[PATCH 2/6] riscv: Rework kasan population functions

Alexandre Ghiti
2022-12-16T16:24:11Z

Our previous kasan population implementation used to have the final kasan
shadow region mapped with kasan_early_shadow_page, because we did not clean
the early mapping and then we had to populate the kasan region "in-place"
which made the code cumbersome.

So now we clear the early mapping, establish a temporary mapping while we
populate the kasan shadow region with just the kernel regions that will
be used.

This new version uses the "generic" way of going through a page table
that may be folded at runtime (avoid the XXX_next macros).

It was tested with outline instrumentation on an Ubuntu kernel
configuration successfully.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
arch/riscv/mm/kasan_init.c | 358 +++++++++++++++++++------------------
1 file changed, 184 insertions(+), 174 deletions(-)

diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index a7314ffe7d76..5c7b1d07faf2 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -18,58 +18,48 @@
* For sv39, the region is aligned on PGDIR_SIZE so we only need to populate
* the page global directory with kasan_early_shadow_pmd.
*
- * For sv48 and sv57, the region is not aligned on PGDIR_SIZE so the mapping
- * must be divided as follows:
- * - the first PGD entry, although incomplete, is populated with
- * kasan_early_shadow_pud/p4d
- * - the PGD entries in the middle are populated with kasan_early_shadow_pud/p4d
- * - the last PGD entry is shared with the kernel mapping so populated at the
- * lower levels pud/p4d
- *
- * In addition, when shallow populating a kasan region (for example vmalloc),
- * this region may also not be aligned on PGDIR size, so we must go down to the
- * pud level too.
+ * For sv48 and sv57, the region start is aligned on PGDIR_SIZE whereas the end
+ * region is not and then we have to go down to the PUD level.
*/

extern pgd_t early_pg_dir[PTRS_PER_PGD];
+pgd_t tmp_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
+p4d_t tmp_p4d[PTRS_PER_P4D] __page_aligned_bss;
+pud_t tmp_pud[PTRS_PER_PUD] __page_aligned_bss;

static void __init kasan_populate_pte(pmd_t *pmd, unsigned long vaddr, unsigned long end)
{
phys_addr_t phys_addr;
- pte_t *ptep, *base_pte;
+ pte_t *ptep, *p;

- if (pmd_none(*pmd))
- base_pte = memblock_alloc(PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE);
- else
- base_pte = (pte_t *)pmd_page_vaddr(*pmd);
+ if (pmd_none(*pmd)) {
+ p = memblock_alloc(PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE);
+ set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(p)), PAGE_TABLE));
+ }

- ptep = base_pte + pte_index(vaddr);
+ ptep = pte_offset_kernel(pmd, vaddr);

do {
if (pte_none(*ptep)) {
phys_addr = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
set_pte(ptep, pfn_pte(PFN_DOWN(phys_addr), PAGE_KERNEL));
+ memset(__va(phys_addr), KASAN_SHADOW_INIT, PAGE_SIZE);
}
} while (ptep++, vaddr += PAGE_SIZE, vaddr != end);
-
- set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(base_pte)), PAGE_TABLE));
}

static void __init kasan_populate_pmd(pud_t *pud, unsigned long vaddr, unsigned long end)
{
phys_addr_t phys_addr;
- pmd_t *pmdp, *base_pmd;
+ pmd_t *pmdp, *p;
unsigned long next;

if (pud_none(*pud)) {
- base_pmd = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
- } else {
- base_pmd = (pmd_t *)pud_pgtable(*pud);
- if (base_pmd == lm_alias(kasan_early_shadow_pmd))
- base_pmd = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
+ p = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
+ set_pud(pud, pfn_pud(PFN_DOWN(__pa(p)), PAGE_TABLE));
}

- pmdp = base_pmd + pmd_index(vaddr);
+ pmdp = pmd_offset(pud, vaddr);

do {
next = pmd_addr_end(vaddr, end);
@@ -78,41 +68,28 @@ static void __init kasan_populate_pmd(pud_t *pud, unsigned long vaddr, unsigned
phys_addr = memblock_phys_alloc(PMD_SIZE, PMD_SIZE);
if (phys_addr) {
set_pmd(pmdp, pfn_pmd(PFN_DOWN(phys_addr), PAGE_KERNEL));
+ memset(__va(phys_addr), KASAN_SHADOW_INIT, PMD_SIZE);
continue;
}
}

kasan_populate_pte(pmdp, vaddr, next);
} while (pmdp++, vaddr = next, vaddr != end);
-
- /*
- * Wait for the whole PGD to be populated before setting the PGD in
- * the page table, otherwise, if we did set the PGD before populating
- * it entirely, memblock could allocate a page at a physical address
- * where KASAN is not populated yet and then we'd get a page fault.
- */
- set_pud(pud, pfn_pud(PFN_DOWN(__pa(base_pmd)), PAGE_TABLE));
}

-static void __init kasan_populate_pud(pgd_t *pgd,
+static void __init kasan_populate_pud(p4d_t *p4d,
unsigned long vaddr, unsigned long end)
{
phys_addr_t phys_addr;
- pud_t *pudp, *base_pud;
+ pud_t *pudp, *p;
unsigned long next;

- if (pgd_none(*pgd)) {
- base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
- } else {
- base_pud = (pud_t *)pgd_page_vaddr(*pgd);
- if (base_pud == lm_alias(kasan_early_shadow_pud)) {
- base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
- memcpy(base_pud, (void *)kasan_early_shadow_pud,
- sizeof(pud_t) * PTRS_PER_PUD);
- }
+ if (p4d_none(*p4d)) {
+ p = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
+ set_p4d(p4d, pfn_p4d(PFN_DOWN(__pa(p)), PAGE_TABLE));
}

- pudp = base_pud + pud_index(vaddr);
+ pudp = pud_offset(p4d, vaddr);

do {
next = pud_addr_end(vaddr, end);
@@ -121,34 +98,28 @@ static void __init kasan_populate_pud(pgd_t *pgd,
phys_addr = memblock_phys_alloc(PUD_SIZE, PUD_SIZE);
if (phys_addr) {
set_pud(pudp, pfn_pud(PFN_DOWN(phys_addr), PAGE_KERNEL));
+ memset(__va(phys_addr), KASAN_SHADOW_INIT, PUD_SIZE);
continue;
}
}

kasan_populate_pmd(pudp, vaddr, next);
} while (pudp++, vaddr = next, vaddr != end);
-
- /*
- * Wait for the whole PGD to be populated before setting the PGD in
- * the page table, otherwise, if we did set the PGD before populating
- * it entirely, memblock could allocate a page at a physical address
- * where KASAN is not populated yet and then we'd get a page fault.
- */
- set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(base_pud)), PAGE_TABLE));
}

static void __init kasan_populate_p4d(pgd_t *pgd,
unsigned long vaddr, unsigned long end)
{
phys_addr_t phys_addr;
- p4d_t *p4dp, *base_p4d;
+ p4d_t *p4dp, *p;
unsigned long next;

- base_p4d = (p4d_t *)pgd_page_vaddr(*pgd);
- if (base_p4d == lm_alias(kasan_early_shadow_p4d))
- base_p4d = memblock_alloc(PTRS_PER_PUD * sizeof(p4d_t), PAGE_SIZE);
+ if (pgd_none(*pgd)) {
+ p = memblock_alloc(PTRS_PER_P4D * sizeof(p4d_t), PAGE_SIZE);
+ set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(p)), PAGE_TABLE));
+ }

- p4dp = base_p4d + p4d_index(vaddr);
+ p4dp = p4d_offset(pgd, vaddr);

do {
next = p4d_addr_end(vaddr, end);
@@ -157,34 +128,15 @@ static void __init kasan_populate_p4d(pgd_t *pgd,
phys_addr = memblock_phys_alloc(P4D_SIZE, P4D_SIZE);
if (phys_addr) {
set_p4d(p4dp, pfn_p4d(PFN_DOWN(phys_addr), PAGE_KERNEL));
+ memset(__va(phys_addr), KASAN_SHADOW_INIT, P4D_SIZE);
continue;
}
}

- kasan_populate_pud((pgd_t *)p4dp, vaddr, next);
+ kasan_populate_pud(p4dp, vaddr, next);
} while (p4dp++, vaddr = next, vaddr != end);
-
- /*
- * Wait for the whole P4D to be populated before setting the P4D in
- * the page table, otherwise, if we did set the P4D before populating
- * it entirely, memblock could allocate a page at a physical address
- * where KASAN is not populated yet and then we'd get a page fault.
- */
- set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(base_p4d)), PAGE_TABLE));
}

-#define kasan_early_shadow_pgd_next (pgtable_l5_enabled ? \
- (uintptr_t)kasan_early_shadow_p4d : \
- (pgtable_l4_enabled ? \
- (uintptr_t)kasan_early_shadow_pud : \
- (uintptr_t)kasan_early_shadow_pmd))
-#define kasan_populate_pgd_next(pgdp, vaddr, next) \
- (pgtable_l5_enabled ? \
- kasan_populate_p4d(pgdp, vaddr, next) : \
- (pgtable_l4_enabled ? \
- kasan_populate_pud(pgdp, vaddr, next) : \
- kasan_populate_pmd((pud_t *)pgdp, vaddr, next)))
-
static void __init kasan_populate_pgd(pgd_t *pgdp,
unsigned long vaddr, unsigned long end)
{
@@ -194,25 +146,86 @@ static void __init kasan_populate_pgd(pgd_t *pgdp,
do {
next = pgd_addr_end(vaddr, end);

- if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >= PGDIR_SIZE) {
- if (pgd_page_vaddr(*pgdp) ==
- (unsigned long)lm_alias(kasan_early_shadow_pgd_next)) {
- /*
- * pgdp can't be none since kasan_early_init
- * initialized all KASAN shadow region with
- * kasan_early_shadow_pud: if this is still the
- * case, that means we can try to allocate a
- * hugepage as a replacement.
- */
- phys_addr = memblock_phys_alloc(PGDIR_SIZE, PGDIR_SIZE);
- if (phys_addr) {
- set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr), PAGE_KERNEL));
- continue;
- }
+ if (pgd_none(*pgdp) && IS_ALIGNED(vaddr, PGDIR_SIZE) &&
+ (next - vaddr) >= PGDIR_SIZE) {
+ phys_addr = memblock_phys_alloc(PGDIR_SIZE, PGDIR_SIZE);
+ if (phys_addr) {
+ set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr), PAGE_KERNEL));
+ memset(__va(phys_addr), KASAN_SHADOW_INIT, PGDIR_SIZE);
+ continue;
}
}

- kasan_populate_pgd_next(pgdp, vaddr, next);
+ kasan_populate_p4d(pgdp, vaddr, next);
+ } while (pgdp++, vaddr = next, vaddr != end);
+}
+
+static void __init kasan_early_clear_pud(p4d_t *p4dp,
+ unsigned long vaddr, unsigned long end)
+{
+ pud_t *pudp, *base_pud;
+ unsigned long next;
+
+ if (!pgtable_l4_enabled) {
+ pudp = (pud_t *)p4dp;
+ } else {
+ base_pud = pt_ops.get_pud_virt(pfn_to_phys(_p4d_pfn(*p4dp)));
+ pudp = base_pud + pud_index(vaddr);
+ }
+
+ do {
+ next = pud_addr_end(vaddr, end);
+
+ if (IS_ALIGNED(vaddr, PUD_SIZE) && (next - vaddr) >= PUD_SIZE) {
+ pud_clear(pudp);
+ continue;
+ }
+
+ BUG();
+ } while (pudp++, vaddr = next, vaddr != end);
+}
+
+static void __init kasan_early_clear_p4d(pgd_t *pgdp,
+ unsigned long vaddr, unsigned long end)
+{
+ p4d_t *p4dp, *base_p4d;
+ unsigned long next;
+
+ if (!pgtable_l5_enabled) {
+ p4dp = (p4d_t *)pgdp;
+ } else {
+ base_p4d = pt_ops.get_p4d_virt(pfn_to_phys(_pgd_pfn(*pgdp)));
+ p4dp = base_p4d + p4d_index(vaddr);
+ }
+
+ do {
+ next = p4d_addr_end(vaddr, end);
+
+ if (pgtable_l4_enabled && IS_ALIGNED(vaddr, P4D_SIZE) &&
+ (next - vaddr) >= P4D_SIZE) {
+ p4d_clear(p4dp);
+ continue;
+ }
+
+ kasan_early_clear_pud(p4dp, vaddr, next);
+ } while (p4dp++, vaddr = next, vaddr != end);
+}
+
+static void __init kasan_early_clear_pgd(pgd_t *pgdp,
+ unsigned long vaddr, unsigned long end)
+{
+ unsigned long next;
+
+ do {
+ next = pgd_addr_end(vaddr, end);
+
+ if (pgtable_l5_enabled && IS_ALIGNED(vaddr, PGDIR_SIZE) &&
+ (next - vaddr) >= PGDIR_SIZE) {
+ pgd_clear(pgdp);
+ continue;
+ }
+
+ kasan_early_clear_p4d(pgdp, vaddr, next);
} while (pgdp++, vaddr = next, vaddr != end);
}

@@ -357,117 +370,64 @@ static void __init kasan_populate(void *start, void *end)
unsigned long vend = PAGE_ALIGN((unsigned long)end);

kasan_populate_pgd(pgd_offset_k(vaddr), vaddr, vend);
-
- local_flush_tlb_all();
- memset(start, KASAN_SHADOW_INIT, end - start);
}

-static void __init kasan_shallow_populate_pmd(pgd_t *pgdp,
+static void __init kasan_shallow_populate_pud(p4d_t *p4d,
unsigned long vaddr, unsigned long end)
{
unsigned long next;
- pmd_t *pmdp, *base_pmd;
- bool is_kasan_pte;
-
- base_pmd = (pmd_t *)pgd_page_vaddr(*pgdp);
- pmdp = base_pmd + pmd_index(vaddr);
-
- do {
- next = pmd_addr_end(vaddr, end);
- is_kasan_pte = (pmd_pgtable(*pmdp) == lm_alias(kasan_early_shadow_pte));
-
- if (is_kasan_pte)
- pmd_clear(pmdp);
- } while (pmdp++, vaddr = next, vaddr != end);
-}
-
-static void __init kasan_shallow_populate_pud(pgd_t *pgdp,
- unsigned long vaddr, unsigned long end)
-{
- unsigned long next;
- pud_t *pudp, *base_pud;
- pmd_t *base_pmd;
- bool is_kasan_pmd;
-
- base_pud = (pud_t *)pgd_page_vaddr(*pgdp);
- pudp = base_pud + pud_index(vaddr);
+ void *p;
+ pud_t *pud_k = pud_offset(p4d, vaddr);

do {
next = pud_addr_end(vaddr, end);
- is_kasan_pmd = (pud_pgtable(*pudp) == lm_alias(kasan_early_shadow_pmd));

- if (!is_kasan_pmd)
- continue;
-
- base_pmd = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
- set_pud(pudp, pfn_pud(PFN_DOWN(__pa(base_pmd)), PAGE_TABLE));
-
- if (IS_ALIGNED(vaddr, PUD_SIZE) && (next - vaddr) >= PUD_SIZE)
+ if (pud_none(*pud_k)) {
+ p = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+ set_pud(pud_k, pfn_pud(PFN_DOWN(__pa(p)), PAGE_TABLE));
continue;
+ }

- memcpy(base_pmd, (void *)kasan_early_shadow_pmd, PAGE_SIZE);
- kasan_shallow_populate_pmd((pgd_t *)pudp, vaddr, next);
- } while (pudp++, vaddr = next, vaddr != end);
+ BUG();
+ } while (pud_k++, vaddr = next, vaddr != end);
}

-static void __init kasan_shallow_populate_p4d(pgd_t *pgdp,
+static void __init kasan_shallow_populate_p4d(pgd_t *pgd,
unsigned long vaddr, unsigned long end)
{
unsigned long next;
- p4d_t *p4dp, *base_p4d;
- pud_t *base_pud;
- bool is_kasan_pud;
-
- base_p4d = (p4d_t *)pgd_page_vaddr(*pgdp);
- p4dp = base_p4d + p4d_index(vaddr);
+ void *p;
+ p4d_t *p4d_k = p4d_offset(pgd, vaddr);

do {
next = p4d_addr_end(vaddr, end);
- is_kasan_pud = (p4d_pgtable(*p4dp) == lm_alias(kasan_early_shadow_pud));
-
- if (!is_kasan_pud)
- continue;
-
- base_pud = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
- set_p4d(p4dp, pfn_p4d(PFN_DOWN(__pa(base_pud)), PAGE_TABLE));

- if (IS_ALIGNED(vaddr, P4D_SIZE) && (next - vaddr) >= P4D_SIZE)
+ if (p4d_none(*p4d_k)) {
+ p = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+ set_p4d(p4d_k, pfn_p4d(PFN_DOWN(__pa(p)), PAGE_TABLE));
continue;
+ }

- memcpy(base_pud, (void *)kasan_early_shadow_pud, PAGE_SIZE);
- kasan_shallow_populate_pud((pgd_t *)p4dp, vaddr, next);
- } while (p4dp++, vaddr = next, vaddr != end);
+ kasan_shallow_populate_pud(p4d_k, vaddr, end);
+ } while (p4d_k++, vaddr = next, vaddr != end);
}

-#define kasan_shallow_populate_pgd_next(pgdp, vaddr, next) \
- (pgtable_l5_enabled ? \
- kasan_shallow_populate_p4d(pgdp, vaddr, next) : \
- (pgtable_l4_enabled ? \
- kasan_shallow_populate_pud(pgdp, vaddr, next) : \
- kasan_shallow_populate_pmd(pgdp, vaddr, next)))
-
static void __init kasan_shallow_populate_pgd(unsigned long vaddr, unsigned long end)
{
unsigned long next;
void *p;
pgd_t *pgd_k = pgd_offset_k(vaddr);
- bool is_kasan_pgd_next;

do {
next = pgd_addr_end(vaddr, end);
- is_kasan_pgd_next = (pgd_page_vaddr(*pgd_k) ==
- (unsigned long)lm_alias(kasan_early_shadow_pgd_next));

- if (is_kasan_pgd_next) {
+ if (pgd_none(*pgd_k)) {
p = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
set_pgd(pgd_k, pfn_pgd(PFN_DOWN(__pa(p)), PAGE_TABLE));
- }
-
- if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >= PGDIR_SIZE)
continue;
+ }

- memcpy(p, (void *)kasan_early_shadow_pgd_next, PAGE_SIZE);
- kasan_shallow_populate_pgd_next(pgd_k, vaddr, next);
+ kasan_shallow_populate_p4d(pgd_k, vaddr, next);
} while (pgd_k++, vaddr = next, vaddr != end);
}

@@ -477,7 +437,37 @@ static void __init kasan_shallow_populate(void *start, void *end)
unsigned long vend = PAGE_ALIGN((unsigned long)end);

kasan_shallow_populate_pgd(vaddr, vend);
- local_flush_tlb_all();
+}
+
+void create_tmp_mapping(void)
+{
+ void *ptr;
+ p4d_t *base_p4d;
+
+ /*
+ * We need to clean the early mapping: this is hard to achieve "in-place",
+ * so install a temporary mapping like arm64 and x86 do.
+ */
+ memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(pgd_t) * PTRS_PER_PGD);
+
+ /* Copy the last p4d since it is shared with the kernel mapping. */
+ if (pgtable_l5_enabled) {
+ ptr = (p4d_t *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
+ memcpy(tmp_p4d, ptr, sizeof(p4d_t) * PTRS_PER_P4D);
+ set_pgd(&tmp_pg_dir[pgd_index(KASAN_SHADOW_END)],
+ pfn_pgd(PFN_DOWN(__pa(tmp_p4d)), PAGE_TABLE));
+ base_p4d = tmp_p4d;
+ } else {
+ base_p4d = (p4d_t *)tmp_pg_dir;
+ }
+
+ /* Copy the last pud since it is shared with the kernel mapping. */
+ if (pgtable_l4_enabled) {
+ ptr = (pud_t *)p4d_page_vaddr(*(base_p4d + p4d_index(KASAN_SHADOW_END)));
+ memcpy(tmp_pud, ptr, sizeof(pud_t) * PTRS_PER_PUD);
+ set_p4d(&base_p4d[p4d_index(KASAN_SHADOW_END)],
+ pfn_p4d(PFN_DOWN(__pa(tmp_pud)), PAGE_TABLE));
+ }
}

void __init kasan_init(void)
@@ -485,10 +475,27 @@ void __init kasan_init(void)
phys_addr_t p_start, p_end;
u64 i;

- if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
+ create_tmp_mapping();
+ csr_write(CSR_SATP, PFN_DOWN(__pa(tmp_pg_dir)) | satp_mode);
+
+ kasan_early_clear_pgd(pgd_offset_k(KASAN_SHADOW_START),
+ KASAN_SHADOW_START, KASAN_SHADOW_END);
+
+ kasan_populate_early_shadow((void *)kasan_mem_to_shadow((void *)FIXADDR_START),
+ (void *)kasan_mem_to_shadow((void *)VMALLOC_START));
+
+ if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
kasan_shallow_populate(
(void *)kasan_mem_to_shadow((void *)VMALLOC_START),
(void *)kasan_mem_to_shadow((void *)VMALLOC_END));
+ /* Shallow populate modules and BPF which are vmalloc-allocated */
+ kasan_shallow_populate(
+ (void *)kasan_mem_to_shadow((void *)MODULES_VADDR),
+ (void *)kasan_mem_to_shadow((void *)MODULES_END));
+ } else {
+ kasan_populate_early_shadow((void *)kasan_mem_to_shadow((void *)VMALLOC_START),
+ (void *)kasan_mem_to_shadow((void *)VMALLOC_END));
+ }

/* Populate the linear mapping */
for_each_mem_range(i, &p_start, &p_end) {
@@ -501,8 +508,8 @@ void __init kasan_init(void)
kasan_populate(kasan_mem_to_shadow(start), kasan_mem_to_shadow(end));
}

- /* Populate kernel, BPF, modules mapping */
- kasan_populate(kasan_mem_to_shadow((const void *)MODULES_VADDR),
+ /* Populate kernel */
+ kasan_populate(kasan_mem_to_shadow((const void *)MODULES_END),
kasan_mem_to_shadow((const void *)MODULES_VADDR + SZ_2G));

for (i = 0; i < PTRS_PER_PTE; i++)
@@ -513,4 +520,7 @@ void __init kasan_init(void)

memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
init_task.kasan_depth = 0;
+
+ csr_write(CSR_SATP, PFN_DOWN(__pa(swapper_pg_dir)) | satp_mode);
+ local_flush_tlb_all();
}