xref: /openbmc/linux/arch/riscv/mm/kasan_init.c (revision e178d670f251b6947d6be99c0014e9a57ad4f0e0)

// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2019 Andes Technology Corporation

#include <linux/pfn.h>
#include <linux/init_task.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/memblock.h>
#include <linux/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/fixmap.h>
#include <asm/pgalloc.h>

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

	if (!ptr)
		panic("%pS: Failed to allocate %zu bytes align=%zx nid=%d from=%llx\n",
			__func__, size, size, node, (u64)__pa(MAX_DMA_ADDRESS));

	return ptr;
}

extern pgd_t early_pg_dir[PTRS_PER_PGD];
asmlinkage void __init kasan_early_init(void)
{
	uintptr_t i;
	pgd_t *pgd = early_pg_dir + pgd_index(KASAN_SHADOW_START);

	for (i = 0; i < PTRS_PER_PTE; ++i)
		set_pte(kasan_early_shadow_pte + i,
			mk_pte(virt_to_page(kasan_early_shadow_page),
			       PAGE_KERNEL));

	for (i = 0; i < PTRS_PER_PMD; ++i)
		set_pmd(kasan_early_shadow_pmd + i,
			pfn_pmd(PFN_DOWN
				(__pa((uintptr_t) kasan_early_shadow_pte)),
				__pgprot(_PAGE_TABLE)));

	for (i = KASAN_SHADOW_START; i < KASAN_SHADOW_END;
	     i += PGDIR_SIZE, ++pgd)
		set_pgd(pgd,
			pfn_pgd(PFN_DOWN
				(__pa(((uintptr_t) kasan_early_shadow_pmd))),
				__pgprot(_PAGE_TABLE)));

	/* init for swapper_pg_dir */
	pgd = pgd_offset_k(KASAN_SHADOW_START);

	for (i = KASAN_SHADOW_START; i < KASAN_SHADOW_END;
	     i += PGDIR_SIZE, ++pgd)
		set_pgd(pgd,
			pfn_pgd(PFN_DOWN
				(__pa(((uintptr_t) kasan_early_shadow_pmd))),
				__pgprot(_PAGE_TABLE)));

	local_flush_tlb_all();
}

static void __init populate(void *start, void *end)
{
	unsigned long i, offset;
	unsigned long vaddr = (unsigned long)start & PAGE_MASK;
	unsigned long vend = PAGE_ALIGN((unsigned long)end);
	unsigned long n_pages = (vend - vaddr) / PAGE_SIZE;
	unsigned long n_ptes =
	    ((n_pages + PTRS_PER_PTE) & -PTRS_PER_PTE) / PTRS_PER_PTE;
	unsigned long n_pmds =
	    ((n_ptes + PTRS_PER_PMD) & -PTRS_PER_PMD) / PTRS_PER_PMD;

	pte_t *pte =
	    memblock_alloc(n_ptes * PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE);
	pmd_t *pmd =
	    memblock_alloc(n_pmds * PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
	pgd_t *pgd = pgd_offset_k(vaddr);

	for (i = 0; i < n_pages; i++) {
		phys_addr_t phys = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
		set_pte(&pte[i], pfn_pte(PHYS_PFN(phys), PAGE_KERNEL));
	}

	for (i = 0, offset = 0; i < n_ptes; i++, offset += PTRS_PER_PTE)
		set_pmd(&pmd[i],
			pfn_pmd(PFN_DOWN(__pa(&pte[offset])),
				__pgprot(_PAGE_TABLE)));

	for (i = 0, offset = 0; i < n_pmds; i++, offset += PTRS_PER_PMD)
		set_pgd(&pgd[i],
			pfn_pgd(PFN_DOWN(__pa(&pmd[offset])),
				__pgprot(_PAGE_TABLE)));

	local_flush_tlb_all();
	memset(start, 0, end - start);
}

void __init kasan_shallow_populate(void *start, void *end)
{
	unsigned long vaddr = (unsigned long)start & PAGE_MASK;
	unsigned long vend = PAGE_ALIGN((unsigned long)end);
	unsigned long pfn;
	int index;
	void *p;
	pud_t *pud_dir, *pud_k;
	pgd_t *pgd_dir, *pgd_k;
	p4d_t *p4d_dir, *p4d_k;

	while (vaddr < vend) {
		index = pgd_index(vaddr);
		pfn = csr_read(CSR_SATP) & SATP_PPN;
		pgd_dir = (pgd_t *)pfn_to_virt(pfn) + index;
		pgd_k = init_mm.pgd + index;
		pgd_dir = pgd_offset_k(vaddr);
		set_pgd(pgd_dir, *pgd_k);

		p4d_dir = p4d_offset(pgd_dir, vaddr);
		p4d_k  = p4d_offset(pgd_k, vaddr);

		vaddr = (vaddr + PUD_SIZE) & PUD_MASK;
		pud_dir = pud_offset(p4d_dir, vaddr);
		pud_k = pud_offset(p4d_k, vaddr);

		if (pud_present(*pud_dir)) {
			p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
			pud_populate(&init_mm, pud_dir, p);
		}
		vaddr += PAGE_SIZE;
	}
}

void __init kasan_init(void)
{
	phys_addr_t _start, _end;
	u64 i;

	kasan_populate_early_shadow((void *)KASAN_SHADOW_START,
				    (void *)kasan_mem_to_shadow((void *)
								VMEMMAP_END));
	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));
	else
		kasan_populate_early_shadow(
			(void *)kasan_mem_to_shadow((void *)VMALLOC_START),
			(void *)kasan_mem_to_shadow((void *)VMALLOC_END));

	for_each_mem_range(i, &_start, &_end) {
		void *start = (void *)_start;
		void *end = (void *)_end;

		if (start >= end)
			break;

		populate(kasan_mem_to_shadow(start), kasan_mem_to_shadow(end));
	};

	for (i = 0; i < PTRS_PER_PTE; i++)
		set_pte(&kasan_early_shadow_pte[i],
			mk_pte(virt_to_page(kasan_early_shadow_page),
			       __pgprot(_PAGE_PRESENT | _PAGE_READ |
					_PAGE_ACCESSED)));

	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
	init_task.kasan_depth = 0;
}