![David S. Miller](/assets/img/avatar_default.png)
Add a sysctl to tweak the RSS limit used to decide when to grow the TSB for an address space. In order to avoid expensive divides and multiplies only simply positive and negative powers of two are supported. The function computed takes the number of TSB translations that will fit at one time in the TSB of a given size, and either adds or subtracts a percentage of entries. This final value is the RSS limit. See tsb_size_to_rss_limit(). Signed-off-by: David S. Miller <davem@davemloft.net>
504 lines
13 KiB
C
504 lines
13 KiB
C
/* arch/sparc64/mm/tsb.c
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*
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* Copyright (C) 2006, 2008 David S. Miller <davem@davemloft.net>
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*/
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#include <linux/kernel.h>
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#include <linux/preempt.h>
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#include <asm/system.h>
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#include <asm/page.h>
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#include <asm/tlbflush.h>
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#include <asm/tlb.h>
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#include <asm/mmu_context.h>
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#include <asm/pgtable.h>
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#include <asm/tsb.h>
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#include <asm/oplib.h>
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extern struct tsb swapper_tsb[KERNEL_TSB_NENTRIES];
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static inline unsigned long tsb_hash(unsigned long vaddr, unsigned long hash_shift, unsigned long nentries)
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{
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vaddr >>= hash_shift;
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return vaddr & (nentries - 1);
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}
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static inline int tag_compare(unsigned long tag, unsigned long vaddr)
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{
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return (tag == (vaddr >> 22));
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}
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/* TSB flushes need only occur on the processor initiating the address
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* space modification, not on each cpu the address space has run on.
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* Only the TLB flush needs that treatment.
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*/
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void flush_tsb_kernel_range(unsigned long start, unsigned long end)
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{
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unsigned long v;
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for (v = start; v < end; v += PAGE_SIZE) {
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unsigned long hash = tsb_hash(v, PAGE_SHIFT,
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KERNEL_TSB_NENTRIES);
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struct tsb *ent = &swapper_tsb[hash];
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if (tag_compare(ent->tag, v))
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ent->tag = (1UL << TSB_TAG_INVALID_BIT);
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}
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}
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static void __flush_tsb_one(struct mmu_gather *mp, unsigned long hash_shift, unsigned long tsb, unsigned long nentries)
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{
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unsigned long i;
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for (i = 0; i < mp->tlb_nr; i++) {
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unsigned long v = mp->vaddrs[i];
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unsigned long tag, ent, hash;
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v &= ~0x1UL;
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hash = tsb_hash(v, hash_shift, nentries);
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ent = tsb + (hash * sizeof(struct tsb));
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tag = (v >> 22UL);
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tsb_flush(ent, tag);
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}
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}
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void flush_tsb_user(struct mmu_gather *mp)
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{
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struct mm_struct *mm = mp->mm;
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unsigned long nentries, base, flags;
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spin_lock_irqsave(&mm->context.lock, flags);
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base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
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nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
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if (tlb_type == cheetah_plus || tlb_type == hypervisor)
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base = __pa(base);
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__flush_tsb_one(mp, PAGE_SHIFT, base, nentries);
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#ifdef CONFIG_HUGETLB_PAGE
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if (mm->context.tsb_block[MM_TSB_HUGE].tsb) {
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base = (unsigned long) mm->context.tsb_block[MM_TSB_HUGE].tsb;
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nentries = mm->context.tsb_block[MM_TSB_HUGE].tsb_nentries;
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if (tlb_type == cheetah_plus || tlb_type == hypervisor)
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base = __pa(base);
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__flush_tsb_one(mp, HPAGE_SHIFT, base, nentries);
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}
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#endif
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spin_unlock_irqrestore(&mm->context.lock, flags);
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}
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#if defined(CONFIG_SPARC64_PAGE_SIZE_8KB)
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#define HV_PGSZ_IDX_BASE HV_PGSZ_IDX_8K
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#define HV_PGSZ_MASK_BASE HV_PGSZ_MASK_8K
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#elif defined(CONFIG_SPARC64_PAGE_SIZE_64KB)
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#define HV_PGSZ_IDX_BASE HV_PGSZ_IDX_64K
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#define HV_PGSZ_MASK_BASE HV_PGSZ_MASK_64K
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#else
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#error Broken base page size setting...
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#endif
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#ifdef CONFIG_HUGETLB_PAGE
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#if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
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#define HV_PGSZ_IDX_HUGE HV_PGSZ_IDX_64K
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#define HV_PGSZ_MASK_HUGE HV_PGSZ_MASK_64K
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#elif defined(CONFIG_HUGETLB_PAGE_SIZE_512K)
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#define HV_PGSZ_IDX_HUGE HV_PGSZ_IDX_512K
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#define HV_PGSZ_MASK_HUGE HV_PGSZ_MASK_512K
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#elif defined(CONFIG_HUGETLB_PAGE_SIZE_4MB)
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#define HV_PGSZ_IDX_HUGE HV_PGSZ_IDX_4MB
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#define HV_PGSZ_MASK_HUGE HV_PGSZ_MASK_4MB
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#else
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#error Broken huge page size setting...
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#endif
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#endif
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static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_idx, unsigned long tsb_bytes)
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{
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unsigned long tsb_reg, base, tsb_paddr;
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unsigned long page_sz, tte;
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mm->context.tsb_block[tsb_idx].tsb_nentries =
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tsb_bytes / sizeof(struct tsb);
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base = TSBMAP_BASE;
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tte = pgprot_val(PAGE_KERNEL_LOCKED);
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tsb_paddr = __pa(mm->context.tsb_block[tsb_idx].tsb);
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BUG_ON(tsb_paddr & (tsb_bytes - 1UL));
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/* Use the smallest page size that can map the whole TSB
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* in one TLB entry.
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*/
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switch (tsb_bytes) {
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case 8192 << 0:
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tsb_reg = 0x0UL;
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#ifdef DCACHE_ALIASING_POSSIBLE
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base += (tsb_paddr & 8192);
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#endif
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page_sz = 8192;
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break;
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case 8192 << 1:
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tsb_reg = 0x1UL;
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page_sz = 64 * 1024;
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break;
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case 8192 << 2:
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tsb_reg = 0x2UL;
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page_sz = 64 * 1024;
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break;
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case 8192 << 3:
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tsb_reg = 0x3UL;
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page_sz = 64 * 1024;
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break;
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case 8192 << 4:
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tsb_reg = 0x4UL;
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page_sz = 512 * 1024;
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break;
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case 8192 << 5:
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tsb_reg = 0x5UL;
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page_sz = 512 * 1024;
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break;
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case 8192 << 6:
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tsb_reg = 0x6UL;
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page_sz = 512 * 1024;
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break;
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case 8192 << 7:
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tsb_reg = 0x7UL;
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page_sz = 4 * 1024 * 1024;
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break;
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default:
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printk(KERN_ERR "TSB[%s:%d]: Impossible TSB size %lu, killing process.\n",
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current->comm, current->pid, tsb_bytes);
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do_exit(SIGSEGV);
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};
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tte |= pte_sz_bits(page_sz);
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if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
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/* Physical mapping, no locked TLB entry for TSB. */
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tsb_reg |= tsb_paddr;
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mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
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mm->context.tsb_block[tsb_idx].tsb_map_vaddr = 0;
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mm->context.tsb_block[tsb_idx].tsb_map_pte = 0;
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} else {
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tsb_reg |= base;
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tsb_reg |= (tsb_paddr & (page_sz - 1UL));
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tte |= (tsb_paddr & ~(page_sz - 1UL));
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mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
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mm->context.tsb_block[tsb_idx].tsb_map_vaddr = base;
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mm->context.tsb_block[tsb_idx].tsb_map_pte = tte;
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}
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/* Setup the Hypervisor TSB descriptor. */
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if (tlb_type == hypervisor) {
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struct hv_tsb_descr *hp = &mm->context.tsb_descr[tsb_idx];
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switch (tsb_idx) {
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case MM_TSB_BASE:
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hp->pgsz_idx = HV_PGSZ_IDX_BASE;
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break;
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#ifdef CONFIG_HUGETLB_PAGE
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case MM_TSB_HUGE:
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hp->pgsz_idx = HV_PGSZ_IDX_HUGE;
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break;
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#endif
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default:
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BUG();
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};
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hp->assoc = 1;
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hp->num_ttes = tsb_bytes / 16;
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hp->ctx_idx = 0;
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switch (tsb_idx) {
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case MM_TSB_BASE:
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hp->pgsz_mask = HV_PGSZ_MASK_BASE;
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break;
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#ifdef CONFIG_HUGETLB_PAGE
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case MM_TSB_HUGE:
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hp->pgsz_mask = HV_PGSZ_MASK_HUGE;
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break;
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#endif
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default:
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BUG();
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};
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hp->tsb_base = tsb_paddr;
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hp->resv = 0;
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}
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}
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static struct kmem_cache *tsb_caches[8] __read_mostly;
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static const char *tsb_cache_names[8] = {
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"tsb_8KB",
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"tsb_16KB",
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"tsb_32KB",
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"tsb_64KB",
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"tsb_128KB",
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"tsb_256KB",
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"tsb_512KB",
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"tsb_1MB",
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};
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void __init pgtable_cache_init(void)
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{
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unsigned long i;
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for (i = 0; i < 8; i++) {
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unsigned long size = 8192 << i;
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const char *name = tsb_cache_names[i];
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tsb_caches[i] = kmem_cache_create(name,
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size, size,
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0, NULL);
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if (!tsb_caches[i]) {
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prom_printf("Could not create %s cache\n", name);
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prom_halt();
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}
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}
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}
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int sysctl_tsb_ratio = -2;
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static unsigned long tsb_size_to_rss_limit(unsigned long new_size)
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{
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unsigned long num_ents = (new_size / sizeof(struct tsb));
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if (sysctl_tsb_ratio < 0)
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return num_ents - (num_ents >> -sysctl_tsb_ratio);
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else
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return num_ents + (num_ents >> sysctl_tsb_ratio);
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}
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/* When the RSS of an address space exceeds tsb_rss_limit for a TSB,
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* do_sparc64_fault() invokes this routine to try and grow it.
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*
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* When we reach the maximum TSB size supported, we stick ~0UL into
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* tsb_rss_limit for that TSB so the grow checks in do_sparc64_fault()
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* will not trigger any longer.
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*
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* The TSB can be anywhere from 8K to 1MB in size, in increasing powers
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* of two. The TSB must be aligned to it's size, so f.e. a 512K TSB
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* must be 512K aligned. It also must be physically contiguous, so we
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* cannot use vmalloc().
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*
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* The idea here is to grow the TSB when the RSS of the process approaches
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* the number of entries that the current TSB can hold at once. Currently,
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* we trigger when the RSS hits 3/4 of the TSB capacity.
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*/
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void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
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{
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unsigned long max_tsb_size = 1 * 1024 * 1024;
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unsigned long new_size, old_size, flags;
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struct tsb *old_tsb, *new_tsb;
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unsigned long new_cache_index, old_cache_index;
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unsigned long new_rss_limit;
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gfp_t gfp_flags;
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if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
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max_tsb_size = (PAGE_SIZE << MAX_ORDER);
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new_cache_index = 0;
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for (new_size = 8192; new_size < max_tsb_size; new_size <<= 1UL) {
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new_rss_limit = tsb_size_to_rss_limit(new_size);
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if (new_rss_limit > rss)
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break;
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new_cache_index++;
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}
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if (new_size == max_tsb_size)
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new_rss_limit = ~0UL;
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retry_tsb_alloc:
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gfp_flags = GFP_KERNEL;
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if (new_size > (PAGE_SIZE * 2))
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gfp_flags = __GFP_NOWARN | __GFP_NORETRY;
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new_tsb = kmem_cache_alloc_node(tsb_caches[new_cache_index],
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gfp_flags, numa_node_id());
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if (unlikely(!new_tsb)) {
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/* Not being able to fork due to a high-order TSB
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* allocation failure is very bad behavior. Just back
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* down to a 0-order allocation and force no TSB
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* growing for this address space.
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*/
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if (mm->context.tsb_block[tsb_index].tsb == NULL &&
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new_cache_index > 0) {
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new_cache_index = 0;
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new_size = 8192;
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new_rss_limit = ~0UL;
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goto retry_tsb_alloc;
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}
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/* If we failed on a TSB grow, we are under serious
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* memory pressure so don't try to grow any more.
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*/
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if (mm->context.tsb_block[tsb_index].tsb != NULL)
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mm->context.tsb_block[tsb_index].tsb_rss_limit = ~0UL;
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return;
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}
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/* Mark all tags as invalid. */
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tsb_init(new_tsb, new_size);
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/* Ok, we are about to commit the changes. If we are
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* growing an existing TSB the locking is very tricky,
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* so WATCH OUT!
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*
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* We have to hold mm->context.lock while committing to the
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* new TSB, this synchronizes us with processors in
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* flush_tsb_user() and switch_mm() for this address space.
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*
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* But even with that lock held, processors run asynchronously
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* accessing the old TSB via TLB miss handling. This is OK
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* because those actions are just propagating state from the
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* Linux page tables into the TSB, page table mappings are not
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* being changed. If a real fault occurs, the processor will
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* synchronize with us when it hits flush_tsb_user(), this is
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* also true for the case where vmscan is modifying the page
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* tables. The only thing we need to be careful with is to
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* skip any locked TSB entries during copy_tsb().
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*
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* When we finish committing to the new TSB, we have to drop
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* the lock and ask all other cpus running this address space
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* to run tsb_context_switch() to see the new TSB table.
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*/
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spin_lock_irqsave(&mm->context.lock, flags);
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old_tsb = mm->context.tsb_block[tsb_index].tsb;
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old_cache_index =
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(mm->context.tsb_block[tsb_index].tsb_reg_val & 0x7UL);
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old_size = (mm->context.tsb_block[tsb_index].tsb_nentries *
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sizeof(struct tsb));
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/* Handle multiple threads trying to grow the TSB at the same time.
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* One will get in here first, and bump the size and the RSS limit.
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* The others will get in here next and hit this check.
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*/
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if (unlikely(old_tsb &&
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(rss < mm->context.tsb_block[tsb_index].tsb_rss_limit))) {
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spin_unlock_irqrestore(&mm->context.lock, flags);
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kmem_cache_free(tsb_caches[new_cache_index], new_tsb);
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return;
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}
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mm->context.tsb_block[tsb_index].tsb_rss_limit = new_rss_limit;
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if (old_tsb) {
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extern void copy_tsb(unsigned long old_tsb_base,
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unsigned long old_tsb_size,
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unsigned long new_tsb_base,
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unsigned long new_tsb_size);
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unsigned long old_tsb_base = (unsigned long) old_tsb;
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unsigned long new_tsb_base = (unsigned long) new_tsb;
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if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
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old_tsb_base = __pa(old_tsb_base);
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new_tsb_base = __pa(new_tsb_base);
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}
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copy_tsb(old_tsb_base, old_size, new_tsb_base, new_size);
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}
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mm->context.tsb_block[tsb_index].tsb = new_tsb;
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setup_tsb_params(mm, tsb_index, new_size);
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spin_unlock_irqrestore(&mm->context.lock, flags);
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/* If old_tsb is NULL, we're being invoked for the first time
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* from init_new_context().
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*/
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if (old_tsb) {
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/* Reload it on the local cpu. */
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tsb_context_switch(mm);
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/* Now force other processors to do the same. */
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preempt_disable();
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smp_tsb_sync(mm);
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preempt_enable();
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/* Now it is safe to free the old tsb. */
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kmem_cache_free(tsb_caches[old_cache_index], old_tsb);
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}
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}
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int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
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{
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#ifdef CONFIG_HUGETLB_PAGE
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unsigned long huge_pte_count;
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#endif
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unsigned int i;
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spin_lock_init(&mm->context.lock);
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mm->context.sparc64_ctx_val = 0UL;
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#ifdef CONFIG_HUGETLB_PAGE
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/* We reset it to zero because the fork() page copying
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* will re-increment the counters as the parent PTEs are
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* copied into the child address space.
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*/
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huge_pte_count = mm->context.huge_pte_count;
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mm->context.huge_pte_count = 0;
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#endif
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/* copy_mm() copies over the parent's mm_struct before calling
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* us, so we need to zero out the TSB pointer or else tsb_grow()
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* will be confused and think there is an older TSB to free up.
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*/
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for (i = 0; i < MM_NUM_TSBS; i++)
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mm->context.tsb_block[i].tsb = NULL;
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/* If this is fork, inherit the parent's TSB size. We would
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* grow it to that size on the first page fault anyways.
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*/
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tsb_grow(mm, MM_TSB_BASE, get_mm_rss(mm));
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#ifdef CONFIG_HUGETLB_PAGE
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if (unlikely(huge_pte_count))
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tsb_grow(mm, MM_TSB_HUGE, huge_pte_count);
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#endif
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if (unlikely(!mm->context.tsb_block[MM_TSB_BASE].tsb))
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void tsb_destroy_one(struct tsb_config *tp)
|
|
{
|
|
unsigned long cache_index;
|
|
|
|
if (!tp->tsb)
|
|
return;
|
|
cache_index = tp->tsb_reg_val & 0x7UL;
|
|
kmem_cache_free(tsb_caches[cache_index], tp->tsb);
|
|
tp->tsb = NULL;
|
|
tp->tsb_reg_val = 0UL;
|
|
}
|
|
|
|
void destroy_context(struct mm_struct *mm)
|
|
{
|
|
unsigned long flags, i;
|
|
|
|
for (i = 0; i < MM_NUM_TSBS; i++)
|
|
tsb_destroy_one(&mm->context.tsb_block[i]);
|
|
|
|
spin_lock_irqsave(&ctx_alloc_lock, flags);
|
|
|
|
if (CTX_VALID(mm->context)) {
|
|
unsigned long nr = CTX_NRBITS(mm->context);
|
|
mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));
|
|
}
|
|
|
|
spin_unlock_irqrestore(&ctx_alloc_lock, flags);
|
|
}
|