xref: /linux/arch/sparc/include/asm/mmu_context_64.h (revision 79790b6818e96c58fe2bffee1b418c16e64e7b80)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __SPARC64_MMU_CONTEXT_H
3 #define __SPARC64_MMU_CONTEXT_H
4 
5 /* Derived heavily from Linus's Alpha/AXP ASN code... */
6 
7 #ifndef __ASSEMBLY__
8 
9 #include <linux/spinlock.h>
10 #include <linux/mm_types.h>
11 #include <linux/smp.h>
12 #include <linux/sched.h>
13 
14 #include <asm/spitfire.h>
15 #include <asm/adi_64.h>
16 #include <asm-generic/mm_hooks.h>
17 #include <asm/percpu.h>
18 
19 extern spinlock_t ctx_alloc_lock;
20 extern unsigned long tlb_context_cache;
21 extern unsigned long mmu_context_bmap[];
22 
23 DECLARE_PER_CPU(struct mm_struct *, per_cpu_secondary_mm);
24 void get_new_mmu_context(struct mm_struct *mm);
25 
26 #define init_new_context init_new_context
27 int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
28 #define destroy_context destroy_context
29 void destroy_context(struct mm_struct *mm);
30 
31 void __tsb_context_switch(unsigned long pgd_pa,
32 			  struct tsb_config *tsb_base,
33 			  struct tsb_config *tsb_huge,
34 			  unsigned long tsb_descr_pa,
35 			  unsigned long secondary_ctx);
36 
tsb_context_switch_ctx(struct mm_struct * mm,unsigned long ctx)37 static inline void tsb_context_switch_ctx(struct mm_struct *mm,
38 					  unsigned long ctx)
39 {
40 	__tsb_context_switch(__pa(mm->pgd),
41 			     &mm->context.tsb_block[MM_TSB_BASE],
42 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
43 			     (mm->context.tsb_block[MM_TSB_HUGE].tsb ?
44 			      &mm->context.tsb_block[MM_TSB_HUGE] :
45 			      NULL)
46 #else
47 			     NULL
48 #endif
49 			     , __pa(&mm->context.tsb_descr[MM_TSB_BASE]),
50 			     ctx);
51 }
52 
53 #define tsb_context_switch(X) tsb_context_switch_ctx(X, 0)
54 
55 void tsb_grow(struct mm_struct *mm,
56 	      unsigned long tsb_index,
57 	      unsigned long mm_rss);
58 #ifdef CONFIG_SMP
59 void smp_tsb_sync(struct mm_struct *mm);
60 #else
61 #define smp_tsb_sync(__mm) do { } while (0)
62 #endif
63 
64 /* Set MMU context in the actual hardware. */
65 #define load_secondary_context(__mm) \
66 	__asm__ __volatile__( \
67 	"\n661:	stxa		%0, [%1] %2\n" \
68 	"	.section	.sun4v_1insn_patch, \"ax\"\n" \
69 	"	.word		661b\n" \
70 	"	stxa		%0, [%1] %3\n" \
71 	"	.previous\n" \
72 	"	flush		%%g6\n" \
73 	: /* No outputs */ \
74 	: "r" (CTX_HWBITS((__mm)->context)), \
75 	  "r" (SECONDARY_CONTEXT), "i" (ASI_DMMU), "i" (ASI_MMU))
76 
77 void __flush_tlb_mm(unsigned long, unsigned long);
78 
79 /* Switch the current MM context. */
switch_mm(struct mm_struct * old_mm,struct mm_struct * mm,struct task_struct * tsk)80 static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, struct task_struct *tsk)
81 {
82 	unsigned long ctx_valid, flags;
83 	int cpu = smp_processor_id();
84 
85 	per_cpu(per_cpu_secondary_mm, cpu) = mm;
86 	if (unlikely(mm == &init_mm))
87 		return;
88 
89 	spin_lock_irqsave(&mm->context.lock, flags);
90 	ctx_valid = CTX_VALID(mm->context);
91 	if (!ctx_valid)
92 		get_new_mmu_context(mm);
93 
94 	/* We have to be extremely careful here or else we will miss
95 	 * a TSB grow if we switch back and forth between a kernel
96 	 * thread and an address space which has its TSB size increased
97 	 * on another processor.
98 	 *
99 	 * It is possible to play some games in order to optimize the
100 	 * switch, but the safest thing to do is to unconditionally
101 	 * perform the secondary context load and the TSB context switch.
102 	 *
103 	 * For reference the bad case is, for address space "A":
104 	 *
105 	 *		CPU 0			CPU 1
106 	 *	run address space A
107 	 *	set cpu0's bits in cpu_vm_mask
108 	 *	switch to kernel thread, borrow
109 	 *	address space A via entry_lazy_tlb
110 	 *					run address space A
111 	 *					set cpu1's bit in cpu_vm_mask
112 	 *					flush_tlb_pending()
113 	 *					reset cpu_vm_mask to just cpu1
114 	 *					TSB grow
115 	 *	run address space A
116 	 *	context was valid, so skip
117 	 *	TSB context switch
118 	 *
119 	 * At that point cpu0 continues to use a stale TSB, the one from
120 	 * before the TSB grow performed on cpu1.  cpu1 did not cross-call
121 	 * cpu0 to update its TSB because at that point the cpu_vm_mask
122 	 * only had cpu1 set in it.
123 	 */
124 	tsb_context_switch_ctx(mm, CTX_HWBITS(mm->context));
125 
126 	/* Any time a processor runs a context on an address space
127 	 * for the first time, we must flush that context out of the
128 	 * local TLB.
129 	 */
130 	if (!ctx_valid || !cpumask_test_cpu(cpu, mm_cpumask(mm))) {
131 		cpumask_set_cpu(cpu, mm_cpumask(mm));
132 		__flush_tlb_mm(CTX_HWBITS(mm->context),
133 			       SECONDARY_CONTEXT);
134 	}
135 	spin_unlock_irqrestore(&mm->context.lock, flags);
136 }
137 
138 #define activate_mm(active_mm, mm) switch_mm(active_mm, mm, NULL)
139 
140 #define  __HAVE_ARCH_START_CONTEXT_SWITCH
arch_start_context_switch(struct task_struct * prev)141 static inline void arch_start_context_switch(struct task_struct *prev)
142 {
143 	/* Save the current state of MCDPER register for the process
144 	 * we are switching from
145 	 */
146 	if (adi_capable()) {
147 		register unsigned long tmp_mcdper;
148 
149 		__asm__ __volatile__(
150 			".word 0x83438000\n\t"	/* rd  %mcdper, %g1 */
151 			"mov %%g1, %0\n\t"
152 			: "=r" (tmp_mcdper)
153 			:
154 			: "g1");
155 		if (tmp_mcdper)
156 			set_tsk_thread_flag(prev, TIF_MCDPER);
157 		else
158 			clear_tsk_thread_flag(prev, TIF_MCDPER);
159 	}
160 }
161 
162 #define finish_arch_post_lock_switch	finish_arch_post_lock_switch
finish_arch_post_lock_switch(void)163 static inline void finish_arch_post_lock_switch(void)
164 {
165 	/* Restore the state of MCDPER register for the new process
166 	 * just switched to.
167 	 */
168 	if (adi_capable()) {
169 		register unsigned long tmp_mcdper;
170 
171 		tmp_mcdper = test_thread_flag(TIF_MCDPER);
172 		__asm__ __volatile__(
173 			"mov %0, %%g1\n\t"
174 			".word 0x9d800001\n\t"	/* wr %g0, %g1, %mcdper" */
175 			".word 0xaf902001\n\t"	/* wrpr %g0, 1, %pmcdper */
176 			:
177 			: "ir" (tmp_mcdper)
178 			: "g1");
179 		if (current && current->mm && current->mm->context.adi) {
180 			struct pt_regs *regs;
181 
182 			regs = task_pt_regs(current);
183 			regs->tstate |= TSTATE_MCDE;
184 		}
185 	}
186 }
187 
188 #define mm_untag_mask mm_untag_mask
mm_untag_mask(struct mm_struct * mm)189 static inline unsigned long mm_untag_mask(struct mm_struct *mm)
190 {
191        return -1UL >> adi_nbits();
192 }
193 
194 #include <asm-generic/mmu_context.h>
195 
196 #endif /* !(__ASSEMBLY__) */
197 
198 #endif /* !(__SPARC64_MMU_CONTEXT_H) */
199