From: Vasily Gorbik gor@linux.ibm.com
[ Upstream commit 327899674eef18f96644be87aa5510b7523fe4f6 ]
When physical memory is defined under z/VM using DEF STOR CONFIG, there may be memory holes that are not hotpluggable memory. In such cases, DCSS mapping could be placed in one of these memory holes. Subsequently, attempting memory access to such DCSS mapping would result in a kasan failure because there is no shadow memory mapping for it.
To maintain consistency with cases where DCSS mapping is positioned after the kernel identity mapping, which is then covered by kasan zero shadow mapping, handle the scenario above by populating zero shadow mapping for memory holes where DCSS mapping could potentially be placed.
Reviewed-by: Heiko Carstens hca@linux.ibm.com Reviewed-by: Gerald Schaefer gerald.schaefer@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/boot/vmem.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/s390/boot/vmem.c b/arch/s390/boot/vmem.c index c67f59db7a512..f66d642251fe8 100644 --- a/arch/s390/boot/vmem.c +++ b/arch/s390/boot/vmem.c @@ -57,6 +57,7 @@ static void kasan_populate_shadow(void) 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); + unsigned long memgap_start = 0; unsigned long untracked_end; unsigned long start, end; int i; @@ -101,8 +102,12 @@ static void kasan_populate_shadow(void) * +- shadow end ----+---------+- shadow end ---+ */
- for_each_physmem_usable_range(i, &start, &end) + for_each_physmem_usable_range(i, &start, &end) { kasan_populate(start, end, POPULATE_KASAN_MAP_SHADOW); + if (memgap_start && physmem_info.info_source == MEM_DETECT_DIAG260) + kasan_populate(memgap_start, start, POPULATE_KASAN_ZERO_SHADOW); + memgap_start = end; + } if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) { untracked_end = VMALLOC_START; /* shallowly populate kasan shadow for vmalloc and modules */