pgtable.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 2015-2016, Aneesh Kumar K.V, IBM Corporation.
 */

#include <linux/sched.h>
#include <linux/mm_types.h>
#include <linux/memblock.h>
#include <linux/memremap.h>
#include <linux/pkeys.h>
#include <linux/debugfs.h>
#include <linux/proc_fs.h>
#include <linux/page_table_check.h>

#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/trace.h>
#include <asm/powernv.h>
#include <asm/firmware.h>
#include <asm/ultravisor.h>
#include <asm/kexec.h>

#include <mm/mmu_decl.h>
#include <trace/events/thp.h>

#include "internal.h"

struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT];
EXPORT_SYMBOL_GPL(mmu_psize_defs);

#ifdef CONFIG_SPARSEMEM_VMEMMAP
int mmu_vmemmap_psize = MMU_PAGE_4K;
#endif

unsigned long __pmd_frag_nr;
EXPORT_SYMBOL(__pmd_frag_nr);
unsigned long __pmd_frag_size_shift;
EXPORT_SYMBOL(__pmd_frag_size_shift);

#ifdef CONFIG_KFENCE
extern bool kfence_early_init;
static int __init parse_kfence_early_init(char *arg)
{
	int val;

	if (get_option(&arg, &val))
		kfence_early_init = !!val;
	return 0;
}
early_param("kfence.sample_interval", parse_kfence_early_init);
#endif

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/*
 * This is called when relaxing access to a hugepage. It's also called in the page
 * fault path when we don't hit any of the major fault cases, ie, a minor
 * update of _PAGE_ACCESSED, _PAGE_DIRTY, etc... The generic code will have
 * handled those two for us, we additionally deal with missing execute
 * permission here on some processors
 */
int pmdp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
			  pmd_t *pmdp, pmd_t entry, int dirty)
{
	int changed;
#ifdef CONFIG_DEBUG_VM
	WARN_ON(!pmd_trans_huge(*pmdp));
	assert_spin_locked(pmd_lockptr(vma->vm_mm, pmdp));
#endif
	changed = !pmd_same(*(pmdp), entry);
	if (changed) {
		/*
		 * We can use MMU_PAGE_2M here, because only radix
		 * path look at the psize.
		 */
		__ptep_set_access_flags(vma, pmdp_ptep(pmdp),
					pmd_pte(entry), address, MMU_PAGE_2M);
	}
	return changed;
}

int pudp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
			  pud_t *pudp, pud_t entry, int dirty)
{
	int changed;
#ifdef CONFIG_DEBUG_VM
	assert_spin_locked(pud_lockptr(vma->vm_mm, pudp));
#endif
	changed = !pud_same(*(pudp), entry);
	if (changed) {
		/*
		 * We can use MMU_PAGE_1G here, because only radix
		 * path look at the psize.
		 */
		__ptep_set_access_flags(vma, pudp_ptep(pudp),
					pud_pte(entry), address, MMU_PAGE_1G);
	}
	return changed;
}


int pmdp_test_and_clear_young(struct vm_area_struct *vma,
			      unsigned long address, pmd_t *pmdp)
{
	return __pmdp_test_and_clear_young(vma->vm_mm, address, pmdp);
}

int pudp_test_and_clear_young(struct vm_area_struct *vma,
			      unsigned long address, pud_t *pudp)
{
	return __pudp_test_and_clear_young(vma->vm_mm, address, pudp);
}

/*
 * set a new huge pmd. We should not be called for updating
 * an existing pmd entry. That should go via pmd_hugepage_update.
 */
void set_pmd_at(struct mm_struct *mm, unsigned long addr,
		pmd_t *pmdp, pmd_t pmd)
{
#ifdef CONFIG_DEBUG_VM
	/*
	 * Make sure hardware valid bit is not set. We don't do
	 * tlb flush for this update.
	 */

	WARN_ON(pte_hw_valid(pmd_pte(*pmdp)) && !pte_protnone(pmd_pte(*pmdp)));
	assert_spin_locked(pmd_lockptr(mm, pmdp));
	WARN_ON(!(pmd_leaf(pmd)));
#endif
	trace_hugepage_set_pmd(addr, pmd_val(pmd));
	page_table_check_pmd_set(mm, addr, pmdp, pmd);
	return set_pte_at_unchecked(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
}

void set_pud_at(struct mm_struct *mm, unsigned long addr,
		pud_t *pudp, pud_t pud)
{
#ifdef CONFIG_DEBUG_VM
	/*
	 * Make sure hardware valid bit is not set. We don't do
	 * tlb flush for this update.
	 */

	WARN_ON(pte_hw_valid(pud_pte(*pudp)));
	assert_spin_locked(pud_lockptr(mm, pudp));
	WARN_ON(!(pud_leaf(pud)));
#endif
	trace_hugepage_set_pud(addr, pud_val(pud));
	page_table_check_pud_set(mm, addr, pudp, pud);
	return set_pte_at_unchecked(mm, addr, pudp_ptep(pudp), pud_pte(pud));
}

static void do_serialize(void *arg)
{
	/* We've taken the IPI, so try to trim the mask while here */
	if (radix_enabled()) {
		struct mm_struct *mm = arg;
		exit_lazy_flush_tlb(mm, false);
	}
}

/*
 * Serialize against __find_linux_pte() 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_linux_pte() to finish.
 */
void serialize_against_pte_lookup(struct mm_struct *mm)
{
	smp_mb();
	smp_call_function_many(mm_cpumask(mm), do_serialize, mm, 1);
}

/*
 * We use this to invalidate a pmdp entry before switching from a
 * hugepte to regular pmd entry.
 */
pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
		     pmd_t *pmdp)
{
	pmd_t old_pmd;

	VM_WARN_ON_ONCE(!pmd_present(*pmdp));
	old_pmd = __pmd(pmd_hugepage_update(vma->vm_mm, address, pmdp, _PAGE_PRESENT, _PAGE_INVALID));
	flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
	page_table_check_pmd_clear(vma->vm_mm, address, old_pmd);

	return old_pmd;
}

pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
		      pud_t *pudp)
{
	pud_t old_pud;

	VM_WARN_ON_ONCE(!pud_present(*pudp));
	old_pud = __pud(pud_hugepage_update(vma->vm_mm, address, pudp, _PAGE_PRESENT, _PAGE_INVALID));
	flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
	page_table_check_pud_clear(vma->vm_mm, address, old_pud);

	return old_pud;
}

pmd_t pmdp_huge_get_and_clear_full(struct vm_area_struct *vma,
				   unsigned long addr, pmd_t *pmdp, int full)
{
	pmd_t pmd;
	VM_BUG_ON(addr & ~HPAGE_PMD_MASK);
	VM_BUG_ON((pmd_present(*pmdp) && !pmd_trans_huge(*pmdp)) ||
		   !pmd_present(*pmdp));
	pmd = pmdp_huge_get_and_clear(vma->vm_mm, addr, pmdp);
	/*
	 * if it not a fullmm flush, then we can possibly end up converting
	 * this PMD pte entry to a regular level 0 PTE by a parallel page fault.
	 * Make sure we flush the tlb in this case.
	 */
	if (!full)
		flush_pmd_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE);
	return pmd;
}

pud_t pudp_huge_get_and_clear_full(struct vm_area_struct *vma,
				   unsigned long addr, pud_t *pudp, int full)
{
	pud_t pud;

	VM_BUG_ON(addr & ~HPAGE_PMD_MASK);
	VM_BUG_ON(!pud_present(*pudp));
	pud = pudp_huge_get_and_clear(vma->vm_mm, addr, pudp);
	/*
	 * if it not a fullmm flush, then we can possibly end up converting
	 * this PMD pte entry to a regular level 0 PTE by a parallel page fault.
	 * Make sure we flush the tlb in this case.
	 */
	if (!full)
		flush_pud_tlb_range(vma, addr, addr + HPAGE_PUD_SIZE);
	return pud;
}

static pmd_t pmd_set_protbits(pmd_t pmd, pgprot_t pgprot)
{
	return __pmd(pmd_val(pmd) | pgprot_val(pgprot));
}

static pud_t pud_set_protbits(pud_t pud, pgprot_t pgprot)
{
	return __pud(pud_val(pud) | pgprot_val(pgprot));
}

/*
 * At some point we should be able to get rid of
 * pmd_mkhuge() and mk_huge_pmd() when we update all the
 * other archs to mark the pmd huge in pfn_pmd()
 */
pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot)
{
	unsigned long pmdv;

	pmdv = (pfn << PAGE_SHIFT) & PTE_RPN_MASK;

	return __pmd_mkhuge(pmd_set_protbits(__pmd(pmdv), pgprot));
}

pud_t pfn_pud(unsigned long pfn, pgprot_t pgprot)
{
	unsigned long pudv;

	pudv = (pfn << PAGE_SHIFT) & PTE_RPN_MASK;

	return __pud_mkhuge(pud_set_protbits(__pud(pudv), pgprot));
}

pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
{
	unsigned long pmdv;

	pmdv = pmd_val(pmd);
	pmdv &= _HPAGE_CHG_MASK;
	return pmd_set_protbits(__pmd(pmdv), newprot);
}

pud_t pud_modify(pud_t pud, pgprot_t newprot)
{
	unsigned long pudv;

	pudv = pud_val(pud);
	pudv &= _HPAGE_CHG_MASK;
	return pud_set_protbits(__pud(pudv), newprot);
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

/* For use by kexec, called with MMU off */
notrace void mmu_cleanup_all(void)
{
	if (radix_enabled())
		radix__mmu_cleanup_all();
	else if (mmu_hash_ops.hpte_clear_all)
		mmu_hash_ops.hpte_clear_all();

	reset_sprs();
}

#ifdef CONFIG_MEMORY_HOTPLUG
int __meminit create_section_mapping(unsigned long start, unsigned long end,
				     int nid, pgprot_t prot)
{
	if (radix_enabled())
		return radix__create_section_mapping(start, end, nid, prot);

	return hash__create_section_mapping(start, end, nid, prot);
}

int __meminit remove_section_mapping(unsigned long start, unsigned long end)
{
	if (radix_enabled())
		return radix__remove_section_mapping(start, end);

	return hash__remove_section_mapping(start, end);
}
#endif /* CONFIG_MEMORY_HOTPLUG */

void __init mmu_partition_table_init(void)
{
	unsigned long patb_size = 1UL << PATB_SIZE_SHIFT;
	unsigned long ptcr;

	/* Initialize the Partition Table with no entries */
	partition_tb = memblock_alloc_or_panic(patb_size, patb_size);
	ptcr = __pa(partition_tb) | (PATB_SIZE_SHIFT - 12);
	set_ptcr_when_no_uv(ptcr);
	powernv_set_nmmu_ptcr(ptcr);
}

static void flush_partition(unsigned int lpid, bool radix)
{
	if (radix) {
		radix__flush_all_lpid(lpid);
		radix__flush_all_lpid_guest(lpid);
	} else {
		asm volatile("ptesync" : : : "memory");
		asm volatile(PPC_TLBIE_5(%0,%1,2,0,0) : :
			     "r" (TLBIEL_INVAL_SET_LPID), "r" (lpid));
		/* do we need fixup here ?*/
		asm volatile("eieio; tlbsync; ptesync" : : : "memory");
		trace_tlbie(lpid, 0, TLBIEL_INVAL_SET_LPID, lpid, 2, 0, 0);
	}
}

void mmu_partition_table_set_entry(unsigned int lpid, unsigned long dw0,
				  unsigned long dw1, bool flush)
{
	unsigned long old = be64_to_cpu(partition_tb[lpid].patb0);

	/*
	 * When ultravisor is enabled, the partition table is stored in secure
	 * memory and can only be accessed doing an ultravisor call. However, we
	 * maintain a copy of the partition table in normal memory to allow Nest
	 * MMU translations to occur (for normal VMs).
	 *
	 * Therefore, here we always update partition_tb, regardless of whether
	 * we are running under an ultravisor or not.
	 */
	partition_tb[lpid].patb0 = cpu_to_be64(dw0);
	partition_tb[lpid].patb1 = cpu_to_be64(dw1);

	/*
	 * If ultravisor is enabled, we do an ultravisor call to register the
	 * partition table entry (PATE), which also do a global flush of TLBs
	 * and partition table caches for the lpid. Otherwise, just do the
	 * flush. The type of flush (hash or radix) depends on what the previous
	 * use of the partition ID was, not the new use.
	 */
	if (firmware_has_feature(FW_FEATURE_ULTRAVISOR)) {
		uv_register_pate(lpid, dw0, dw1);
		pr_info("PATE registered by ultravisor: dw0 = 0x%lx, dw1 = 0x%lx\n",
			dw0, dw1);
	} else if (flush) {
		/*
		 * Boot does not need to flush, because MMU is off and each
		 * CPU does a tlbiel_all() before switching them on, which
		 * flushes everything.
		 */
		flush_partition(lpid, (old & PATB_HR));
	}
}
EXPORT_SYMBOL_GPL(mmu_partition_table_set_entry);

static pmd_t *get_pmd_from_cache(struct mm_struct *mm)
{
	void *pmd_frag, *ret;

	if (PMD_FRAG_NR == 1)
		return NULL;

	spin_lock(&mm->page_table_lock);
	ret = mm->context.pmd_frag;
	if (ret) {
		pmd_frag = ret + PMD_FRAG_SIZE;
		/*
		 * If we have taken up all the fragments mark PTE page NULL
		 */
		if (((unsigned long)pmd_frag & ~PAGE_MASK) == 0)
			pmd_frag = NULL;
		mm->context.pmd_frag = pmd_frag;
	}
	spin_unlock(&mm->page_table_lock);
	return (pmd_t *)ret;
}

static pmd_t *__alloc_for_pmdcache(struct mm_struct *mm)
{
	void *ret = NULL;
	struct ptdesc *ptdesc;
	gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO;

	if (mm == &init_mm)
		gfp &= ~__GFP_ACCOUNT;
	ptdesc = pagetable_alloc(gfp, 0);
	if (!ptdesc)
		return NULL;
	if (!pagetable_pmd_ctor(mm, ptdesc)) {
		pagetable_free(ptdesc);
		return NULL;
	}

	atomic_set(&ptdesc->pt_frag_refcount, 1);

	ret = ptdesc_address(ptdesc);
	/*
	 * if we support only one fragment just return the
	 * allocated page.
	 */
	if (PMD_FRAG_NR == 1)
		return ret;

	spin_lock(&mm->page_table_lock);
	/*
	 * If we find ptdesc_page set, we return
	 * the allocated page with single fragment
	 * count.
	 */
	if (likely(!mm->context.pmd_frag)) {
		atomic_set(&ptdesc->pt_frag_refcount, PMD_FRAG_NR);
		mm->context.pmd_frag = ret + PMD_FRAG_SIZE;
	}
	spin_unlock(&mm->page_table_lock);

	return (pmd_t *)ret;
}

pmd_t *pmd_fragment_alloc(struct mm_struct *mm, unsigned long vmaddr)
{
	pmd_t *pmd;

	pmd = get_pmd_from_cache(mm);
	if (pmd)
		return pmd;

	return __alloc_for_pmdcache(mm);
}

void pmd_fragment_free(unsigned long *pmd)
{
	struct ptdesc *ptdesc = virt_to_ptdesc(pmd);

	if (pagetable_is_reserved(ptdesc))
		return free_reserved_ptdesc(ptdesc);

	BUG_ON(atomic_read(&ptdesc->pt_frag_refcount) <= 0);
	if (atomic_dec_and_test(&ptdesc->pt_frag_refcount)) {
		pagetable_dtor(ptdesc);
		pagetable_free(ptdesc);
	}
}

static inline void pgtable_free(void *table, int index)
{
	switch (index) {
	case PTE_INDEX:
		pte_fragment_free(table, 0);
		break;
	case PMD_INDEX:
		pmd_fragment_free(table);
		break;
	case PUD_INDEX:
		__pud_free(table);
		break;
		/* We don't free pgd table via RCU callback */
	default:
		BUG();
	}
}

void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int index)
{
	unsigned long pgf = (unsigned long)table;

	BUG_ON(index > MAX_PGTABLE_INDEX_SIZE);
	pgf |= index;
	tlb_remove_table(tlb, (void *)pgf);
}

void __tlb_remove_table(void *_table)
{
	void *table = (void *)((unsigned long)_table & ~MAX_PGTABLE_INDEX_SIZE);
	unsigned int index = (unsigned long)_table & MAX_PGTABLE_INDEX_SIZE;

	return pgtable_free(table, index);
}

#ifdef CONFIG_PROC_FS
atomic_long_t direct_pages_count[MMU_PAGE_COUNT];

void arch_report_meminfo(struct seq_file *m)
{
	seq_printf(m, "DirectMap4k:    %8lu kB\n",
		   atomic_long_read(&direct_pages_count[MMU_PAGE_4K]) << 2);
	seq_printf(m, "DirectMap64k:   %8lu kB\n",
		   atomic_long_read(&direct_pages_count[MMU_PAGE_64K]) << 6);
	if (radix_enabled()) {
		seq_printf(m, "DirectMap2M:    %8lu kB\n",
			   atomic_long_read(&direct_pages_count[MMU_PAGE_2M]) << 11);
		seq_printf(m, "DirectMap1G:    %8lu kB\n",
			   atomic_long_read(&direct_pages_count[MMU_PAGE_1G]) << 20);
	} else {
		seq_printf(m, "DirectMap16M:   %8lu kB\n",
			   atomic_long_read(&direct_pages_count[MMU_PAGE_16M]) << 14);
		seq_printf(m, "DirectMap16G:   %8lu kB\n",
			   atomic_long_read(&direct_pages_count[MMU_PAGE_16G]) << 24);
	}
}
#endif /* CONFIG_PROC_FS */

pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr,
			     pte_t *ptep)
{
	unsigned long pte_val;

	/*
	 * Clear the _PAGE_PRESENT so that no hardware parallel update is
	 * possible. Also keep the pte_present true so that we don't take
	 * wrong fault.
	 */
	pte_val = pte_update(vma->vm_mm, addr, ptep, _PAGE_PRESENT, _PAGE_INVALID, 0);

	return __pte(pte_val);

}

void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr,
			     pte_t *ptep, pte_t old_pte, pte_t pte)
{
	if (radix_enabled())
		return radix__ptep_modify_prot_commit(vma, addr,
						      ptep, old_pte, pte);
	set_pte_at_unchecked(vma->vm_mm, addr, ptep, pte);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/*
 * For hash translation mode, we use the deposited table to store hash slot
 * information and they are stored at PTRS_PER_PMD offset from related pmd
 * location. Hence a pmd move requires deposit and withdraw.
 *
 * For radix translation with split pmd ptl, we store the deposited table in the
 * pmd page. Hence if we have different pmd page we need to withdraw during pmd
 * move.
 *
 * With hash we use deposited table always irrespective of anon or not.
 * With radix we use deposited table only for anonymous mapping.
 */
int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
			   struct spinlock *old_pmd_ptl,
			   struct vm_area_struct *vma)
{
	if (radix_enabled())
		return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);

	return true;
}
#endif

/*
 * Does the CPU support tlbie?
 */
bool tlbie_capable __read_mostly = IS_ENABLED(CONFIG_PPC_RADIX_BROADCAST_TLBIE);
EXPORT_SYMBOL(tlbie_capable);

/*
 * Should tlbie be used for management of CPU TLBs, for kernel and process
 * address spaces? tlbie may still be used for nMMU accelerators, and for KVM
 * guest address spaces.
 */
bool tlbie_enabled __read_mostly = IS_ENABLED(CONFIG_PPC_RADIX_BROADCAST_TLBIE);

static int __init setup_disable_tlbie(char *str)
{
	if (!radix_enabled()) {
		pr_err("disable_tlbie: Unable to disable TLBIE with Hash MMU.\n");
		return 1;
	}

	tlbie_capable = false;
	tlbie_enabled = false;

        return 1;
}
__setup("disable_tlbie", setup_disable_tlbie);

static int __init pgtable_debugfs_setup(void)
{
	if (!tlbie_capable)
		return 0;

	/*
	 * There is no locking vs tlb flushing when changing this value.
	 * The tlb flushers will see one value or another, and use either
	 * tlbie or tlbiel with IPIs. In both cases the TLBs will be
	 * invalidated as expected.
	 */
	debugfs_create_bool("tlbie_enabled", 0600,
			arch_debugfs_dir,
			&tlbie_enabled);

	return 0;
}
arch_initcall(pgtable_debugfs_setup);

#if defined(CONFIG_ZONE_DEVICE) && defined(CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN)
/*
 * Override the generic version in mm/memremap.c.
 *
 * With hash translation, the direct-map range is mapped with just one
 * page size selected by htab_init_page_sizes(). Consult
 * mmu_psize_defs[] to determine the minimum page size alignment.
*/
unsigned long memremap_compat_align(void)
{
	if (!radix_enabled()) {
		unsigned int shift = mmu_psize_defs[mmu_linear_psize].shift;
		return max(SUBSECTION_SIZE, 1UL << shift);
	}

	return SUBSECTION_SIZE;
}
EXPORT_SYMBOL_GPL(memremap_compat_align);
#endif

pgprot_t vm_get_page_prot(vm_flags_t vm_flags)
{
	unsigned long prot;

	/* Radix supports execute-only, but protection_map maps X -> RX */
	if (!radix_enabled() && ((vm_flags & VM_ACCESS_FLAGS) == VM_EXEC))
		vm_flags |= VM_READ;

	prot = pgprot_val(protection_map[vm_flags & (VM_ACCESS_FLAGS | VM_SHARED)]);

	if (vm_flags & VM_SAO)
		prot |= _PAGE_SAO;

#ifdef CONFIG_PPC_MEM_KEYS
	prot |= vmflag_to_pte_pkey_bits(vm_flags);
#endif

	return __pgprot(prot);
}
EXPORT_SYMBOL(vm_get_page_prot);