1/*
2 * Switch a MMU context.
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License.  See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 1996, 1997, 1998, 1999 by Ralf Baechle
9 * Copyright (C) 1999 Silicon Graphics, Inc.
10 */
11#ifndef _ASM_MMU_CONTEXT_H
12#define _ASM_MMU_CONTEXT_H
13
14#include <linux/errno.h>
15#include <linux/sched.h>
16#include <linux/slab.h>
17#include <asm/cacheflush.h>
18#include <asm/tlbflush.h>
19#ifdef CONFIG_MIPS_MT_SMTC
20#include <asm/mipsmtregs.h>
21#include <asm/smtc.h>
22#endif /* SMTC */
23#include <asm-generic/mm_hooks.h>
24
25/*
26 * For the fast tlb miss handlers, we keep a per cpu array of pointers
27 * to the current pgd for each processor. Also, the proc. id is stuffed
28 * into the context register.
29 */
30extern unsigned long pgd_current[];
31
32#define TLBMISS_HANDLER_SETUP_PGD(pgd) \
33	pgd_current[smp_processor_id()] = (unsigned long)(pgd)
34
35#ifdef CONFIG_32BIT
36#define TLBMISS_HANDLER_SETUP()						\
37	write_c0_context((unsigned long) smp_processor_id() << 25);	\
38	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
39#endif
40#ifdef CONFIG_64BIT
41#define TLBMISS_HANDLER_SETUP()						\
42	write_c0_context((unsigned long) smp_processor_id() << 26);	\
43	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
44#endif
45
46#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
47
48#define ASID_INC	0x40
49#define ASID_MASK	0xfc0
50
51#elif defined(CONFIG_CPU_R8000)
52
53#define ASID_INC	0x10
54#define ASID_MASK	0xff0
55
56#elif defined(CONFIG_CPU_RM9000)
57
58#define ASID_INC	0x1
59#define ASID_MASK	0xfff
60
61/* SMTC/34K debug hack - but maybe we'll keep it */
62#elif defined(CONFIG_MIPS_MT_SMTC)
63
64#define ASID_INC	0x1
65extern unsigned long smtc_asid_mask;
66#define ASID_MASK	(smtc_asid_mask)
67#define	HW_ASID_MASK	0xff
68/* End SMTC/34K debug hack */
69#else
70
71#define ASID_INC	0x1
72#define ASID_MASK	0xff
73
74#endif
75
76#define cpu_context(cpu, mm)	((mm)->context[cpu])
77#define cpu_asid(cpu, mm)	(cpu_context((cpu), (mm)) & ASID_MASK)
78#define asid_cache(cpu)		(cpu_data[cpu].asid_cache)
79
80static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
81{
82}
83
84/*
85 *  All unused by hardware upper bits will be considered
86 *  as a software asid extension.
87 */
88#define ASID_VERSION_MASK  ((unsigned long)~(ASID_MASK|(ASID_MASK-1)))
89#define ASID_FIRST_VERSION ((unsigned long)(~ASID_VERSION_MASK) + 1)
90
91#ifndef CONFIG_MIPS_MT_SMTC
92/* Normal, classic MIPS get_new_mmu_context */
93static inline void
94get_new_mmu_context(struct mm_struct *mm, unsigned long cpu)
95{
96	unsigned long asid = asid_cache(cpu);
97
98	if (! ((asid += ASID_INC) & ASID_MASK) ) {
99		if (cpu_has_vtag_icache)
100			flush_icache_all();
101		local_flush_tlb_all();	/* start new asid cycle */
102		if (!asid)		/* fix version if needed */
103			asid = ASID_FIRST_VERSION;
104	}
105	cpu_context(cpu, mm) = asid_cache(cpu) = asid;
106}
107
108#else /* CONFIG_MIPS_MT_SMTC */
109
110#define get_new_mmu_context(mm,cpu) smtc_get_new_mmu_context((mm),(cpu))
111
112#endif /* CONFIG_MIPS_MT_SMTC */
113
114/*
115 * Initialize the context related info for a new mm_struct
116 * instance.
117 */
118static inline int
119init_new_context(struct task_struct *tsk, struct mm_struct *mm)
120{
121	int i;
122
123	for (i = 0; i < num_online_cpus(); i++)
124		cpu_context(i, mm) = 0;
125
126	return 0;
127}
128
129static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
130                             struct task_struct *tsk)
131{
132	unsigned int cpu = smp_processor_id();
133	unsigned long flags;
134#ifdef CONFIG_MIPS_MT_SMTC
135	unsigned long oldasid;
136	unsigned long mtflags;
137	int mytlb = (smtc_status & SMTC_TLB_SHARED) ? 0 : cpu_data[cpu].vpe_id;
138	local_irq_save(flags);
139	mtflags = dvpe();
140#else /* Not SMTC */
141	local_irq_save(flags);
142#endif /* CONFIG_MIPS_MT_SMTC */
143
144	/* Check if our ASID is of an older version and thus invalid */
145	if ((cpu_context(cpu, next) ^ asid_cache(cpu)) & ASID_VERSION_MASK)
146		get_new_mmu_context(next, cpu);
147#ifdef CONFIG_MIPS_MT_SMTC
148	/*
149	 * If the EntryHi ASID being replaced happens to be
150	 * the value flagged at ASID recycling time as having
151	 * an extended life, clear the bit showing it being
152	 * in use by this "CPU", and if that's the last bit,
153	 * free up the ASID value for use and flush any old
154	 * instances of it from the TLB.
155	 */
156	oldasid = (read_c0_entryhi() & ASID_MASK);
157	if(smtc_live_asid[mytlb][oldasid]) {
158		smtc_live_asid[mytlb][oldasid] &= ~(0x1 << cpu);
159		if(smtc_live_asid[mytlb][oldasid] == 0)
160			smtc_flush_tlb_asid(oldasid);
161	}
162	/*
163	 * Tread softly on EntryHi, and so long as we support
164	 * having ASID_MASK smaller than the hardware maximum,
165	 * make sure no "soft" bits become "hard"...
166	 */
167	write_c0_entryhi((read_c0_entryhi() & ~HW_ASID_MASK)
168			| (cpu_context(cpu, next) & ASID_MASK));
169	ehb(); /* Make sure it propagates to TCStatus */
170	evpe(mtflags);
171#else
172	write_c0_entryhi(cpu_context(cpu, next));
173#endif /* CONFIG_MIPS_MT_SMTC */
174	TLBMISS_HANDLER_SETUP_PGD(next->pgd);
175
176	/*
177	 * Mark current->active_mm as not "active" anymore.
178	 * We don't want to mislead possible IPI tlb flush routines.
179	 */
180	cpu_clear(cpu, prev->cpu_vm_mask);
181	cpu_set(cpu, next->cpu_vm_mask);
182
183	local_irq_restore(flags);
184}
185
186/*
187 * Destroy context related info for an mm_struct that is about
188 * to be put to rest.
189 */
190static inline void destroy_context(struct mm_struct *mm)
191{
192}
193
194#define deactivate_mm(tsk,mm)	do { } while (0)
195
196/*
197 * After we have set current->mm to a new value, this activates
198 * the context for the new mm so we see the new mappings.
199 */
200static inline void
201activate_mm(struct mm_struct *prev, struct mm_struct *next)
202{
203	unsigned long flags;
204	unsigned int cpu = smp_processor_id();
205
206#ifdef CONFIG_MIPS_MT_SMTC
207	unsigned long oldasid;
208	unsigned long mtflags;
209	int mytlb = (smtc_status & SMTC_TLB_SHARED) ? 0 : cpu_data[cpu].vpe_id;
210#endif /* CONFIG_MIPS_MT_SMTC */
211
212	local_irq_save(flags);
213
214	/* Unconditionally get a new ASID.  */
215	get_new_mmu_context(next, cpu);
216
217#ifdef CONFIG_MIPS_MT_SMTC
218	/* See comments for similar code above */
219	mtflags = dvpe();
220	oldasid = read_c0_entryhi() & ASID_MASK;
221	if(smtc_live_asid[mytlb][oldasid]) {
222		smtc_live_asid[mytlb][oldasid] &= ~(0x1 << cpu);
223       		if(smtc_live_asid[mytlb][oldasid] == 0)
224               		 smtc_flush_tlb_asid(oldasid);
225	}
226	/* See comments for similar code above */
227	write_c0_entryhi((read_c0_entryhi() & ~HW_ASID_MASK) |
228	                 (cpu_context(cpu, next) & ASID_MASK));
229	ehb(); /* Make sure it propagates to TCStatus */
230	evpe(mtflags);
231#else
232	write_c0_entryhi(cpu_context(cpu, next));
233#endif /* CONFIG_MIPS_MT_SMTC */
234	TLBMISS_HANDLER_SETUP_PGD(next->pgd);
235
236	/* mark mmu ownership change */
237	cpu_clear(cpu, prev->cpu_vm_mask);
238	cpu_set(cpu, next->cpu_vm_mask);
239
240	local_irq_restore(flags);
241}
242
243/*
244 * If mm is currently active_mm, we can't really drop it.  Instead,
245 * we will get a new one for it.
246 */
247static inline void
248drop_mmu_context(struct mm_struct *mm, unsigned cpu)
249{
250	unsigned long flags;
251#ifdef CONFIG_MIPS_MT_SMTC
252	unsigned long oldasid;
253	/* Can't use spinlock because called from TLB flush within DVPE */
254	unsigned int prevvpe;
255	int mytlb = (smtc_status & SMTC_TLB_SHARED) ? 0 : cpu_data[cpu].vpe_id;
256#endif /* CONFIG_MIPS_MT_SMTC */
257
258	local_irq_save(flags);
259
260	if (cpu_isset(cpu, mm->cpu_vm_mask))  {
261		get_new_mmu_context(mm, cpu);
262#ifdef CONFIG_MIPS_MT_SMTC
263		/* See comments for similar code above */
264		prevvpe = dvpe();
265		oldasid = (read_c0_entryhi() & ASID_MASK);
266		if (smtc_live_asid[mytlb][oldasid]) {
267			smtc_live_asid[mytlb][oldasid] &= ~(0x1 << cpu);
268			if(smtc_live_asid[mytlb][oldasid] == 0)
269				smtc_flush_tlb_asid(oldasid);
270		}
271		/* See comments for similar code above */
272		write_c0_entryhi((read_c0_entryhi() & ~HW_ASID_MASK)
273				| cpu_asid(cpu, mm));
274		ehb(); /* Make sure it propagates to TCStatus */
275		evpe(prevvpe);
276#else /* not CONFIG_MIPS_MT_SMTC */
277		write_c0_entryhi(cpu_asid(cpu, mm));
278#endif /* CONFIG_MIPS_MT_SMTC */
279	} else {
280		/* will get a new context next time */
281#ifndef CONFIG_MIPS_MT_SMTC
282		cpu_context(cpu, mm) = 0;
283#else /* SMTC */
284		int i;
285
286		/* SMTC shares the TLB (and ASIDs) across VPEs */
287		for (i = 0; i < num_online_cpus(); i++) {
288	    	    if((smtc_status & SMTC_TLB_SHARED)
289	    	    || (cpu_data[i].vpe_id == cpu_data[cpu].vpe_id))
290			cpu_context(i, mm) = 0;
291		}
292#endif /* CONFIG_MIPS_MT_SMTC */
293	}
294	local_irq_restore(flags);
295}
296
297#endif /* _ASM_MMU_CONTEXT_H */
298