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>

diff --git a/arch/s390/boot/kaslr.c b/arch/s390/boot/kaslr.c
index 9cab7bb..70ff68d 100644 (file)
--- a/arch/s390/boot/kaslr.c
+++ b/arch/s390/boot/kaslr.c
@@ -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);

diff --git a/arch/s390/mm/kasan_init.c b/arch/s390/mm/kasan_init.c
index 1aaea71..4f66782 100644 (file)
--- a/arch/s390/mm/kasan_init.c
+++ b/arch/s390/mm/kasan_init.c
@@ -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 */