// SPDX-License-Identifier: GPL-2.0

#define DISABLE_BRANCH_PROFILING

#include <linux/kasan.h>
#include <linux/printk.h>
#include <linux/memblock.h>
#include <linux/sched/task.h>
#include <asm/pgalloc.h>
#include <asm/text-patching.h>
#include <mm/mmu_decl.h>

static pgprot_t __init kasan_prot_ro(void)
{
        if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
                return PAGE_READONLY;

        return PAGE_KERNEL_RO;
}

static void __init kasan_populate_pte(pte_t *ptep, pgprot_t prot)
{
        unsigned long va = (unsigned long)kasan_early_shadow_page;
        phys_addr_t pa = __pa(kasan_early_shadow_page);
        int i;

        for (i = 0; i < PTRS_PER_PTE; i++, ptep++)
                __set_pte_at(&init_mm, va, ptep, pfn_pte(PHYS_PFN(pa), prot), 1);
}

int __init kasan_init_shadow_page_tables(unsigned long k_start, unsigned long k_end)
{
        pmd_t *pmd;
        unsigned long k_cur, k_next;

        pmd = pmd_off_k(k_start);

        for (k_cur = k_start; k_cur != k_end; k_cur = k_next, pmd++) {
                pte_t *new;

                k_next = pgd_addr_end(k_cur, k_end);
                if ((void *)pmd_page_vaddr(*pmd) != kasan_early_shadow_pte)
                        continue;

                new = memblock_alloc(PTE_FRAG_SIZE, PTE_FRAG_SIZE);

                if (!new)
                        return -ENOMEM;
                kasan_populate_pte(new, PAGE_KERNEL);
                pmd_populate_kernel(&init_mm, pmd, new);
        }
        return 0;
}

int __init __weak kasan_init_region(void *start, size_t size)
{
        unsigned long k_start = (unsigned long)kasan_mem_to_shadow(start);
        unsigned long k_end = (unsigned long)kasan_mem_to_shadow(start + size);
        unsigned long k_cur;
        int ret;
        void *block;

        ret = kasan_init_shadow_page_tables(k_start, k_end);
        if (ret)
                return ret;

        k_start = k_start & PAGE_MASK;
        block = memblock_alloc(k_end - k_start, PAGE_SIZE);
        if (!block)
                return -ENOMEM;

        for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) {
                pmd_t *pmd = pmd_off_k(k_cur);
                void *va = block + k_cur - k_start;
                pte_t pte = pfn_pte(PHYS_PFN(__pa(va)), PAGE_KERNEL);

                __set_pte_at(&init_mm, k_cur, pte_offset_kernel(pmd, k_cur), pte, 0);
        }
        flush_tlb_kernel_range(k_start, k_end);
        return 0;
}

void __init
kasan_update_early_region(unsigned long k_start, unsigned long k_end, pte_t pte)
{
        unsigned long k_cur;

        for (k_cur = k_start; k_cur != k_end; k_cur += PAGE_SIZE) {
                pmd_t *pmd = pmd_off_k(k_cur);
                pte_t *ptep = pte_offset_kernel(pmd, k_cur);

                if (pte_page(*ptep) != virt_to_page(lm_alias(kasan_early_shadow_page)))
                        continue;

                __set_pte_at(&init_mm, k_cur, ptep, pte, 0);
        }

        flush_tlb_kernel_range(k_start, k_end);
}

static void __init kasan_remap_early_shadow_ro(void)
{
        pgprot_t prot = kasan_prot_ro();
        phys_addr_t pa = __pa(kasan_early_shadow_page);

        kasan_populate_pte(kasan_early_shadow_pte, prot);

        kasan_update_early_region(KASAN_SHADOW_START, KASAN_SHADOW_END,
                                  pfn_pte(PHYS_PFN(pa), prot));
}

static void __init kasan_unmap_early_shadow_vmalloc(void)
{
        unsigned long k_start = (unsigned long)kasan_mem_to_shadow((void *)VMALLOC_START);
        unsigned long k_end = (unsigned long)kasan_mem_to_shadow((void *)VMALLOC_END);

        kasan_update_early_region(k_start, k_end, __pte(0));

#ifdef MODULES_VADDR
        k_start = (unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR);
        k_end = (unsigned long)kasan_mem_to_shadow((void *)MODULES_END);
        kasan_update_early_region(k_start, k_end, __pte(0));
#endif
}

void __init kasan_mmu_init(void)
{
        int ret;

        if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE)) {
                ret = kasan_init_shadow_page_tables(KASAN_SHADOW_START, KASAN_SHADOW_END);

                if (ret)
                        panic("kasan: kasan_init_shadow_page_tables() failed");
        }
}

void __init kasan_init(void)
{
        phys_addr_t base, end;
        u64 i;
        int ret;

        for_each_mem_range(i, &base, &end) {
                phys_addr_t top = min(end, total_lowmem);

                if (base >= top)
                        continue;

                ret = kasan_init_region(__va(base), top - base);
                if (ret)
                        panic("kasan: kasan_init_region() failed");
        }

        if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
                ret = kasan_init_shadow_page_tables(KASAN_SHADOW_START, KASAN_SHADOW_END);

                if (ret)
                        panic("kasan: kasan_init_shadow_page_tables() failed");
        }

        kasan_remap_early_shadow_ro();

        clear_page(kasan_early_shadow_page);

        /* At this point kasan is fully initialized. Enable error messages */
        init_task.kasan_depth = 0;
        kasan_init_generic();
}

void __init kasan_late_init(void)
{
        if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
                kasan_unmap_early_shadow_vmalloc();
}

void __init kasan_early_init(void)
{
        unsigned long addr = KASAN_SHADOW_START;
        unsigned long end = KASAN_SHADOW_END;
        unsigned long next;
        pmd_t *pmd = pmd_off_k(addr);

        BUILD_BUG_ON(KASAN_SHADOW_START & ~PGDIR_MASK);

        kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL);

        do {
                next = pgd_addr_end(addr, end);
                pmd_populate_kernel(&init_mm, pmd, kasan_early_shadow_pte);
        } while (pmd++, addr = next, addr != end);
}