// SPDX-License-Identifier: GPL-2.0
#define DISABLE_BRANCH_PROFILING
#define pr_fmt(fmt) "kasan: " fmt

/* cpu_feature_enabled() cannot be used this early */
#define USE_EARLY_PGTABLE_L5

#include <linux/memblock.h>
#include <linux/kasan.h>
#include <linux/kdebug.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/vmalloc.h>

#include <asm/e820/types.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/cpu_entry_area.h>

extern struct range pfn_mapped[E820_MAX_ENTRIES];

static p4d_t tmp_p4d_table[MAX_PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);

static __init void *early_alloc(size_t size, int nid, bool should_panic)
{
        void *ptr = memblock_alloc_try_nid(size, size,
                        __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, nid);

        if (!ptr && should_panic)
                panic("%pS: Failed to allocate page, nid=%d from=%lx\n",
                      (void *)_RET_IP_, nid, __pa(MAX_DMA_ADDRESS));

        return ptr;
}

static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
                                      unsigned long end, int nid)
{
        pte_t *pte;

        if (pmd_none(*pmd)) {
                void *p;

                if (boot_cpu_has(X86_FEATURE_PSE) &&
                    ((end - addr) == PMD_SIZE) &&
                    IS_ALIGNED(addr, PMD_SIZE)) {
                        p = early_alloc(PMD_SIZE, nid, false);
                        if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
                                return;
                        memblock_free(p, PMD_SIZE);
                }

                p = early_alloc(PAGE_SIZE, nid, true);
                pmd_populate_kernel(&init_mm, pmd, p);
        }

        pte = pte_offset_kernel(pmd, addr);
        do {
                pte_t entry;
                void *p;

                if (!pte_none(*pte))
                        continue;

                p = early_alloc(PAGE_SIZE, nid, true);
                entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
                set_pte_at(&init_mm, addr, pte, entry);
        } while (pte++, addr += PAGE_SIZE, addr != end);
}

static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
                                      unsigned long end, int nid)
{
        pmd_t *pmd;
        unsigned long next;

        if (pud_none(*pud)) {
                void *p;

                if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
                    ((end - addr) == PUD_SIZE) &&
                    IS_ALIGNED(addr, PUD_SIZE)) {
                        p = early_alloc(PUD_SIZE, nid, false);
                        if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
                                return;
                        memblock_free(p, PUD_SIZE);
                }

                p = early_alloc(PAGE_SIZE, nid, true);
                pud_populate(&init_mm, pud, p);
        }

        pmd = pmd_offset(pud, addr);
        do {
                next = pmd_addr_end(addr, end);
                if (!pmd_large(*pmd))
                        kasan_populate_pmd(pmd, addr, next, nid);
        } while (pmd++, addr = next, addr != end);
}

static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
                                      unsigned long end, int nid)
{
        pud_t *pud;
        unsigned long next;

        if (p4d_none(*p4d)) {
                void *p = early_alloc(PAGE_SIZE, nid, true);

                p4d_populate(&init_mm, p4d, p);
        }

        pud = pud_offset(p4d, addr);
        do {
                next = pud_addr_end(addr, end);
                if (!pud_large(*pud))
                        kasan_populate_pud(pud, addr, next, nid);
        } while (pud++, addr = next, addr != end);
}

static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
                                      unsigned long end, int nid)
{
        void *p;
        p4d_t *p4d;
        unsigned long next;

        if (pgd_none(*pgd)) {
                p = early_alloc(PAGE_SIZE, nid, true);
                pgd_populate(&init_mm, pgd, p);
        }

        p4d = p4d_offset(pgd, addr);
        do {
                next = p4d_addr_end(addr, end);
                kasan_populate_p4d(p4d, addr, next, nid);
        } while (p4d++, addr = next, addr != end);
}

static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
                                         int nid)
{
        pgd_t *pgd;
        unsigned long next;

        addr = addr & PAGE_MASK;
        end = round_up(end, PAGE_SIZE);
        pgd = pgd_offset_k(addr);
        do {
                next = pgd_addr_end(addr, end);
                kasan_populate_pgd(pgd, addr, next, nid);
        } while (pgd++, addr = next, addr != end);
}

static void __init map_range(struct range *range)
{
        unsigned long start;
        unsigned long end;

        start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
        end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));

        kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
}

static void __init clear_pgds(unsigned long start,
                        unsigned long end)
{
        pgd_t *pgd;
        /* See comment in kasan_init() */
        unsigned long pgd_end = end & PGDIR_MASK;

        for (; start < pgd_end; start += PGDIR_SIZE) {
                pgd = pgd_offset_k(start);
                /*
                 * With folded p4d, pgd_clear() is nop, use p4d_clear()
                 * instead.
                 */
                if (pgtable_l5_enabled())
                        pgd_clear(pgd);
                else
                        p4d_clear(p4d_offset(pgd, start));
        }

        pgd = pgd_offset_k(start);
        for (; start < end; start += P4D_SIZE)
                p4d_clear(p4d_offset(pgd, start));
}

static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
{
        unsigned long p4d;

        if (!pgtable_l5_enabled())
                return (p4d_t *)pgd;

        p4d = pgd_val(*pgd) & PTE_PFN_MASK;
        p4d += __START_KERNEL_map - phys_base;
        return (p4d_t *)p4d + p4d_index(addr);
}

static void __init kasan_early_p4d_populate(pgd_t *pgd,
                unsigned long addr,
                unsigned long end)
{
        pgd_t pgd_entry;
        p4d_t *p4d, p4d_entry;
        unsigned long next;

        if (pgd_none(*pgd)) {
                pgd_entry = __pgd(_KERNPG_TABLE |
                                        __pa_nodebug(kasan_early_shadow_p4d));
                set_pgd(pgd, pgd_entry);
        }

        p4d = early_p4d_offset(pgd, addr);
        do {
                next = p4d_addr_end(addr, end);

                if (!p4d_none(*p4d))
                        continue;

                p4d_entry = __p4d(_KERNPG_TABLE |
                                        __pa_nodebug(kasan_early_shadow_pud));
                set_p4d(p4d, p4d_entry);
        } while (p4d++, addr = next, addr != end && p4d_none(*p4d));
}

static void __init kasan_map_early_shadow(pgd_t *pgd)
{
        /* See comment in kasan_init() */
        unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
        unsigned long end = KASAN_SHADOW_END;
        unsigned long next;

        pgd += pgd_index(addr);
        do {
                next = pgd_addr_end(addr, end);
                kasan_early_p4d_populate(pgd, addr, next);
        } while (pgd++, addr = next, addr != end);
}

static void __init kasan_shallow_populate_p4ds(pgd_t *pgd,
                                               unsigned long addr,
                                               unsigned long end)
{
        p4d_t *p4d;
        unsigned long next;
        void *p;

        p4d = p4d_offset(pgd, addr);
        do {
                next = p4d_addr_end(addr, end);

                if (p4d_none(*p4d)) {
                        p = early_alloc(PAGE_SIZE, NUMA_NO_NODE, true);
                        p4d_populate(&init_mm, p4d, p);
                }
        } while (p4d++, addr = next, addr != end);
}

static void __init kasan_shallow_populate_pgds(void *start, void *end)
{
        unsigned long addr, next;
        pgd_t *pgd;
        void *p;

        addr = (unsigned long)start;
        pgd = pgd_offset_k(addr);
        do {
                next = pgd_addr_end(addr, (unsigned long)end);

                if (pgd_none(*pgd)) {
                        p = early_alloc(PAGE_SIZE, NUMA_NO_NODE, true);
                        pgd_populate(&init_mm, pgd, p);
                }

                /*
                 * we need to populate p4ds to be synced when running in
                 * four level mode - see sync_global_pgds_l4()
                 */
                kasan_shallow_populate_p4ds(pgd, addr, next);
        } while (pgd++, addr = next, addr != (unsigned long)end);
}

void __init kasan_early_init(void)
{
        int i;
        pteval_t pte_val = __pa_nodebug(kasan_early_shadow_page) |
                                __PAGE_KERNEL | _PAGE_ENC;
        pmdval_t pmd_val = __pa_nodebug(kasan_early_shadow_pte) | _KERNPG_TABLE;
        pudval_t pud_val = __pa_nodebug(kasan_early_shadow_pmd) | _KERNPG_TABLE;
        p4dval_t p4d_val = __pa_nodebug(kasan_early_shadow_pud) | _KERNPG_TABLE;

        /* Mask out unsupported __PAGE_KERNEL bits: */
        pte_val &= __default_kernel_pte_mask;
        pmd_val &= __default_kernel_pte_mask;
        pud_val &= __default_kernel_pte_mask;
        p4d_val &= __default_kernel_pte_mask;

        for (i = 0; i < PTRS_PER_PTE; i++)
                kasan_early_shadow_pte[i] = __pte(pte_val);

        for (i = 0; i < PTRS_PER_PMD; i++)
                kasan_early_shadow_pmd[i] = __pmd(pmd_val);

        for (i = 0; i < PTRS_PER_PUD; i++)
                kasan_early_shadow_pud[i] = __pud(pud_val);

        for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++)
                kasan_early_shadow_p4d[i] = __p4d(p4d_val);

        kasan_map_early_shadow(early_top_pgt);
        kasan_map_early_shadow(init_top_pgt);
}

void __init kasan_init(void)
{
        int i;
        void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;

        memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));

        /*
         * We use the same shadow offset for 4- and 5-level paging to
         * facilitate boot-time switching between paging modes.
         * As result in 5-level paging mode KASAN_SHADOW_START and
         * KASAN_SHADOW_END are not aligned to PGD boundary.
         *
         * KASAN_SHADOW_START doesn't share PGD with anything else.
         * We claim whole PGD entry to make things easier.
         *
         * KASAN_SHADOW_END lands in the last PGD entry and it collides with
         * bunch of things like kernel code, modules, EFI mapping, etc.
         * We need to take extra steps to not overwrite them.
         */
        if (pgtable_l5_enabled()) {
                void *ptr;

                ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
                memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
                set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
                                __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
        }

        load_cr3(early_top_pgt);
        __flush_tlb_all();

        clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);

        kasan_populate_early_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
                        kasan_mem_to_shadow((void *)PAGE_OFFSET));

        for (i = 0; i < E820_MAX_ENTRIES; i++) {
                if (pfn_mapped[i].end == 0)
                        break;

                map_range(&pfn_mapped[i]);
        }

        shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
        shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
        shadow_cpu_entry_begin = (void *)round_down(
                        (unsigned long)shadow_cpu_entry_begin, PAGE_SIZE);

        shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
                                        CPU_ENTRY_AREA_MAP_SIZE);
        shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
        shadow_cpu_entry_end = (void *)round_up(
                        (unsigned long)shadow_cpu_entry_end, PAGE_SIZE);

        kasan_populate_early_shadow(
                kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
                kasan_mem_to_shadow((void *)VMALLOC_START));

        /*
         * If we're in full vmalloc mode, don't back vmalloc space with early
         * shadow pages. Instead, prepopulate pgds/p4ds so they are synced to
         * the global table and we can populate the lower levels on demand.
         */
        if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
                kasan_shallow_populate_pgds(
                        kasan_mem_to_shadow((void *)VMALLOC_START),
                        kasan_mem_to_shadow((void *)VMALLOC_END));
        else
                kasan_populate_early_shadow(
                        kasan_mem_to_shadow((void *)VMALLOC_START),
                        kasan_mem_to_shadow((void *)VMALLOC_END));

        kasan_populate_early_shadow(
                kasan_mem_to_shadow((void *)VMALLOC_END + 1),
                shadow_cpu_entry_begin);

        kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
                              (unsigned long)shadow_cpu_entry_end, 0);

        kasan_populate_early_shadow(shadow_cpu_entry_end,
                        kasan_mem_to_shadow((void *)__START_KERNEL_map));

        kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
                              (unsigned long)kasan_mem_to_shadow(_end),
                              early_pfn_to_nid(__pa(_stext)));

        kasan_populate_early_shadow(kasan_mem_to_shadow((void *)MODULES_END),
                                        (void *)KASAN_SHADOW_END);

        load_cr3(init_top_pgt);
        __flush_tlb_all();

        /*
         * kasan_early_shadow_page has been used as early shadow memory, thus
         * it may contain some garbage. Now we can clear and write protect it,
         * since after the TLB flush no one should write to it.
         */
        memset(kasan_early_shadow_page, 0, PAGE_SIZE);
        for (i = 0; i < PTRS_PER_PTE; i++) {
                pte_t pte;
                pgprot_t prot;

                prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC);
                pgprot_val(prot) &= __default_kernel_pte_mask;

                pte = __pte(__pa(kasan_early_shadow_page) | pgprot_val(prot));
                set_pte(&kasan_early_shadow_pte[i], pte);
        }
        /* Flush TLBs again to be sure that write protection applied. */
        __flush_tlb_all();

        init_task.kasan_depth = 0;
        pr_info("KernelAddressSanitizer initialized\n");
}