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TOMOYO Linux Cross Reference
Linux/arch/tile/kernel/hardwall.c

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  1 /*
  2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
  3  *
  4  *   This program is free software; you can redistribute it and/or
  5  *   modify it under the terms of the GNU General Public License
  6  *   as published by the Free Software Foundation, version 2.
  7  *
  8  *   This program is distributed in the hope that it will be useful, but
  9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
 10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 11  *   NON INFRINGEMENT.  See the GNU General Public License for
 12  *   more details.
 13  */
 14 
 15 #include <linux/fs.h>
 16 #include <linux/proc_fs.h>
 17 #include <linux/seq_file.h>
 18 #include <linux/rwsem.h>
 19 #include <linux/kprobes.h>
 20 #include <linux/sched.h>
 21 #include <linux/hardirq.h>
 22 #include <linux/uaccess.h>
 23 #include <linux/smp.h>
 24 #include <linux/cdev.h>
 25 #include <linux/compat.h>
 26 #include <asm/hardwall.h>
 27 #include <asm/traps.h>
 28 #include <asm/siginfo.h>
 29 #include <asm/irq_regs.h>
 30 
 31 #include <arch/interrupts.h>
 32 #include <arch/spr_def.h>
 33 
 34 
 35 /*
 36  * Implement a per-cpu "hardwall" resource class such as UDN or IPI.
 37  * We use "hardwall" nomenclature throughout for historical reasons.
 38  * The lock here controls access to the list data structure as well as
 39  * to the items on the list.
 40  */
 41 struct hardwall_type {
 42         int index;
 43         int is_xdn;
 44         int is_idn;
 45         int disabled;
 46         const char *name;
 47         struct list_head list;
 48         spinlock_t lock;
 49         struct proc_dir_entry *proc_dir;
 50 };
 51 
 52 enum hardwall_index {
 53         HARDWALL_UDN = 0,
 54 #ifndef __tilepro__
 55         HARDWALL_IDN = 1,
 56         HARDWALL_IPI = 2,
 57 #endif
 58         _HARDWALL_TYPES
 59 };
 60 
 61 static struct hardwall_type hardwall_types[] = {
 62         {  /* user-space access to UDN */
 63                 0,
 64                 1,
 65                 0,
 66                 0,
 67                 "udn",
 68                 LIST_HEAD_INIT(hardwall_types[HARDWALL_UDN].list),
 69                 __SPIN_LOCK_INITIALIZER(hardwall_types[HARDWALL_UDN].lock),
 70                 NULL
 71         },
 72 #ifndef __tilepro__
 73         {  /* user-space access to IDN */
 74                 1,
 75                 1,
 76                 1,
 77                 1,  /* disabled pending hypervisor support */
 78                 "idn",
 79                 LIST_HEAD_INIT(hardwall_types[HARDWALL_IDN].list),
 80                 __SPIN_LOCK_INITIALIZER(hardwall_types[HARDWALL_IDN].lock),
 81                 NULL
 82         },
 83         {  /* access to user-space IPI */
 84                 2,
 85                 0,
 86                 0,
 87                 0,
 88                 "ipi",
 89                 LIST_HEAD_INIT(hardwall_types[HARDWALL_IPI].list),
 90                 __SPIN_LOCK_INITIALIZER(hardwall_types[HARDWALL_IPI].lock),
 91                 NULL
 92         },
 93 #endif
 94 };
 95 
 96 /*
 97  * This data structure tracks the cpu data, etc., associated
 98  * one-to-one with a "struct file *" from opening a hardwall device file.
 99  * Note that the file's private data points back to this structure.
100  */
101 struct hardwall_info {
102         struct list_head list;             /* for hardwall_types.list */
103         struct list_head task_head;        /* head of tasks in this hardwall */
104         struct hardwall_type *type;        /* type of this resource */
105         struct cpumask cpumask;            /* cpus reserved */
106         int id;                            /* integer id for this hardwall */
107         int teardown_in_progress;          /* are we tearing this one down? */
108 
109         /* Remaining fields only valid for user-network resources. */
110         int ulhc_x;                        /* upper left hand corner x coord */
111         int ulhc_y;                        /* upper left hand corner y coord */
112         int width;                         /* rectangle width */
113         int height;                        /* rectangle height */
114 #if CHIP_HAS_REV1_XDN()
115         atomic_t xdn_pending_count;        /* cores in phase 1 of drain */
116 #endif
117 };
118 
119 
120 /* /proc/tile/hardwall */
121 static struct proc_dir_entry *hardwall_proc_dir;
122 
123 /* Functions to manage files in /proc/tile/hardwall. */
124 static void hardwall_add_proc(struct hardwall_info *);
125 static void hardwall_remove_proc(struct hardwall_info *);
126 
127 /* Allow disabling UDN access. */
128 static int __init noudn(char *str)
129 {
130         pr_info("User-space UDN access is disabled\n");
131         hardwall_types[HARDWALL_UDN].disabled = 1;
132         return 0;
133 }
134 early_param("noudn", noudn);
135 
136 #ifndef __tilepro__
137 /* Allow disabling IDN access. */
138 static int __init noidn(char *str)
139 {
140         pr_info("User-space IDN access is disabled\n");
141         hardwall_types[HARDWALL_IDN].disabled = 1;
142         return 0;
143 }
144 early_param("noidn", noidn);
145 
146 /* Allow disabling IPI access. */
147 static int __init noipi(char *str)
148 {
149         pr_info("User-space IPI access is disabled\n");
150         hardwall_types[HARDWALL_IPI].disabled = 1;
151         return 0;
152 }
153 early_param("noipi", noipi);
154 #endif
155 
156 
157 /*
158  * Low-level primitives for UDN/IDN
159  */
160 
161 #ifdef __tilepro__
162 #define mtspr_XDN(hwt, name, val) \
163         do { (void)(hwt); __insn_mtspr(SPR_UDN_##name, (val)); } while (0)
164 #define mtspr_MPL_XDN(hwt, name, val) \
165         do { (void)(hwt); __insn_mtspr(SPR_MPL_UDN_##name, (val)); } while (0)
166 #define mfspr_XDN(hwt, name) \
167         ((void)(hwt), __insn_mfspr(SPR_UDN_##name))
168 #else
169 #define mtspr_XDN(hwt, name, val)                                       \
170         do {                                                            \
171                 if ((hwt)->is_idn)                                      \
172                         __insn_mtspr(SPR_IDN_##name, (val));            \
173                 else                                                    \
174                         __insn_mtspr(SPR_UDN_##name, (val));            \
175         } while (0)
176 #define mtspr_MPL_XDN(hwt, name, val)                                   \
177         do {                                                            \
178                 if ((hwt)->is_idn)                                      \
179                         __insn_mtspr(SPR_MPL_IDN_##name, (val));        \
180                 else                                                    \
181                         __insn_mtspr(SPR_MPL_UDN_##name, (val));        \
182         } while (0)
183 #define mfspr_XDN(hwt, name) \
184   ((hwt)->is_idn ? __insn_mfspr(SPR_IDN_##name) : __insn_mfspr(SPR_UDN_##name))
185 #endif
186 
187 /* Set a CPU bit if the CPU is online. */
188 #define cpu_online_set(cpu, dst) do { \
189         if (cpu_online(cpu))          \
190                 cpumask_set_cpu(cpu, dst);    \
191 } while (0)
192 
193 
194 /* Does the given rectangle contain the given x,y coordinate? */
195 static int contains(struct hardwall_info *r, int x, int y)
196 {
197         return (x >= r->ulhc_x && x < r->ulhc_x + r->width) &&
198                 (y >= r->ulhc_y && y < r->ulhc_y + r->height);
199 }
200 
201 /* Compute the rectangle parameters and validate the cpumask. */
202 static int check_rectangle(struct hardwall_info *r, struct cpumask *mask)
203 {
204         int x, y, cpu, ulhc, lrhc;
205 
206         /* The first cpu is the ULHC, the last the LRHC. */
207         ulhc = find_first_bit(cpumask_bits(mask), nr_cpumask_bits);
208         lrhc = find_last_bit(cpumask_bits(mask), nr_cpumask_bits);
209 
210         /* Compute the rectangle attributes from the cpus. */
211         r->ulhc_x = cpu_x(ulhc);
212         r->ulhc_y = cpu_y(ulhc);
213         r->width = cpu_x(lrhc) - r->ulhc_x + 1;
214         r->height = cpu_y(lrhc) - r->ulhc_y + 1;
215 
216         /* Width and height must be positive */
217         if (r->width <= 0 || r->height <= 0)
218                 return -EINVAL;
219 
220         /* Confirm that the cpumask is exactly the rectangle. */
221         for (y = 0, cpu = 0; y < smp_height; ++y)
222                 for (x = 0; x < smp_width; ++x, ++cpu)
223                         if (cpumask_test_cpu(cpu, mask) != contains(r, x, y))
224                                 return -EINVAL;
225 
226         /*
227          * Note that offline cpus can't be drained when this user network
228          * rectangle eventually closes.  We used to detect this
229          * situation and print a warning, but it annoyed users and
230          * they ignored it anyway, so now we just return without a
231          * warning.
232          */
233         return 0;
234 }
235 
236 /*
237  * Hardware management of hardwall setup, teardown, trapping,
238  * and enabling/disabling PL0 access to the networks.
239  */
240 
241 /* Bit field values to mask together for writes to SPR_XDN_DIRECTION_PROTECT */
242 enum direction_protect {
243         N_PROTECT = (1 << 0),
244         E_PROTECT = (1 << 1),
245         S_PROTECT = (1 << 2),
246         W_PROTECT = (1 << 3),
247         C_PROTECT = (1 << 4),
248 };
249 
250 static inline int xdn_which_interrupt(struct hardwall_type *hwt)
251 {
252 #ifndef __tilepro__
253         if (hwt->is_idn)
254                 return INT_IDN_FIREWALL;
255 #endif
256         return INT_UDN_FIREWALL;
257 }
258 
259 static void enable_firewall_interrupts(struct hardwall_type *hwt)
260 {
261         arch_local_irq_unmask_now(xdn_which_interrupt(hwt));
262 }
263 
264 static void disable_firewall_interrupts(struct hardwall_type *hwt)
265 {
266         arch_local_irq_mask_now(xdn_which_interrupt(hwt));
267 }
268 
269 /* Set up hardwall on this cpu based on the passed hardwall_info. */
270 static void hardwall_setup_func(void *info)
271 {
272         struct hardwall_info *r = info;
273         struct hardwall_type *hwt = r->type;
274 
275         int cpu = smp_processor_id();
276         int x = cpu % smp_width;
277         int y = cpu / smp_width;
278         int bits = 0;
279         if (x == r->ulhc_x)
280                 bits |= W_PROTECT;
281         if (x == r->ulhc_x + r->width - 1)
282                 bits |= E_PROTECT;
283         if (y == r->ulhc_y)
284                 bits |= N_PROTECT;
285         if (y == r->ulhc_y + r->height - 1)
286                 bits |= S_PROTECT;
287         BUG_ON(bits == 0);
288         mtspr_XDN(hwt, DIRECTION_PROTECT, bits);
289         enable_firewall_interrupts(hwt);
290 }
291 
292 /* Set up all cpus on edge of rectangle to enable/disable hardwall SPRs. */
293 static void hardwall_protect_rectangle(struct hardwall_info *r)
294 {
295         int x, y, cpu, delta;
296         struct cpumask rect_cpus;
297 
298         cpumask_clear(&rect_cpus);
299 
300         /* First include the top and bottom edges */
301         cpu = r->ulhc_y * smp_width + r->ulhc_x;
302         delta = (r->height - 1) * smp_width;
303         for (x = 0; x < r->width; ++x, ++cpu) {
304                 cpu_online_set(cpu, &rect_cpus);
305                 cpu_online_set(cpu + delta, &rect_cpus);
306         }
307 
308         /* Then the left and right edges */
309         cpu -= r->width;
310         delta = r->width - 1;
311         for (y = 0; y < r->height; ++y, cpu += smp_width) {
312                 cpu_online_set(cpu, &rect_cpus);
313                 cpu_online_set(cpu + delta, &rect_cpus);
314         }
315 
316         /* Then tell all the cpus to set up their protection SPR */
317         on_each_cpu_mask(&rect_cpus, hardwall_setup_func, r, 1);
318 }
319 
320 void __kprobes do_hardwall_trap(struct pt_regs* regs, int fault_num)
321 {
322         struct hardwall_info *rect;
323         struct hardwall_type *hwt;
324         struct task_struct *p;
325         struct siginfo info;
326         int cpu = smp_processor_id();
327         int found_processes;
328         unsigned long flags;
329         struct pt_regs *old_regs = set_irq_regs(regs);
330 
331         irq_enter();
332 
333         /* Figure out which network trapped. */
334         switch (fault_num) {
335 #ifndef __tilepro__
336         case INT_IDN_FIREWALL:
337                 hwt = &hardwall_types[HARDWALL_IDN];
338                 break;
339 #endif
340         case INT_UDN_FIREWALL:
341                 hwt = &hardwall_types[HARDWALL_UDN];
342                 break;
343         default:
344                 BUG();
345         }
346         BUG_ON(hwt->disabled);
347 
348         /* This tile trapped a network access; find the rectangle. */
349         spin_lock_irqsave(&hwt->lock, flags);
350         list_for_each_entry(rect, &hwt->list, list) {
351                 if (cpumask_test_cpu(cpu, &rect->cpumask))
352                         break;
353         }
354 
355         /*
356          * It shouldn't be possible not to find this cpu on the
357          * rectangle list, since only cpus in rectangles get hardwalled.
358          * The hardwall is only removed after the user network is drained.
359          */
360         BUG_ON(&rect->list == &hwt->list);
361 
362         /*
363          * If we already started teardown on this hardwall, don't worry;
364          * the abort signal has been sent and we are just waiting for things
365          * to quiesce.
366          */
367         if (rect->teardown_in_progress) {
368                 pr_notice("cpu %d: detected %s hardwall violation %#lx"
369                        " while teardown already in progress\n",
370                           cpu, hwt->name,
371                           (long)mfspr_XDN(hwt, DIRECTION_PROTECT));
372                 goto done;
373         }
374 
375         /*
376          * Kill off any process that is activated in this rectangle.
377          * We bypass security to deliver the signal, since it must be
378          * one of the activated processes that generated the user network
379          * message that caused this trap, and all the activated
380          * processes shared a single open file so are pretty tightly
381          * bound together from a security point of view to begin with.
382          */
383         rect->teardown_in_progress = 1;
384         wmb(); /* Ensure visibility of rectangle before notifying processes. */
385         pr_notice("cpu %d: detected %s hardwall violation %#lx...\n",
386                   cpu, hwt->name, (long)mfspr_XDN(hwt, DIRECTION_PROTECT));
387         info.si_signo = SIGILL;
388         info.si_errno = 0;
389         info.si_code = ILL_HARDWALL;
390         found_processes = 0;
391         list_for_each_entry(p, &rect->task_head,
392                             thread.hardwall[hwt->index].list) {
393                 BUG_ON(p->thread.hardwall[hwt->index].info != rect);
394                 if (!(p->flags & PF_EXITING)) {
395                         found_processes = 1;
396                         pr_notice("hardwall: killing %d\n", p->pid);
397                         do_send_sig_info(info.si_signo, &info, p, false);
398                 }
399         }
400         if (!found_processes)
401                 pr_notice("hardwall: no associated processes!\n");
402 
403  done:
404         spin_unlock_irqrestore(&hwt->lock, flags);
405 
406         /*
407          * We have to disable firewall interrupts now, or else when we
408          * return from this handler, we will simply re-interrupt back to
409          * it.  However, we can't clear the protection bits, since we
410          * haven't yet drained the network, and that would allow packets
411          * to cross out of the hardwall region.
412          */
413         disable_firewall_interrupts(hwt);
414 
415         irq_exit();
416         set_irq_regs(old_regs);
417 }
418 
419 /* Allow access from user space to the user network. */
420 void grant_hardwall_mpls(struct hardwall_type *hwt)
421 {
422 #ifndef __tilepro__
423         if (!hwt->is_xdn) {
424                 __insn_mtspr(SPR_MPL_IPI_0_SET_0, 1);
425                 return;
426         }
427 #endif
428         mtspr_MPL_XDN(hwt, ACCESS_SET_0, 1);
429         mtspr_MPL_XDN(hwt, AVAIL_SET_0, 1);
430         mtspr_MPL_XDN(hwt, COMPLETE_SET_0, 1);
431         mtspr_MPL_XDN(hwt, TIMER_SET_0, 1);
432 #if !CHIP_HAS_REV1_XDN()
433         mtspr_MPL_XDN(hwt, REFILL_SET_0, 1);
434         mtspr_MPL_XDN(hwt, CA_SET_0, 1);
435 #endif
436 }
437 
438 /* Deny access from user space to the user network. */
439 void restrict_hardwall_mpls(struct hardwall_type *hwt)
440 {
441 #ifndef __tilepro__
442         if (!hwt->is_xdn) {
443                 __insn_mtspr(SPR_MPL_IPI_0_SET_1, 1);
444                 return;
445         }
446 #endif
447         mtspr_MPL_XDN(hwt, ACCESS_SET_1, 1);
448         mtspr_MPL_XDN(hwt, AVAIL_SET_1, 1);
449         mtspr_MPL_XDN(hwt, COMPLETE_SET_1, 1);
450         mtspr_MPL_XDN(hwt, TIMER_SET_1, 1);
451 #if !CHIP_HAS_REV1_XDN()
452         mtspr_MPL_XDN(hwt, REFILL_SET_1, 1);
453         mtspr_MPL_XDN(hwt, CA_SET_1, 1);
454 #endif
455 }
456 
457 /* Restrict or deny as necessary for the task we're switching to. */
458 void hardwall_switch_tasks(struct task_struct *prev,
459                            struct task_struct *next)
460 {
461         int i;
462         for (i = 0; i < HARDWALL_TYPES; ++i) {
463                 if (prev->thread.hardwall[i].info != NULL) {
464                         if (next->thread.hardwall[i].info == NULL)
465                                 restrict_hardwall_mpls(&hardwall_types[i]);
466                 } else if (next->thread.hardwall[i].info != NULL) {
467                         grant_hardwall_mpls(&hardwall_types[i]);
468                 }
469         }
470 }
471 
472 /* Does this task have the right to IPI the given cpu? */
473 int hardwall_ipi_valid(int cpu)
474 {
475 #ifdef __tilegx__
476         struct hardwall_info *info =
477                 current->thread.hardwall[HARDWALL_IPI].info;
478         return info && cpumask_test_cpu(cpu, &info->cpumask);
479 #else
480         return 0;
481 #endif
482 }
483 
484 /*
485  * Code to create, activate, deactivate, and destroy hardwall resources.
486  */
487 
488 /* Create a hardwall for the given resource */
489 static struct hardwall_info *hardwall_create(struct hardwall_type *hwt,
490                                              size_t size,
491                                              const unsigned char __user *bits)
492 {
493         struct hardwall_info *iter, *info;
494         struct cpumask mask;
495         unsigned long flags;
496         int rc;
497 
498         /* Reject crazy sizes out of hand, a la sys_mbind(). */
499         if (size > PAGE_SIZE)
500                 return ERR_PTR(-EINVAL);
501 
502         /* Copy whatever fits into a cpumask. */
503         if (copy_from_user(&mask, bits, min(sizeof(struct cpumask), size)))
504                 return ERR_PTR(-EFAULT);
505 
506         /*
507          * If the size was short, clear the rest of the mask;
508          * otherwise validate that the rest of the user mask was zero
509          * (we don't try hard to be efficient when validating huge masks).
510          */
511         if (size < sizeof(struct cpumask)) {
512                 memset((char *)&mask + size, 0, sizeof(struct cpumask) - size);
513         } else if (size > sizeof(struct cpumask)) {
514                 size_t i;
515                 for (i = sizeof(struct cpumask); i < size; ++i) {
516                         char c;
517                         if (get_user(c, &bits[i]))
518                                 return ERR_PTR(-EFAULT);
519                         if (c)
520                                 return ERR_PTR(-EINVAL);
521                 }
522         }
523 
524         /* Allocate a new hardwall_info optimistically. */
525         info = kmalloc(sizeof(struct hardwall_info),
526                         GFP_KERNEL | __GFP_ZERO);
527         if (info == NULL)
528                 return ERR_PTR(-ENOMEM);
529         INIT_LIST_HEAD(&info->task_head);
530         info->type = hwt;
531 
532         /* Compute the rectangle size and validate that it's plausible. */
533         cpumask_copy(&info->cpumask, &mask);
534         info->id = find_first_bit(cpumask_bits(&mask), nr_cpumask_bits);
535         if (hwt->is_xdn) {
536                 rc = check_rectangle(info, &mask);
537                 if (rc != 0) {
538                         kfree(info);
539                         return ERR_PTR(rc);
540                 }
541         }
542 
543         /* Confirm it doesn't overlap and add it to the list. */
544         spin_lock_irqsave(&hwt->lock, flags);
545         list_for_each_entry(iter, &hwt->list, list) {
546                 if (cpumask_intersects(&iter->cpumask, &info->cpumask)) {
547                         spin_unlock_irqrestore(&hwt->lock, flags);
548                         kfree(info);
549                         return ERR_PTR(-EBUSY);
550                 }
551         }
552         list_add_tail(&info->list, &hwt->list);
553         spin_unlock_irqrestore(&hwt->lock, flags);
554 
555         /* Set up appropriate hardwalling on all affected cpus. */
556         if (hwt->is_xdn)
557                 hardwall_protect_rectangle(info);
558 
559         /* Create a /proc/tile/hardwall entry. */
560         hardwall_add_proc(info);
561 
562         return info;
563 }
564 
565 /* Activate a given hardwall on this cpu for this process. */
566 static int hardwall_activate(struct hardwall_info *info)
567 {
568         int cpu;
569         unsigned long flags;
570         struct task_struct *p = current;
571         struct thread_struct *ts = &p->thread;
572         struct hardwall_type *hwt;
573 
574         /* Require a hardwall. */
575         if (info == NULL)
576                 return -ENODATA;
577 
578         /* Not allowed to activate a hardwall that is being torn down. */
579         if (info->teardown_in_progress)
580                 return -EINVAL;
581 
582         /*
583          * Get our affinity; if we're not bound to this tile uniquely,
584          * we can't access the network registers.
585          */
586         if (cpumask_weight(&p->cpus_allowed) != 1)
587                 return -EPERM;
588 
589         /* Make sure we are bound to a cpu assigned to this resource. */
590         cpu = smp_processor_id();
591         BUG_ON(cpumask_first(&p->cpus_allowed) != cpu);
592         if (!cpumask_test_cpu(cpu, &info->cpumask))
593                 return -EINVAL;
594 
595         /* If we are already bound to this hardwall, it's a no-op. */
596         hwt = info->type;
597         if (ts->hardwall[hwt->index].info) {
598                 BUG_ON(ts->hardwall[hwt->index].info != info);
599                 return 0;
600         }
601 
602         /* Success!  This process gets to use the resource on this cpu. */
603         ts->hardwall[hwt->index].info = info;
604         spin_lock_irqsave(&hwt->lock, flags);
605         list_add(&ts->hardwall[hwt->index].list, &info->task_head);
606         spin_unlock_irqrestore(&hwt->lock, flags);
607         grant_hardwall_mpls(hwt);
608         printk(KERN_DEBUG "Pid %d (%s) activated for %s hardwall: cpu %d\n",
609                p->pid, p->comm, hwt->name, cpu);
610         return 0;
611 }
612 
613 /*
614  * Deactivate a task's hardwall.  Must hold lock for hardwall_type.
615  * This method may be called from free_task(), so we don't want to
616  * rely on too many fields of struct task_struct still being valid.
617  * We assume the cpus_allowed, pid, and comm fields are still valid.
618  */
619 static void _hardwall_deactivate(struct hardwall_type *hwt,
620                                  struct task_struct *task)
621 {
622         struct thread_struct *ts = &task->thread;
623 
624         if (cpumask_weight(&task->cpus_allowed) != 1) {
625                 pr_err("pid %d (%s) releasing %s hardwall with"
626                        " an affinity mask containing %d cpus!\n",
627                        task->pid, task->comm, hwt->name,
628                        cpumask_weight(&task->cpus_allowed));
629                 BUG();
630         }
631 
632         BUG_ON(ts->hardwall[hwt->index].info == NULL);
633         ts->hardwall[hwt->index].info = NULL;
634         list_del(&ts->hardwall[hwt->index].list);
635         if (task == current)
636                 restrict_hardwall_mpls(hwt);
637 }
638 
639 /* Deactivate a task's hardwall. */
640 static int hardwall_deactivate(struct hardwall_type *hwt,
641                                struct task_struct *task)
642 {
643         unsigned long flags;
644         int activated;
645 
646         spin_lock_irqsave(&hwt->lock, flags);
647         activated = (task->thread.hardwall[hwt->index].info != NULL);
648         if (activated)
649                 _hardwall_deactivate(hwt, task);
650         spin_unlock_irqrestore(&hwt->lock, flags);
651 
652         if (!activated)
653                 return -EINVAL;
654 
655         printk(KERN_DEBUG "Pid %d (%s) deactivated for %s hardwall: cpu %d\n",
656                task->pid, task->comm, hwt->name, smp_processor_id());
657         return 0;
658 }
659 
660 void hardwall_deactivate_all(struct task_struct *task)
661 {
662         int i;
663         for (i = 0; i < HARDWALL_TYPES; ++i)
664                 if (task->thread.hardwall[i].info)
665                         hardwall_deactivate(&hardwall_types[i], task);
666 }
667 
668 /* Stop the switch before draining the network. */
669 static void stop_xdn_switch(void *arg)
670 {
671 #if !CHIP_HAS_REV1_XDN()
672         /* Freeze the switch and the demux. */
673         __insn_mtspr(SPR_UDN_SP_FREEZE,
674                      SPR_UDN_SP_FREEZE__SP_FRZ_MASK |
675                      SPR_UDN_SP_FREEZE__DEMUX_FRZ_MASK |
676                      SPR_UDN_SP_FREEZE__NON_DEST_EXT_MASK);
677 #else
678         /*
679          * Drop all packets bound for the core or off the edge.
680          * We rely on the normal hardwall protection setup code
681          * to have set the low four bits to trigger firewall interrupts,
682          * and shift those bits up to trigger "drop on send" semantics,
683          * plus adding "drop on send to core" for all switches.
684          * In practice it seems the switches latch the DIRECTION_PROTECT
685          * SPR so they won't start dropping if they're already
686          * delivering the last message to the core, but it doesn't
687          * hurt to enable it here.
688          */
689         struct hardwall_type *hwt = arg;
690         unsigned long protect = mfspr_XDN(hwt, DIRECTION_PROTECT);
691         mtspr_XDN(hwt, DIRECTION_PROTECT, (protect | C_PROTECT) << 5);
692 #endif
693 }
694 
695 static void empty_xdn_demuxes(struct hardwall_type *hwt)
696 {
697 #ifndef __tilepro__
698         if (hwt->is_idn) {
699                 while (__insn_mfspr(SPR_IDN_DATA_AVAIL) & (1 << 0))
700                         (void) __tile_idn0_receive();
701                 while (__insn_mfspr(SPR_IDN_DATA_AVAIL) & (1 << 1))
702                         (void) __tile_idn1_receive();
703                 return;
704         }
705 #endif
706         while (__insn_mfspr(SPR_UDN_DATA_AVAIL) & (1 << 0))
707                 (void) __tile_udn0_receive();
708         while (__insn_mfspr(SPR_UDN_DATA_AVAIL) & (1 << 1))
709                 (void) __tile_udn1_receive();
710         while (__insn_mfspr(SPR_UDN_DATA_AVAIL) & (1 << 2))
711                 (void) __tile_udn2_receive();
712         while (__insn_mfspr(SPR_UDN_DATA_AVAIL) & (1 << 3))
713                 (void) __tile_udn3_receive();
714 }
715 
716 /* Drain all the state from a stopped switch. */
717 static void drain_xdn_switch(void *arg)
718 {
719         struct hardwall_info *info = arg;
720         struct hardwall_type *hwt = info->type;
721 
722 #if CHIP_HAS_REV1_XDN()
723         /*
724          * The switches have been configured to drop any messages
725          * destined for cores (or off the edge of the rectangle).
726          * But the current message may continue to be delivered,
727          * so we wait until all the cores have finished any pending
728          * messages before we stop draining.
729          */
730         int pending = mfspr_XDN(hwt, PENDING);
731         while (pending--) {
732                 empty_xdn_demuxes(hwt);
733                 if (hwt->is_idn)
734                         __tile_idn_send(0);
735                 else
736                         __tile_udn_send(0);
737         }
738         atomic_dec(&info->xdn_pending_count);
739         while (atomic_read(&info->xdn_pending_count))
740                 empty_xdn_demuxes(hwt);
741 #else
742         int i;
743         int from_tile_words, ca_count;
744 
745         /* Empty out the 5 switch point fifos. */
746         for (i = 0; i < 5; i++) {
747                 int words, j;
748                 __insn_mtspr(SPR_UDN_SP_FIFO_SEL, i);
749                 words = __insn_mfspr(SPR_UDN_SP_STATE) & 0xF;
750                 for (j = 0; j < words; j++)
751                         (void) __insn_mfspr(SPR_UDN_SP_FIFO_DATA);
752                 BUG_ON((__insn_mfspr(SPR_UDN_SP_STATE) & 0xF) != 0);
753         }
754 
755         /* Dump out the 3 word fifo at top. */
756         from_tile_words = (__insn_mfspr(SPR_UDN_DEMUX_STATUS) >> 10) & 0x3;
757         for (i = 0; i < from_tile_words; i++)
758                 (void) __insn_mfspr(SPR_UDN_DEMUX_WRITE_FIFO);
759 
760         /* Empty out demuxes. */
761         empty_xdn_demuxes(hwt);
762 
763         /* Empty out catch all. */
764         ca_count = __insn_mfspr(SPR_UDN_DEMUX_CA_COUNT);
765         for (i = 0; i < ca_count; i++)
766                 (void) __insn_mfspr(SPR_UDN_CA_DATA);
767         BUG_ON(__insn_mfspr(SPR_UDN_DEMUX_CA_COUNT) != 0);
768 
769         /* Clear demux logic. */
770         __insn_mtspr(SPR_UDN_DEMUX_CTL, 1);
771 
772         /*
773          * Write switch state; experimentation indicates that 0xc3000
774          * is an idle switch point.
775          */
776         for (i = 0; i < 5; i++) {
777                 __insn_mtspr(SPR_UDN_SP_FIFO_SEL, i);
778                 __insn_mtspr(SPR_UDN_SP_STATE, 0xc3000);
779         }
780 #endif
781 }
782 
783 /* Reset random XDN state registers at boot up and during hardwall teardown. */
784 static void reset_xdn_network_state(struct hardwall_type *hwt)
785 {
786         if (hwt->disabled)
787                 return;
788 
789         /* Clear out other random registers so we have a clean slate. */
790         mtspr_XDN(hwt, DIRECTION_PROTECT, 0);
791         mtspr_XDN(hwt, AVAIL_EN, 0);
792         mtspr_XDN(hwt, DEADLOCK_TIMEOUT, 0);
793 
794 #if !CHIP_HAS_REV1_XDN()
795         /* Reset UDN coordinates to their standard value */
796         {
797                 unsigned int cpu = smp_processor_id();
798                 unsigned int x = cpu % smp_width;
799                 unsigned int y = cpu / smp_width;
800                 __insn_mtspr(SPR_UDN_TILE_COORD, (x << 18) | (y << 7));
801         }
802 
803         /* Set demux tags to predefined values and enable them. */
804         __insn_mtspr(SPR_UDN_TAG_VALID, 0xf);
805         __insn_mtspr(SPR_UDN_TAG_0, (1 << 0));
806         __insn_mtspr(SPR_UDN_TAG_1, (1 << 1));
807         __insn_mtspr(SPR_UDN_TAG_2, (1 << 2));
808         __insn_mtspr(SPR_UDN_TAG_3, (1 << 3));
809 
810         /* Set other rev0 random registers to a clean state. */
811         __insn_mtspr(SPR_UDN_REFILL_EN, 0);
812         __insn_mtspr(SPR_UDN_DEMUX_QUEUE_SEL, 0);
813         __insn_mtspr(SPR_UDN_SP_FIFO_SEL, 0);
814 
815         /* Start the switch and demux. */
816         __insn_mtspr(SPR_UDN_SP_FREEZE, 0);
817 #endif
818 }
819 
820 void reset_network_state(void)
821 {
822         reset_xdn_network_state(&hardwall_types[HARDWALL_UDN]);
823 #ifndef __tilepro__
824         reset_xdn_network_state(&hardwall_types[HARDWALL_IDN]);
825 #endif
826 }
827 
828 /* Restart an XDN switch after draining. */
829 static void restart_xdn_switch(void *arg)
830 {
831         struct hardwall_type *hwt = arg;
832 
833 #if CHIP_HAS_REV1_XDN()
834         /* One last drain step to avoid races with injection and draining. */
835         empty_xdn_demuxes(hwt);
836 #endif
837 
838         reset_xdn_network_state(hwt);
839 
840         /* Disable firewall interrupts. */
841         disable_firewall_interrupts(hwt);
842 }
843 
844 /* Last reference to a hardwall is gone, so clear the network. */
845 static void hardwall_destroy(struct hardwall_info *info)
846 {
847         struct task_struct *task;
848         struct hardwall_type *hwt;
849         unsigned long flags;
850 
851         /* Make sure this file actually represents a hardwall. */
852         if (info == NULL)
853                 return;
854 
855         /*
856          * Deactivate any remaining tasks.  It's possible to race with
857          * some other thread that is exiting and hasn't yet called
858          * deactivate (when freeing its thread_info), so we carefully
859          * deactivate any remaining tasks before freeing the
860          * hardwall_info object itself.
861          */
862         hwt = info->type;
863         info->teardown_in_progress = 1;
864         spin_lock_irqsave(&hwt->lock, flags);
865         list_for_each_entry(task, &info->task_head,
866                             thread.hardwall[hwt->index].list)
867                 _hardwall_deactivate(hwt, task);
868         spin_unlock_irqrestore(&hwt->lock, flags);
869 
870         if (hwt->is_xdn) {
871                 /* Configure the switches for draining the user network. */
872                 printk(KERN_DEBUG
873                        "Clearing %s hardwall rectangle %dx%d %d,%d\n",
874                        hwt->name, info->width, info->height,
875                        info->ulhc_x, info->ulhc_y);
876                 on_each_cpu_mask(&info->cpumask, stop_xdn_switch, hwt, 1);
877 
878                 /* Drain the network. */
879 #if CHIP_HAS_REV1_XDN()
880                 atomic_set(&info->xdn_pending_count,
881                            cpumask_weight(&info->cpumask));
882                 on_each_cpu_mask(&info->cpumask, drain_xdn_switch, info, 0);
883 #else
884                 on_each_cpu_mask(&info->cpumask, drain_xdn_switch, info, 1);
885 #endif
886 
887                 /* Restart switch and disable firewall. */
888                 on_each_cpu_mask(&info->cpumask, restart_xdn_switch, hwt, 1);
889         }
890 
891         /* Remove the /proc/tile/hardwall entry. */
892         hardwall_remove_proc(info);
893 
894         /* Now free the hardwall from the list. */
895         spin_lock_irqsave(&hwt->lock, flags);
896         BUG_ON(!list_empty(&info->task_head));
897         list_del(&info->list);
898         spin_unlock_irqrestore(&hwt->lock, flags);
899         kfree(info);
900 }
901 
902 
903 static int hardwall_proc_show(struct seq_file *sf, void *v)
904 {
905         struct hardwall_info *info = sf->private;
906         char buf[256];
907 
908         int rc = cpulist_scnprintf(buf, sizeof(buf), &info->cpumask);
909         buf[rc++] = '\n';
910         seq_write(sf, buf, rc);
911         return 0;
912 }
913 
914 static int hardwall_proc_open(struct inode *inode,
915                               struct file *file)
916 {
917         return single_open(file, hardwall_proc_show, PDE_DATA(inode));
918 }
919 
920 static const struct file_operations hardwall_proc_fops = {
921         .open           = hardwall_proc_open,
922         .read           = seq_read,
923         .llseek         = seq_lseek,
924         .release        = single_release,
925 };
926 
927 static void hardwall_add_proc(struct hardwall_info *info)
928 {
929         char buf[64];
930         snprintf(buf, sizeof(buf), "%d", info->id);
931         proc_create_data(buf, 0444, info->type->proc_dir,
932                          &hardwall_proc_fops, info);
933 }
934 
935 static void hardwall_remove_proc(struct hardwall_info *info)
936 {
937         char buf[64];
938         snprintf(buf, sizeof(buf), "%d", info->id);
939         remove_proc_entry(buf, info->type->proc_dir);
940 }
941 
942 int proc_pid_hardwall(struct task_struct *task, char *buffer)
943 {
944         int i;
945         int n = 0;
946         for (i = 0; i < HARDWALL_TYPES; ++i) {
947                 struct hardwall_info *info = task->thread.hardwall[i].info;
948                 if (info)
949                         n += sprintf(&buffer[n], "%s: %d\n",
950                                      info->type->name, info->id);
951         }
952         return n;
953 }
954 
955 void proc_tile_hardwall_init(struct proc_dir_entry *root)
956 {
957         int i;
958         for (i = 0; i < HARDWALL_TYPES; ++i) {
959                 struct hardwall_type *hwt = &hardwall_types[i];
960                 if (hwt->disabled)
961                         continue;
962                 if (hardwall_proc_dir == NULL)
963                         hardwall_proc_dir = proc_mkdir("hardwall", root);
964                 hwt->proc_dir = proc_mkdir(hwt->name, hardwall_proc_dir);
965         }
966 }
967 
968 
969 /*
970  * Character device support via ioctl/close.
971  */
972 
973 static long hardwall_ioctl(struct file *file, unsigned int a, unsigned long b)
974 {
975         struct hardwall_info *info = file->private_data;
976         int minor = iminor(file->f_mapping->host);
977         struct hardwall_type* hwt;
978 
979         if (_IOC_TYPE(a) != HARDWALL_IOCTL_BASE)
980                 return -EINVAL;
981 
982         BUILD_BUG_ON(HARDWALL_TYPES != _HARDWALL_TYPES);
983         BUILD_BUG_ON(HARDWALL_TYPES !=
984                      sizeof(hardwall_types)/sizeof(hardwall_types[0]));
985 
986         if (minor < 0 || minor >= HARDWALL_TYPES)
987                 return -EINVAL;
988         hwt = &hardwall_types[minor];
989         WARN_ON(info && hwt != info->type);
990 
991         switch (_IOC_NR(a)) {
992         case _HARDWALL_CREATE:
993                 if (hwt->disabled)
994                         return -ENOSYS;
995                 if (info != NULL)
996                         return -EALREADY;
997                 info = hardwall_create(hwt, _IOC_SIZE(a),
998                                        (const unsigned char __user *)b);
999                 if (IS_ERR(info))
1000                         return PTR_ERR(info);
1001                 file->private_data = info;
1002                 return 0;
1003 
1004         case _HARDWALL_ACTIVATE:
1005                 return hardwall_activate(info);
1006 
1007         case _HARDWALL_DEACTIVATE:
1008                 if (current->thread.hardwall[hwt->index].info != info)
1009                         return -EINVAL;
1010                 return hardwall_deactivate(hwt, current);
1011 
1012         case _HARDWALL_GET_ID:
1013                 return info ? info->id : -EINVAL;
1014 
1015         default:
1016                 return -EINVAL;
1017         }
1018 }
1019 
1020 #ifdef CONFIG_COMPAT
1021 static long hardwall_compat_ioctl(struct file *file,
1022                                   unsigned int a, unsigned long b)
1023 {
1024         /* Sign-extend the argument so it can be used as a pointer. */
1025         return hardwall_ioctl(file, a, (unsigned long)compat_ptr(b));
1026 }
1027 #endif
1028 
1029 /* The user process closed the file; revoke access to user networks. */
1030 static int hardwall_flush(struct file *file, fl_owner_t owner)
1031 {
1032         struct hardwall_info *info = file->private_data;
1033         struct task_struct *task, *tmp;
1034         unsigned long flags;
1035 
1036         if (info) {
1037                 /*
1038                  * NOTE: if multiple threads are activated on this hardwall
1039                  * file, the other threads will continue having access to the
1040                  * user network until they are context-switched out and back
1041                  * in again.
1042                  *
1043                  * NOTE: A NULL files pointer means the task is being torn
1044                  * down, so in that case we also deactivate it.
1045                  */
1046                 struct hardwall_type *hwt = info->type;
1047                 spin_lock_irqsave(&hwt->lock, flags);
1048                 list_for_each_entry_safe(task, tmp, &info->task_head,
1049                                          thread.hardwall[hwt->index].list) {
1050                         if (task->files == owner || task->files == NULL)
1051                                 _hardwall_deactivate(hwt, task);
1052                 }
1053                 spin_unlock_irqrestore(&hwt->lock, flags);
1054         }
1055 
1056         return 0;
1057 }
1058 
1059 /* This hardwall is gone, so destroy it. */
1060 static int hardwall_release(struct inode *inode, struct file *file)
1061 {
1062         hardwall_destroy(file->private_data);
1063         return 0;
1064 }
1065 
1066 static const struct file_operations dev_hardwall_fops = {
1067         .open           = nonseekable_open,
1068         .unlocked_ioctl = hardwall_ioctl,
1069 #ifdef CONFIG_COMPAT
1070         .compat_ioctl   = hardwall_compat_ioctl,
1071 #endif
1072         .flush          = hardwall_flush,
1073         .release        = hardwall_release,
1074 };
1075 
1076 static struct cdev hardwall_dev;
1077 
1078 static int __init dev_hardwall_init(void)
1079 {
1080         int rc;
1081         dev_t dev;
1082 
1083         rc = alloc_chrdev_region(&dev, 0, HARDWALL_TYPES, "hardwall");
1084         if (rc < 0)
1085                 return rc;
1086         cdev_init(&hardwall_dev, &dev_hardwall_fops);
1087         rc = cdev_add(&hardwall_dev, dev, HARDWALL_TYPES);
1088         if (rc < 0)
1089                 return rc;
1090 
1091         return 0;
1092 }
1093 late_initcall(dev_hardwall_init);
1094 

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