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| author | Heiko Carstens <hca@linux.ibm.com> | 2020-11-16 08:06:41 +0100 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2020-11-23 12:01:12 +0100 |
| commit | 0290c9e328e04052e317171953feb18177a34aed (patch) | |
| tree | 9ba70533fc8727ef2d664542b62f90180d44819c /arch/s390/mm | |
| parent | 87d5986345219a7e4f204726d9085ea87f3e22d0 (diff) | |
| download | linux-stable-0290c9e328e04052e317171953feb18177a34aed.tar.gz linux-stable-0290c9e328e04052e317171953feb18177a34aed.tar.bz2 linux-stable-0290c9e328e04052e317171953feb18177a34aed.zip | |
s390/mm: use invalid asce instead of kernel asce
Create a region 3 page table which contains only invalid entries, and
use that via "s390_invalid_asce" instead of the kernel ASCE whenever
there is either
- no user address space available, e.g. during early startup
- as an intermediate ASCE when address spaces are switched
This makes sure that user space accesses in such situations are
guaranteed to fail.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'arch/s390/mm')
| -rw-r--r-- | arch/s390/mm/init.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c index 69e6e2a5072e..73a163065b95 100644 --- a/arch/s390/mm/init.c +++ b/arch/s390/mm/init.c @@ -49,6 +49,9 @@ #include <linux/virtio_config.h> pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(".bss..swapper_pg_dir"); +static pgd_t invalid_pg_dir[PTRS_PER_PGD] __section(".bss..invalid_pg_dir"); + +unsigned long s390_invalid_asce; unsigned long empty_zero_page, zero_page_mask; EXPORT_SYMBOL(empty_zero_page); @@ -92,6 +95,9 @@ void __init paging_init(void) unsigned long pgd_type, asce_bits; psw_t psw; + s390_invalid_asce = (unsigned long)invalid_pg_dir; + s390_invalid_asce |= _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH; + crst_table_init((unsigned long *)invalid_pg_dir, _REGION3_ENTRY_EMPTY); init_mm.pgd = swapper_pg_dir; if (VMALLOC_END > _REGION2_SIZE) { asce_bits = _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH; @@ -102,14 +108,14 @@ void __init paging_init(void) } init_mm.context.asce = (__pa(init_mm.pgd) & PAGE_MASK) | asce_bits; S390_lowcore.kernel_asce = init_mm.context.asce; - S390_lowcore.user_asce = S390_lowcore.kernel_asce; + S390_lowcore.user_asce = s390_invalid_asce; crst_table_init((unsigned long *) init_mm.pgd, pgd_type); vmem_map_init(); kasan_copy_shadow_mapping(); /* enable virtual mapping in kernel mode */ __ctl_load(S390_lowcore.kernel_asce, 1, 1); - __ctl_load(S390_lowcore.kernel_asce, 7, 7); + __ctl_load(S390_lowcore.user_asce, 7, 7); __ctl_load(S390_lowcore.kernel_asce, 13, 13); psw.mask = __extract_psw(); psw_bits(psw).dat = 1; |