/arch/sparc/include/asm/mmu_context_64.h

  1#ifndef __SPARC64_MMU_CONTEXT_H
  2#define __SPARC64_MMU_CONTEXT_H
  3
  4/* Derived heavily from Linus's Alpha/AXP ASN code... */
  5
  6#ifndef __ASSEMBLY__
  7
  8#include <linux/spinlock.h>
  9#include <asm/system.h>
 10#include <asm/spitfire.h>
 11#include <asm-generic/mm_hooks.h>
 12
 13static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 14{
 15}
 16
 17extern spinlock_t ctx_alloc_lock;
 18extern unsigned long tlb_context_cache;
 19extern unsigned long mmu_context_bmap[];
 20
 21extern void get_new_mmu_context(struct mm_struct *mm);
 22#ifdef CONFIG_SMP
 23extern void smp_new_mmu_context_version(void);
 24#else
 25#define smp_new_mmu_context_version() do { } while (0)
 26#endif
 27
 28extern int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
 29extern void destroy_context(struct mm_struct *mm);
 30
 31extern 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
 36static inline void tsb_context_switch(struct mm_struct *mm)
 37{
 38	__tsb_context_switch(__pa(mm->pgd),
 39			     &mm->context.tsb_block[0],
 40#ifdef CONFIG_HUGETLB_PAGE
 41			     (mm->context.tsb_block[1].tsb ?
 42			      &mm->context.tsb_block[1] :
 43			      NULL)
 44#else
 45			     NULL
 46#endif
 47			     , __pa(&mm->context.tsb_descr[0]));
 48}
 49
 50extern void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long mm_rss);
 51#ifdef CONFIG_SMP
 52extern void smp_tsb_sync(struct mm_struct *mm);
 53#else
 54#define smp_tsb_sync(__mm) do { } while (0)
 55#endif
 56
 57/* Set MMU context in the actual hardware. */
 58#define load_secondary_context(__mm) \
 59	__asm__ __volatile__( \
 60	"\n661:	stxa		%0, [%1] %2\n" \
 61	"	.section	.sun4v_1insn_patch, \"ax\"\n" \
 62	"	.word		661b\n" \
 63	"	stxa		%0, [%1] %3\n" \
 64	"	.previous\n" \
 65	"	flush		%%g6\n" \
 66	: /* No outputs */ \
 67	: "r" (CTX_HWBITS((__mm)->context)), \
 68	  "r" (SECONDARY_CONTEXT), "i" (ASI_DMMU), "i" (ASI_MMU))
 69
 70extern void __flush_tlb_mm(unsigned long, unsigned long);
 71
 72/* Switch the current MM context.  Interrupts are disabled.  */
 73static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, struct task_struct *tsk)
 74{
 75	unsigned long ctx_valid, flags;
 76	int cpu;
 77
 78	if (unlikely(mm == &init_mm))
 79		return;
 80
 81	spin_lock_irqsave(&mm->context.lock, flags);
 82	ctx_valid = CTX_VALID(mm->context);
 83	if (!ctx_valid)
 84		get_new_mmu_context(mm);
 85
 86	/* We have to be extremely careful here or else we will miss
 87	 * a TSB grow if we switch back and forth between a kernel
 88	 * thread and an address space which has it's TSB size increased
 89	 * on another processor.
 90	 *
 91	 * It is possible to play some games in order to optimize the
 92	 * switch, but the safest thing to do is to unconditionally
 93	 * perform the secondary context load and the TSB context switch.
 94	 *
 95	 * For reference the bad case is, for address space "A":
 96	 *
 97	 *		CPU 0			CPU 1
 98	 *	run address space A
 99	 *	set cpu0's bits in cpu_vm_mask
100	 *	switch to kernel thread, borrow
101	 *	address space A via entry_lazy_tlb
102	 *					run address space A
103	 *					set cpu1's bit in cpu_vm_mask
104	 *					flush_tlb_pending()
105	 *					reset cpu_vm_mask to just cpu1
106	 *					TSB grow
107	 *	run address space A
108	 *	context was valid, so skip
109	 *	TSB context switch
110	 *
111	 * At that point cpu0 continues to use a stale TSB, the one from
112	 * before the TSB grow performed on cpu1.  cpu1 did not cross-call
113	 * cpu0 to update it's TSB because at that point the cpu_vm_mask
114	 * only had cpu1 set in it.
115	 */
116	load_secondary_context(mm);
117	tsb_context_switch(mm);
118
119	/* Any time a processor runs a context on an address space
120	 * for the first time, we must flush that context out of the
121	 * local TLB.
122	 */
123	cpu = smp_processor_id();
124	if (!ctx_valid || !cpumask_test_cpu(cpu, mm_cpumask(mm))) {
125		cpumask_set_cpu(cpu, mm_cpumask(mm));
126		__flush_tlb_mm(CTX_HWBITS(mm->context),
127			       SECONDARY_CONTEXT);
128	}
129	spin_unlock_irqrestore(&mm->context.lock, flags);
130}
131
132#define deactivate_mm(tsk,mm)	do { } while (0)
133
134/* Activate a new MM instance for the current task. */
135static inline void activate_mm(struct mm_struct *active_mm, struct mm_struct *mm)
136{
137	unsigned long flags;
138	int cpu;
139
140	spin_lock_irqsave(&mm->context.lock, flags);
141	if (!CTX_VALID(mm->context))
142		get_new_mmu_context(mm);
143	cpu = smp_processor_id();
144	if (!cpumask_test_cpu(cpu, mm_cpumask(mm)))
145		cpumask_set_cpu(cpu, mm_cpumask(mm));
146
147	load_secondary_context(mm);
148	__flush_tlb_mm(CTX_HWBITS(mm->context), SECONDARY_CONTEXT);
149	tsb_context_switch(mm);
150	spin_unlock_irqrestore(&mm->context.lock, flags);
151}
152
153#endif /* !(__ASSEMBLY__) */
154
155#endif /* !(__SPARC64_MMU_CONTEXT_H) */