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-rw-r--r--arch/powerpc/mm/book3s64/hash_pgtable.c463
1 files changed, 463 insertions, 0 deletions
diff --git a/arch/powerpc/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c
new file mode 100644
index 000000000000..1fd025dba4a3
--- /dev/null
+++ b/arch/powerpc/mm/book3s64/hash_pgtable.c
@@ -0,0 +1,463 @@
+/*
+ * Copyright 2005, Paul Mackerras, IBM Corporation.
+ * Copyright 2009, Benjamin Herrenschmidt, IBM Corporation.
+ * Copyright 2015-2016, Aneesh Kumar K.V, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/sched.h>
+#include <linux/mm_types.h>
+#include <linux/mm.h>
+
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/sections.h>
+#include <asm/mmu.h>
+#include <asm/tlb.h>
+
+#include <mm/mmu_decl.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/thp.h>
+
+#if H_PGTABLE_RANGE > (USER_VSID_RANGE * (TASK_SIZE_USER64 / TASK_CONTEXT_SIZE))
+#warning Limited user VSID range means pagetable space is wasted
+#endif
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+/*
+ * vmemmap is the starting address of the virtual address space where
+ * struct pages are allocated for all possible PFNs present on the system
+ * including holes and bad memory (hence sparse). These virtual struct
+ * pages are stored in sequence in this virtual address space irrespective
+ * of the fact whether the corresponding PFN is valid or not. This achieves
+ * constant relationship between address of struct page and its PFN.
+ *
+ * During boot or memory hotplug operation when a new memory section is
+ * added, physical memory allocation (including hash table bolting) will
+ * be performed for the set of struct pages which are part of the memory
+ * section. This saves memory by not allocating struct pages for PFNs
+ * which are not valid.
+ *
+ * ----------------------------------------------
+ * | PHYSICAL ALLOCATION OF VIRTUAL STRUCT PAGES|
+ * ----------------------------------------------
+ *
+ * f000000000000000 c000000000000000
+ * vmemmap +--------------+ +--------------+
+ * + | page struct | +--------------> | page struct |
+ * | +--------------+ +--------------+
+ * | | page struct | +--------------> | page struct |
+ * | +--------------+ | +--------------+
+ * | | page struct | + +------> | page struct |
+ * | +--------------+ | +--------------+
+ * | | page struct | | +--> | page struct |
+ * | +--------------+ | | +--------------+
+ * | | page struct | | |
+ * | +--------------+ | |
+ * | | page struct | | |
+ * | +--------------+ | |
+ * | | page struct | | |
+ * | +--------------+ | |
+ * | | page struct | | |
+ * | +--------------+ | |
+ * | | page struct | +-------+ |
+ * | +--------------+ |
+ * | | page struct | +-----------+
+ * | +--------------+
+ * | | page struct | No mapping
+ * | +--------------+
+ * | | page struct | No mapping
+ * v +--------------+
+ *
+ * -----------------------------------------
+ * | RELATION BETWEEN STRUCT PAGES AND PFNS|
+ * -----------------------------------------
+ *
+ * vmemmap +--------------+ +---------------+
+ * + | page struct | +-------------> | PFN |
+ * | +--------------+ +---------------+
+ * | | page struct | +-------------> | PFN |
+ * | +--------------+ +---------------+
+ * | | page struct | +-------------> | PFN |
+ * | +--------------+ +---------------+
+ * | | page struct | +-------------> | PFN |
+ * | +--------------+ +---------------+
+ * | | |
+ * | +--------------+
+ * | | |
+ * | +--------------+
+ * | | |
+ * | +--------------+ +---------------+
+ * | | page struct | +-------------> | PFN |
+ * | +--------------+ +---------------+
+ * | | |
+ * | +--------------+
+ * | | |
+ * | +--------------+ +---------------+
+ * | | page struct | +-------------> | PFN |
+ * | +--------------+ +---------------+
+ * | | page struct | +-------------> | PFN |
+ * v +--------------+ +---------------+
+ */
+/*
+ * On hash-based CPUs, the vmemmap is bolted in the hash table.
+ *
+ */
+int __meminit hash__vmemmap_create_mapping(unsigned long start,
+ unsigned long page_size,
+ unsigned long phys)
+{
+ int rc;
+
+ if ((start + page_size) >= H_VMEMMAP_END) {
+ pr_warn("Outside the supported range\n");
+ return -1;
+ }
+
+ rc = htab_bolt_mapping(start, start + page_size, phys,
+ pgprot_val(PAGE_KERNEL),
+ mmu_vmemmap_psize, mmu_kernel_ssize);
+ if (rc < 0) {
+ int rc2 = htab_remove_mapping(start, start + page_size,
+ mmu_vmemmap_psize,
+ mmu_kernel_ssize);
+ BUG_ON(rc2 && (rc2 != -ENOENT));
+ }
+ return rc;
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+void hash__vmemmap_remove_mapping(unsigned long start,
+ unsigned long page_size)
+{
+ int rc = htab_remove_mapping(start, start + page_size,
+ mmu_vmemmap_psize,
+ mmu_kernel_ssize);
+ BUG_ON((rc < 0) && (rc != -ENOENT));
+ WARN_ON(rc == -ENOENT);
+}
+#endif
+#endif /* CONFIG_SPARSEMEM_VMEMMAP */
+
+/*
+ * map_kernel_page currently only called by __ioremap
+ * map_kernel_page adds an entry to the ioremap page table
+ * and adds an entry to the HPT, possibly bolting it
+ */
+int hash__map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
+{
+ pgd_t *pgdp;
+ pud_t *pudp;
+ pmd_t *pmdp;
+ pte_t *ptep;
+
+ BUILD_BUG_ON(TASK_SIZE_USER64 > H_PGTABLE_RANGE);
+ if (slab_is_available()) {
+ pgdp = pgd_offset_k(ea);
+ pudp = pud_alloc(&init_mm, pgdp, ea);
+ if (!pudp)
+ return -ENOMEM;
+ pmdp = pmd_alloc(&init_mm, pudp, ea);
+ if (!pmdp)
+ return -ENOMEM;
+ ptep = pte_alloc_kernel(pmdp, ea);
+ if (!ptep)
+ return -ENOMEM;
+ set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot));
+ } else {
+ /*
+ * If the mm subsystem is not fully up, we cannot create a
+ * linux page table entry for this mapping. Simply bolt an
+ * entry in the hardware page table.
+ *
+ */
+ if (htab_bolt_mapping(ea, ea + PAGE_SIZE, pa, pgprot_val(prot),
+ mmu_io_psize, mmu_kernel_ssize)) {
+ printk(KERN_ERR "Failed to do bolted mapping IO "
+ "memory at %016lx !\n", pa);
+ return -ENOMEM;
+ }
+ }
+
+ smp_wmb();
+ return 0;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+
+unsigned long hash__pmd_hugepage_update(struct mm_struct *mm, unsigned long addr,
+ pmd_t *pmdp, unsigned long clr,
+ unsigned long set)
+{
+ __be64 old_be, tmp;
+ unsigned long old;
+
+#ifdef CONFIG_DEBUG_VM
+ WARN_ON(!hash__pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp));
+ assert_spin_locked(pmd_lockptr(mm, pmdp));
+#endif
+
+ __asm__ __volatile__(
+ "1: ldarx %0,0,%3\n\
+ and. %1,%0,%6\n\
+ bne- 1b \n\
+ andc %1,%0,%4 \n\
+ or %1,%1,%7\n\
+ stdcx. %1,0,%3 \n\
+ bne- 1b"
+ : "=&r" (old_be), "=&r" (tmp), "=m" (*pmdp)
+ : "r" (pmdp), "r" (cpu_to_be64(clr)), "m" (*pmdp),
+ "r" (cpu_to_be64(H_PAGE_BUSY)), "r" (cpu_to_be64(set))
+ : "cc" );
+
+ old = be64_to_cpu(old_be);
+
+ trace_hugepage_update(addr, old, clr, set);
+ if (old & H_PAGE_HASHPTE)
+ hpte_do_hugepage_flush(mm, addr, pmdp, old);
+ return old;
+}
+
+pmd_t hash__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
+ pmd_t *pmdp)
+{
+ pmd_t pmd;
+
+ VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+ VM_BUG_ON(pmd_trans_huge(*pmdp));
+ VM_BUG_ON(pmd_devmap(*pmdp));
+
+ pmd = *pmdp;
+ pmd_clear(pmdp);
+ /*
+ * Wait for all pending hash_page to finish. This is needed
+ * in case of subpage collapse. When we collapse normal pages
+ * to hugepage, we first clear the pmd, then invalidate all
+ * the PTE entries. The assumption here is that any low level
+ * page fault will see a none pmd and take the slow path that
+ * will wait on mmap_sem. But we could very well be in a
+ * hash_page with local ptep pointer value. Such a hash page
+ * can result in adding new HPTE entries for normal subpages.
+ * That means we could be modifying the page content as we
+ * copy them to a huge page. So wait for parallel hash_page
+ * to finish before invalidating HPTE entries. We can do this
+ * by sending an IPI to all the cpus and executing a dummy
+ * function there.
+ */
+ serialize_against_pte_lookup(vma->vm_mm);
+ /*
+ * Now invalidate the hpte entries in the range
+ * covered by pmd. This make sure we take a
+ * fault and will find the pmd as none, which will
+ * result in a major fault which takes mmap_sem and
+ * hence wait for collapse to complete. Without this
+ * the __collapse_huge_page_copy can result in copying
+ * the old content.
+ */
+ flush_tlb_pmd_range(vma->vm_mm, &pmd, address);
+ return pmd;
+}
+
+/*
+ * We want to put the pgtable in pmd and use pgtable for tracking
+ * the base page size hptes
+ */
+void hash__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
+ pgtable_t pgtable)
+{
+ pgtable_t *pgtable_slot;
+
+ assert_spin_locked(pmd_lockptr(mm, pmdp));
+ /*
+ * we store the pgtable in the second half of PMD
+ */
+ pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD;
+ *pgtable_slot = pgtable;
+ /*
+ * expose the deposited pgtable to other cpus.
+ * before we set the hugepage PTE at pmd level
+ * hash fault code looks at the deposted pgtable
+ * to store hash index values.
+ */
+ smp_wmb();
+}
+
+pgtable_t hash__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
+{
+ pgtable_t pgtable;
+ pgtable_t *pgtable_slot;
+
+ assert_spin_locked(pmd_lockptr(mm, pmdp));
+
+ pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD;
+ pgtable = *pgtable_slot;
+ /*
+ * Once we withdraw, mark the entry NULL.
+ */
+ *pgtable_slot = NULL;
+ /*
+ * We store HPTE information in the deposited PTE fragment.
+ * zero out the content on withdraw.
+ */
+ memset(pgtable, 0, PTE_FRAG_SIZE);
+ return pgtable;
+}
+
+/*
+ * A linux hugepage PMD was changed and the corresponding hash table entries
+ * neesd to be flushed.
+ */
+void hpte_do_hugepage_flush(struct mm_struct *mm, unsigned long addr,
+ pmd_t *pmdp, unsigned long old_pmd)
+{
+ int ssize;
+ unsigned int psize;
+ unsigned long vsid;
+ unsigned long flags = 0;
+
+ /* get the base page size,vsid and segment size */
+#ifdef CONFIG_DEBUG_VM
+ psize = get_slice_psize(mm, addr);
+ BUG_ON(psize == MMU_PAGE_16M);
+#endif
+ if (old_pmd & H_PAGE_COMBO)
+ psize = MMU_PAGE_4K;
+ else
+ psize = MMU_PAGE_64K;
+
+ if (!is_kernel_addr(addr)) {
+ ssize = user_segment_size(addr);
+ vsid = get_user_vsid(&mm->context, addr, ssize);
+ WARN_ON(vsid == 0);
+ } else {
+ vsid = get_kernel_vsid(addr, mmu_kernel_ssize);
+ ssize = mmu_kernel_ssize;
+ }
+
+ if (mm_is_thread_local(mm))
+ flags |= HPTE_LOCAL_UPDATE;
+
+ return flush_hash_hugepage(vsid, addr, pmdp, psize, ssize, flags);
+}
+
+pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm,
+ unsigned long addr, pmd_t *pmdp)
+{
+ pmd_t old_pmd;
+ pgtable_t pgtable;
+ unsigned long old;
+ pgtable_t *pgtable_slot;
+
+ old = pmd_hugepage_update(mm, addr, pmdp, ~0UL, 0);
+ old_pmd = __pmd(old);
+ /*
+ * We have pmd == none and we are holding page_table_lock.
+ * So we can safely go and clear the pgtable hash
+ * index info.
+ */
+ pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD;
+ pgtable = *pgtable_slot;
+ /*
+ * Let's zero out old valid and hash index details
+ * hash fault look at them.
+ */
+ memset(pgtable, 0, PTE_FRAG_SIZE);
+ /*
+ * Serialize against find_current_mm_pte variants which does lock-less
+ * lookup in page tables with local interrupts disabled. For huge pages
+ * it casts pmd_t to pte_t. Since format of pte_t is different from
+ * pmd_t we want to prevent transit from pmd pointing to page table
+ * to pmd pointing to huge page (and back) while interrupts are disabled.
+ * We clear pmd to possibly replace it with page table pointer in
+ * different code paths. So make sure we wait for the parallel
+ * find_curren_mm_pte to finish.
+ */
+ serialize_against_pte_lookup(mm);
+ return old_pmd;
+}
+
+int hash__has_transparent_hugepage(void)
+{
+
+ if (!mmu_has_feature(MMU_FTR_16M_PAGE))
+ return 0;
+ /*
+ * We support THP only if PMD_SIZE is 16MB.
+ */
+ if (mmu_psize_defs[MMU_PAGE_16M].shift != PMD_SHIFT)
+ return 0;
+ /*
+ * We need to make sure that we support 16MB hugepage in a segement
+ * with base page size 64K or 4K. We only enable THP with a PAGE_SIZE
+ * of 64K.
+ */
+ /*
+ * If we have 64K HPTE, we will be using that by default
+ */
+ if (mmu_psize_defs[MMU_PAGE_64K].shift &&
+ (mmu_psize_defs[MMU_PAGE_64K].penc[MMU_PAGE_16M] == -1))
+ return 0;
+ /*
+ * Ok we only have 4K HPTE
+ */
+ if (mmu_psize_defs[MMU_PAGE_4K].penc[MMU_PAGE_16M] == -1)
+ return 0;
+
+ return 1;
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+#ifdef CONFIG_STRICT_KERNEL_RWX
+static bool hash__change_memory_range(unsigned long start, unsigned long end,
+ unsigned long newpp)
+{
+ unsigned long idx;
+ unsigned int step, shift;
+
+ shift = mmu_psize_defs[mmu_linear_psize].shift;
+ step = 1 << shift;
+
+ start = ALIGN_DOWN(start, step);
+ end = ALIGN(end, step); // aligns up
+
+ if (start >= end)
+ return false;
+
+ pr_debug("Changing page protection on range 0x%lx-0x%lx, to 0x%lx, step 0x%x\n",
+ start, end, newpp, step);
+
+ for (idx = start; idx < end; idx += step)
+ /* Not sure if we can do much with the return value */
+ mmu_hash_ops.hpte_updateboltedpp(newpp, idx, mmu_linear_psize,
+ mmu_kernel_ssize);
+
+ return true;
+}
+
+void hash__mark_rodata_ro(void)
+{
+ unsigned long start, end;
+
+ start = (unsigned long)_stext;
+ end = (unsigned long)__init_begin;
+
+ WARN_ON(!hash__change_memory_range(start, end, PP_RXXX));
+}
+
+void hash__mark_initmem_nx(void)
+{
+ unsigned long start, end, pp;
+
+ start = (unsigned long)__init_begin;
+ end = (unsigned long)__init_end;
+
+ pp = htab_convert_pte_flags(pgprot_val(PAGE_KERNEL));
+
+ WARN_ON(!hash__change_memory_range(start, end, pp));
+}
+#endif
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.