// SPDX-License-Identifier: GPL-2.0-or-later
/*
* This file contains common routines for dealing with free of page tables
* Along with common page table handling code
*
* Derived from arch/powerpc/mm/tlb_64.c:
* Copyright (C) 1995-1996 Gary Thomas ([email protected])
*
* Modifications by Paul Mackerras (PowerMac) ([email protected])
* and Cort Dougan (PReP) ([email protected])
* Copyright (C) 1996 Paul Mackerras
*
* Derived from "arch/i386/mm/init.c"
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*
* Dave Engebretsen <[email protected]>
* Rework for PPC64 port.
*/
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
#include <linux/hugetlb.h>
#include <asm/tlbflush.h>
#include <asm/tlb.h>
#include <asm/hugetlb.h>
#include <asm/pte-walk.h>
#ifdef CONFIG_PPC64
#define PGD_ALIGN (sizeof(pgd_t) * MAX_PTRS_PER_PGD)
#else
#define PGD_ALIGN PAGE_SIZE
#endif
pgd_t swapper_pg_dir[MAX_PTRS_PER_PGD] __section(".bss..page_aligned") __aligned(PGD_ALIGN);
static inline int is_exec_fault(void)
{
return current->thread.regs && TRAP(current->thread.regs) == 0x400;
}
/* We only try to do i/d cache coherency on stuff that looks like
* reasonably "normal" PTEs. We currently require a PTE to be present
* and we avoid _PAGE_SPECIAL and cache inhibited pte. We also only do that
* on userspace PTEs
*/
static inline int pte_looks_normal(pte_t pte, unsigned long addr)
{
if (pte_present(pte) && !pte_special(pte)) {
if (pte_ci(pte))
return 0;
if (!is_kernel_addr(addr))
return 1;
}
return 0;
}
static struct folio *maybe_pte_to_folio(pte_t pte)
{
unsigned long pfn = pte_pfn(pte);
struct page *page;
if (unlikely(!pfn_valid(pfn)))
return NULL;
page = pfn_to_page(pfn);
if (PageReserved(page))
return NULL;
return page_folio(page);
}
#ifdef CONFIG_PPC_BOOK3S
/* Server-style MMU handles coherency when hashing if HW exec permission
* is supposed per page (currently 64-bit only). If not, then, we always
* flush the cache for valid PTEs in set_pte. Embedded CPU without HW exec
* support falls into the same category.
*/
static pte_t set_pte_filter_hash(pte_t pte, unsigned long addr)
{
pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
if (pte_looks_normal(pte, addr) && !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) ||
cpu_has_feature(CPU_FTR_NOEXECUTE))) {
struct folio *folio = maybe_pte_to_folio(pte);
if (!folio)
return pte;
if (!test_bit(PG_dcache_clean, &folio->flags)) {
flush_dcache_icache_folio(folio);
set_bit(PG_dcache_clean, &folio->flags);
}
}
return pte;
}
#else /* CONFIG_PPC_BOOK3S */
static pte_t set_pte_filter_hash(pte_t pte, unsigned long addr) { return pte; }
#endif /* CONFIG_PPC_BOOK3S */
/* Embedded type MMU with HW exec support. This is a bit more complicated
* as we don't have two bits to spare for _PAGE_EXEC and _PAGE_HWEXEC so
* instead we "filter out" the exec permission for non clean pages.
*
* This is also called once for the folio. So only work with folio->flags here.
*/
static inline pte_t set_pte_filter(pte_t pte, unsigned long addr)
{
struct folio *folio;
if (radix_enabled())
return pte;
if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
return set_pte_filter_hash(pte, addr);
/* No exec permission in the first place, move on */
if (!pte_exec(pte) || !pte_looks_normal(pte, addr))
return pte;
/* If you set _PAGE_EXEC on weird pages you're on your own */
folio = maybe_pte_to_folio(pte);
if (unlikely(!folio))
return pte;
/* If the page clean, we move on */
if (test_bit(PG_dcache_clean, &folio->flags))
return pte;
/* If it's an exec fault, we flush the cache and make it clean */
if (is_exec_fault()) {
flush_dcache_icache_folio(folio);
set_bit(PG_dcache_clean, &folio->flags);
return pte;
}
/* Else, we filter out _PAGE_EXEC */
return pte_exprotect(pte);
}
static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
int dirty)
{
struct folio *folio;
if (IS_ENABLED(CONFIG_PPC_BOOK3S_64))
return pte;
if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
return pte;
/* So here, we only care about exec faults, as we use them
* to recover lost _PAGE_EXEC and perform I$/D$ coherency
* if necessary. Also if _PAGE_EXEC is already set, same deal,
* we just bail out
*/
if (dirty || pte_exec(pte) || !is_exec_fault())
return pte;
#ifdef CONFIG_DEBUG_VM
/* So this is an exec fault, _PAGE_EXEC is not set. If it was
* an error we would have bailed out earlier in do_page_fault()
* but let's make sure of it
*/
if (WARN_ON(!(vma->vm_flags & VM_EXEC)))
return pte;
#endif /* CONFIG_DEBUG_VM */
/* If you set _PAGE_EXEC on weird pages you're on your own */
folio = maybe_pte_to_folio(pte);
if (unlikely(!folio))
goto bail;
/* If the page is already clean, we move on */
if (test_bit(PG_dcache_clean, &folio->flags))
goto bail;
/* Clean the page and set PG_dcache_clean */
flush_dcache_icache_folio(folio);
set_bit(PG_dcache_clean, &folio->flags);
bail:
return pte_mkexec(pte);
}
/*
* set_pte stores a linux PTE into the linux page table.
*/
void set_ptes(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
pte_t pte, unsigned int nr)
{
/* Note: mm->context.id might not yet have been assigned as
* this context might not have been activated yet when this
* is called. Filter the pte value and use the filtered value
* to setup all the ptes in the range.
*/
pte = set_pte_filter(pte, addr);
/*
* We don't need to call arch_enter/leave_lazy_mmu_mode()
* because we expect set_ptes to be only be used on not present
* and not hw_valid ptes. Hence there is no translation cache flush
* involved that need to be batched.
*/
for (;;) {
/*
* Make sure hardware valid bit is not set. We don't do
* tlb flush for this update.
*/
VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep));
/* Perform the setting of the PTE */
__set_pte_at(mm, addr, ptep, pte, 0);
if (--nr == 0)
break;
ptep++;
addr += PAGE_SIZE;
pte = pte_next_pfn(pte);
}
}
void unmap_kernel_page(unsigned long va)
{
pmd_t *pmdp = pmd_off_k(va);
pte_t *ptep = pte_offset_kernel(pmdp, va);
pte_clear(&init_mm, va, ptep);
flush_tlb_kernel_range(va, va + PAGE_SIZE);
}
/*
* This is called when relaxing access to a PTE. 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 ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address,
pte_t *ptep, pte_t entry, int dirty)
{
int changed;
entry = set_access_flags_filter(entry, vma, dirty);
changed = !pte_same(*(ptep), entry);
if (changed) {
assert_pte_locked(vma->vm_mm, address);
__ptep_set_access_flags(vma, ptep, entry,
address, mmu_virtual_psize);
}
return changed;
}
#ifdef CONFIG_HUGETLB_PAGE
int huge_ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep,
pte_t pte, int dirty)
{
#ifdef HUGETLB_NEED_PRELOAD
/*
* The "return 1" forces a call of update_mmu_cache, which will write a
* TLB entry. Without this, platforms that don't do a write of the TLB
* entry in the TLB miss handler asm will fault ad infinitum.
*/
ptep_set_access_flags(vma, addr, ptep, pte, dirty);
return 1;
#else
int changed, psize;
pte = set_access_flags_filter(pte, vma, dirty);
changed = !pte_same(*(ptep), pte);
if (changed) {
#ifdef CONFIG_PPC_BOOK3S_64
struct hstate *h = hstate_vma(vma);
psize = hstate_get_psize(h);
#ifdef CONFIG_DEBUG_VM
assert_spin_locked(huge_pte_lockptr(h, vma->vm_mm, ptep));
#endif
#else
/*
* Not used on non book3s64 platforms.
* 8xx compares it with mmu_virtual_psize to
* know if it is a huge page or not.
*/
psize = MMU_PAGE_COUNT;
#endif
__ptep_set_access_flags(vma, ptep, pte, addr, psize);
}
return changed;
#endif
}
#if defined(CONFIG_PPC_8xx)
static void __set_huge_pte_at(pmd_t *pmd, pte_t *ptep, pte_basic_t val)
{
pte_basic_t *entry = (pte_basic_t *)ptep;
int num, i;
/*
* Make sure hardware valid bit is not set. We don't do
* tlb flush for this update.
*/
VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep));
num = number_of_cells_per_pte(pmd, val, 1);
for (i = 0; i < num; i++, entry++, val += SZ_4K)
*entry = val;
}
void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
pte_t pte, unsigned long sz)
{
pmd_t *pmdp = pmd_off(mm, addr);
pte = set_pte_filter(pte, addr);
if (sz == SZ_8M) { /* Flag both PMD entries as 8M and fill both page tables */
*pmdp = __pmd(pmd_val(*pmdp) | _PMD_PAGE_8M);
*(pmdp + 1) = __pmd(pmd_val(*(pmdp + 1)) | _PMD_PAGE_8M);
__set_huge_pte_at(pmdp, pte_offset_kernel(pmdp, 0), pte_val(pte));
__set_huge_pte_at(pmdp, pte_offset_kernel(pmdp + 1, 0), pte_val(pte) + SZ_4M);
} else {
__set_huge_pte_at(pmdp, ptep, pte_val(pte));
}
}
#else
void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
pte_t pte, unsigned long sz)
{
unsigned long pdsize;
int i;
pte = set_pte_filter(pte, addr);
/*
* Make sure hardware valid bit is not set. We don't do
* tlb flush for this update.
*/
VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep));
if (sz < PMD_SIZE)
pdsize = PAGE_SIZE;
else if (sz < PUD_SIZE)
pdsize = PMD_SIZE;
else if (sz < P4D_SIZE)
pdsize = PUD_SIZE;
else if (sz < PGDIR_SIZE)
pdsize = P4D_SIZE;
else
pdsize = PGDIR_SIZE;
for (i = 0; i < sz / pdsize; i++, ptep++, addr += pdsize) {
__set_pte_at(mm, addr, ptep, pte, 0);
pte = __pte(pte_val(pte) + ((unsigned long long)pdsize / PAGE_SIZE << PFN_PTE_SHIFT));
}
}
#endif
#endif /* CONFIG_HUGETLB_PAGE */
#ifdef CONFIG_DEBUG_VM
void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
{
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
spinlock_t *ptl;
if (mm == &init_mm)
return;
pgd = mm->pgd + pgd_index(addr);
BUG_ON(pgd_none(*pgd));
p4d = p4d_offset(pgd, addr);
BUG_ON(p4d_none(*p4d));
pud = pud_offset(p4d, addr);
BUG_ON(pud_none(*pud));
pmd = pmd_offset(pud, addr);
/*
* khugepaged to collapse normal pages to hugepage, first set
* pmd to none to force page fault/gup to take mmap_lock. After
* pmd is set to none, we do a pte_clear which does this assertion
* so if we find pmd none, return.
*/
if (pmd_none(*pmd))
return;
pte = pte_offset_map_nolock(mm, pmd, addr, &ptl);
BUG_ON(!pte);
assert_spin_locked(ptl);
pte_unmap(pte);
}
#endif /* CONFIG_DEBUG_VM */
unsigned long vmalloc_to_phys(void *va)
{
unsigned long pfn = vmalloc_to_pfn(va);
BUG_ON(!pfn);
return __pa(pfn_to_kaddr(pfn)) + offset_in_page(va);
}
EXPORT_SYMBOL_GPL(vmalloc_to_phys);
/*
* We have 3 cases for pgds and pmds:
* (1) invalid (all zeroes)
* (2) pointer to next table, as normal; bottom 6 bits == 0
* (3) leaf pte for huge page _PAGE_PTE set
*
* So long as we atomically load page table pointers we are safe against teardown,
* we can follow the address down to the page and take a ref on it.
* This function need to be called with interrupts disabled. We use this variant
* when we have MSR[EE] = 0 but the paca->irq_soft_mask = IRQS_ENABLED
*/
pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
bool *is_thp, unsigned *hpage_shift)
{
pgd_t *pgdp;
#ifdef CONFIG_PPC64
p4d_t p4d, *p4dp;
pud_t pud, *pudp;
#endif
pmd_t pmd, *pmdp;
pte_t *ret_pte;
unsigned pdshift;
if (hpage_shift)
*hpage_shift = 0;
if (is_thp)
*is_thp = false;
/*
* Always operate on the local stack value. This make sure the
* value don't get updated by a parallel THP split/collapse,
* page fault or a page unmap. The return pte_t * is still not
* stable. So should be checked there for above conditions.
* Top level is an exception because it is folded into p4d.
*
* On PPC32, P4D/PUD/PMD are folded into PGD so go straight to
* PMD level.
*/
pgdp = pgdir + pgd_index(ea);
#ifdef CONFIG_PPC64
p4dp = p4d_offset(pgdp, ea);
p4d = READ_ONCE(*p4dp);
pdshift = P4D_SHIFT;
if (p4d_none(p4d))
return NULL;
if (p4d_leaf(p4d)) {
ret_pte = (pte_t *)p4dp;
goto out;
}
/*
* Even if we end up with an unmap, the pgtable will not
* be freed, because we do an rcu free and here we are
* irq disabled
*/
pdshift = PUD_SHIFT;
pudp = pud_offset(&p4d, ea);
pud = READ_ONCE(*pudp);
if (pud_none(pud))
return NULL;
if (pud_leaf(pud)) {
ret_pte = (pte_t *)pudp;
goto out;
}
pmdp = pmd_offset(&pud, ea);
#else
pmdp = pmd_offset(pud_offset(p4d_offset(pgdp, ea), ea), ea);
#endif
pdshift = PMD_SHIFT;
pmd = READ_ONCE(*pmdp);
/*
* A hugepage collapse is captured by this condition, see
* pmdp_collapse_flush.
*/
if (pmd_none(pmd))
return NULL;
#ifdef CONFIG_PPC_BOOK3S_64
/*
* A hugepage split is captured by this condition, see
* pmdp_invalidate.
*
* Huge page modification can be caught here too.
*/
if (pmd_is_serializing(pmd))
return NULL;
#endif
if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
if (is_thp)
*is_thp = true;
ret_pte = (pte_t *)pmdp;
goto out;
}
if (pmd_leaf(pmd)) {
ret_pte = (pte_t *)pmdp;
goto out;
}
return pte_offset_kernel(&pmd, ea);
out:
if (hpage_shift)
*hpage_shift = pdshift;
return ret_pte;
}
EXPORT_SYMBOL_GPL(__find_linux_pte);
/* Note due to the way vm flags are laid out, the bits are XWR */
const pgprot_t protection_map[16] = {
[VM_NONE] = PAGE_NONE,
[VM_READ] = PAGE_READONLY,
[VM_WRITE] = PAGE_COPY,
[VM_WRITE | VM_READ] = PAGE_COPY,
[VM_EXEC] = PAGE_EXECONLY_X,
[VM_EXEC | VM_READ] = PAGE_READONLY_X,
[VM_EXEC | VM_WRITE] = PAGE_COPY_X,
[VM_EXEC | VM_WRITE | VM_READ] = PAGE_COPY_X,
[VM_SHARED] = PAGE_NONE,
[VM_SHARED | VM_READ] = PAGE_READONLY,
[VM_SHARED | VM_WRITE] = PAGE_SHARED,
[VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED,
[VM_SHARED | VM_EXEC] = PAGE_EXECONLY_X,
[VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY_X,
[VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED_X,
[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_X
};
#ifndef CONFIG_PPC_BOOK3S_64
DECLARE_VM_GET_PAGE_PROT
#endif
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