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linux/arch/arm64/mm/mmu.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Based on arch/arm/mm/mmu.c
*
* Copyright (C) 1995-2005 Russell King
* Copyright (C) 2012 ARM Ltd.
*/
#include <linux/cache.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/kexec.h>
#include <linux/libfdt.h>
#include <linux/mman.h>
#include <linux/nodemask.h>
#include <linux/memblock.h>
#include <linux/memremap.h>
#include <linux/memory.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/set_memory.h>
#include <linux/kfence.h>
#include <linux/pkeys.h>
#include <linux/mm_inline.h>
#include <linux/pagewalk.h>
#include <linux/stop_machine.h>
#include <asm/barrier.h>
#include <asm/cputype.h>
#include <asm/fixmap.h>
#include <asm/kasan.h>
#include <asm/kernel-pgtable.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <linux/sizes.h>
#include <asm/tlb.h>
#include <asm/mmu_context.h>
#include <asm/ptdump.h>
#include <asm/tlbflush.h>
#include <asm/pgalloc.h>
#include <asm/kfence.h>
#define NO_BLOCK_MAPPINGS BIT(0)
#define NO_CONT_MAPPINGS BIT(1)
#define NO_EXEC_MAPPINGS BIT(2) /* assumes FEAT_HPDS is not used */
DEFINE_STATIC_KEY_FALSE(arm64_ptdump_lock_key);
u64 kimage_voffset __ro_after_init;
EXPORT_SYMBOL(kimage_voffset);
u32 __boot_cpu_mode[] = { BOOT_CPU_MODE_EL2, BOOT_CPU_MODE_EL1 };
static bool rodata_is_rw __ro_after_init = true;
/*
* The booting CPU updates the failed status @__early_cpu_boot_status,
* with MMU turned off.
*/
long __section(".mmuoff.data.write") __early_cpu_boot_status;
/*
* Empty_zero_page is a special page that is used for zero-initialized data
* and COW.
*/
unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
EXPORT_SYMBOL(empty_zero_page);
static DEFINE_SPINLOCK(swapper_pgdir_lock);
static DEFINE_MUTEX(fixmap_lock);
void noinstr set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
{
pgd_t *fixmap_pgdp;
/*
* Don't bother with the fixmap if swapper_pg_dir is still mapped
* writable in the kernel mapping.
*/
if (rodata_is_rw) {
WRITE_ONCE(*pgdp, pgd);
dsb(ishst);
isb();
return;
}
spin_lock(&swapper_pgdir_lock);
fixmap_pgdp = pgd_set_fixmap(__pa_symbol(pgdp));
WRITE_ONCE(*fixmap_pgdp, pgd);
/*
* We need dsb(ishst) here to ensure the page-table-walker sees
* our new entry before set_p?d() returns. The fixmap's
* flush_tlb_kernel_range() via clear_fixmap() does this for us.
*/
pgd_clear_fixmap();
spin_unlock(&swapper_pgdir_lock);
}
pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
unsigned long size, pgprot_t vma_prot)
{
if (!pfn_is_map_memory(pfn))
return pgprot_noncached(vma_prot);
else if (file->f_flags & O_SYNC)
return pgprot_writecombine(vma_prot);
return vma_prot;
}
EXPORT_SYMBOL(phys_mem_access_prot);
static phys_addr_t __init early_pgtable_alloc(enum pgtable_type pgtable_type)
{
phys_addr_t phys;
phys = memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE, 0,
MEMBLOCK_ALLOC_NOLEAKTRACE);
if (!phys)
panic("Failed to allocate page table page\n");
return phys;
}
bool pgattr_change_is_safe(pteval_t old, pteval_t new)
{
/*
* The following mapping attributes may be updated in live
* kernel mappings without the need for break-before-make.
*/
pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE | PTE_NG |
PTE_SWBITS_MASK;
/* creating or taking down mappings is always safe */
if (!pte_valid(__pte(old)) || !pte_valid(__pte(new)))
return true;
/* A live entry's pfn should not change */
if (pte_pfn(__pte(old)) != pte_pfn(__pte(new)))
return false;
/* live contiguous mappings may not be manipulated at all */
if ((old | new) & PTE_CONT)
return false;
/* Transitioning from Non-Global to Global is unsafe */
if (old & ~new & PTE_NG)
return false;
/*
* Changing the memory type between Normal and Normal-Tagged is safe
* since Tagged is considered a permission attribute from the
* mismatched attribute aliases perspective.
*/
if (((old & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL) ||
(old & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL_TAGGED)) &&
((new & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL) ||
(new & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL_TAGGED)))
mask |= PTE_ATTRINDX_MASK;
return ((old ^ new) & ~mask) == 0;
}
static void init_clear_pgtable(void *table)
{
clear_page(table);
/* Ensure the zeroing is observed by page table walks. */
dsb(ishst);
}
static void init_pte(pte_t *ptep, unsigned long addr, unsigned long end,
phys_addr_t phys, pgprot_t prot)
{
do {
pte_t old_pte = __ptep_get(ptep);
/*
* Required barriers to make this visible to the table walker
* are deferred to the end of alloc_init_cont_pte().
*/
__set_pte_nosync(ptep, pfn_pte(__phys_to_pfn(phys), prot));
/*
* After the PTE entry has been populated once, we
* only allow updates to the permission attributes.
*/
BUG_ON(!pgattr_change_is_safe(pte_val(old_pte),
pte_val(__ptep_get(ptep))));
phys += PAGE_SIZE;
} while (ptep++, addr += PAGE_SIZE, addr != end);
}
static int alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr,
unsigned long end, phys_addr_t phys,
pgprot_t prot,
phys_addr_t (*pgtable_alloc)(enum pgtable_type),
int flags)
{
unsigned long next;
pmd_t pmd = READ_ONCE(*pmdp);
pte_t *ptep;
BUG_ON(pmd_sect(pmd));
if (pmd_none(pmd)) {
pmdval_t pmdval = PMD_TYPE_TABLE | PMD_TABLE_UXN | PMD_TABLE_AF;
phys_addr_t pte_phys;
if (flags & NO_EXEC_MAPPINGS)
pmdval |= PMD_TABLE_PXN;
BUG_ON(!pgtable_alloc);
pte_phys = pgtable_alloc(TABLE_PTE);
if (pte_phys == INVALID_PHYS_ADDR)
return -ENOMEM;
ptep = pte_set_fixmap(pte_phys);
init_clear_pgtable(ptep);
ptep += pte_index(addr);
__pmd_populate(pmdp, pte_phys, pmdval);
} else {
BUG_ON(pmd_bad(pmd));
ptep = pte_set_fixmap_offset(pmdp, addr);
}
do {
pgprot_t __prot = prot;
next = pte_cont_addr_end(addr, end);
/* use a contiguous mapping if the range is suitably aligned */
if ((((addr | next | phys) & ~CONT_PTE_MASK) == 0) &&
(flags & NO_CONT_MAPPINGS) == 0)
__prot = __pgprot(pgprot_val(prot) | PTE_CONT);
init_pte(ptep, addr, next, phys, __prot);
ptep += pte_index(next) - pte_index(addr);
phys += next - addr;
} while (addr = next, addr != end);
/*
* Note: barriers and maintenance necessary to clear the fixmap slot
* ensure that all previous pgtable writes are visible to the table
* walker.
*/
pte_clear_fixmap();
return 0;
}
static int init_pmd(pmd_t *pmdp, unsigned long addr, unsigned long end,
phys_addr_t phys, pgprot_t prot,
phys_addr_t (*pgtable_alloc)(enum pgtable_type), int flags)
{
unsigned long next;
do {
pmd_t old_pmd = READ_ONCE(*pmdp);
next = pmd_addr_end(addr, end);
/* try section mapping first */
if (((addr | next | phys) & ~PMD_MASK) == 0 &&
(flags & NO_BLOCK_MAPPINGS) == 0) {
pmd_set_huge(pmdp, phys, prot);
/*
* After the PMD entry has been populated once, we
* only allow updates to the permission attributes.
*/
BUG_ON(!pgattr_change_is_safe(pmd_val(old_pmd),
READ_ONCE(pmd_val(*pmdp))));
} else {
int ret;
ret = alloc_init_cont_pte(pmdp, addr, next, phys, prot,
pgtable_alloc, flags);
if (ret)
return ret;
BUG_ON(pmd_val(old_pmd) != 0 &&
pmd_val(old_pmd) != READ_ONCE(pmd_val(*pmdp)));
}
phys += next - addr;
} while (pmdp++, addr = next, addr != end);
return 0;
}
static int alloc_init_cont_pmd(pud_t *pudp, unsigned long addr,
unsigned long end, phys_addr_t phys,
pgprot_t prot,
phys_addr_t (*pgtable_alloc)(enum pgtable_type),
int flags)
{
int ret;
unsigned long next;
pud_t pud = READ_ONCE(*pudp);
pmd_t *pmdp;
/*
* Check for initial section mappings in the pgd/pud.
*/
BUG_ON(pud_sect(pud));
if (pud_none(pud)) {
pudval_t pudval = PUD_TYPE_TABLE | PUD_TABLE_UXN | PUD_TABLE_AF;
phys_addr_t pmd_phys;
if (flags & NO_EXEC_MAPPINGS)
pudval |= PUD_TABLE_PXN;
BUG_ON(!pgtable_alloc);
pmd_phys = pgtable_alloc(TABLE_PMD);
if (pmd_phys == INVALID_PHYS_ADDR)
return -ENOMEM;
pmdp = pmd_set_fixmap(pmd_phys);
init_clear_pgtable(pmdp);
pmdp += pmd_index(addr);
__pud_populate(pudp, pmd_phys, pudval);
} else {
BUG_ON(pud_bad(pud));
pmdp = pmd_set_fixmap_offset(pudp, addr);
}
do {
pgprot_t __prot = prot;
next = pmd_cont_addr_end(addr, end);
/* use a contiguous mapping if the range is suitably aligned */
if ((((addr | next | phys) & ~CONT_PMD_MASK) == 0) &&
(flags & NO_CONT_MAPPINGS) == 0)
__prot = __pgprot(pgprot_val(prot) | PTE_CONT);
ret = init_pmd(pmdp, addr, next, phys, __prot, pgtable_alloc, flags);
if (ret)
goto out;
pmdp += pmd_index(next) - pmd_index(addr);
phys += next - addr;
} while (addr = next, addr != end);
out:
pmd_clear_fixmap();
return ret;
}
static int alloc_init_pud(p4d_t *p4dp, unsigned long addr, unsigned long end,
phys_addr_t phys, pgprot_t prot,
phys_addr_t (*pgtable_alloc)(enum pgtable_type),
int flags)
{
int ret = 0;
unsigned long next;
p4d_t p4d = READ_ONCE(*p4dp);
pud_t *pudp;
if (p4d_none(p4d)) {
p4dval_t p4dval = P4D_TYPE_TABLE | P4D_TABLE_UXN | P4D_TABLE_AF;
phys_addr_t pud_phys;
if (flags & NO_EXEC_MAPPINGS)
p4dval |= P4D_TABLE_PXN;
BUG_ON(!pgtable_alloc);
pud_phys = pgtable_alloc(TABLE_PUD);
if (pud_phys == INVALID_PHYS_ADDR)
return -ENOMEM;
pudp = pud_set_fixmap(pud_phys);
init_clear_pgtable(pudp);
pudp += pud_index(addr);
__p4d_populate(p4dp, pud_phys, p4dval);
} else {
BUG_ON(p4d_bad(p4d));
pudp = pud_set_fixmap_offset(p4dp, addr);
}
do {
pud_t old_pud = READ_ONCE(*pudp);
next = pud_addr_end(addr, end);
/*
* For 4K granule only, attempt to put down a 1GB block
*/
if (pud_sect_supported() &&
((addr | next | phys) & ~PUD_MASK) == 0 &&
(flags & NO_BLOCK_MAPPINGS) == 0) {
pud_set_huge(pudp, phys, prot);
/*
* After the PUD entry has been populated once, we
* only allow updates to the permission attributes.
*/
BUG_ON(!pgattr_change_is_safe(pud_val(old_pud),
READ_ONCE(pud_val(*pudp))));
} else {
ret = alloc_init_cont_pmd(pudp, addr, next, phys, prot,
pgtable_alloc, flags);
if (ret)
goto out;
BUG_ON(pud_val(old_pud) != 0 &&
pud_val(old_pud) != READ_ONCE(pud_val(*pudp)));
}
phys += next - addr;
} while (pudp++, addr = next, addr != end);
out:
pud_clear_fixmap();
return ret;
}
static int alloc_init_p4d(pgd_t *pgdp, unsigned long addr, unsigned long end,
phys_addr_t phys, pgprot_t prot,
phys_addr_t (*pgtable_alloc)(enum pgtable_type),
int flags)
{
int ret;
unsigned long next;
pgd_t pgd = READ_ONCE(*pgdp);
p4d_t *p4dp;
if (pgd_none(pgd)) {
pgdval_t pgdval = PGD_TYPE_TABLE | PGD_TABLE_UXN | PGD_TABLE_AF;
phys_addr_t p4d_phys;
if (flags & NO_EXEC_MAPPINGS)
pgdval |= PGD_TABLE_PXN;
BUG_ON(!pgtable_alloc);
p4d_phys = pgtable_alloc(TABLE_P4D);
if (p4d_phys == INVALID_PHYS_ADDR)
return -ENOMEM;
p4dp = p4d_set_fixmap(p4d_phys);
init_clear_pgtable(p4dp);
p4dp += p4d_index(addr);
__pgd_populate(pgdp, p4d_phys, pgdval);
} else {
BUG_ON(pgd_bad(pgd));
p4dp = p4d_set_fixmap_offset(pgdp, addr);
}
do {
p4d_t old_p4d = READ_ONCE(*p4dp);
next = p4d_addr_end(addr, end);
ret = alloc_init_pud(p4dp, addr, next, phys, prot,
pgtable_alloc, flags);
if (ret)
goto out;
BUG_ON(p4d_val(old_p4d) != 0 &&
p4d_val(old_p4d) != READ_ONCE(p4d_val(*p4dp)));
phys += next - addr;
} while (p4dp++, addr = next, addr != end);
out:
p4d_clear_fixmap();
return ret;
}
static int __create_pgd_mapping_locked(pgd_t *pgdir, phys_addr_t phys,
unsigned long virt, phys_addr_t size,
pgprot_t prot,
phys_addr_t (*pgtable_alloc)(enum pgtable_type),
int flags)
{
int ret;
unsigned long addr, end, next;
pgd_t *pgdp = pgd_offset_pgd(pgdir, virt);
/*
* If the virtual and physical address don't have the same offset
* within a page, we cannot map the region as the caller expects.
*/
if (WARN_ON((phys ^ virt) & ~PAGE_MASK))
return -EINVAL;
phys &= PAGE_MASK;
addr = virt & PAGE_MASK;
end = PAGE_ALIGN(virt + size);
do {
next = pgd_addr_end(addr, end);
ret = alloc_init_p4d(pgdp, addr, next, phys, prot, pgtable_alloc,
flags);
if (ret)
return ret;
phys += next - addr;
} while (pgdp++, addr = next, addr != end);
return 0;
}
static int __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
unsigned long virt, phys_addr_t size,
pgprot_t prot,
phys_addr_t (*pgtable_alloc)(enum pgtable_type),
int flags)
{
int ret;
mutex_lock(&fixmap_lock);
ret = __create_pgd_mapping_locked(pgdir, phys, virt, size, prot,
pgtable_alloc, flags);
mutex_unlock(&fixmap_lock);
return ret;
}
static void early_create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
unsigned long virt, phys_addr_t size,
pgprot_t prot,
phys_addr_t (*pgtable_alloc)(enum pgtable_type),
int flags)
{
int ret;
ret = __create_pgd_mapping(pgdir, phys, virt, size, prot, pgtable_alloc,
flags);
if (ret)
panic("Failed to create page tables\n");
}
static phys_addr_t __pgd_pgtable_alloc(struct mm_struct *mm, gfp_t gfp,
enum pgtable_type pgtable_type)
{
/* Page is zeroed by init_clear_pgtable() so don't duplicate effort. */
struct ptdesc *ptdesc = pagetable_alloc(gfp & ~__GFP_ZERO, 0);
phys_addr_t pa;
if (!ptdesc)
return INVALID_PHYS_ADDR;
pa = page_to_phys(ptdesc_page(ptdesc));
switch (pgtable_type) {
case TABLE_PTE:
BUG_ON(!pagetable_pte_ctor(mm, ptdesc));
break;
case TABLE_PMD:
BUG_ON(!pagetable_pmd_ctor(mm, ptdesc));
break;
case TABLE_PUD:
pagetable_pud_ctor(ptdesc);
break;
case TABLE_P4D:
pagetable_p4d_ctor(ptdesc);
break;
}
return pa;
}
static phys_addr_t
pgd_pgtable_alloc_init_mm_gfp(enum pgtable_type pgtable_type, gfp_t gfp)
{
return __pgd_pgtable_alloc(&init_mm, gfp, pgtable_type);
}
static phys_addr_t __maybe_unused
pgd_pgtable_alloc_init_mm(enum pgtable_type pgtable_type)
{
return pgd_pgtable_alloc_init_mm_gfp(pgtable_type, GFP_PGTABLE_KERNEL);
}
static phys_addr_t
pgd_pgtable_alloc_special_mm(enum pgtable_type pgtable_type)
{
return __pgd_pgtable_alloc(NULL, GFP_PGTABLE_KERNEL, pgtable_type);
}
static void split_contpte(pte_t *ptep)
{
int i;
ptep = PTR_ALIGN_DOWN(ptep, sizeof(*ptep) * CONT_PTES);
for (i = 0; i < CONT_PTES; i++, ptep++)
__set_pte(ptep, pte_mknoncont(__ptep_get(ptep)));
}
static int split_pmd(pmd_t *pmdp, pmd_t pmd, gfp_t gfp, bool to_cont)
{
pmdval_t tableprot = PMD_TYPE_TABLE | PMD_TABLE_UXN | PMD_TABLE_AF;
unsigned long pfn = pmd_pfn(pmd);
pgprot_t prot = pmd_pgprot(pmd);
phys_addr_t pte_phys;
pte_t *ptep;
int i;
pte_phys = pgd_pgtable_alloc_init_mm_gfp(TABLE_PTE, gfp);
if (pte_phys == INVALID_PHYS_ADDR)
return -ENOMEM;
ptep = (pte_t *)phys_to_virt(pte_phys);
if (pgprot_val(prot) & PMD_SECT_PXN)
tableprot |= PMD_TABLE_PXN;
prot = __pgprot((pgprot_val(prot) & ~PTE_TYPE_MASK) | PTE_TYPE_PAGE);
prot = __pgprot(pgprot_val(prot) & ~PTE_CONT);
if (to_cont)
prot = __pgprot(pgprot_val(prot) | PTE_CONT);
for (i = 0; i < PTRS_PER_PTE; i++, ptep++, pfn++)
__set_pte(ptep, pfn_pte(pfn, prot));
/*
* Ensure the pte entries are visible to the table walker by the time
* the pmd entry that points to the ptes is visible.
*/
dsb(ishst);
__pmd_populate(pmdp, pte_phys, tableprot);
return 0;
}
static void split_contpmd(pmd_t *pmdp)
{
int i;
pmdp = PTR_ALIGN_DOWN(pmdp, sizeof(*pmdp) * CONT_PMDS);
for (i = 0; i < CONT_PMDS; i++, pmdp++)
set_pmd(pmdp, pmd_mknoncont(pmdp_get(pmdp)));
}
static int split_pud(pud_t *pudp, pud_t pud, gfp_t gfp, bool to_cont)
{
pudval_t tableprot = PUD_TYPE_TABLE | PUD_TABLE_UXN | PUD_TABLE_AF;
unsigned int step = PMD_SIZE >> PAGE_SHIFT;
unsigned long pfn = pud_pfn(pud);
pgprot_t prot = pud_pgprot(pud);
phys_addr_t pmd_phys;
pmd_t *pmdp;
int i;
pmd_phys = pgd_pgtable_alloc_init_mm_gfp(TABLE_PMD, gfp);
if (pmd_phys == INVALID_PHYS_ADDR)
return -ENOMEM;
pmdp = (pmd_t *)phys_to_virt(pmd_phys);
if (pgprot_val(prot) & PMD_SECT_PXN)
tableprot |= PUD_TABLE_PXN;
prot = __pgprot((pgprot_val(prot) & ~PMD_TYPE_MASK) | PMD_TYPE_SECT);
prot = __pgprot(pgprot_val(prot) & ~PTE_CONT);
if (to_cont)
prot = __pgprot(pgprot_val(prot) | PTE_CONT);
for (i = 0; i < PTRS_PER_PMD; i++, pmdp++, pfn += step)
set_pmd(pmdp, pfn_pmd(pfn, prot));
/*
* Ensure the pmd entries are visible to the table walker by the time
* the pud entry that points to the pmds is visible.
*/
dsb(ishst);
__pud_populate(pudp, pmd_phys, tableprot);
return 0;
}
static int split_kernel_leaf_mapping_locked(unsigned long addr)
{
pgd_t *pgdp, pgd;
p4d_t *p4dp, p4d;
pud_t *pudp, pud;
pmd_t *pmdp, pmd;
pte_t *ptep, pte;
int ret = 0;
/*
* PGD: If addr is PGD aligned then addr already describes a leaf
* boundary. If not present then there is nothing to split.
*/
if (ALIGN_DOWN(addr, PGDIR_SIZE) == addr)
goto out;
pgdp = pgd_offset_k(addr);
pgd = pgdp_get(pgdp);
if (!pgd_present(pgd))
goto out;
/*
* P4D: If addr is P4D aligned then addr already describes a leaf
* boundary. If not present then there is nothing to split.
*/
if (ALIGN_DOWN(addr, P4D_SIZE) == addr)
goto out;
p4dp = p4d_offset(pgdp, addr);
p4d = p4dp_get(p4dp);
if (!p4d_present(p4d))
goto out;
/*
* PUD: If addr is PUD aligned then addr already describes a leaf
* boundary. If not present then there is nothing to split. Otherwise,
* if we have a pud leaf, split to contpmd.
*/
if (ALIGN_DOWN(addr, PUD_SIZE) == addr)
goto out;
pudp = pud_offset(p4dp, addr);
pud = pudp_get(pudp);
if (!pud_present(pud))
goto out;
if (pud_leaf(pud)) {
ret = split_pud(pudp, pud, GFP_PGTABLE_KERNEL, true);
if (ret)
goto out;
}
/*
* CONTPMD: If addr is CONTPMD aligned then addr already describes a
* leaf boundary. If not present then there is nothing to split.
* Otherwise, if we have a contpmd leaf, split to pmd.
*/
if (ALIGN_DOWN(addr, CONT_PMD_SIZE) == addr)
goto out;
pmdp = pmd_offset(pudp, addr);
pmd = pmdp_get(pmdp);
if (!pmd_present(pmd))
goto out;
if (pmd_leaf(pmd)) {
if (pmd_cont(pmd))
split_contpmd(pmdp);
/*
* PMD: If addr is PMD aligned then addr already describes a
* leaf boundary. Otherwise, split to contpte.
*/
if (ALIGN_DOWN(addr, PMD_SIZE) == addr)
goto out;
ret = split_pmd(pmdp, pmd, GFP_PGTABLE_KERNEL, true);
if (ret)
goto out;
}
/*
* CONTPTE: If addr is CONTPTE aligned then addr already describes a
* leaf boundary. If not present then there is nothing to split.
* Otherwise, if we have a contpte leaf, split to pte.
*/
if (ALIGN_DOWN(addr, CONT_PTE_SIZE) == addr)
goto out;
ptep = pte_offset_kernel(pmdp, addr);
pte = __ptep_get(ptep);
if (!pte_present(pte))
goto out;
if (pte_cont(pte))
split_contpte(ptep);
out:
return ret;
}
static inline bool force_pte_mapping(void)
{
const bool bbml2 = system_capabilities_finalized() ?
system_supports_bbml2_noabort() : cpu_supports_bbml2_noabort();
if (debug_pagealloc_enabled())
return true;
if (bbml2)
return false;
return rodata_full || arm64_kfence_can_set_direct_map() || is_realm_world();
}
static inline bool split_leaf_mapping_possible(void)
{
/*
* !BBML2_NOABORT systems should never run into scenarios where we would
* have to split. So exit early and let calling code detect it and raise
* a warning.
*/
if (!system_supports_bbml2_noabort())
return false;
return !force_pte_mapping();
}
static DEFINE_MUTEX(pgtable_split_lock);
int split_kernel_leaf_mapping(unsigned long start, unsigned long end)
{
int ret;
/*
* Exit early if the region is within a pte-mapped area or if we can't
* split. For the latter case, the permission change code will raise a
* warning if not already pte-mapped.
*/
if (!split_leaf_mapping_possible() || is_kfence_address((void *)start))
return 0;
/*
* Ensure start and end are at least page-aligned since this is the
* finest granularity we can split to.
*/
if (start != PAGE_ALIGN(start) || end != PAGE_ALIGN(end))
return -EINVAL;
mutex_lock(&pgtable_split_lock);
arch_enter_lazy_mmu_mode();
/*
* The split_kernel_leaf_mapping_locked() may sleep, it is not a
* problem for ARM64 since ARM64's lazy MMU implementation allows
* sleeping.
*
* Optimize for the common case of splitting out a single page from a
* larger mapping. Here we can just split on the "least aligned" of
* start and end and this will guarantee that there must also be a split
* on the more aligned address since the both addresses must be in the
* same contpte block and it must have been split to ptes.
*/
if (end - start == PAGE_SIZE) {
start = __ffs(start) < __ffs(end) ? start : end;
ret = split_kernel_leaf_mapping_locked(start);
} else {
ret = split_kernel_leaf_mapping_locked(start);
if (!ret)
ret = split_kernel_leaf_mapping_locked(end);
}
arch_leave_lazy_mmu_mode();
mutex_unlock(&pgtable_split_lock);
return ret;
}
static int split_to_ptes_pud_entry(pud_t *pudp, unsigned long addr,
unsigned long next, struct mm_walk *walk)
{
gfp_t gfp = *(gfp_t *)walk->private;
pud_t pud = pudp_get(pudp);
int ret = 0;
if (pud_leaf(pud))
ret = split_pud(pudp, pud, gfp, false);
return ret;
}
static int split_to_ptes_pmd_entry(pmd_t *pmdp, unsigned long addr,
unsigned long next, struct mm_walk *walk)
{
gfp_t gfp = *(gfp_t *)walk->private;
pmd_t pmd = pmdp_get(pmdp);
int ret = 0;
if (pmd_leaf(pmd)) {
if (pmd_cont(pmd))
split_contpmd(pmdp);
ret = split_pmd(pmdp, pmd, gfp, false);
/*
* We have split the pmd directly to ptes so there is no need to
* visit each pte to check if they are contpte.
*/
walk->action = ACTION_CONTINUE;
}
return ret;
}
static int split_to_ptes_pte_entry(pte_t *ptep, unsigned long addr,
unsigned long next, struct mm_walk *walk)
{
pte_t pte = __ptep_get(ptep);
if (pte_cont(pte))
split_contpte(ptep);
return 0;
}
static const struct mm_walk_ops split_to_ptes_ops = {
.pud_entry = split_to_ptes_pud_entry,
.pmd_entry = split_to_ptes_pmd_entry,
.pte_entry = split_to_ptes_pte_entry,
};
static int range_split_to_ptes(unsigned long start, unsigned long end, gfp_t gfp)
{
int ret;
arch_enter_lazy_mmu_mode();
ret = walk_kernel_page_table_range_lockless(start, end,
&split_to_ptes_ops, NULL, &gfp);
arch_leave_lazy_mmu_mode();
return ret;
}
static bool linear_map_requires_bbml2 __initdata;
u32 idmap_kpti_bbml2_flag;
static void __init init_idmap_kpti_bbml2_flag(void)
{
WRITE_ONCE(idmap_kpti_bbml2_flag, 1);
/* Must be visible to other CPUs before stop_machine() is called. */
smp_mb();
}
static int __init linear_map_split_to_ptes(void *__unused)
{
/*
* Repainting the linear map must be done by CPU0 (the boot CPU) because
* that's the only CPU that we know supports BBML2. The other CPUs will
* be held in a waiting area with the idmap active.
*/
if (!smp_processor_id()) {
unsigned long lstart = _PAGE_OFFSET(vabits_actual);
unsigned long lend = PAGE_END;
unsigned long kstart = (unsigned long)lm_alias(_stext);
unsigned long kend = (unsigned long)lm_alias(__init_begin);
int ret;
/*
* Wait for all secondary CPUs to be put into the waiting area.
*/
smp_cond_load_acquire(&idmap_kpti_bbml2_flag, VAL == num_online_cpus());
/*
* Walk all of the linear map [lstart, lend), except the kernel
* linear map alias [kstart, kend), and split all mappings to
* PTE. The kernel alias remains static throughout runtime so
* can continue to be safely mapped with large mappings.
*/
ret = range_split_to_ptes(lstart, kstart, GFP_ATOMIC);
if (!ret)
ret = range_split_to_ptes(kend, lend, GFP_ATOMIC);
if (ret)
panic("Failed to split linear map\n");
flush_tlb_kernel_range(lstart, lend);
/*
* Relies on dsb in flush_tlb_kernel_range() to avoid reordering
* before any page table split operations.
*/
WRITE_ONCE(idmap_kpti_bbml2_flag, 0);
} else {
typedef void (wait_split_fn)(void);
extern wait_split_fn wait_linear_map_split_to_ptes;
wait_split_fn *wait_fn;
wait_fn = (void *)__pa_symbol(wait_linear_map_split_to_ptes);
/*
* At least one secondary CPU doesn't support BBML2 so cannot
* tolerate the size of the live mappings changing. So have the
* secondary CPUs wait for the boot CPU to make the changes
* with the idmap active and init_mm inactive.
*/
cpu_install_idmap();
wait_fn();
cpu_uninstall_idmap();
}
return 0;
}
void __init linear_map_maybe_split_to_ptes(void)
{
if (linear_map_requires_bbml2 && !system_supports_bbml2_noabort()) {
init_idmap_kpti_bbml2_flag();
stop_machine(linear_map_split_to_ptes, NULL, cpu_online_mask);
}
}
/*
* This function can only be used to modify existing table entries,
* without allocating new levels of table. Note that this permits the
* creation of new section or page entries.
*/
void __init create_mapping_noalloc(phys_addr_t phys, unsigned long virt,
phys_addr_t size, pgprot_t prot)
{
if (virt < PAGE_OFFSET) {
pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n",
&phys, virt);
return;
}
early_create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL,
NO_CONT_MAPPINGS);
}
void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
unsigned long virt, phys_addr_t size,
pgprot_t prot, bool page_mappings_only)
{
int flags = 0;
BUG_ON(mm == &init_mm);
if (page_mappings_only)
flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
early_create_pgd_mapping(mm->pgd, phys, virt, size, prot,
pgd_pgtable_alloc_special_mm, flags);
}
static void update_mapping_prot(phys_addr_t phys, unsigned long virt,
phys_addr_t size, pgprot_t prot)
{
if (virt < PAGE_OFFSET) {
pr_warn("BUG: not updating mapping for %pa at 0x%016lx - outside kernel range\n",
&phys, virt);
return;
}
early_create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL,
NO_CONT_MAPPINGS);
/* flush the TLBs after updating live kernel mappings */
flush_tlb_kernel_range(virt, virt + size);
}
static void __init __map_memblock(pgd_t *pgdp, phys_addr_t start,
phys_addr_t end, pgprot_t prot, int flags)
{
early_create_pgd_mapping(pgdp, start, __phys_to_virt(start), end - start,
prot, early_pgtable_alloc, flags);
}
void __init mark_linear_text_alias_ro(void)
{
/*
* Remove the write permissions from the linear alias of .text/.rodata
*/
update_mapping_prot(__pa_symbol(_text), (unsigned long)lm_alias(_text),
(unsigned long)__init_begin - (unsigned long)_text,
PAGE_KERNEL_RO);
}
#ifdef CONFIG_KFENCE
bool __ro_after_init kfence_early_init = !!CONFIG_KFENCE_SAMPLE_INTERVAL;
/* early_param() will be parsed before map_mem() below. */
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);
static phys_addr_t __init arm64_kfence_alloc_pool(void)
{
phys_addr_t kfence_pool;
if (!kfence_early_init)
return 0;
kfence_pool = memblock_phys_alloc(KFENCE_POOL_SIZE, PAGE_SIZE);
if (!kfence_pool) {
pr_err("failed to allocate kfence pool\n");
kfence_early_init = false;
return 0;
}
/* Temporarily mark as NOMAP. */
memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE);
return kfence_pool;
}
static void __init arm64_kfence_map_pool(phys_addr_t kfence_pool, pgd_t *pgdp)
{
if (!kfence_pool)
return;
/* KFENCE pool needs page-level mapping. */
__map_memblock(pgdp, kfence_pool, kfence_pool + KFENCE_POOL_SIZE,
pgprot_tagged(PAGE_KERNEL),
NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE);
__kfence_pool = phys_to_virt(kfence_pool);
}
bool arch_kfence_init_pool(void)
{
unsigned long start = (unsigned long)__kfence_pool;
unsigned long end = start + KFENCE_POOL_SIZE;
int ret;
/* Exit early if we know the linear map is already pte-mapped. */
if (!split_leaf_mapping_possible())
return true;
/* Kfence pool is already pte-mapped for the early init case. */
if (kfence_early_init)
return true;
mutex_lock(&pgtable_split_lock);
ret = range_split_to_ptes(start, end, GFP_PGTABLE_KERNEL);
mutex_unlock(&pgtable_split_lock);
/*
* Since the system supports bbml2_noabort, tlb invalidation is not
* required here; the pgtable mappings have been split to pte but larger
* entries may safely linger in the TLB.
*/
return !ret;
}
#else /* CONFIG_KFENCE */
static inline phys_addr_t arm64_kfence_alloc_pool(void) { return 0; }
static inline void arm64_kfence_map_pool(phys_addr_t kfence_pool, pgd_t *pgdp) { }
#endif /* CONFIG_KFENCE */
static void __init map_mem(pgd_t *pgdp)
{
static const u64 direct_map_end = _PAGE_END(VA_BITS_MIN);
phys_addr_t kernel_start = __pa_symbol(_text);
phys_addr_t kernel_end = __pa_symbol(__init_begin);
phys_addr_t start, end;
phys_addr_t early_kfence_pool;
int flags = NO_EXEC_MAPPINGS;
u64 i;
/*
* Setting hierarchical PXNTable attributes on table entries covering
* the linear region is only possible if it is guaranteed that no table
* entries at any level are being shared between the linear region and
* the vmalloc region. Check whether this is true for the PGD level, in
* which case it is guaranteed to be true for all other levels as well.
* (Unless we are running with support for LPA2, in which case the
* entire reduced VA space is covered by a single pgd_t which will have
* been populated without the PXNTable attribute by the time we get here.)
*/
BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end) &&
pgd_index(_PAGE_OFFSET(VA_BITS_MIN)) != PTRS_PER_PGD - 1);
early_kfence_pool = arm64_kfence_alloc_pool();
linear_map_requires_bbml2 = !force_pte_mapping() && can_set_direct_map();
if (force_pte_mapping())
flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
/*
* Take care not to create a writable alias for the
* read-only text and rodata sections of the kernel image.
* So temporarily mark them as NOMAP to skip mappings in
* the following for-loop
*/
memblock_mark_nomap(kernel_start, kernel_end - kernel_start);
/* map all the memory banks */
for_each_mem_range(i, &start, &end) {
if (start >= end)
break;
/*
* The linear map must allow allocation tags reading/writing
* if MTE is present. Otherwise, it has the same attributes as
* PAGE_KERNEL.
*/
__map_memblock(pgdp, start, end, pgprot_tagged(PAGE_KERNEL),
flags);
}
/*
* Map the linear alias of the [_text, __init_begin) interval
* as non-executable now, and remove the write permission in
* mark_linear_text_alias_ro() below (which will be called after
* alternative patching has completed). This makes the contents
* of the region accessible to subsystems such as hibernate,
* but protects it from inadvertent modification or execution.
* Note that contiguous mappings cannot be remapped in this way,
* so we should avoid them here.
*/
__map_memblock(pgdp, kernel_start, kernel_end,
PAGE_KERNEL, NO_CONT_MAPPINGS);
memblock_clear_nomap(kernel_start, kernel_end - kernel_start);
arm64_kfence_map_pool(early_kfence_pool, pgdp);
}
void mark_rodata_ro(void)
{
unsigned long section_size;
/*
* mark .rodata as read only. Use __init_begin rather than __end_rodata
* to cover NOTES and EXCEPTION_TABLE.
*/
section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata;
WRITE_ONCE(rodata_is_rw, false);
update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata,
section_size, PAGE_KERNEL_RO);
/* mark the range between _text and _stext as read only. */
update_mapping_prot(__pa_symbol(_text), (unsigned long)_text,
(unsigned long)_stext - (unsigned long)_text,
PAGE_KERNEL_RO);
}
static void __init declare_vma(struct vm_struct *vma,
void *va_start, void *va_end,
unsigned long vm_flags)
{
phys_addr_t pa_start = __pa_symbol(va_start);
unsigned long size = va_end - va_start;
BUG_ON(!PAGE_ALIGNED(pa_start));
BUG_ON(!PAGE_ALIGNED(size));
if (!(vm_flags & VM_NO_GUARD))
size += PAGE_SIZE;
vma->addr = va_start;
vma->phys_addr = pa_start;
vma->size = size;
vma->flags = VM_MAP | vm_flags;
vma->caller = __builtin_return_address(0);
vm_area_add_early(vma);
}
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
#define KPTI_NG_TEMP_VA (-(1UL << PMD_SHIFT))
static phys_addr_t kpti_ng_temp_alloc __initdata;
static phys_addr_t __init kpti_ng_pgd_alloc(enum pgtable_type type)
{
kpti_ng_temp_alloc -= PAGE_SIZE;
return kpti_ng_temp_alloc;
}
static int __init __kpti_install_ng_mappings(void *__unused)
{
typedef void (kpti_remap_fn)(int, int, phys_addr_t, unsigned long);
extern kpti_remap_fn idmap_kpti_install_ng_mappings;
kpti_remap_fn *remap_fn;
int cpu = smp_processor_id();
int levels = CONFIG_PGTABLE_LEVELS;
int order = order_base_2(levels);
u64 kpti_ng_temp_pgd_pa = 0;
pgd_t *kpti_ng_temp_pgd;
u64 alloc = 0;
if (levels == 5 && !pgtable_l5_enabled())
levels = 4;
else if (levels == 4 && !pgtable_l4_enabled())
levels = 3;
remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings);
if (!cpu) {
int ret;
alloc = __get_free_pages(GFP_ATOMIC | __GFP_ZERO, order);
kpti_ng_temp_pgd = (pgd_t *)(alloc + (levels - 1) * PAGE_SIZE);
kpti_ng_temp_alloc = kpti_ng_temp_pgd_pa = __pa(kpti_ng_temp_pgd);
//
// Create a minimal page table hierarchy that permits us to map
// the swapper page tables temporarily as we traverse them.
//
// The physical pages are laid out as follows:
//
// +--------+-/-------+-/------ +-/------ +-\\\--------+
// : PTE[] : | PMD[] : | PUD[] : | P4D[] : ||| PGD[] :
// +--------+-\-------+-\------ +-\------ +-///--------+
// ^
// The first page is mapped into this hierarchy at a PMD_SHIFT
// aligned virtual address, so that we can manipulate the PTE
// level entries while the mapping is active. The first entry
// covers the PTE[] page itself, the remaining entries are free
// to be used as a ad-hoc fixmap.
//
ret = __create_pgd_mapping_locked(kpti_ng_temp_pgd, __pa(alloc),
KPTI_NG_TEMP_VA, PAGE_SIZE, PAGE_KERNEL,
kpti_ng_pgd_alloc, 0);
if (ret)
panic("Failed to create page tables\n");
}
cpu_install_idmap();
remap_fn(cpu, num_online_cpus(), kpti_ng_temp_pgd_pa, KPTI_NG_TEMP_VA);
cpu_uninstall_idmap();
if (!cpu) {
free_pages(alloc, order);
arm64_use_ng_mappings = true;
}
return 0;
}
void __init kpti_install_ng_mappings(void)
{
/* Check whether KPTI is going to be used */
if (!arm64_kernel_unmapped_at_el0())
return;
/*
* We don't need to rewrite the page-tables if either we've done
* it already or we have KASLR enabled and therefore have not
* created any global mappings at all.
*/
if (arm64_use_ng_mappings)
return;
init_idmap_kpti_bbml2_flag();
stop_machine(__kpti_install_ng_mappings, NULL, cpu_online_mask);
}
static pgprot_t __init kernel_exec_prot(void)
{
return rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
}
static int __init map_entry_trampoline(void)
{
int i;
if (!arm64_kernel_unmapped_at_el0())
return 0;
pgprot_t prot = kernel_exec_prot();
phys_addr_t pa_start = __pa_symbol(__entry_tramp_text_start);
/* The trampoline is always mapped and can therefore be global */
pgprot_val(prot) &= ~PTE_NG;
/* Map only the text into the trampoline page table */
memset(tramp_pg_dir, 0, PGD_SIZE);
early_create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS,
entry_tramp_text_size(), prot,
pgd_pgtable_alloc_init_mm, NO_BLOCK_MAPPINGS);
/* Map both the text and data into the kernel page table */
for (i = 0; i < DIV_ROUND_UP(entry_tramp_text_size(), PAGE_SIZE); i++)
__set_fixmap(FIX_ENTRY_TRAMP_TEXT1 - i,
pa_start + i * PAGE_SIZE, prot);
if (IS_ENABLED(CONFIG_RELOCATABLE))
__set_fixmap(FIX_ENTRY_TRAMP_TEXT1 - i,
pa_start + i * PAGE_SIZE, PAGE_KERNEL_RO);
return 0;
}
core_initcall(map_entry_trampoline);
#endif
/*
* Declare the VMA areas for the kernel
*/
static void __init declare_kernel_vmas(void)
{
static struct vm_struct vmlinux_seg[KERNEL_SEGMENT_COUNT];
declare_vma(&vmlinux_seg[0], _text, _etext, VM_NO_GUARD);
declare_vma(&vmlinux_seg[1], __start_rodata, __inittext_begin, VM_NO_GUARD);
declare_vma(&vmlinux_seg[2], __inittext_begin, __inittext_end, VM_NO_GUARD);
declare_vma(&vmlinux_seg[3], __initdata_begin, __initdata_end, VM_NO_GUARD);
declare_vma(&vmlinux_seg[4], _data, _end, 0);
}
void __pi_map_range(phys_addr_t *pte, u64 start, u64 end, phys_addr_t pa,
pgprot_t prot, int level, pte_t *tbl, bool may_use_cont,
u64 va_offset);
static u8 idmap_ptes[IDMAP_LEVELS - 1][PAGE_SIZE] __aligned(PAGE_SIZE) __ro_after_init,
kpti_bbml2_ptes[IDMAP_LEVELS - 1][PAGE_SIZE] __aligned(PAGE_SIZE) __ro_after_init;
static void __init create_idmap(void)
{
phys_addr_t start = __pa_symbol(__idmap_text_start);
phys_addr_t end = __pa_symbol(__idmap_text_end);
phys_addr_t ptep = __pa_symbol(idmap_ptes);
__pi_map_range(&ptep, start, end, start, PAGE_KERNEL_ROX,
IDMAP_ROOT_LEVEL, (pte_t *)idmap_pg_dir, false,
__phys_to_virt(ptep) - ptep);
if (linear_map_requires_bbml2 ||
(IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0) && !arm64_use_ng_mappings)) {
phys_addr_t pa = __pa_symbol(&idmap_kpti_bbml2_flag);
/*
* The KPTI G-to-nG conversion code needs a read-write mapping
* of its synchronization flag in the ID map. This is also used
* when splitting the linear map to ptes if a secondary CPU
* doesn't support bbml2.
*/
ptep = __pa_symbol(kpti_bbml2_ptes);
__pi_map_range(&ptep, pa, pa + sizeof(u32), pa, PAGE_KERNEL,
IDMAP_ROOT_LEVEL, (pte_t *)idmap_pg_dir, false,
__phys_to_virt(ptep) - ptep);
}
}
void __init paging_init(void)
{
map_mem(swapper_pg_dir);
memblock_allow_resize();
create_idmap();
declare_kernel_vmas();
}
#ifdef CONFIG_MEMORY_HOTPLUG
static void free_hotplug_page_range(struct page *page, size_t size,
struct vmem_altmap *altmap)
{
if (altmap) {
vmem_altmap_free(altmap, size >> PAGE_SHIFT);
} else {
WARN_ON(PageReserved(page));
__free_pages(page, get_order(size));
}
}
static void free_hotplug_pgtable_page(struct page *page)
{
free_hotplug_page_range(page, PAGE_SIZE, NULL);
}
static bool pgtable_range_aligned(unsigned long start, unsigned long end,
unsigned long floor, unsigned long ceiling,
unsigned long mask)
{
start &= mask;
if (start < floor)
return false;
if (ceiling) {
ceiling &= mask;
if (!ceiling)
return false;
}
if (end - 1 > ceiling - 1)
return false;
return true;
}
static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr,
unsigned long end, bool free_mapped,
struct vmem_altmap *altmap)
{
pte_t *ptep, pte;
do {
ptep = pte_offset_kernel(pmdp, addr);
pte = __ptep_get(ptep);
if (pte_none(pte))
continue;
WARN_ON(!pte_present(pte));
__pte_clear(&init_mm, addr, ptep);
flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
if (free_mapped)
free_hotplug_page_range(pte_page(pte),
PAGE_SIZE, altmap);
} while (addr += PAGE_SIZE, addr < end);
}
static void unmap_hotplug_pmd_range(pud_t *pudp, unsigned long addr,
unsigned long end, bool free_mapped,
struct vmem_altmap *altmap)
{
unsigned long next;
pmd_t *pmdp, pmd;
do {
next = pmd_addr_end(addr, end);
pmdp = pmd_offset(pudp, addr);
pmd = READ_ONCE(*pmdp);
if (pmd_none(pmd))
continue;
WARN_ON(!pmd_present(pmd));
if (pmd_sect(pmd)) {
pmd_clear(pmdp);
/*
* One TLBI should be sufficient here as the PMD_SIZE
* range is mapped with a single block entry.
*/
flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
if (free_mapped)
free_hotplug_page_range(pmd_page(pmd),
PMD_SIZE, altmap);
continue;
}
WARN_ON(!pmd_table(pmd));
unmap_hotplug_pte_range(pmdp, addr, next, free_mapped, altmap);
} while (addr = next, addr < end);
}
static void unmap_hotplug_pud_range(p4d_t *p4dp, unsigned long addr,
unsigned long end, bool free_mapped,
struct vmem_altmap *altmap)
{
unsigned long next;
pud_t *pudp, pud;
do {
next = pud_addr_end(addr, end);
pudp = pud_offset(p4dp, addr);
pud = READ_ONCE(*pudp);
if (pud_none(pud))
continue;
WARN_ON(!pud_present(pud));
if (pud_sect(pud)) {
pud_clear(pudp);
/*
* One TLBI should be sufficient here as the PUD_SIZE
* range is mapped with a single block entry.
*/
flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
if (free_mapped)
free_hotplug_page_range(pud_page(pud),
PUD_SIZE, altmap);
continue;
}
WARN_ON(!pud_table(pud));
unmap_hotplug_pmd_range(pudp, addr, next, free_mapped, altmap);
} while (addr = next, addr < end);
}
static void unmap_hotplug_p4d_range(pgd_t *pgdp, unsigned long addr,
unsigned long end, bool free_mapped,
struct vmem_altmap *altmap)
{
unsigned long next;
p4d_t *p4dp, p4d;
do {
next = p4d_addr_end(addr, end);
p4dp = p4d_offset(pgdp, addr);
p4d = READ_ONCE(*p4dp);
if (p4d_none(p4d))
continue;
WARN_ON(!p4d_present(p4d));
unmap_hotplug_pud_range(p4dp, addr, next, free_mapped, altmap);
} while (addr = next, addr < end);
}
static void unmap_hotplug_range(unsigned long addr, unsigned long end,
bool free_mapped, struct vmem_altmap *altmap)
{
unsigned long next;
pgd_t *pgdp, pgd;
/*
* altmap can only be used as vmemmap mapping backing memory.
* In case the backing memory itself is not being freed, then
* altmap is irrelevant. Warn about this inconsistency when
* encountered.
*/
WARN_ON(!free_mapped && altmap);
do {
next = pgd_addr_end(addr, end);
pgdp = pgd_offset_k(addr);
pgd = READ_ONCE(*pgdp);
if (pgd_none(pgd))
continue;
WARN_ON(!pgd_present(pgd));
unmap_hotplug_p4d_range(pgdp, addr, next, free_mapped, altmap);
} while (addr = next, addr < end);
}
static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr,
unsigned long end, unsigned long floor,
unsigned long ceiling)
{
pte_t *ptep, pte;
unsigned long i, start = addr;
do {
ptep = pte_offset_kernel(pmdp, addr);
pte = __ptep_get(ptep);
/*
* This is just a sanity check here which verifies that
* pte clearing has been done by earlier unmap loops.
*/
WARN_ON(!pte_none(pte));
} while (addr += PAGE_SIZE, addr < end);
if (!pgtable_range_aligned(start, end, floor, ceiling, PMD_MASK))
return;
/*
* Check whether we can free the pte page if the rest of the
* entries are empty. Overlap with other regions have been
* handled by the floor/ceiling check.
*/
ptep = pte_offset_kernel(pmdp, 0UL);
for (i = 0; i < PTRS_PER_PTE; i++) {
if (!pte_none(__ptep_get(&ptep[i])))
return;
}
pmd_clear(pmdp);
__flush_tlb_kernel_pgtable(start);
free_hotplug_pgtable_page(virt_to_page(ptep));
}
static void free_empty_pmd_table(pud_t *pudp, unsigned long addr,
unsigned long end, unsigned long floor,
unsigned long ceiling)
{
pmd_t *pmdp, pmd;
unsigned long i, next, start = addr;
do {
next = pmd_addr_end(addr, end);
pmdp = pmd_offset(pudp, addr);
pmd = READ_ONCE(*pmdp);
if (pmd_none(pmd))
continue;
WARN_ON(!pmd_present(pmd) || !pmd_table(pmd) || pmd_sect(pmd));
free_empty_pte_table(pmdp, addr, next, floor, ceiling);
} while (addr = next, addr < end);
if (CONFIG_PGTABLE_LEVELS <= 2)
return;
if (!pgtable_range_aligned(start, end, floor, ceiling, PUD_MASK))
return;
/*
* Check whether we can free the pmd page if the rest of the
* entries are empty. Overlap with other regions have been
* handled by the floor/ceiling check.
*/
pmdp = pmd_offset(pudp, 0UL);
for (i = 0; i < PTRS_PER_PMD; i++) {
if (!pmd_none(READ_ONCE(pmdp[i])))
return;
}
pud_clear(pudp);
__flush_tlb_kernel_pgtable(start);
free_hotplug_pgtable_page(virt_to_page(pmdp));
}
static void free_empty_pud_table(p4d_t *p4dp, unsigned long addr,
unsigned long end, unsigned long floor,
unsigned long ceiling)
{
pud_t *pudp, pud;
unsigned long i, next, start = addr;
do {
next = pud_addr_end(addr, end);
pudp = pud_offset(p4dp, addr);
pud = READ_ONCE(*pudp);
if (pud_none(pud))
continue;
WARN_ON(!pud_present(pud) || !pud_table(pud) || pud_sect(pud));
free_empty_pmd_table(pudp, addr, next, floor, ceiling);
} while (addr = next, addr < end);
if (!pgtable_l4_enabled())
return;
if (!pgtable_range_aligned(start, end, floor, ceiling, P4D_MASK))
return;
/*
* Check whether we can free the pud page if the rest of the
* entries are empty. Overlap with other regions have been
* handled by the floor/ceiling check.
*/
pudp = pud_offset(p4dp, 0UL);
for (i = 0; i < PTRS_PER_PUD; i++) {
if (!pud_none(READ_ONCE(pudp[i])))
return;
}
p4d_clear(p4dp);
__flush_tlb_kernel_pgtable(start);
free_hotplug_pgtable_page(virt_to_page(pudp));
}
static void free_empty_p4d_table(pgd_t *pgdp, unsigned long addr,
unsigned long end, unsigned long floor,
unsigned long ceiling)
{
p4d_t *p4dp, p4d;
unsigned long i, next, start = addr;
do {
next = p4d_addr_end(addr, end);
p4dp = p4d_offset(pgdp, addr);
p4d = READ_ONCE(*p4dp);
if (p4d_none(p4d))
continue;
WARN_ON(!p4d_present(p4d));
free_empty_pud_table(p4dp, addr, next, floor, ceiling);
} while (addr = next, addr < end);
if (!pgtable_l5_enabled())
return;
if (!pgtable_range_aligned(start, end, floor, ceiling, PGDIR_MASK))
return;
/*
* Check whether we can free the p4d page if the rest of the
* entries are empty. Overlap with other regions have been
* handled by the floor/ceiling check.
*/
p4dp = p4d_offset(pgdp, 0UL);
for (i = 0; i < PTRS_PER_P4D; i++) {
if (!p4d_none(READ_ONCE(p4dp[i])))
return;
}
pgd_clear(pgdp);
__flush_tlb_kernel_pgtable(start);
free_hotplug_pgtable_page(virt_to_page(p4dp));
}
static void free_empty_tables(unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
unsigned long next;
pgd_t *pgdp, pgd;
do {
next = pgd_addr_end(addr, end);
pgdp = pgd_offset_k(addr);
pgd = READ_ONCE(*pgdp);
if (pgd_none(pgd))
continue;
WARN_ON(!pgd_present(pgd));
free_empty_p4d_table(pgdp, addr, next, floor, ceiling);
} while (addr = next, addr < end);
}
#endif
void __meminit vmemmap_set_pmd(pmd_t *pmdp, void *p, int node,
unsigned long addr, unsigned long next)
{
pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
}
int __meminit vmemmap_check_pmd(pmd_t *pmdp, int node,
unsigned long addr, unsigned long next)
{
vmemmap_verify((pte_t *)pmdp, node, addr, next);
return pmd_sect(READ_ONCE(*pmdp));
}
int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
struct vmem_altmap *altmap)
{
WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END));
/* [start, end] should be within one section */
WARN_ON_ONCE(end - start > PAGES_PER_SECTION * sizeof(struct page));
if (!IS_ENABLED(CONFIG_ARM64_4K_PAGES) ||
(end - start < PAGES_PER_SECTION * sizeof(struct page)))
return vmemmap_populate_basepages(start, end, node, altmap);
else
return vmemmap_populate_hugepages(start, end, node, altmap);
}
#ifdef CONFIG_MEMORY_HOTPLUG
void vmemmap_free(unsigned long start, unsigned long end,
struct vmem_altmap *altmap)
{
WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END));
unmap_hotplug_range(start, end, true, altmap);
free_empty_tables(start, end, VMEMMAP_START, VMEMMAP_END);
}
#endif /* CONFIG_MEMORY_HOTPLUG */
int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
{
pud_t new_pud = pfn_pud(__phys_to_pfn(phys), mk_pud_sect_prot(prot));
/* Only allow permission changes for now */
if (!pgattr_change_is_safe(READ_ONCE(pud_val(*pudp)),
pud_val(new_pud)))
return 0;
VM_BUG_ON(phys & ~PUD_MASK);
set_pud(pudp, new_pud);
return 1;
}
int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot)
{
pmd_t new_pmd = pfn_pmd(__phys_to_pfn(phys), mk_pmd_sect_prot(prot));
/* Only allow permission changes for now */
if (!pgattr_change_is_safe(READ_ONCE(pmd_val(*pmdp)),
pmd_val(new_pmd)))
return 0;
VM_BUG_ON(phys & ~PMD_MASK);
set_pmd(pmdp, new_pmd);
return 1;
}
#ifndef __PAGETABLE_P4D_FOLDED
void p4d_clear_huge(p4d_t *p4dp)
{
}
#endif
int pud_clear_huge(pud_t *pudp)
{
if (!pud_sect(READ_ONCE(*pudp)))
return 0;
pud_clear(pudp);
return 1;
}
int pmd_clear_huge(pmd_t *pmdp)
{
if (!pmd_sect(READ_ONCE(*pmdp)))
return 0;
pmd_clear(pmdp);
return 1;
}
static int __pmd_free_pte_page(pmd_t *pmdp, unsigned long addr,
bool acquire_mmap_lock)
{
pte_t *table;
pmd_t pmd;
pmd = READ_ONCE(*pmdp);
if (!pmd_table(pmd)) {
VM_WARN_ON(1);
return 1;
}
/* See comment in pud_free_pmd_page for static key logic */
table = pte_offset_kernel(pmdp, addr);
pmd_clear(pmdp);
__flush_tlb_kernel_pgtable(addr);
if (static_branch_unlikely(&arm64_ptdump_lock_key) && acquire_mmap_lock) {
mmap_read_lock(&init_mm);
mmap_read_unlock(&init_mm);
}
pte_free_kernel(NULL, table);
return 1;
}
int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
{
/* If ptdump is walking the pagetables, acquire init_mm.mmap_lock */
return __pmd_free_pte_page(pmdp, addr, /* acquire_mmap_lock = */ true);
}
int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
{
pmd_t *table;
pmd_t *pmdp;
pud_t pud;
unsigned long next, end;
pud = READ_ONCE(*pudp);
if (!pud_table(pud)) {
VM_WARN_ON(1);
return 1;
}
table = pmd_offset(pudp, addr);
/*
* Our objective is to prevent ptdump from reading a PMD table which has
* been freed. In this race, if pud_free_pmd_page observes the key on
* (which got flipped by ptdump) then the mmap lock sequence here will,
* as a result of the mmap write lock/unlock sequence in ptdump, give
* us the correct synchronization. If not, this means that ptdump has
* yet not started walking the pagetables - the sequence of barriers
* issued by __flush_tlb_kernel_pgtable() guarantees that ptdump will
* observe an empty PUD.
*/
pud_clear(pudp);
__flush_tlb_kernel_pgtable(addr);
if (static_branch_unlikely(&arm64_ptdump_lock_key)) {
mmap_read_lock(&init_mm);
mmap_read_unlock(&init_mm);
}
pmdp = table;
next = addr;
end = addr + PUD_SIZE;
do {
if (pmd_present(pmdp_get(pmdp)))
/*
* PMD has been isolated, so ptdump won't see it. No
* need to acquire init_mm.mmap_lock.
*/
__pmd_free_pte_page(pmdp, next, /* acquire_mmap_lock = */ false);
} while (pmdp++, next += PMD_SIZE, next != end);
pmd_free(NULL, table);
return 1;
}
#ifdef CONFIG_MEMORY_HOTPLUG
static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size)
{
unsigned long end = start + size;
WARN_ON(pgdir != init_mm.pgd);
WARN_ON((start < PAGE_OFFSET) || (end > PAGE_END));
unmap_hotplug_range(start, end, false, NULL);
free_empty_tables(start, end, PAGE_OFFSET, PAGE_END);
}
struct range arch_get_mappable_range(void)
{
struct range mhp_range;
phys_addr_t start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual));
phys_addr_t end_linear_pa = __pa(PAGE_END - 1);
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
/*
* Check for a wrap, it is possible because of randomized linear
* mapping the start physical address is actually bigger than
* the end physical address. In this case set start to zero
* because [0, end_linear_pa] range must still be able to cover
* all addressable physical addresses.
*/
if (start_linear_pa > end_linear_pa)
start_linear_pa = 0;
}
WARN_ON(start_linear_pa > end_linear_pa);
/*
* Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)]
* accommodating both its ends but excluding PAGE_END. Max physical
* range which can be mapped inside this linear mapping range, must
* also be derived from its end points.
*/
mhp_range.start = start_linear_pa;
mhp_range.end = end_linear_pa;
return mhp_range;
}
int arch_add_memory(int nid, u64 start, u64 size,
struct mhp_params *params)
{
int ret, flags = NO_EXEC_MAPPINGS;
VM_BUG_ON(!mhp_range_allowed(start, size, true));
if (force_pte_mapping())
flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
ret = __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
size, params->pgprot, pgd_pgtable_alloc_init_mm,
flags);
if (ret)
goto err;
memblock_clear_nomap(start, size);
ret = __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,
params);
if (ret)
goto err;
/* Address of hotplugged memory can be smaller */
max_pfn = max(max_pfn, PFN_UP(start + size));
max_low_pfn = max_pfn;
return 0;
err:
__remove_pgd_mapping(swapper_pg_dir,
__phys_to_virt(start), size);
return ret;
}
void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
{
unsigned long start_pfn = start >> PAGE_SHIFT;
unsigned long nr_pages = size >> PAGE_SHIFT;
__remove_pages(start_pfn, nr_pages, altmap);
__remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size);
}
/*
* This memory hotplug notifier helps prevent boot memory from being
* inadvertently removed as it blocks pfn range offlining process in
* __offline_pages(). Hence this prevents both offlining as well as
* removal process for boot memory which is initially always online.
* In future if and when boot memory could be removed, this notifier
* should be dropped and free_hotplug_page_range() should handle any
* reserved pages allocated during boot.
*/
static int prevent_bootmem_remove_notifier(struct notifier_block *nb,
unsigned long action, void *data)
{
struct mem_section *ms;
struct memory_notify *arg = data;
unsigned long end_pfn = arg->start_pfn + arg->nr_pages;
unsigned long pfn = arg->start_pfn;
if ((action != MEM_GOING_OFFLINE) && (action != MEM_OFFLINE))
return NOTIFY_OK;
for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
unsigned long start = PFN_PHYS(pfn);
unsigned long end = start + (1UL << PA_SECTION_SHIFT);
ms = __pfn_to_section(pfn);
if (!early_section(ms))
continue;
if (action == MEM_GOING_OFFLINE) {
/*
* Boot memory removal is not supported. Prevent
* it via blocking any attempted offline request
* for the boot memory and just report it.
*/
pr_warn("Boot memory [%lx %lx] offlining attempted\n", start, end);
return NOTIFY_BAD;
} else if (action == MEM_OFFLINE) {
/*
* This should have never happened. Boot memory
* offlining should have been prevented by this
* very notifier. Probably some memory removal
* procedure might have changed which would then
* require further debug.
*/
pr_err("Boot memory [%lx %lx] offlined\n", start, end);
/*
* Core memory hotplug does not process a return
* code from the notifier for MEM_OFFLINE events.
* The error condition has been reported. Return
* from here as if ignored.
*/
return NOTIFY_DONE;
}
}
return NOTIFY_OK;
}
static struct notifier_block prevent_bootmem_remove_nb = {
.notifier_call = prevent_bootmem_remove_notifier,
};
/*
* This ensures that boot memory sections on the platform are online
* from early boot. Memory sections could not be prevented from being
* offlined, unless for some reason they are not online to begin with.
* This helps validate the basic assumption on which the above memory
* event notifier works to prevent boot memory section offlining and
* its possible removal.
*/
static void validate_bootmem_online(void)
{
phys_addr_t start, end, addr;
struct mem_section *ms;
u64 i;
/*
* Scanning across all memblock might be expensive
* on some big memory systems. Hence enable this
* validation only with DEBUG_VM.
*/
if (!IS_ENABLED(CONFIG_DEBUG_VM))
return;
for_each_mem_range(i, &start, &end) {
for (addr = start; addr < end; addr += (1UL << PA_SECTION_SHIFT)) {
ms = __pfn_to_section(PHYS_PFN(addr));
/*
* All memory ranges in the system at this point
* should have been marked as early sections.
*/
WARN_ON(!early_section(ms));
/*
* Memory notifier mechanism here to prevent boot
* memory offlining depends on the fact that each
* early section memory on the system is initially
* online. Otherwise a given memory section which
* is already offline will be overlooked and can
* be removed completely. Call out such sections.
*/
if (!online_section(ms))
pr_err("Boot memory [%llx %llx] is offline, can be removed\n",
addr, addr + (1UL << PA_SECTION_SHIFT));
}
}
}
static int __init prevent_bootmem_remove_init(void)
{
int ret = 0;
if (!IS_ENABLED(CONFIG_MEMORY_HOTREMOVE))
return ret;
validate_bootmem_online();
ret = register_memory_notifier(&prevent_bootmem_remove_nb);
if (ret)
pr_err("%s: Notifier registration failed %d\n", __func__, ret);
return ret;
}
early_initcall(prevent_bootmem_remove_init);
#endif
pte_t modify_prot_start_ptes(struct vm_area_struct *vma, unsigned long addr,
pte_t *ptep, unsigned int nr)
{
pte_t pte = get_and_clear_ptes(vma->vm_mm, addr, ptep, nr);
if (alternative_has_cap_unlikely(ARM64_WORKAROUND_2645198)) {
/*
* Break-before-make (BBM) is required for all user space mappings
* when the permission changes from executable to non-executable
* in cases where cpu is affected with errata #2645198.
*/
if (pte_accessible(vma->vm_mm, pte) && pte_user_exec(pte))
__flush_tlb_range(vma, addr, nr * PAGE_SIZE,
PAGE_SIZE, true, 3);
}
return pte;
}
pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
{
return modify_prot_start_ptes(vma, addr, ptep, 1);
}
void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr,
pte_t *ptep, pte_t old_pte, pte_t pte,
unsigned int nr)
{
set_ptes(vma->vm_mm, addr, ptep, pte, nr);
}
void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep,
pte_t old_pte, pte_t pte)
{
modify_prot_commit_ptes(vma, addr, ptep, old_pte, pte, 1);
}
/*
* Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible PGD,
* avoiding the possibility of conflicting TLB entries being allocated.
*/
void __cpu_replace_ttbr1(pgd_t *pgdp, bool cnp)
{
typedef void (ttbr_replace_func)(phys_addr_t);
extern ttbr_replace_func idmap_cpu_replace_ttbr1;
ttbr_replace_func *replace_phys;
unsigned long daif;
/* phys_to_ttbr() zeros lower 2 bits of ttbr with 52-bit PA */
phys_addr_t ttbr1 = phys_to_ttbr(virt_to_phys(pgdp));
if (cnp)
ttbr1 |= TTBR_CNP_BIT;
replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1);
cpu_install_idmap();
/*
* We really don't want to take *any* exceptions while TTBR1 is
* in the process of being replaced so mask everything.
*/
daif = local_daif_save();
replace_phys(ttbr1);
local_daif_restore(daif);
cpu_uninstall_idmap();
}
#ifdef CONFIG_ARCH_HAS_PKEYS
int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, unsigned long init_val)
{
u64 new_por;
u64 old_por;
if (!system_supports_poe())
return -ENOSPC;
/*
* This code should only be called with valid 'pkey'
* values originating from in-kernel users. Complain
* if a bad value is observed.
*/
if (WARN_ON_ONCE(pkey >= arch_max_pkey()))
return -EINVAL;
/* Set the bits we need in POR: */
new_por = POE_RWX;
if (init_val & PKEY_DISABLE_WRITE)
new_por &= ~POE_W;
if (init_val & PKEY_DISABLE_ACCESS)
new_por &= ~POE_RW;
if (init_val & PKEY_DISABLE_READ)
new_por &= ~POE_R;
if (init_val & PKEY_DISABLE_EXECUTE)
new_por &= ~POE_X;
/* Shift the bits in to the correct place in POR for pkey: */
new_por = POR_ELx_PERM_PREP(pkey, new_por);
/* Get old POR and mask off any old bits in place: */
old_por = read_sysreg_s(SYS_POR_EL0);
old_por &= ~(POE_MASK << POR_ELx_PERM_SHIFT(pkey));
/* Write old part along with new part: */
write_sysreg_s(old_por | new_por, SYS_POR_EL0);
return 0;
}
#endif
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