static void
160mspec_close(struct vm_area_struct *vma)
161{
162    struct vma_data *vdata;
163    int index, last_index;
164    unsigned long my_page;
165
166    vdata = vma->vm_private_data;
167
168    if (!atomic_dec_and_test(&vdata->refcnt))
169        return;
170
171    last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
172    for (index = 0; index < last_index; index++) {
173        if (vdata->maddr[index] == 0)
174            continue;
175        /*
176         * Clear the page before sticking it back
177         * into the pool.
178         */
179        my_page = vdata->maddr[index];
180        vdata->maddr[index] = 0;
181        if (!mspec_zero_block(my_page, PAGE_SIZE))
182            uncached_free_page(my_page, 1);
183        else
184            printk(KERN_WARNING "mspec_close(): "
185                   "failed to zero page %ld\n", my_page);
186    }
187
188    if (vdata->flags & VMD_VMALLOCED)
189        vfree(vdata);
190    else
191        kfree(vdata);
192}
193
194/*
195 * mspec_fault
196 *
197 * Creates a mspec page and maps it to user space.
198 */
199static int
200mspec_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
201{
202    unsigned long paddr, maddr;
203    unsigned long pfn;
204    pgoff_t index = vmf->pgoff;
205    struct vma_data *vdata = vma->vm_private_data;
206
207    maddr = (volatile unsigned long) vdata->maddr[index];
208    if (maddr == 0) {
209        maddr = uncached_alloc_page(numa_node_id(), 1);
210        if (maddr == 0)
211            return VM_FAULT_OOM;
212
213        spin_lock(&vdata->lock);
214        if (vdata->maddr[index] == 0) {
215            vdata->count++;
216            vdata->maddr[index] = maddr;
217        } else {
218            uncached_free_page(maddr, 1);
219            maddr = vdata->maddr[index];
220        }
221        spin_unlock(&vdata->lock);
222    }
223
224    if (vdata->type == MSPEC_FETCHOP)
225        paddr = TO_AMO(maddr);
226    else
227        paddr = maddr & ~__IA64_UNCACHED_OFFSET;
228
229    pfn = paddr >> PAGE_SHIFT;
230
231    /*
232     * vm_insert_pfn can fail with -EBUSY, but in that case it will
233     * be because another thread has installed the pte first, so it
234     * is no problem.
235     */
236    vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);
237
238    return VM_FAULT_NOPAGE;
239}
240
241static const struct vm_operations_struct mspec_vm_ops = {
242    .open = mspec_open,
243    .close = mspec_close,
244    .fault = mspec_fault,
245};
246
247/*
248 * mspec_mmap
249 *
250 * Called when mmapping the device. Initializes the vma with a fault handler
251 * and private data structure necessary to allocate, track, and free the
252 * underlying pages.
253 */
254static int
255mspec_mmap(struct file *file, struct vm_area_struct *vma,
256                    enum mspec_page_type type)
257{
258    struct vma_data *vdata;
259    int pages, vdata_size, flags = 0;
260
261    if (vma->vm_pgoff != 0)
262        return -EINVAL;
263
264    if ((vma->vm_flags & VM_SHARED) == 0)
265        return -EINVAL;
266
267    if ((vma->vm_flags & VM_WRITE) == 0)
268        return -EPERM;
269
270    pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
271    vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
272    if (vdata_size <= PAGE_SIZE)
273        vdata = kzalloc(vdata_size, GFP_KERNEL);
274    else {
275        vdata = vzalloc(vdata_size);
276        flags = VMD_VMALLOCED;
277    }
278    if (!vdata)
279        return -ENOMEM;
280
281    vdata->vm_start = vma->vm_start;
282    vdata->vm_end = vma->vm_end;
283    vdata->flags = flags;
284    vdata->type = type;
285    spin_lock_init(&vdata->lock);
286    atomic_set(&vdata->refcnt, 1);
287    vma->vm_private_data = vdata;
288
289    vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP | VM_DONTEXPAND);
290    if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
291        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
292    vma->vm_ops = &mspec_vm_ops;
293
294    return 0;
295}
296
297static int
298fetchop_mmap(struct file *file, struct vm_area_struct *vma)
299{
300    return mspec_mmap(file, vma, MSPEC_FETCHOP);
301}
302
303static int
304cached_mmap(struct file *file, struct vm_area_struct *vma)
305{
306    return mspec_mmap(file, vma, MSPEC_CACHED);
307}
308
309static int
310uncached_mmap(struct file *file, struct vm_area_struct *vma)
311{
312    return mspec_mmap(file, vma, MSPEC_UNCACHED);
313}
314
315static const struct file_operations fetchop_fops = {
316    .owner = THIS_MODULE,
317    .mmap = fetchop_mmap,
318    .llseek = noop_llseek,
319};
320
321static struct miscdevice fetchop_miscdev = {
322    .minor = MISC_DYNAMIC_MINOR,
323    .name = "sgi_fetchop",
324    .fops = &fetchop_fops
325};
326
327static const struct file_operations cached_fops = {
328    .owner = THIS_MODULE,
329    .mmap = cached_mmap,
330    .llseek = noop_llseek,
331};
332
333static struct miscdevice cached_miscdev = {
334    .minor = MISC_DYNAMIC_MINOR,
335    .name = "mspec_cached",
336    .fops = &cached_fops
337};
338
339static const struct file_operations uncached_fops = {
340    .owner = THIS_MODULE,
341    .mmap = uncached_mmap,
342    .llseek = noop_llseek,
343};
344
345static struct miscdevice uncached_miscdev = {
346    .minor = MISC_DYNAMIC_MINOR,
347    .name = "mspec_uncached",
348    .fops = &uncached_fops
349};
350
351/*
352 * mspec_init
353 *
354 * Called at boot time to initialize the mspec facility.
355 */
356static int __init
357mspec_init(void)
358{
359    int ret;
360    int nid;
361
362    /*
363     * The fetchop device only works on SN2 hardware, uncached and cached
364     * memory drivers should both be valid on all ia64 hardware
365     */
366#ifdef CONFIG_SGI_SN
367    if (ia64_platform_is("sn2")) {
368        is_sn2 = 1;
369        if (is_shub2()) {
370            ret = -ENOMEM;
371            for_each_node_state(nid, N_ONLINE) {
372                int actual_nid;
373                int nasid;
374                unsigned long phys;
375
376                scratch_page[nid] = uncached_alloc_page(nid, 1);
377                if (scratch_page[nid] == 0)
378                    goto free_scratch_pages;
379                phys = __pa(scratch_page[nid]);
380                nasid = get_node_number(phys);
381                actual_nid = nasid_to_cnodeid(nasid);
382                if (actual_nid != nid)
383                    goto free_scratch_pages;
384            }
385        }
386
387        ret = misc_register(&fetchop_miscdev);
388        if (ret) {
389            printk(KERN_ERR
390                   "%s: failed to register device %i\n",
391                   FETCHOP_ID, ret);
392            goto free_scratch_pages;
393        }
394    }
395#endif
396    ret = misc_register(&cached_miscdev);
397    if (ret) {
398        printk(KERN_ERR "%s: failed to register device %i\n",
399               CACHED_ID, ret);
400        if (is_sn2)
401            misc_deregister(&fetchop_miscdev);
402        goto free_scratch_pages;
403    }
404    ret = misc_register(&uncached_miscdev);
405    if (ret) {
406        printk(KERN_ERR "%s: failed to register device %i\n",
407               UNCACHED_ID, ret);
408        misc_deregister(&cached_miscdev);
409        if (is_sn2)
410            misc_deregister(&fetchop_miscdev);
411        goto free_scratch_pages;
412    }
413
414    printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
415           MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
416           CACHED_ID, UNCACHED_ID);
417
418    return 0;
419
420 free_scratch_pages:
421    for_each_node(nid) {
422        if (scratch_page[nid] != 0)
423            uncached_free_page(scratch_page[nid], 1);
424    }
425    return ret;
426}
427
428static void __exit
429mspec_exit(void)
430{
431    int nid;
432
433    misc_deregister(&uncached_miscdev);
434    misc_deregister(&cached_miscdev);
435    if (is_sn2) {
436        misc_deregister(&fetchop_miscdev);
437
438        for_each_node(nid) {
439            if (scratch_page[nid] != 0)
440                uncached_free_page(scratch_page[nid], 1);
441        }
442    }
443}
444
445module_init(mspec_init);
446module_exit(mspec_exit);
447
448MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
449MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
450MODULE_LICENSE("GPL");
451

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