diff options
Diffstat (limited to 'arch/s390/mm/kasan_init.c')
| -rw-r--r-- | arch/s390/mm/kasan_init.c | 403 |
1 files changed, 403 insertions, 0 deletions
diff --git a/arch/s390/mm/kasan_init.c b/arch/s390/mm/kasan_init.c new file mode 100644 index 000000000..9f988d458 --- /dev/null +++ b/arch/s390/mm/kasan_init.c @@ -0,0 +1,403 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/kasan.h> +#include <linux/sched/task.h> +#include <linux/memblock.h> +#include <linux/pgtable.h> +#include <asm/pgalloc.h> +#include <asm/kasan.h> +#include <asm/mem_detect.h> +#include <asm/processor.h> +#include <asm/sclp.h> +#include <asm/facility.h> +#include <asm/sections.h> +#include <asm/setup.h> +#include <asm/uv.h> + +static unsigned long segment_pos __initdata; +static unsigned long segment_low __initdata; +static unsigned long pgalloc_pos __initdata; +static unsigned long pgalloc_low __initdata; +static unsigned long pgalloc_freeable __initdata; +static bool has_edat __initdata; +static bool has_nx __initdata; + +#define __sha(x) ((unsigned long)kasan_mem_to_shadow((void *)x)) + +static pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE); + +static void __init kasan_early_panic(const char *reason) +{ + sclp_early_printk("The Linux kernel failed to boot with the KernelAddressSanitizer:\n"); + sclp_early_printk(reason); + disabled_wait(); +} + +static void * __init kasan_early_alloc_segment(void) +{ + segment_pos -= _SEGMENT_SIZE; + + if (segment_pos < segment_low) + kasan_early_panic("out of memory during initialisation\n"); + + return (void *)segment_pos; +} + +static void * __init kasan_early_alloc_pages(unsigned int order) +{ + pgalloc_pos -= (PAGE_SIZE << order); + + if (pgalloc_pos < pgalloc_low) + kasan_early_panic("out of memory during initialisation\n"); + + return (void *)pgalloc_pos; +} + +static void * __init kasan_early_crst_alloc(unsigned long val) +{ + unsigned long *table; + + table = kasan_early_alloc_pages(CRST_ALLOC_ORDER); + if (table) + crst_table_init(table, val); + return table; +} + +static pte_t * __init kasan_early_pte_alloc(void) +{ + static void *pte_leftover; + pte_t *pte; + + BUILD_BUG_ON(_PAGE_TABLE_SIZE * 2 != PAGE_SIZE); + + if (!pte_leftover) { + pte_leftover = kasan_early_alloc_pages(0); + pte = pte_leftover + _PAGE_TABLE_SIZE; + } else { + pte = pte_leftover; + pte_leftover = NULL; + } + memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE); + return pte; +} + +enum populate_mode { + POPULATE_ONE2ONE, + POPULATE_MAP, + POPULATE_ZERO_SHADOW, + POPULATE_SHALLOW +}; +static void __init kasan_early_pgtable_populate(unsigned long address, + unsigned long end, + enum populate_mode mode) +{ + unsigned long pgt_prot_zero, pgt_prot, sgt_prot; + pgd_t *pg_dir; + p4d_t *p4_dir; + pud_t *pu_dir; + pmd_t *pm_dir; + pte_t *pt_dir; + + pgt_prot_zero = pgprot_val(PAGE_KERNEL_RO); + if (!has_nx) + pgt_prot_zero &= ~_PAGE_NOEXEC; + pgt_prot = pgprot_val(PAGE_KERNEL); + sgt_prot = pgprot_val(SEGMENT_KERNEL); + if (!has_nx || mode == POPULATE_ONE2ONE) { + pgt_prot &= ~_PAGE_NOEXEC; + sgt_prot &= ~_SEGMENT_ENTRY_NOEXEC; + } + + /* + * The first 1MB of 1:1 mapping is mapped with 4KB pages + */ + while (address < end) { + pg_dir = pgd_offset_k(address); + if (pgd_none(*pg_dir)) { + if (mode == POPULATE_ZERO_SHADOW && + IS_ALIGNED(address, PGDIR_SIZE) && + end - address >= PGDIR_SIZE) { + pgd_populate(&init_mm, pg_dir, + kasan_early_shadow_p4d); + address = (address + PGDIR_SIZE) & PGDIR_MASK; + continue; + } + p4_dir = kasan_early_crst_alloc(_REGION2_ENTRY_EMPTY); + pgd_populate(&init_mm, pg_dir, p4_dir); + } + + if (mode == POPULATE_SHALLOW) { + address = (address + P4D_SIZE) & P4D_MASK; + continue; + } + + p4_dir = p4d_offset(pg_dir, address); + if (p4d_none(*p4_dir)) { + if (mode == POPULATE_ZERO_SHADOW && + IS_ALIGNED(address, P4D_SIZE) && + end - address >= P4D_SIZE) { + p4d_populate(&init_mm, p4_dir, + kasan_early_shadow_pud); + address = (address + P4D_SIZE) & P4D_MASK; + continue; + } + pu_dir = kasan_early_crst_alloc(_REGION3_ENTRY_EMPTY); + p4d_populate(&init_mm, p4_dir, pu_dir); + } + + pu_dir = pud_offset(p4_dir, address); + if (pud_none(*pu_dir)) { + if (mode == POPULATE_ZERO_SHADOW && + IS_ALIGNED(address, PUD_SIZE) && + end - address >= PUD_SIZE) { + pud_populate(&init_mm, pu_dir, + kasan_early_shadow_pmd); + address = (address + PUD_SIZE) & PUD_MASK; + continue; + } + pm_dir = kasan_early_crst_alloc(_SEGMENT_ENTRY_EMPTY); + pud_populate(&init_mm, pu_dir, pm_dir); + } + + pm_dir = pmd_offset(pu_dir, address); + if (pmd_none(*pm_dir)) { + if (IS_ALIGNED(address, PMD_SIZE) && + end - address >= PMD_SIZE) { + if (mode == POPULATE_ZERO_SHADOW) { + pmd_populate(&init_mm, pm_dir, kasan_early_shadow_pte); + address = (address + PMD_SIZE) & PMD_MASK; + continue; + } else if (has_edat && address) { + void *page; + + if (mode == POPULATE_ONE2ONE) { + page = (void *)address; + } else { + page = kasan_early_alloc_segment(); + memset(page, 0, _SEGMENT_SIZE); + } + set_pmd(pm_dir, __pmd(__pa(page) | sgt_prot)); + address = (address + PMD_SIZE) & PMD_MASK; + continue; + } + } + pt_dir = kasan_early_pte_alloc(); + pmd_populate(&init_mm, pm_dir, pt_dir); + } else if (pmd_large(*pm_dir)) { + address = (address + PMD_SIZE) & PMD_MASK; + continue; + } + + pt_dir = pte_offset_kernel(pm_dir, address); + if (pte_none(*pt_dir)) { + void *page; + + switch (mode) { + case POPULATE_ONE2ONE: + page = (void *)address; + set_pte(pt_dir, __pte(__pa(page) | pgt_prot)); + break; + case POPULATE_MAP: + page = kasan_early_alloc_pages(0); + memset(page, 0, PAGE_SIZE); + set_pte(pt_dir, __pte(__pa(page) | pgt_prot)); + break; + case POPULATE_ZERO_SHADOW: + page = kasan_early_shadow_page; + set_pte(pt_dir, __pte(__pa(page) | pgt_prot_zero)); + break; + case POPULATE_SHALLOW: + /* should never happen */ + break; + } + } + address += PAGE_SIZE; + } +} + +static void __init kasan_set_pgd(pgd_t *pgd, unsigned long asce_type) +{ + unsigned long asce_bits; + + asce_bits = asce_type | _ASCE_TABLE_LENGTH; + S390_lowcore.kernel_asce = (__pa(pgd) & PAGE_MASK) | asce_bits; + S390_lowcore.user_asce = S390_lowcore.kernel_asce; + + __ctl_load(S390_lowcore.kernel_asce, 1, 1); + __ctl_load(S390_lowcore.kernel_asce, 7, 7); + __ctl_load(S390_lowcore.kernel_asce, 13, 13); +} + +static void __init kasan_enable_dat(void) +{ + psw_t psw; + + psw.mask = __extract_psw(); + psw_bits(psw).dat = 1; + psw_bits(psw).as = PSW_BITS_AS_HOME; + __load_psw_mask(psw.mask); +} + +static void __init kasan_early_detect_facilities(void) +{ + if (test_facility(8)) { + has_edat = true; + __ctl_set_bit(0, 23); + } + if (!noexec_disabled && test_facility(130)) { + has_nx = true; + __ctl_set_bit(0, 20); + } +} + +void __init kasan_early_init(void) +{ + unsigned long shadow_alloc_size; + unsigned long initrd_end; + unsigned long memsize; + unsigned long pgt_prot = pgprot_val(PAGE_KERNEL_RO); + pte_t pte_z; + pmd_t pmd_z = __pmd(__pa(kasan_early_shadow_pte) | _SEGMENT_ENTRY); + pud_t pud_z = __pud(__pa(kasan_early_shadow_pmd) | _REGION3_ENTRY); + p4d_t p4d_z = __p4d(__pa(kasan_early_shadow_pud) | _REGION2_ENTRY); + + kasan_early_detect_facilities(); + if (!has_nx) + pgt_prot &= ~_PAGE_NOEXEC; + pte_z = __pte(__pa(kasan_early_shadow_page) | pgt_prot); + + memsize = get_mem_detect_end(); + if (!memsize) + kasan_early_panic("cannot detect physical memory size\n"); + /* + * Kasan currently supports standby memory but only if it follows + * online memory (default allocation), i.e. no memory holes. + * - memsize represents end of online memory + * - ident_map_size represents online + standby and memory limits + * accounted. + * Kasan maps "memsize" right away. + * [0, memsize] - as identity mapping + * [__sha(0), __sha(memsize)] - shadow memory for identity mapping + * The rest [memsize, ident_map_size] if memsize < ident_map_size + * could be mapped/unmapped dynamically later during memory hotplug. + */ + memsize = min(memsize, ident_map_size); + + BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE)); + BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE)); + crst_table_init((unsigned long *)early_pg_dir, _REGION2_ENTRY_EMPTY); + + /* init kasan zero shadow */ + crst_table_init((unsigned long *)kasan_early_shadow_p4d, + p4d_val(p4d_z)); + crst_table_init((unsigned long *)kasan_early_shadow_pud, + pud_val(pud_z)); + crst_table_init((unsigned long *)kasan_early_shadow_pmd, + pmd_val(pmd_z)); + memset64((u64 *)kasan_early_shadow_pte, pte_val(pte_z), PTRS_PER_PTE); + + shadow_alloc_size = memsize >> KASAN_SHADOW_SCALE_SHIFT; + pgalloc_low = round_up((unsigned long)_end, _SEGMENT_SIZE); + if (IS_ENABLED(CONFIG_BLK_DEV_INITRD)) { + initrd_end = + round_up(initrd_data.start + initrd_data.size, _SEGMENT_SIZE); + pgalloc_low = max(pgalloc_low, initrd_end); + } + + if (pgalloc_low + shadow_alloc_size > memsize) + kasan_early_panic("out of memory during initialisation\n"); + + if (has_edat) { + segment_pos = round_down(memsize, _SEGMENT_SIZE); + segment_low = segment_pos - shadow_alloc_size; + pgalloc_pos = segment_low; + } else { + pgalloc_pos = memsize; + } + init_mm.pgd = early_pg_dir; + /* + * Current memory layout: + * +- 0 -------------+ +- shadow start -+ + * | 1:1 ram mapping | /| 1/8 ram | + * | | / | | + * +- end of ram ----+ / +----------------+ + * | ... gap ... | / | | + * | |/ | kasan | + * +- shadow start --+ | zero | + * | 1/8 addr space | | page | + * +- shadow end -+ | mapping | + * | ... gap ... |\ | (untracked) | + * +- vmalloc area -+ \ | | + * | vmalloc_size | \ | | + * +- modules vaddr -+ \ +----------------+ + * | 2Gb | \| unmapped | allocated per module + * +-----------------+ +- shadow end ---+ + * + * Current memory layout (KASAN_VMALLOC): + * +- 0 -------------+ +- shadow start -+ + * | 1:1 ram mapping | /| 1/8 ram | + * | | / | | + * +- end of ram ----+ / +----------------+ + * | ... gap ... | / | kasan | + * | |/ | zero | + * +- shadow start --+ | page | + * | 1/8 addr space | | mapping | + * +- shadow end -+ | (untracked) | + * | ... gap ... |\ | | + * +- vmalloc area -+ \ +- vmalloc area -+ + * | vmalloc_size | \ |shallow populate| + * +- 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); +} |