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mmu.c
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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/memory.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/vmalloc.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>
#define NO_BLOCK_MAPPINGS BIT(0)
#define NO_CONT_MAPPINGS BIT(1)
u64 idmap_t0sz = TCR_T0SZ(VA_BITS_MIN);
u64 idmap_ptrs_per_pgd = PTRS_PER_PGD;
u64 __section(".mmuoff.data.write") vabits_actual;
EXPORT_SYMBOL(vabits_actual);
u64 kimage_voffset __ro_after_init;
EXPORT_SYMBOL(kimage_voffset);
/*
* 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 pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss;
static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss __maybe_unused;
static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss __maybe_unused;
static DEFINE_SPINLOCK(swapper_pgdir_lock);
void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
{
pgd_t *fixmap_pgdp;
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_valid(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(int shift)
{
phys_addr_t phys;
void *ptr;
phys = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
if (!phys)
panic("Failed to allocate page table page\n");
/*
* The FIX_{PGD,PUD,PMD} slots may be in active use, but the FIX_PTE
* slot will be free, so we can (ab)use the FIX_PTE slot to initialise
* any level of table.
*/
ptr = pte_set_fixmap(phys);
memset(ptr, 0, PAGE_SIZE);
/*
* Implicit barriers also ensure the zeroed page is visible to the page
* table walker
*/
pte_clear_fixmap();
return phys;
}
static bool pgattr_change_is_safe(u64 old, u64 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;
/* creating or taking down mappings is always safe */
if (old == 0 || new == 0)
return true;
/* 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_pte(pmd_t *pmdp, unsigned long addr, unsigned long end,
phys_addr_t phys, pgprot_t prot)
{
pte_t *ptep;
ptep = pte_set_fixmap_offset(pmdp, addr);
do {
pte_t old_pte = READ_ONCE(*ptep);
set_pte(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),
READ_ONCE(pte_val(*ptep))));
phys += PAGE_SIZE;
} while (ptep++, addr += PAGE_SIZE, addr != end);
pte_clear_fixmap();
}
static void 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)(int),
int flags)
{
unsigned long next;
pmd_t pmd = READ_ONCE(*pmdp);
BUG_ON(pmd_sect(pmd));
if (pmd_none(pmd)) {
phys_addr_t pte_phys;
BUG_ON(!pgtable_alloc);
pte_phys = pgtable_alloc(PAGE_SHIFT);
__pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
pmd = READ_ONCE(*pmdp);
}
BUG_ON(pmd_bad(pmd));
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(pmdp, addr, next, phys, __prot);
phys += next - addr;
} while (addr = next, addr != end);
}
static void init_pmd(pud_t *pudp, unsigned long addr, unsigned long end,
phys_addr_t phys, pgprot_t prot,
phys_addr_t (*pgtable_alloc)(int), int flags)
{
unsigned long next;
pmd_t *pmdp;
pmdp = pmd_set_fixmap_offset(pudp, addr);
do {
pmd_t old_pmd = READ_ONCE(*pmdp);
next = pmd_addr_end(addr, end);
/* try section mapping first */
if (((addr | next | phys) & ~SECTION_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 {
alloc_init_cont_pte(pmdp, addr, next, phys, prot,
pgtable_alloc, flags);
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);
pmd_clear_fixmap();
}
static void 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)(int), int flags)
{
unsigned long next;
pud_t pud = READ_ONCE(*pudp);
/*
* Check for initial section mappings in the pgd/pud.
*/
BUG_ON(pud_sect(pud));
if (pud_none(pud)) {
phys_addr_t pmd_phys;
BUG_ON(!pgtable_alloc);
pmd_phys = pgtable_alloc(PMD_SHIFT);
__pud_populate(pudp, pmd_phys, PUD_TYPE_TABLE);
pud = READ_ONCE(*pudp);
}
BUG_ON(pud_bad(pud));
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);
init_pmd(pudp, addr, next, phys, __prot, pgtable_alloc, flags);
phys += next - addr;
} while (addr = next, addr != end);
}
static inline bool use_1G_block(unsigned long addr, unsigned long next,
unsigned long phys)
{
if (PAGE_SHIFT != 12)
return false;
if (((addr | next | phys) & ~PUD_MASK) != 0)
return false;
return true;
}
static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end,
phys_addr_t phys, pgprot_t prot,
phys_addr_t (*pgtable_alloc)(int),
int flags)
{
unsigned long next;
pud_t *pudp;
p4d_t *p4dp = p4d_offset(pgdp, addr);
p4d_t p4d = READ_ONCE(*p4dp);
if (p4d_none(p4d)) {
phys_addr_t pud_phys;
BUG_ON(!pgtable_alloc);
pud_phys = pgtable_alloc(PUD_SHIFT);
__p4d_populate(p4dp, pud_phys, PUD_TYPE_TABLE);
p4d = READ_ONCE(*p4dp);
}
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 (use_1G_block(addr, next, phys) &&
(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 {
alloc_init_cont_pmd(pudp, addr, next, phys, prot,
pgtable_alloc, flags);
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);
pud_clear_fixmap();
}
static void __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)(int),
int flags)
{
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;
phys &= PAGE_MASK;
addr = virt & PAGE_MASK;
end = PAGE_ALIGN(virt + size);
do {
next = pgd_addr_end(addr, end);
alloc_init_pud(pgdp, addr, next, phys, prot, pgtable_alloc,
flags);
phys += next - addr;
} while (pgdp++, addr = next, addr != end);
}
static phys_addr_t __pgd_pgtable_alloc(int shift)
{
void *ptr = (void *)__get_free_page(GFP_PGTABLE_KERNEL);
BUG_ON(!ptr);
/* Ensure the zeroed page is visible to the page table walker */
dsb(ishst);
return __pa(ptr);
}
static phys_addr_t pgd_pgtable_alloc(int shift)
{
phys_addr_t pa = __pgd_pgtable_alloc(shift);
/*
* Call proper page table ctor in case later we need to
* call core mm functions like apply_to_page_range() on
* this pre-allocated page table.
*
* We don't select ARCH_ENABLE_SPLIT_PMD_PTLOCK if pmd is
* folded, and if so pgtable_pmd_page_ctor() becomes nop.
*/
if (shift == PAGE_SHIFT)
BUG_ON(!pgtable_pte_page_ctor(phys_to_page(pa)));
else if (shift == PMD_SHIFT)
BUG_ON(!pgtable_pmd_page_ctor(phys_to_page(pa)));
return pa;
}
/*
* 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.
*/
static void __init create_mapping_noalloc(phys_addr_t phys, unsigned long virt,
phys_addr_t size, pgprot_t prot)
{
if ((virt >= PAGE_END) && (virt < VMALLOC_START)) {
pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n",
&phys, virt);
return;
}
__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;
__create_pgd_mapping(mm->pgd, phys, virt, size, prot,
pgd_pgtable_alloc, flags);
}
static void update_mapping_prot(phys_addr_t phys, unsigned long virt,
phys_addr_t size, pgprot_t prot)
{
if ((virt >= PAGE_END) && (virt < VMALLOC_START)) {
pr_warn("BUG: not updating mapping for %pa at 0x%016lx - outside kernel range\n",
&phys, virt);
return;
}
__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)
{
__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(_stext), (unsigned long)lm_alias(_stext),
(unsigned long)__init_begin - (unsigned long)_stext,
PAGE_KERNEL_RO);
}
static bool crash_mem_map __initdata;
static int __init enable_crash_mem_map(char *arg)
{
/*
* Proper parameter parsing is done by reserve_crashkernel(). We only
* need to know if the linear map has to avoid block mappings so that
* the crashkernel reservations can be unmapped later.
*/
crash_mem_map = true;
return 0;
}
early_param("crashkernel", enable_crash_mem_map);
static void __init map_mem(pgd_t *pgdp)
{
phys_addr_t kernel_start = __pa_symbol(_stext);
phys_addr_t kernel_end = __pa_symbol(__init_begin);
phys_addr_t start, end;
int flags = 0;
u64 i;
if (rodata_full || crash_mem_map || debug_pagealloc_enabled())
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 [_stext, __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);
}
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;
update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata,
section_size, PAGE_KERNEL_RO);
debug_checkwx();
}
static void __init map_kernel_segment(pgd_t *pgdp, void *va_start, void *va_end,
pgprot_t prot, struct vm_struct *vma,
int flags, 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));
__create_pgd_mapping(pgdp, pa_start, (unsigned long)va_start, size, prot,
early_pgtable_alloc, flags);
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);
}
static int __init parse_rodata(char *arg)
{
int ret = strtobool(arg, &rodata_enabled);
if (!ret) {
rodata_full = false;
return 0;
}
/* permit 'full' in addition to boolean options */
if (strcmp(arg, "full"))
return -EINVAL;
rodata_enabled = true;
rodata_full = true;
return 0;
}
early_param("rodata", parse_rodata);
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
static int __init map_entry_trampoline(void)
{
pgprot_t prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
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);
__create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE,
prot, __pgd_pgtable_alloc, 0);
/* Map both the text and data into the kernel page table */
__set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot);
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
extern char __entry_tramp_data_start[];
__set_fixmap(FIX_ENTRY_TRAMP_DATA,
__pa_symbol(__entry_tramp_data_start),
PAGE_KERNEL_RO);
}
return 0;
}
core_initcall(map_entry_trampoline);
#endif
/*
* Open coded check for BTI, only for use to determine configuration
* for early mappings for before the cpufeature code has run.
*/
static bool arm64_early_this_cpu_has_bti(void)
{
u64 pfr1;
if (!IS_ENABLED(CONFIG_ARM64_BTI_KERNEL))
return false;
pfr1 = read_sysreg_s(SYS_ID_AA64PFR1_EL1);
return cpuid_feature_extract_unsigned_field(pfr1,
ID_AA64PFR1_BT_SHIFT);
}
/*
* Create fine-grained mappings for the kernel.
*/
static void __init map_kernel(pgd_t *pgdp)
{
static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_inittext,
vmlinux_initdata, vmlinux_data;
/*
* External debuggers may need to write directly to the text
* mapping to install SW breakpoints. Allow this (only) when
* explicitly requested with rodata=off.
*/
pgprot_t text_prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
/*
* If we have a CPU that supports BTI and a kernel built for
* BTI then mark the kernel executable text as guarded pages
* now so we don't have to rewrite the page tables later.
*/
if (arm64_early_this_cpu_has_bti())
text_prot = __pgprot_modify(text_prot, PTE_GP, PTE_GP);
/*
* Only rodata will be remapped with different permissions later on,
* all other segments are allowed to use contiguous mappings.
*/
map_kernel_segment(pgdp, _stext, _etext, text_prot, &vmlinux_text, 0,
VM_NO_GUARD);
map_kernel_segment(pgdp, __start_rodata, __inittext_begin, PAGE_KERNEL,
&vmlinux_rodata, NO_CONT_MAPPINGS, VM_NO_GUARD);
map_kernel_segment(pgdp, __inittext_begin, __inittext_end, text_prot,
&vmlinux_inittext, 0, VM_NO_GUARD);
map_kernel_segment(pgdp, __initdata_begin, __initdata_end, PAGE_KERNEL,
&vmlinux_initdata, 0, VM_NO_GUARD);
map_kernel_segment(pgdp, _data, _end, PAGE_KERNEL, &vmlinux_data, 0, 0);
if (!READ_ONCE(pgd_val(*pgd_offset_pgd(pgdp, FIXADDR_START)))) {
/*
* The fixmap falls in a separate pgd to the kernel, and doesn't
* live in the carveout for the swapper_pg_dir. We can simply
* re-use the existing dir for the fixmap.
*/
set_pgd(pgd_offset_pgd(pgdp, FIXADDR_START),
READ_ONCE(*pgd_offset_k(FIXADDR_START)));
} else if (CONFIG_PGTABLE_LEVELS > 3) {
pgd_t *bm_pgdp;
p4d_t *bm_p4dp;
pud_t *bm_pudp;
/*
* The fixmap shares its top level pgd entry with the kernel
* mapping. This can really only occur when we are running
* with 16k/4 levels, so we can simply reuse the pud level
* entry instead.
*/
BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
bm_pgdp = pgd_offset_pgd(pgdp, FIXADDR_START);
bm_p4dp = p4d_offset(bm_pgdp, FIXADDR_START);
bm_pudp = pud_set_fixmap_offset(bm_p4dp, FIXADDR_START);
pud_populate(&init_mm, bm_pudp, lm_alias(bm_pmd));
pud_clear_fixmap();
} else {
BUG();
}
kasan_copy_shadow(pgdp);
}
void __init paging_init(void)
{
pgd_t *pgdp = pgd_set_fixmap(__pa_symbol(swapper_pg_dir));
map_kernel(pgdp);
map_mem(pgdp);
pgd_clear_fixmap();
cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
init_mm.pgd = swapper_pg_dir;
memblock_free(__pa_symbol(init_pg_dir),
__pa_symbol(init_pg_end) - __pa_symbol(init_pg_dir));
memblock_allow_resize();
}
/*
* Check whether a kernel address is valid (derived from arch/x86/).
*/
int kern_addr_valid(unsigned long addr)
{
pgd_t *pgdp;
p4d_t *p4dp;
pud_t *pudp, pud;
pmd_t *pmdp, pmd;
pte_t *ptep, pte;
addr = arch_kasan_reset_tag(addr);
if ((((long)addr) >> VA_BITS) != -1UL)
return 0;
pgdp = pgd_offset_k(addr);
if (pgd_none(READ_ONCE(*pgdp)))
return 0;
p4dp = p4d_offset(pgdp, addr);
if (p4d_none(READ_ONCE(*p4dp)))
return 0;
pudp = pud_offset(p4dp, addr);
pud = READ_ONCE(*pudp);
if (pud_none(pud))
return 0;
if (pud_sect(pud))
return pfn_valid(pud_pfn(pud));
pmdp = pmd_offset(pudp, addr);
pmd = READ_ONCE(*pmdp);
if (pmd_none(pmd))
return 0;
if (pmd_sect(pmd))
return pfn_valid(pmd_pfn(pmd));
ptep = pte_offset_kernel(pmdp, addr);
pte = READ_ONCE(*ptep);
if (pte_none(pte))
return 0;
return pfn_valid(pte_pfn(pte));
}
#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((unsigned long)page_address(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 = READ_ONCE(*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 = READ_ONCE(*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(READ_ONCE(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