arch/powerpc/mm/kasan/kasan_init_32.c

// 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 <linux/vmalloc.h>
#include <asm/pgalloc.h>
#include <asm/code-patching.h>
#include <mm/mmu_decl.h>

static void 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), 0);
}

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

	pmd = pmd_offset(pud_offset(pgd_offset_k(k_start), k_start), 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 = pte_alloc_one_kernel(&init_mm);

		if (!new)
			return -ENOMEM;
		if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
			kasan_populate_pte(new, PAGE_READONLY);
		else
			kasan_populate_pte(new, PAGE_KERNEL_RO);
		pmd_populate_kernel(&init_mm, pmd, new);
	}
	return 0;
}

static void __ref *kasan_get_one_page(void)
{
	if (slab_is_available())
		return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);

	return memblock_alloc(PAGE_SIZE, PAGE_SIZE);
}

static int __ref 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 = NULL;

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

	if (!slab_is_available())
		block = memblock_alloc(k_end - k_start, PAGE_SIZE);

	for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE) {
		pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
		void *va = block ? block + k_cur - k_start : kasan_get_one_page();
		pte_t pte = pfn_pte(PHYS_PFN(__pa(va)), PAGE_KERNEL);

		if (!va)
			return -ENOMEM;

		__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;
}

static void __init kasan_remap_early_shadow_ro(void)
{
	if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
		kasan_populate_pte(kasan_early_shadow_pte, PAGE_READONLY);
	else
		kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL_RO);

	flush_tlb_kernel_range(KASAN_SHADOW_START, KASAN_SHADOW_END);
}

void __init kasan_mmu_init(void)
{
	int ret;
	struct memblock_region *reg;

	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");
	}

	for_each_memblock(memory, reg) {
		phys_addr_t base = reg->base;
		phys_addr_t top = min(base + reg->size, total_lowmem);

		if (base >= top)
			continue;

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

void __init kasan_init(void)
{
	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;
	pr_info("KASAN init done\n");
}

#ifdef CONFIG_MODULES
void *module_alloc(unsigned long size)
{
	void *base = vmalloc_exec(size);

	if (!base)
		return NULL;

	if (!kasan_init_region(base, size))
		return base;

	vfree(base);

	return NULL;
}
#endif

#ifdef CONFIG_PPC_BOOK3S_32
u8 __initdata early_hash[256 << 10] __aligned(256 << 10) = {0};

static void __init kasan_early_hash_table(void)
{
	modify_instruction_site(&patch__hash_page_A0, 0xffff, __pa(early_hash) >> 16);
	modify_instruction_site(&patch__flush_hash_A0, 0xffff, __pa(early_hash) >> 16);

	Hash = (struct hash_pte *)early_hash;
}
#else
static void __init kasan_early_hash_table(void) {}
#endif

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_offset(pud_offset(pgd_offset_k(addr), addr), 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);

	if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
		kasan_early_hash_table();
}