diff options
Diffstat (limited to 'include/asm-sparc64/mmu_context.h')
| -rw-r--r-- | include/asm-sparc64/mmu_context.h | 50 |
1 files changed, 38 insertions, 12 deletions
diff --git a/include/asm-sparc64/mmu_context.h b/include/asm-sparc64/mmu_context.h index ca36ea9..e797432 100644 --- a/include/asm-sparc64/mmu_context.h +++ b/include/asm-sparc64/mmu_context.h @@ -42,7 +42,7 @@ static inline void tsb_context_switch(struct mm_struct *mm) __pa(&mm->context.tsb_descr)); } -extern void tsb_grow(struct mm_struct *mm, unsigned long mm_rss, gfp_t gfp_flags); +extern void tsb_grow(struct mm_struct *mm, unsigned long mm_rss); #ifdef CONFIG_SMP extern void smp_tsb_sync(struct mm_struct *mm); #else @@ -74,18 +74,43 @@ static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, str ctx_valid = CTX_VALID(mm->context); if (!ctx_valid) get_new_mmu_context(mm); - spin_unlock_irqrestore(&mm->context.lock, flags); - if (!ctx_valid || (old_mm != mm)) { - load_secondary_context(mm); - tsb_context_switch(mm); - } + /* We have to be extremely careful here or else we will miss + * a TSB grow if we switch back and forth between a kernel + * thread and an address space which has it's TSB size increased + * on another processor. + * + * It is possible to play some games in order to optimize the + * switch, but the safest thing to do is to unconditionally + * perform the secondary context load and the TSB context switch. + * + * For reference the bad case is, for address space "A": + * + * CPU 0 CPU 1 + * run address space A + * set cpu0's bits in cpu_vm_mask + * switch to kernel thread, borrow + * address space A via entry_lazy_tlb + * run address space A + * set cpu1's bit in cpu_vm_mask + * flush_tlb_pending() + * reset cpu_vm_mask to just cpu1 + * TSB grow + * run address space A + * context was valid, so skip + * TSB context switch + * + * At that point cpu0 continues to use a stale TSB, the one from + * before the TSB grow performed on cpu1. cpu1 did not cross-call + * cpu0 to update it's TSB because at that point the cpu_vm_mask + * only had cpu1 set in it. + */ + load_secondary_context(mm); + tsb_context_switch(mm); - /* Even if (mm == old_mm) we _must_ check - * the cpu_vm_mask. If we do not we could - * corrupt the TLB state because of how - * smp_flush_tlb_{page,range,mm} on sparc64 - * and lazy tlb switches work. -DaveM + /* Any time a processor runs a context on an address space + * for the first time, we must flush that context out of the + * local TLB. */ cpu = smp_processor_id(); if (!ctx_valid || !cpu_isset(cpu, mm->cpu_vm_mask)) { @@ -93,6 +118,7 @@ static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, str __flush_tlb_mm(CTX_HWBITS(mm->context), SECONDARY_CONTEXT); } + spin_unlock_irqrestore(&mm->context.lock, flags); } #define deactivate_mm(tsk,mm) do { } while (0) @@ -109,11 +135,11 @@ static inline void activate_mm(struct mm_struct *active_mm, struct mm_struct *mm cpu = smp_processor_id(); if (!cpu_isset(cpu, mm->cpu_vm_mask)) cpu_set(cpu, mm->cpu_vm_mask); - spin_unlock_irqrestore(&mm->context.lock, flags); load_secondary_context(mm); __flush_tlb_mm(CTX_HWBITS(mm->context), SECONDARY_CONTEXT); tsb_context_switch(mm); + spin_unlock_irqrestore(&mm->context.lock, flags); } #endif /* !(__ASSEMBLY__) */ |