xref: /linux/arch/arc/mm/tlb.c (revision 08b7174fb8d126e607e385e34b9e1da4f3be274f) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * TLB Management (flush/create/diagnostics) for MMUv3 and MMUv4
4  *
5  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
6  *
7  */
8 
9 #include <linux/module.h>
10 #include <linux/bug.h>
11 #include <linux/mm_types.h>
12 
13 #include <asm/arcregs.h>
14 #include <asm/setup.h>
15 #include <asm/mmu_context.h>
16 #include <asm/mmu.h>
17 
18 /* A copy of the ASID from the PID reg is kept in asid_cache */
19 DEFINE_PER_CPU(unsigned int, asid_cache) = MM_CTXT_FIRST_CYCLE;
20 
21 static struct cpuinfo_arc_mmu {
22 	unsigned int ver, pg_sz_k, s_pg_sz_m, pae, sets, ways;
23 } mmuinfo;
24 
25 /*
26  * Utility Routine to erase a J-TLB entry
27  * Caller needs to setup Index Reg (manually or via getIndex)
28  */
29 static inline void __tlb_entry_erase(void)
30 {
31 	write_aux_reg(ARC_REG_TLBPD1, 0);
32 
33 	if (is_pae40_enabled())
34 		write_aux_reg(ARC_REG_TLBPD1HI, 0);
35 
36 	write_aux_reg(ARC_REG_TLBPD0, 0);
37 	write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
38 }
39 
40 static void utlb_invalidate(void)
41 {
42 	write_aux_reg(ARC_REG_TLBCOMMAND, TLBIVUTLB);
43 }
44 
45 #ifdef CONFIG_ARC_MMU_V3
46 
47 static inline unsigned int tlb_entry_lkup(unsigned long vaddr_n_asid)
48 {
49 	unsigned int idx;
50 
51 	write_aux_reg(ARC_REG_TLBPD0, vaddr_n_asid);
52 
53 	write_aux_reg(ARC_REG_TLBCOMMAND, TLBProbe);
54 	idx = read_aux_reg(ARC_REG_TLBINDEX);
55 
56 	return idx;
57 }
58 
59 static void tlb_entry_erase(unsigned int vaddr_n_asid)
60 {
61 	unsigned int idx;
62 
63 	/* Locate the TLB entry for this vaddr + ASID */
64 	idx = tlb_entry_lkup(vaddr_n_asid);
65 
66 	/* No error means entry found, zero it out */
67 	if (likely(!(idx & TLB_LKUP_ERR))) {
68 		__tlb_entry_erase();
69 	} else {
70 		/* Duplicate entry error */
71 		WARN(idx == TLB_DUP_ERR, "Probe returned Dup PD for %x\n",
72 					   vaddr_n_asid);
73 	}
74 }
75 
76 static void tlb_entry_insert(unsigned int pd0, phys_addr_t pd1)
77 {
78 	unsigned int idx;
79 
80 	/*
81 	 * First verify if entry for this vaddr+ASID already exists
82 	 * This also sets up PD0 (vaddr, ASID..) for final commit
83 	 */
84 	idx = tlb_entry_lkup(pd0);
85 
86 	/*
87 	 * If Not already present get a free slot from MMU.
88 	 * Otherwise, Probe would have located the entry and set INDEX Reg
89 	 * with existing location. This will cause Write CMD to over-write
90 	 * existing entry with new PD0 and PD1
91 	 */
92 	if (likely(idx & TLB_LKUP_ERR))
93 		write_aux_reg(ARC_REG_TLBCOMMAND, TLBGetIndex);
94 
95 	/* setup the other half of TLB entry (pfn, rwx..) */
96 	write_aux_reg(ARC_REG_TLBPD1, pd1);
97 
98 	/*
99 	 * Commit the Entry to MMU
100 	 * It doesn't sound safe to use the TLBWriteNI cmd here
101 	 * which doesn't flush uTLBs. I'd rather be safe than sorry.
102 	 */
103 	write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
104 }
105 
106 #else	/* MMUv4 */
107 
108 static void tlb_entry_erase(unsigned int vaddr_n_asid)
109 {
110 	write_aux_reg(ARC_REG_TLBPD0, vaddr_n_asid | _PAGE_PRESENT);
111 	write_aux_reg(ARC_REG_TLBCOMMAND, TLBDeleteEntry);
112 }
113 
114 static void tlb_entry_insert(unsigned int pd0, phys_addr_t pd1)
115 {
116 	write_aux_reg(ARC_REG_TLBPD0, pd0);
117 
118 	if (!is_pae40_enabled()) {
119 		write_aux_reg(ARC_REG_TLBPD1, pd1);
120 	} else {
121 		write_aux_reg(ARC_REG_TLBPD1, pd1 & 0xFFFFFFFF);
122 		write_aux_reg(ARC_REG_TLBPD1HI, (u64)pd1 >> 32);
123 	}
124 
125 	write_aux_reg(ARC_REG_TLBCOMMAND, TLBInsertEntry);
126 }
127 
128 #endif
129 
130 /*
131  * Un-conditionally (without lookup) erase the entire MMU contents
132  */
133 
134 noinline void local_flush_tlb_all(void)
135 {
136 	struct cpuinfo_arc_mmu *mmu = &mmuinfo;
137 	unsigned long flags;
138 	unsigned int entry;
139 	int num_tlb = mmu->sets * mmu->ways;
140 
141 	local_irq_save(flags);
142 
143 	/* Load PD0 and PD1 with template for a Blank Entry */
144 	write_aux_reg(ARC_REG_TLBPD1, 0);
145 
146 	if (is_pae40_enabled())
147 		write_aux_reg(ARC_REG_TLBPD1HI, 0);
148 
149 	write_aux_reg(ARC_REG_TLBPD0, 0);
150 
151 	for (entry = 0; entry < num_tlb; entry++) {
152 		/* write this entry to the TLB */
153 		write_aux_reg(ARC_REG_TLBINDEX, entry);
154 		write_aux_reg(ARC_REG_TLBCOMMAND, TLBWriteNI);
155 	}
156 
157 	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
158 		const int stlb_idx = 0x800;
159 
160 		/* Blank sTLB entry */
161 		write_aux_reg(ARC_REG_TLBPD0, _PAGE_HW_SZ);
162 
163 		for (entry = stlb_idx; entry < stlb_idx + 16; entry++) {
164 			write_aux_reg(ARC_REG_TLBINDEX, entry);
165 			write_aux_reg(ARC_REG_TLBCOMMAND, TLBWriteNI);
166 		}
167 	}
168 
169 	utlb_invalidate();
170 
171 	local_irq_restore(flags);
172 }
173 
174 /*
175  * Flush the entire MM for userland. The fastest way is to move to Next ASID
176  */
177 noinline void local_flush_tlb_mm(struct mm_struct *mm)
178 {
179 	/*
180 	 * Small optimisation courtesy IA64
181 	 * flush_mm called during fork,exit,munmap etc, multiple times as well.
182 	 * Only for fork( ) do we need to move parent to a new MMU ctxt,
183 	 * all other cases are NOPs, hence this check.
184 	 */
185 	if (atomic_read(&mm->mm_users) == 0)
186 		return;
187 
188 	/*
189 	 * - Move to a new ASID, but only if the mm is still wired in
190 	 *   (Android Binder ended up calling this for vma->mm != tsk->mm,
191 	 *    causing h/w - s/w ASID to get out of sync)
192 	 * - Also get_new_mmu_context() new implementation allocates a new
193 	 *   ASID only if it is not allocated already - so unallocate first
194 	 */
195 	destroy_context(mm);
196 	if (current->mm == mm)
197 		get_new_mmu_context(mm);
198 }
199 
200 /*
201  * Flush a Range of TLB entries for userland.
202  * @start is inclusive, while @end is exclusive
203  * Difference between this and Kernel Range Flush is
204  *  -Here the fastest way (if range is too large) is to move to next ASID
205  *      without doing any explicit Shootdown
206  *  -In case of kernel Flush, entry has to be shot down explicitly
207  */
208 void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
209 			   unsigned long end)
210 {
211 	const unsigned int cpu = smp_processor_id();
212 	unsigned long flags;
213 
214 	/* If range @start to @end is more than 32 TLB entries deep,
215 	 * its better to move to a new ASID rather than searching for
216 	 * individual entries and then shooting them down
217 	 *
218 	 * The calc above is rough, doesn't account for unaligned parts,
219 	 * since this is heuristics based anyways
220 	 */
221 	if (unlikely((end - start) >= PAGE_SIZE * 32)) {
222 		local_flush_tlb_mm(vma->vm_mm);
223 		return;
224 	}
225 
226 	/*
227 	 * @start moved to page start: this alone suffices for checking
228 	 * loop end condition below, w/o need for aligning @end to end
229 	 * e.g. 2000 to 4001 will anyhow loop twice
230 	 */
231 	start &= PAGE_MASK;
232 
233 	local_irq_save(flags);
234 
235 	if (asid_mm(vma->vm_mm, cpu) != MM_CTXT_NO_ASID) {
236 		while (start < end) {
237 			tlb_entry_erase(start | hw_pid(vma->vm_mm, cpu));
238 			start += PAGE_SIZE;
239 		}
240 	}
241 
242 	local_irq_restore(flags);
243 }
244 
245 /* Flush the kernel TLB entries - vmalloc/modules (Global from MMU perspective)
246  *  @start, @end interpreted as kvaddr
247  * Interestingly, shared TLB entries can also be flushed using just
248  * @start,@end alone (interpreted as user vaddr), although technically SASID
249  * is also needed. However our smart TLbProbe lookup takes care of that.
250  */
251 void local_flush_tlb_kernel_range(unsigned long start, unsigned long end)
252 {
253 	unsigned long flags;
254 
255 	/* exactly same as above, except for TLB entry not taking ASID */
256 
257 	if (unlikely((end - start) >= PAGE_SIZE * 32)) {
258 		local_flush_tlb_all();
259 		return;
260 	}
261 
262 	start &= PAGE_MASK;
263 
264 	local_irq_save(flags);
265 	while (start < end) {
266 		tlb_entry_erase(start);
267 		start += PAGE_SIZE;
268 	}
269 
270 	local_irq_restore(flags);
271 }
272 
273 /*
274  * Delete TLB entry in MMU for a given page (??? address)
275  * NOTE One TLB entry contains translation for single PAGE
276  */
277 
278 void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
279 {
280 	const unsigned int cpu = smp_processor_id();
281 	unsigned long flags;
282 
283 	/* Note that it is critical that interrupts are DISABLED between
284 	 * checking the ASID and using it flush the TLB entry
285 	 */
286 	local_irq_save(flags);
287 
288 	if (asid_mm(vma->vm_mm, cpu) != MM_CTXT_NO_ASID) {
289 		tlb_entry_erase((page & PAGE_MASK) | hw_pid(vma->vm_mm, cpu));
290 	}
291 
292 	local_irq_restore(flags);
293 }
294 
295 #ifdef CONFIG_SMP
296 
297 struct tlb_args {
298 	struct vm_area_struct *ta_vma;
299 	unsigned long ta_start;
300 	unsigned long ta_end;
301 };
302 
303 static inline void ipi_flush_tlb_page(void *arg)
304 {
305 	struct tlb_args *ta = arg;
306 
307 	local_flush_tlb_page(ta->ta_vma, ta->ta_start);
308 }
309 
310 static inline void ipi_flush_tlb_range(void *arg)
311 {
312 	struct tlb_args *ta = arg;
313 
314 	local_flush_tlb_range(ta->ta_vma, ta->ta_start, ta->ta_end);
315 }
316 
317 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
318 static inline void ipi_flush_pmd_tlb_range(void *arg)
319 {
320 	struct tlb_args *ta = arg;
321 
322 	local_flush_pmd_tlb_range(ta->ta_vma, ta->ta_start, ta->ta_end);
323 }
324 #endif
325 
326 static inline void ipi_flush_tlb_kernel_range(void *arg)
327 {
328 	struct tlb_args *ta = (struct tlb_args *)arg;
329 
330 	local_flush_tlb_kernel_range(ta->ta_start, ta->ta_end);
331 }
332 
333 void flush_tlb_all(void)
334 {
335 	on_each_cpu((smp_call_func_t)local_flush_tlb_all, NULL, 1);
336 }
337 
338 void flush_tlb_mm(struct mm_struct *mm)
339 {
340 	on_each_cpu_mask(mm_cpumask(mm), (smp_call_func_t)local_flush_tlb_mm,
341 			 mm, 1);
342 }
343 
344 void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
345 {
346 	struct tlb_args ta = {
347 		.ta_vma = vma,
348 		.ta_start = uaddr
349 	};
350 
351 	on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_tlb_page, &ta, 1);
352 }
353 
354 void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
355 		     unsigned long end)
356 {
357 	struct tlb_args ta = {
358 		.ta_vma = vma,
359 		.ta_start = start,
360 		.ta_end = end
361 	};
362 
363 	on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_tlb_range, &ta, 1);
364 }
365 
366 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
367 void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
368 			 unsigned long end)
369 {
370 	struct tlb_args ta = {
371 		.ta_vma = vma,
372 		.ta_start = start,
373 		.ta_end = end
374 	};
375 
376 	on_each_cpu_mask(mm_cpumask(vma->vm_mm), ipi_flush_pmd_tlb_range, &ta, 1);
377 }
378 #endif
379 
380 void flush_tlb_kernel_range(unsigned long start, unsigned long end)
381 {
382 	struct tlb_args ta = {
383 		.ta_start = start,
384 		.ta_end = end
385 	};
386 
387 	on_each_cpu(ipi_flush_tlb_kernel_range, &ta, 1);
388 }
389 #endif
390 
391 /*
392  * Routine to create a TLB entry
393  */
394 static void create_tlb(struct vm_area_struct *vma, unsigned long vaddr, pte_t *ptep)
395 {
396 	unsigned long flags;
397 	unsigned int asid_or_sasid, rwx;
398 	unsigned long pd0;
399 	phys_addr_t pd1;
400 
401 	/*
402 	 * create_tlb() assumes that current->mm == vma->mm, since
403 	 * -it ASID for TLB entry is fetched from MMU ASID reg (valid for curr)
404 	 * -completes the lazy write to SASID reg (again valid for curr tsk)
405 	 *
406 	 * Removing the assumption involves
407 	 * -Using vma->mm->context{ASID,SASID}, as opposed to MMU reg.
408 	 * -More importantly it makes this handler inconsistent with fast-path
409 	 *  TLB Refill handler which always deals with "current"
410 	 *
411 	 * Lets see the use cases when current->mm != vma->mm and we land here
412 	 *  1. execve->copy_strings()->__get_user_pages->handle_mm_fault
413 	 *     Here VM wants to pre-install a TLB entry for user stack while
414 	 *     current->mm still points to pre-execve mm (hence the condition).
415 	 *     However the stack vaddr is soon relocated (randomization) and
416 	 *     move_page_tables() tries to undo that TLB entry.
417 	 *     Thus not creating TLB entry is not any worse.
418 	 *
419 	 *  2. ptrace(POKETEXT) causes a CoW - debugger(current) inserting a
420 	 *     breakpoint in debugged task. Not creating a TLB now is not
421 	 *     performance critical.
422 	 *
423 	 * Both the cases above are not good enough for code churn.
424 	 */
425 	if (current->active_mm != vma->vm_mm)
426 		return;
427 
428 	local_irq_save(flags);
429 
430 	vaddr &= PAGE_MASK;
431 
432 	/* update this PTE credentials */
433 	pte_val(*ptep) |= (_PAGE_PRESENT | _PAGE_ACCESSED);
434 
435 	/* Create HW TLB(PD0,PD1) from PTE  */
436 
437 	/* ASID for this task */
438 	asid_or_sasid = read_aux_reg(ARC_REG_PID) & 0xff;
439 
440 	pd0 = vaddr | asid_or_sasid | (pte_val(*ptep) & PTE_BITS_IN_PD0);
441 
442 	/*
443 	 * ARC MMU provides fully orthogonal access bits for K/U mode,
444 	 * however Linux only saves 1 set to save PTE real-estate
445 	 * Here we convert 3 PTE bits into 6 MMU bits:
446 	 * -Kernel only entries have Kr Kw Kx 0 0 0
447 	 * -User entries have mirrored K and U bits
448 	 */
449 	rwx = pte_val(*ptep) & PTE_BITS_RWX;
450 
451 	if (pte_val(*ptep) & _PAGE_GLOBAL)
452 		rwx <<= 3;		/* r w x => Kr Kw Kx 0 0 0 */
453 	else
454 		rwx |= (rwx << 3);	/* r w x => Kr Kw Kx Ur Uw Ux */
455 
456 	pd1 = rwx | (pte_val(*ptep) & PTE_BITS_NON_RWX_IN_PD1);
457 
458 	tlb_entry_insert(pd0, pd1);
459 
460 	local_irq_restore(flags);
461 }
462 
463 /*
464  * Called at the end of pagefault, for a userspace mapped page
465  *  -pre-install the corresponding TLB entry into MMU
466  *  -Finalize the delayed D-cache flush of kernel mapping of page due to
467  *  	flush_dcache_page(), copy_user_page()
468  *
469  * Note that flush (when done) involves both WBACK - so physical page is
470  * in sync as well as INV - so any non-congruent aliases don't remain
471  */
472 void update_mmu_cache_range(struct vm_fault *vmf, struct vm_area_struct *vma,
473 		unsigned long vaddr_unaligned, pte_t *ptep, unsigned int nr)
474 {
475 	unsigned long vaddr = vaddr_unaligned & PAGE_MASK;
476 	phys_addr_t paddr = pte_val(*ptep) & PAGE_MASK_PHYS;
477 	struct page *page = pfn_to_page(pte_pfn(*ptep));
478 
479 	create_tlb(vma, vaddr, ptep);
480 
481 	if (page == ZERO_PAGE(0)) {
482 		return;
483 	}
484 
485 	/*
486 	 * Exec page : Independent of aliasing/page-color considerations,
487 	 *	       since icache doesn't snoop dcache on ARC, any dirty
488 	 *	       K-mapping of a code page needs to be wback+inv so that
489 	 *	       icache fetch by userspace sees code correctly.
490 	 * !EXEC page: If K-mapping is NOT congruent to U-mapping, flush it
491 	 *	       so userspace sees the right data.
492 	 *  (Avoids the flush for Non-exec + congruent mapping case)
493 	 */
494 	if ((vma->vm_flags & VM_EXEC) ||
495 	     addr_not_cache_congruent(paddr, vaddr)) {
496 		struct folio *folio = page_folio(page);
497 		int dirty = !test_and_set_bit(PG_dc_clean, &folio->flags);
498 		if (dirty) {
499 			unsigned long offset = offset_in_folio(folio, paddr);
500 			nr = folio_nr_pages(folio);
501 			paddr -= offset;
502 			vaddr -= offset;
503 			/* wback + inv dcache lines (K-mapping) */
504 			__flush_dcache_pages(paddr, paddr, nr);
505 
506 			/* invalidate any existing icache lines (U-mapping) */
507 			if (vma->vm_flags & VM_EXEC)
508 				__inv_icache_pages(paddr, vaddr, nr);
509 		}
510 	}
511 }
512 
513 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
514 
515 /*
516  * MMUv4 in HS38x cores supports Super Pages which are basis for Linux THP
517  * support.
518  *
519  * Normal and Super pages can co-exist (ofcourse not overlap) in TLB with a
520  * new bit "SZ" in TLB page descriptor to distinguish between them.
521  * Super Page size is configurable in hardware (4K to 16M), but fixed once
522  * RTL builds.
523  *
524  * The exact THP size a Linux configuration will support is a function of:
525  *  - MMU page size (typical 8K, RTL fixed)
526  *  - software page walker address split between PGD:PTE:PFN (typical
527  *    11:8:13, but can be changed with 1 line)
528  * So for above default, THP size supported is 8K * (2^8) = 2M
529  *
530  * Default Page Walker is 2 levels, PGD:PTE:PFN, which in THP regime
531  * reduces to 1 level (as PTE is folded into PGD and canonically referred
532  * to as PMD).
533  * Thus THP PMD accessors are implemented in terms of PTE (just like sparc)
534  */
535 
536 void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
537 				 pmd_t *pmd)
538 {
539 	pte_t pte = __pte(pmd_val(*pmd));
540 	update_mmu_cache_range(NULL, vma, addr, &pte, HPAGE_PMD_NR);
541 }
542 
543 void local_flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
544 			       unsigned long end)
545 {
546 	unsigned int cpu;
547 	unsigned long flags;
548 
549 	local_irq_save(flags);
550 
551 	cpu = smp_processor_id();
552 
553 	if (likely(asid_mm(vma->vm_mm, cpu) != MM_CTXT_NO_ASID)) {
554 		unsigned int asid = hw_pid(vma->vm_mm, cpu);
555 
556 		/* No need to loop here: this will always be for 1 Huge Page */
557 		tlb_entry_erase(start | _PAGE_HW_SZ | asid);
558 	}
559 
560 	local_irq_restore(flags);
561 }
562 
563 #endif
564 
565 /* Read the Cache Build Configuration Registers, Decode them and save into
566  * the cpuinfo structure for later use.
567  * No Validation is done here, simply read/convert the BCRs
568  */
569 int arc_mmu_mumbojumbo(int c, char *buf, int len)
570 {
571 	struct cpuinfo_arc_mmu *mmu = &mmuinfo;
572 	unsigned int bcr, u_dtlb, u_itlb, sasid;
573 	struct bcr_mmu_3 *mmu3;
574 	struct bcr_mmu_4 *mmu4;
575 	char super_pg[64] = "";
576 	int n = 0;
577 
578 	bcr = read_aux_reg(ARC_REG_MMU_BCR);
579 	mmu->ver = (bcr >> 24);
580 
581 	if (is_isa_arcompact() && mmu->ver == 3) {
582 		mmu3 = (struct bcr_mmu_3 *)&bcr;
583 		mmu->pg_sz_k = 1 << (mmu3->pg_sz - 1);
584 		mmu->sets = 1 << mmu3->sets;
585 		mmu->ways = 1 << mmu3->ways;
586 		u_dtlb = mmu3->u_dtlb;
587 		u_itlb = mmu3->u_itlb;
588 		sasid = mmu3->sasid;
589 	} else {
590 		mmu4 = (struct bcr_mmu_4 *)&bcr;
591 		mmu->pg_sz_k = 1 << (mmu4->sz0 - 1);
592 		mmu->s_pg_sz_m = 1 << (mmu4->sz1 - 11);
593 		mmu->sets = 64 << mmu4->n_entry;
594 		mmu->ways = mmu4->n_ways * 2;
595 		u_dtlb = mmu4->u_dtlb * 4;
596 		u_itlb = mmu4->u_itlb * 4;
597 		sasid = mmu4->sasid;
598 		mmu->pae = mmu4->pae;
599 	}
600 
601 	if (mmu->s_pg_sz_m)
602 		scnprintf(super_pg, 64, "/%dM%s",
603 			  mmu->s_pg_sz_m,
604 			  IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) ? " (THP enabled)":"");
605 
606 	n += scnprintf(buf + n, len - n,
607 		      "MMU [v%x]\t: %dk%s, swalk %d lvl, JTLB %dx%d, uDTLB %d, uITLB %d%s%s%s\n",
608 		       mmu->ver, mmu->pg_sz_k, super_pg, CONFIG_PGTABLE_LEVELS,
609 		       mmu->sets, mmu->ways,
610 		       u_dtlb, u_itlb,
611 		       IS_AVAIL1(sasid, ", SASID"),
612 		       IS_AVAIL2(mmu->pae, ", PAE40 ", CONFIG_ARC_HAS_PAE40));
613 
614 	return n;
615 }
616 
617 int pae40_exist_but_not_enab(void)
618 {
619 	return mmuinfo.pae && !is_pae40_enabled();
620 }
621 
622 void arc_mmu_init(void)
623 {
624 	struct cpuinfo_arc_mmu *mmu = &mmuinfo;
625 	int compat = 0;
626 
627 	/*
628 	 * Can't be done in processor.h due to header include dependencies
629 	 */
630 	BUILD_BUG_ON(!IS_ALIGNED((CONFIG_ARC_KVADDR_SIZE << 20), PMD_SIZE));
631 
632 	/*
633 	 * stack top size sanity check,
634 	 * Can't be done in processor.h due to header include dependencies
635 	 */
636 	BUILD_BUG_ON(!IS_ALIGNED(STACK_TOP, PMD_SIZE));
637 
638 	/*
639 	 * Ensure that MMU features assumed by kernel exist in hardware.
640 	 *  - For older ARC700 cpus, only v3 supported
641 	 *  - For HS cpus, v4 was baseline and v5 is backwards compatible
642 	 *    (will run older software).
643 	 */
644 	if (is_isa_arcompact() && mmu->ver == 3)
645 		compat = 1;
646 	else if (is_isa_arcv2() && mmu->ver >= 4)
647 		compat = 1;
648 
649 	if (!compat)
650 		panic("MMU ver %d doesn't match kernel built for\n", mmu->ver);
651 
652 	if (mmu->pg_sz_k != TO_KB(PAGE_SIZE))
653 		panic("MMU pg size != PAGE_SIZE (%luk)\n", TO_KB(PAGE_SIZE));
654 
655 	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
656 	    mmu->s_pg_sz_m != TO_MB(HPAGE_PMD_SIZE))
657 		panic("MMU Super pg size != Linux HPAGE_PMD_SIZE (%luM)\n",
658 		      (unsigned long)TO_MB(HPAGE_PMD_SIZE));
659 
660 	if (IS_ENABLED(CONFIG_ARC_HAS_PAE40) && !mmu->pae)
661 		panic("Hardware doesn't support PAE40\n");
662 
663 	/* Enable the MMU with ASID 0 */
664 	mmu_setup_asid(NULL, 0);
665 
666 	/* cache the pgd pointer in MMU SCRATCH reg (ARCv2 only) */
667 	mmu_setup_pgd(NULL, swapper_pg_dir);
668 
669 	if (pae40_exist_but_not_enab())
670 		write_aux_reg(ARC_REG_TLBPD1HI, 0);
671 }
672 
673 /*
674  * TLB Programmer's Model uses Linear Indexes: 0 to {255, 511} for 128 x {2,4}
675  * The mapping is Column-first.
676  *		---------------------	-----------
677  *		|way0|way1|way2|way3|	|way0|way1|
678  *		---------------------	-----------
679  * [set0]	|  0 |  1 |  2 |  3 |	|  0 |  1 |
680  * [set1]	|  4 |  5 |  6 |  7 |	|  2 |  3 |
681  *		~		    ~	~	  ~
682  * [set127]	| 508| 509| 510| 511|	| 254| 255|
683  *		---------------------	-----------
684  * For normal operations we don't(must not) care how above works since
685  * MMU cmd getIndex(vaddr) abstracts that out.
686  * However for walking WAYS of a SET, we need to know this
687  */
688 #define SET_WAY_TO_IDX(mmu, set, way)  ((set) * mmu->ways + (way))
689 
690 /* Handling of Duplicate PD (TLB entry) in MMU.
691  * -Could be due to buggy customer tapeouts or obscure kernel bugs
692  * -MMU complaints not at the time of duplicate PD installation, but at the
693  *      time of lookup matching multiple ways.
694  * -Ideally these should never happen - but if they do - workaround by deleting
695  *      the duplicate one.
696  * -Knob to be verbose abt it.(TODO: hook them up to debugfs)
697  */
698 volatile int dup_pd_silent; /* Be silent abt it or complain (default) */
699 
700 void do_tlb_overlap_fault(unsigned long cause, unsigned long address,
701 			  struct pt_regs *regs)
702 {
703 	struct cpuinfo_arc_mmu *mmu = &mmuinfo;
704 	unsigned long flags;
705 	int set, n_ways = mmu->ways;
706 
707 	n_ways = min(n_ways, 4);
708 	BUG_ON(mmu->ways > 4);
709 
710 	local_irq_save(flags);
711 
712 	/* loop thru all sets of TLB */
713 	for (set = 0; set < mmu->sets; set++) {
714 
715 		int is_valid, way;
716 		unsigned int pd0[4];
717 
718 		/* read out all the ways of current set */
719 		for (way = 0, is_valid = 0; way < n_ways; way++) {
720 			write_aux_reg(ARC_REG_TLBINDEX,
721 					  SET_WAY_TO_IDX(mmu, set, way));
722 			write_aux_reg(ARC_REG_TLBCOMMAND, TLBRead);
723 			pd0[way] = read_aux_reg(ARC_REG_TLBPD0);
724 			is_valid |= pd0[way] & _PAGE_PRESENT;
725 			pd0[way] &= PAGE_MASK;
726 		}
727 
728 		/* If all the WAYS in SET are empty, skip to next SET */
729 		if (!is_valid)
730 			continue;
731 
732 		/* Scan the set for duplicate ways: needs a nested loop */
733 		for (way = 0; way < n_ways - 1; way++) {
734 
735 			int n;
736 
737 			if (!pd0[way])
738 				continue;
739 
740 			for (n = way + 1; n < n_ways; n++) {
741 				if (pd0[way] != pd0[n])
742 					continue;
743 
744 				if (!dup_pd_silent)
745 					pr_info("Dup TLB PD0 %08x @ set %d ways %d,%d\n",
746 						pd0[way], set, way, n);
747 
748 				/*
749 				 * clear entry @way and not @n.
750 				 * This is critical to our optimised loop
751 				 */
752 				pd0[way] = 0;
753 				write_aux_reg(ARC_REG_TLBINDEX,
754 						SET_WAY_TO_IDX(mmu, set, way));
755 				__tlb_entry_erase();
756 			}
757 		}
758 	}
759 
760 	local_irq_restore(flags);
761 }
762