404 lines
12 KiB
C
404 lines
12 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/kasan.h>
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#include <linux/sched/task.h>
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#include <linux/memblock.h>
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#include <linux/pgtable.h>
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#include <asm/pgalloc.h>
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#include <asm/kasan.h>
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#include <asm/mem_detect.h>
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#include <asm/processor.h>
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#include <asm/sclp.h>
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#include <asm/facility.h>
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#include <asm/sections.h>
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#include <asm/setup.h>
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#include <asm/uv.h>
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static unsigned long segment_pos __initdata;
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static unsigned long segment_low __initdata;
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static unsigned long pgalloc_pos __initdata;
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static unsigned long pgalloc_low __initdata;
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static unsigned long pgalloc_freeable __initdata;
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static bool has_edat __initdata;
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static bool has_nx __initdata;
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#define __sha(x) ((unsigned long)kasan_mem_to_shadow((void *)x))
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static pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
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static void __init kasan_early_panic(const char *reason)
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{
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sclp_early_printk("The Linux kernel failed to boot with the KernelAddressSanitizer:\n");
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sclp_early_printk(reason);
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disabled_wait();
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}
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static void * __init kasan_early_alloc_segment(void)
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{
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segment_pos -= _SEGMENT_SIZE;
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if (segment_pos < segment_low)
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kasan_early_panic("out of memory during initialisation\n");
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return (void *)segment_pos;
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}
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static void * __init kasan_early_alloc_pages(unsigned int order)
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{
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pgalloc_pos -= (PAGE_SIZE << order);
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if (pgalloc_pos < pgalloc_low)
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kasan_early_panic("out of memory during initialisation\n");
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return (void *)pgalloc_pos;
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}
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static void * __init kasan_early_crst_alloc(unsigned long val)
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{
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unsigned long *table;
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table = kasan_early_alloc_pages(CRST_ALLOC_ORDER);
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if (table)
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crst_table_init(table, val);
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return table;
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}
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static pte_t * __init kasan_early_pte_alloc(void)
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{
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static void *pte_leftover;
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pte_t *pte;
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BUILD_BUG_ON(_PAGE_TABLE_SIZE * 2 != PAGE_SIZE);
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if (!pte_leftover) {
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pte_leftover = kasan_early_alloc_pages(0);
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pte = pte_leftover + _PAGE_TABLE_SIZE;
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} else {
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pte = pte_leftover;
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pte_leftover = NULL;
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}
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memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
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return pte;
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}
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enum populate_mode {
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POPULATE_ONE2ONE,
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POPULATE_MAP,
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POPULATE_ZERO_SHADOW,
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POPULATE_SHALLOW
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};
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static void __init kasan_early_pgtable_populate(unsigned long address,
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unsigned long end,
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enum populate_mode mode)
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{
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unsigned long pgt_prot_zero, pgt_prot, sgt_prot;
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pgd_t *pg_dir;
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p4d_t *p4_dir;
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pud_t *pu_dir;
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pmd_t *pm_dir;
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pte_t *pt_dir;
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pgt_prot_zero = pgprot_val(PAGE_KERNEL_RO);
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if (!has_nx)
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pgt_prot_zero &= ~_PAGE_NOEXEC;
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pgt_prot = pgprot_val(PAGE_KERNEL);
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sgt_prot = pgprot_val(SEGMENT_KERNEL);
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if (!has_nx || mode == POPULATE_ONE2ONE) {
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pgt_prot &= ~_PAGE_NOEXEC;
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sgt_prot &= ~_SEGMENT_ENTRY_NOEXEC;
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}
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/*
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* The first 1MB of 1:1 mapping is mapped with 4KB pages
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*/
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while (address < end) {
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pg_dir = pgd_offset_k(address);
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if (pgd_none(*pg_dir)) {
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if (mode == POPULATE_ZERO_SHADOW &&
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IS_ALIGNED(address, PGDIR_SIZE) &&
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end - address >= PGDIR_SIZE) {
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pgd_populate(&init_mm, pg_dir,
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kasan_early_shadow_p4d);
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address = (address + PGDIR_SIZE) & PGDIR_MASK;
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continue;
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}
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p4_dir = kasan_early_crst_alloc(_REGION2_ENTRY_EMPTY);
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pgd_populate(&init_mm, pg_dir, p4_dir);
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}
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if (mode == POPULATE_SHALLOW) {
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address = (address + P4D_SIZE) & P4D_MASK;
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continue;
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}
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p4_dir = p4d_offset(pg_dir, address);
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if (p4d_none(*p4_dir)) {
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if (mode == POPULATE_ZERO_SHADOW &&
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IS_ALIGNED(address, P4D_SIZE) &&
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end - address >= P4D_SIZE) {
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p4d_populate(&init_mm, p4_dir,
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kasan_early_shadow_pud);
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address = (address + P4D_SIZE) & P4D_MASK;
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continue;
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}
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pu_dir = kasan_early_crst_alloc(_REGION3_ENTRY_EMPTY);
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p4d_populate(&init_mm, p4_dir, pu_dir);
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}
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pu_dir = pud_offset(p4_dir, address);
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if (pud_none(*pu_dir)) {
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if (mode == POPULATE_ZERO_SHADOW &&
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IS_ALIGNED(address, PUD_SIZE) &&
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end - address >= PUD_SIZE) {
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pud_populate(&init_mm, pu_dir,
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kasan_early_shadow_pmd);
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address = (address + PUD_SIZE) & PUD_MASK;
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continue;
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}
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pm_dir = kasan_early_crst_alloc(_SEGMENT_ENTRY_EMPTY);
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pud_populate(&init_mm, pu_dir, pm_dir);
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}
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pm_dir = pmd_offset(pu_dir, address);
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if (pmd_none(*pm_dir)) {
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if (IS_ALIGNED(address, PMD_SIZE) &&
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end - address >= PMD_SIZE) {
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if (mode == POPULATE_ZERO_SHADOW) {
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pmd_populate(&init_mm, pm_dir, kasan_early_shadow_pte);
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address = (address + PMD_SIZE) & PMD_MASK;
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continue;
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} else if (has_edat && address) {
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void *page;
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if (mode == POPULATE_ONE2ONE) {
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page = (void *)address;
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} else {
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page = kasan_early_alloc_segment();
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memset(page, 0, _SEGMENT_SIZE);
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}
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set_pmd(pm_dir, __pmd(__pa(page) | sgt_prot));
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address = (address + PMD_SIZE) & PMD_MASK;
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continue;
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}
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}
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pt_dir = kasan_early_pte_alloc();
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pmd_populate(&init_mm, pm_dir, pt_dir);
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} else if (pmd_large(*pm_dir)) {
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address = (address + PMD_SIZE) & PMD_MASK;
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continue;
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}
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pt_dir = pte_offset_kernel(pm_dir, address);
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if (pte_none(*pt_dir)) {
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void *page;
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switch (mode) {
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case POPULATE_ONE2ONE:
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page = (void *)address;
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set_pte(pt_dir, __pte(__pa(page) | pgt_prot));
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break;
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case POPULATE_MAP:
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page = kasan_early_alloc_pages(0);
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memset(page, 0, PAGE_SIZE);
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set_pte(pt_dir, __pte(__pa(page) | pgt_prot));
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break;
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case POPULATE_ZERO_SHADOW:
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page = kasan_early_shadow_page;
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set_pte(pt_dir, __pte(__pa(page) | pgt_prot_zero));
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break;
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case POPULATE_SHALLOW:
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/* should never happen */
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break;
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}
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}
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address += PAGE_SIZE;
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}
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}
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static void __init kasan_set_pgd(pgd_t *pgd, unsigned long asce_type)
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{
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unsigned long asce_bits;
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asce_bits = asce_type | _ASCE_TABLE_LENGTH;
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S390_lowcore.kernel_asce = (__pa(pgd) & PAGE_MASK) | asce_bits;
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S390_lowcore.user_asce = S390_lowcore.kernel_asce;
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__ctl_load(S390_lowcore.kernel_asce, 1, 1);
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__ctl_load(S390_lowcore.kernel_asce, 7, 7);
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__ctl_load(S390_lowcore.kernel_asce, 13, 13);
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}
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static void __init kasan_enable_dat(void)
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{
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psw_t psw;
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psw.mask = __extract_psw();
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psw_bits(psw).dat = 1;
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psw_bits(psw).as = PSW_BITS_AS_HOME;
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__load_psw_mask(psw.mask);
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}
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static void __init kasan_early_detect_facilities(void)
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{
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if (test_facility(8)) {
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has_edat = true;
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__ctl_set_bit(0, 23);
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}
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if (!noexec_disabled && test_facility(130)) {
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has_nx = true;
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__ctl_set_bit(0, 20);
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}
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}
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void __init kasan_early_init(void)
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{
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unsigned long shadow_alloc_size;
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unsigned long initrd_end;
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unsigned long memsize;
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unsigned long pgt_prot = pgprot_val(PAGE_KERNEL_RO);
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pte_t pte_z;
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pmd_t pmd_z = __pmd(__pa(kasan_early_shadow_pte) | _SEGMENT_ENTRY);
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pud_t pud_z = __pud(__pa(kasan_early_shadow_pmd) | _REGION3_ENTRY);
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p4d_t p4d_z = __p4d(__pa(kasan_early_shadow_pud) | _REGION2_ENTRY);
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kasan_early_detect_facilities();
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if (!has_nx)
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pgt_prot &= ~_PAGE_NOEXEC;
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pte_z = __pte(__pa(kasan_early_shadow_page) | pgt_prot);
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memsize = get_mem_detect_end();
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if (!memsize)
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kasan_early_panic("cannot detect physical memory size\n");
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/*
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* Kasan currently supports standby memory but only if it follows
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* online memory (default allocation), i.e. no memory holes.
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* - memsize represents end of online memory
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* - ident_map_size represents online + standby and memory limits
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* accounted.
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* Kasan maps "memsize" right away.
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* [0, memsize] - as identity mapping
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* [__sha(0), __sha(memsize)] - shadow memory for identity mapping
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* The rest [memsize, ident_map_size] if memsize < ident_map_size
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* could be mapped/unmapped dynamically later during memory hotplug.
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*/
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memsize = min(memsize, ident_map_size);
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BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE));
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BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE));
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crst_table_init((unsigned long *)early_pg_dir, _REGION2_ENTRY_EMPTY);
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/* init kasan zero shadow */
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crst_table_init((unsigned long *)kasan_early_shadow_p4d,
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p4d_val(p4d_z));
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crst_table_init((unsigned long *)kasan_early_shadow_pud,
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pud_val(pud_z));
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crst_table_init((unsigned long *)kasan_early_shadow_pmd,
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pmd_val(pmd_z));
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memset64((u64 *)kasan_early_shadow_pte, pte_val(pte_z), PTRS_PER_PTE);
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shadow_alloc_size = memsize >> KASAN_SHADOW_SCALE_SHIFT;
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pgalloc_low = round_up((unsigned long)_end, _SEGMENT_SIZE);
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if (IS_ENABLED(CONFIG_BLK_DEV_INITRD)) {
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initrd_end =
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round_up(initrd_data.start + initrd_data.size, _SEGMENT_SIZE);
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pgalloc_low = max(pgalloc_low, initrd_end);
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}
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if (pgalloc_low + shadow_alloc_size > memsize)
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kasan_early_panic("out of memory during initialisation\n");
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if (has_edat) {
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segment_pos = round_down(memsize, _SEGMENT_SIZE);
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segment_low = segment_pos - shadow_alloc_size;
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pgalloc_pos = segment_low;
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} else {
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pgalloc_pos = memsize;
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}
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init_mm.pgd = early_pg_dir;
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/*
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* Current memory layout:
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* +- 0 -------------+ +- shadow start -+
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* | 1:1 ram mapping | /| 1/8 ram |
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* | | / | |
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* +- end of ram ----+ / +----------------+
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* | ... gap ... | / | |
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* | |/ | kasan |
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* +- shadow start --+ | zero |
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* | 1/8 addr space | | page |
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* +- shadow end -+ | mapping |
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* | ... gap ... |\ | (untracked) |
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* +- vmalloc area -+ \ | |
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* | vmalloc_size | \ | |
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* +- modules vaddr -+ \ +----------------+
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* | 2Gb | \| unmapped | allocated per module
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* +-----------------+ +- shadow end ---+
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*
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* Current memory layout (KASAN_VMALLOC):
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* +- 0 -------------+ +- shadow start -+
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* | 1:1 ram mapping | /| 1/8 ram |
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* | | / | |
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* +- end of ram ----+ / +----------------+
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* | ... gap ... | / | kasan |
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* | |/ | zero |
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* +- shadow start --+ | page |
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* | 1/8 addr space | | mapping |
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* +- shadow end -+ | (untracked) |
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* | ... gap ... |\ | |
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* +- vmalloc area -+ \ +- vmalloc area -+
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* | vmalloc_size | \ |shallow populate|
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* +- modules vaddr -+ \ +- modules area -+
|
||
|
|
* | 2Gb | \|shallow populate|
|
||
|
|
* +-----------------+ +- shadow end ---+
|
||
|
|
*/
|
||
|
|
/* populate kasan shadow (for identity mapping and zero page mapping) */
|
||
|
|
kasan_early_pgtable_populate(__sha(0), __sha(memsize), POPULATE_MAP);
|
||
|
|
if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
|
||
|
|
/* shallowly populate kasan shadow for vmalloc and modules */
|
||
|
|
kasan_early_pgtable_populate(__sha(VMALLOC_START), __sha(MODULES_END),
|
||
|
|
POPULATE_SHALLOW);
|
||
|
|
}
|
||
|
|
/* populate kasan shadow for untracked memory */
|
||
|
|
kasan_early_pgtable_populate(__sha(ident_map_size),
|
||
|
|
IS_ENABLED(CONFIG_KASAN_VMALLOC) ?
|
||
|
|
__sha(VMALLOC_START) :
|
||
|
|
__sha(MODULES_VADDR),
|
||
|
|
POPULATE_ZERO_SHADOW);
|
||
|
|
kasan_early_pgtable_populate(__sha(MODULES_END), __sha(_REGION1_SIZE),
|
||
|
|
POPULATE_ZERO_SHADOW);
|
||
|
|
/* memory allocated for identity mapping structs will be freed later */
|
||
|
|
pgalloc_freeable = pgalloc_pos;
|
||
|
|
/* populate identity mapping */
|
||
|
|
kasan_early_pgtable_populate(0, memsize, POPULATE_ONE2ONE);
|
||
|
|
kasan_set_pgd(early_pg_dir, _ASCE_TYPE_REGION2);
|
||
|
|
kasan_enable_dat();
|
||
|
|
/* enable kasan */
|
||
|
|
init_task.kasan_depth = 0;
|
||
|
|
memblock_reserve(pgalloc_pos, memsize - pgalloc_pos);
|
||
|
|
sclp_early_printk("KernelAddressSanitizer initialized\n");
|
||
|
|
}
|
||
|
|
|
||
|
|
void __init kasan_copy_shadow_mapping(void)
|
||
|
|
{
|
||
|
|
/*
|
||
|
|
* At this point we are still running on early pages setup early_pg_dir,
|
||
|
|
* while swapper_pg_dir has just been initialized with identity mapping.
|
||
|
|
* Carry over shadow memory region from early_pg_dir to swapper_pg_dir.
|
||
|
|
*/
|
||
|
|
|
||
|
|
pgd_t *pg_dir_src;
|
||
|
|
pgd_t *pg_dir_dst;
|
||
|
|
p4d_t *p4_dir_src;
|
||
|
|
p4d_t *p4_dir_dst;
|
||
|
|
|
||
|
|
pg_dir_src = pgd_offset_raw(early_pg_dir, KASAN_SHADOW_START);
|
||
|
|
pg_dir_dst = pgd_offset_raw(init_mm.pgd, KASAN_SHADOW_START);
|
||
|
|
p4_dir_src = p4d_offset(pg_dir_src, KASAN_SHADOW_START);
|
||
|
|
p4_dir_dst = p4d_offset(pg_dir_dst, KASAN_SHADOW_START);
|
||
|
|
memcpy(p4_dir_dst, p4_dir_src,
|
||
|
|
(KASAN_SHADOW_SIZE >> P4D_SHIFT) * sizeof(p4d_t));
|
||
|
|
}
|
||
|
|
|
||
|
|
void __init kasan_free_early_identity(void)
|
||
|
|
{
|
||
|
|
memblock_phys_free(pgalloc_pos, pgalloc_freeable - pgalloc_pos);
|
||
|
|
}
|