init_book3e_64.c

// SPDX-License-Identifier: GPL-2.0
/*
 * KASAN for 64-bit Book3e powerpc
 *
 * Copyright 2022, Christophe Leroy, CS GROUP France
 */

#define DISABLE_BRANCH_PROFILING

#include <linux/kasan.h>
#include <linux/printk.h>
#include <linux/memblock.h>
#include <linux/set_memory.h>

#include <asm/pgalloc.h>

static inline bool kasan_pud_table(p4d_t p4d)
{
	return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
}

static inline bool kasan_pmd_table(pud_t pud)
{
	return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
}

static inline bool kasan_pte_table(pmd_t pmd)
{
	return pmd_page(pmd) == virt_to_page(lm_alias(kasan_early_shadow_pte));
}

static int __init kasan_map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
{
	pgd_t *pgdp;
	p4d_t *p4dp;
	pud_t *pudp;
	pmd_t *pmdp;
	pte_t *ptep;

	pgdp = pgd_offset_k(ea);
	p4dp = p4d_offset(pgdp, ea);
	if (kasan_pud_table(*p4dp)) {
		pudp = memblock_alloc_or_panic(PUD_TABLE_SIZE, PUD_TABLE_SIZE);
		memcpy(pudp, kasan_early_shadow_pud, PUD_TABLE_SIZE);
		p4d_populate(&init_mm, p4dp, pudp);
	}
	pudp = pud_offset(p4dp, ea);
	if (kasan_pmd_table(*pudp)) {
		pmdp = memblock_alloc_or_panic(PMD_TABLE_SIZE, PMD_TABLE_SIZE);
		memcpy(pmdp, kasan_early_shadow_pmd, PMD_TABLE_SIZE);
		pud_populate(&init_mm, pudp, pmdp);
	}
	pmdp = pmd_offset(pudp, ea);
	if (kasan_pte_table(*pmdp)) {
		ptep = memblock_alloc_or_panic(PTE_TABLE_SIZE, PTE_TABLE_SIZE);
		memcpy(ptep, kasan_early_shadow_pte, PTE_TABLE_SIZE);
		pmd_populate_kernel(&init_mm, pmdp, ptep);
	}
	ptep = pte_offset_kernel(pmdp, ea);

	__set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot), 0);

	return 0;
}

static void __init kasan_init_phys_region(void *start, void *end)
{
	unsigned long k_start, k_end, k_cur;
	void *va;

	if (start >= end)
		return;

	k_start = ALIGN_DOWN((unsigned long)kasan_mem_to_shadow(start), PAGE_SIZE);
	k_end = ALIGN((unsigned long)kasan_mem_to_shadow(end), PAGE_SIZE);

	va = memblock_alloc_or_panic(k_end - k_start, PAGE_SIZE);
	for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE, va += PAGE_SIZE)
		kasan_map_kernel_page(k_cur, __pa(va), PAGE_KERNEL);
}

void __init kasan_early_init(void)
{
	int i;
	unsigned long addr;
	pgd_t *pgd = pgd_offset_k(KASAN_SHADOW_START);
	pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL);

	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));

	for (i = 0; i < PTRS_PER_PTE; i++)
		__set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
			     &kasan_early_shadow_pte[i], zero_pte, 0);

	for (i = 0; i < PTRS_PER_PMD; i++)
		pmd_populate_kernel(&init_mm, &kasan_early_shadow_pmd[i],
				    kasan_early_shadow_pte);

	for (i = 0; i < PTRS_PER_PUD; i++)
		pud_populate(&init_mm, &kasan_early_shadow_pud[i],
			     kasan_early_shadow_pmd);

	for (addr = KASAN_SHADOW_START; addr != KASAN_SHADOW_END; addr += PGDIR_SIZE)
		p4d_populate(&init_mm, p4d_offset(pgd++, addr), kasan_early_shadow_pud);
}

void __init kasan_init(void)
{
	phys_addr_t start, end;
	u64 i;
	pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL_RO);

	for_each_mem_range(i, &start, &end)
		kasan_init_phys_region(phys_to_virt(start), phys_to_virt(end));

	if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
		kasan_remove_zero_shadow((void *)VMALLOC_START, VMALLOC_SIZE);

	for (i = 0; i < PTRS_PER_PTE; i++)
		__set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
			     &kasan_early_shadow_pte[i], zero_pte, 0);

	flush_tlb_kernel_range(KASAN_SHADOW_START, KASAN_SHADOW_END);

	memset(kasan_early_shadow_page, 0, PAGE_SIZE);

	/* Enable error messages */
	init_task.kasan_depth = 0;
	pr_info("KASAN init done\n");
}

void __init kasan_late_init(void) { }