diff options
Diffstat (limited to 'arch/sparc64/mm/tsb.c')
-rw-r--r-- | arch/sparc64/mm/tsb.c | 185 |
1 files changed, 82 insertions, 103 deletions
diff --git a/arch/sparc64/mm/tsb.c b/arch/sparc64/mm/tsb.c index f36799b..7fbe1e0 100644 --- a/arch/sparc64/mm/tsb.c +++ b/arch/sparc64/mm/tsb.c @@ -48,11 +48,15 @@ void flush_tsb_kernel_range(unsigned long start, unsigned long end) void flush_tsb_user(struct mmu_gather *mp) { struct mm_struct *mm = mp->mm; - struct tsb *tsb = mm->context.tsb; - unsigned long nentries = mm->context.tsb_nentries; - unsigned long base; + unsigned long nentries, base, flags; + struct tsb *tsb; int i; + spin_lock_irqsave(&mm->context.lock, flags); + + tsb = mm->context.tsb; + nentries = mm->context.tsb_nentries; + if (tlb_type == cheetah_plus || tlb_type == hypervisor) base = __pa(tsb); else @@ -70,6 +74,8 @@ void flush_tsb_user(struct mmu_gather *mp) tsb_flush(ent, tag); } + + spin_unlock_irqrestore(&mm->context.lock, flags); } static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_bytes) @@ -201,86 +207,9 @@ static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_bytes) } } -/* The page tables are locked against modifications while this - * runs. - * - * XXX do some prefetching... - */ -static void copy_tsb(struct tsb *old_tsb, unsigned long old_size, - struct tsb *new_tsb, unsigned long new_size) -{ - unsigned long old_nentries = old_size / sizeof(struct tsb); - unsigned long new_nentries = new_size / sizeof(struct tsb); - unsigned long i; - - for (i = 0; i < old_nentries; i++) { - register unsigned long tag asm("o4"); - register unsigned long pte asm("o5"); - unsigned long v, hash; - - if (tlb_type == hypervisor) { - __asm__ __volatile__( - "ldda [%2] %3, %0" - : "=r" (tag), "=r" (pte) - : "r" (__pa(&old_tsb[i])), - "i" (ASI_QUAD_LDD_PHYS_4V)); - } else if (tlb_type == cheetah_plus) { - __asm__ __volatile__( - "ldda [%2] %3, %0" - : "=r" (tag), "=r" (pte) - : "r" (__pa(&old_tsb[i])), - "i" (ASI_QUAD_LDD_PHYS)); - } else { - __asm__ __volatile__( - "ldda [%2] %3, %0" - : "=r" (tag), "=r" (pte) - : "r" (&old_tsb[i]), - "i" (ASI_NUCLEUS_QUAD_LDD)); - } - - if (tag & ((1UL << TSB_TAG_LOCK_BIT) | - (1UL << TSB_TAG_INVALID_BIT))) - continue; - - /* We only put base page size PTEs into the TSB, - * but that might change in the future. This code - * would need to be changed if we start putting larger - * page size PTEs into there. - */ - WARN_ON((pte & _PAGE_ALL_SZ_BITS) != _PAGE_SZBITS); - - /* The tag holds bits 22 to 63 of the virtual address - * and the context. Clear out the context, and shift - * up to make a virtual address. - */ - v = (tag & ((1UL << 42UL) - 1UL)) << 22UL; - - /* The implied bits of the tag (bits 13 to 21) are - * determined by the TSB entry index, so fill that in. - */ - v |= (i & (512UL - 1UL)) << 13UL; - - hash = tsb_hash(v, new_nentries); - if (tlb_type == cheetah_plus || - tlb_type == hypervisor) { - __asm__ __volatile__( - "stxa %0, [%1] %2\n\t" - "stxa %3, [%4] %2" - : /* no outputs */ - : "r" (tag), - "r" (__pa(&new_tsb[hash].tag)), - "i" (ASI_PHYS_USE_EC), - "r" (pte), - "r" (__pa(&new_tsb[hash].pte))); - } else { - new_tsb[hash].tag = tag; - new_tsb[hash].pte = pte; - } - } -} - /* When the RSS of an address space exceeds mm->context.tsb_rss_limit, - * update_mmu_cache() invokes this routine to try and grow the TSB. + * do_sparc64_fault() invokes this routine to try and grow the TSB. + * * When we reach the maximum TSB size supported, we stick ~0UL into * mm->context.tsb_rss_limit so the grow checks in update_mmu_cache() * will not trigger any longer. @@ -293,12 +222,12 @@ static void copy_tsb(struct tsb *old_tsb, unsigned long old_size, * the number of entries that the current TSB can hold at once. Currently, * we trigger when the RSS hits 3/4 of the TSB capacity. */ -void tsb_grow(struct mm_struct *mm, unsigned long rss, gfp_t gfp_flags) +void tsb_grow(struct mm_struct *mm, unsigned long rss) { unsigned long max_tsb_size = 1 * 1024 * 1024; - unsigned long size, old_size; + unsigned long size, old_size, flags; struct page *page; - struct tsb *old_tsb; + struct tsb *old_tsb, *new_tsb; if (max_tsb_size > (PAGE_SIZE << MAX_ORDER)) max_tsb_size = (PAGE_SIZE << MAX_ORDER); @@ -311,12 +240,51 @@ void tsb_grow(struct mm_struct *mm, unsigned long rss, gfp_t gfp_flags) break; } - page = alloc_pages(gfp_flags, get_order(size)); + page = alloc_pages(GFP_KERNEL, get_order(size)); if (unlikely(!page)) return; /* Mark all tags as invalid. */ - memset(page_address(page), 0x40, size); + new_tsb = page_address(page); + memset(new_tsb, 0x40, size); + + /* Ok, we are about to commit the changes. If we are + * growing an existing TSB the locking is very tricky, + * so WATCH OUT! + * + * We have to hold mm->context.lock while committing to the + * new TSB, this synchronizes us with processors in + * flush_tsb_user() and switch_mm() for this address space. + * + * But even with that lock held, processors run asynchronously + * accessing the old TSB via TLB miss handling. This is OK + * because those actions are just propagating state from the + * Linux page tables into the TSB, page table mappings are not + * being changed. If a real fault occurs, the processor will + * synchronize with us when it hits flush_tsb_user(), this is + * also true for the case where vmscan is modifying the page + * tables. The only thing we need to be careful with is to + * skip any locked TSB entries during copy_tsb(). + * + * When we finish committing to the new TSB, we have to drop + * the lock and ask all other cpus running this address space + * to run tsb_context_switch() to see the new TSB table. + */ + spin_lock_irqsave(&mm->context.lock, flags); + + old_tsb = mm->context.tsb; + old_size = mm->context.tsb_nentries * sizeof(struct tsb); + + /* Handle multiple threads trying to grow the TSB at the same time. + * One will get in here first, and bump the size and the RSS limit. + * The others will get in here next and hit this check. + */ + if (unlikely(old_tsb && (rss < mm->context.tsb_rss_limit))) { + spin_unlock_irqrestore(&mm->context.lock, flags); + + free_pages((unsigned long) new_tsb, get_order(size)); + return; + } if (size == max_tsb_size) mm->context.tsb_rss_limit = ~0UL; @@ -324,30 +292,37 @@ void tsb_grow(struct mm_struct *mm, unsigned long rss, gfp_t gfp_flags) mm->context.tsb_rss_limit = ((size / sizeof(struct tsb)) * 3) / 4; - old_tsb = mm->context.tsb; - old_size = mm->context.tsb_nentries * sizeof(struct tsb); - - if (old_tsb) - copy_tsb(old_tsb, old_size, page_address(page), size); + if (old_tsb) { + extern void copy_tsb(unsigned long old_tsb_base, + unsigned long old_tsb_size, + unsigned long new_tsb_base, + unsigned long new_tsb_size); + unsigned long old_tsb_base = (unsigned long) old_tsb; + unsigned long new_tsb_base = (unsigned long) new_tsb; + + if (tlb_type == cheetah_plus || tlb_type == hypervisor) { + old_tsb_base = __pa(old_tsb_base); + new_tsb_base = __pa(new_tsb_base); + } + copy_tsb(old_tsb_base, old_size, new_tsb_base, size); + } - mm->context.tsb = page_address(page); + mm->context.tsb = new_tsb; setup_tsb_params(mm, size); + spin_unlock_irqrestore(&mm->context.lock, flags); + /* If old_tsb is NULL, we're being invoked for the first time * from init_new_context(). */ if (old_tsb) { - /* Now force all other processors to reload the new - * TSB state. - */ - smp_tsb_sync(mm); - - /* Finally reload it on the local cpu. No further - * references will remain to the old TSB and we can - * thus free it up. - */ + /* Reload it on the local cpu. */ tsb_context_switch(mm); + /* Now force other processors to do the same. */ + smp_tsb_sync(mm); + + /* Now it is safe to free the old tsb. */ free_pages((unsigned long) old_tsb, get_order(old_size)); } } @@ -363,7 +338,11 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm) * will be confused and think there is an older TSB to free up. */ mm->context.tsb = NULL; - tsb_grow(mm, 0, GFP_KERNEL); + + /* If this is fork, inherit the parent's TSB size. We would + * grow it to that size on the first page fault anyways. + */ + tsb_grow(mm, get_mm_rss(mm)); if (unlikely(!mm->context.tsb)) return -ENOMEM; |