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s390/kasan: avoid mapping KASAN shadow for standby memory 

KASAN common code is able to handle memory hotplug and create KASAN shadow
memory on a fly. Online memory ranges are available from mem_detect,
use this information to avoid mapping KASAN shadow for standby memory.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2023-01-30 02:11:39 +01:00 committed by Heiko Carstens
parent 8382c96324
commit 26ced8124a
2 changed files with 6 additions and 22 deletions
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2
arch/s390/boot/kaslr.c
View File

@ -182,7 +182,7 @@ unsigned long get_random_base(unsigned long safe_addr)
* which vmem and kasan code will use for shadow memory and
* pgtable mapping allocations.
*/
memory_limit -= kasan_estimate_memory_needs(memory_limit);
memory_limit -= kasan_estimate_memory_needs(online_mem_total);
memory_limit -= vmem_estimate_memory_needs(online_mem_total);
safe_addr = ALIGN(safe_addr, THREAD_SIZE);

26
arch/s390/mm/kasan_init.c
View File

@ -227,26 +227,13 @@ void __init kasan_early_init(void)
p4d_t p4d_z = __p4d(__pa(kasan_early_shadow_pud) | _REGION2_ENTRY);
unsigned long untracked_end = MODULES_VADDR;
unsigned long shadow_alloc_size;
unsigned long memsize;
unsigned long start, end;
int i;
kasan_early_detect_facilities();
if (!has_nx)
pte_z = clear_pte_bit(pte_z, __pgprot(_PAGE_NOEXEC));
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.
* [__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.
*/
BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE));
BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE));
@ -256,12 +243,8 @@ void __init kasan_early_init(void)
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;
if (pgalloc_low + shadow_alloc_size > memsize)
kasan_early_panic("out of memory during initialisation\n");
if (has_edat) {
shadow_alloc_size = get_mem_detect_online_total() >> KASAN_SHADOW_SCALE_SHIFT;
segment_pos = round_down(pgalloc_pos, _SEGMENT_SIZE);
segment_low = segment_pos - shadow_alloc_size;
segment_low = round_down(segment_low, _SEGMENT_SIZE);
@ -299,7 +282,8 @@ void __init kasan_early_init(void)
* +- shadow end ----+---------+- shadow end ---+
*/
/* populate kasan shadow (for identity mapping and zero page mapping) */
kasan_early_pgtable_populate(__sha(0), __sha(memsize), POPULATE_MAP);
for_each_mem_detect_block(i, &start, &end)
kasan_early_pgtable_populate(__sha(start), __sha(end), POPULATE_MAP);
if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
untracked_end = VMALLOC_START;
/* shallowly populate kasan shadow for vmalloc and modules */