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s390/mm: split lowcore pages with set_memory_4k() 

Use set_memory_4k() to split lowcore pages within the kernel mapping
instead of using the quite subtle !addr check within modify_pmd_table()
and modify_pud_table() to prevent large pages for address zero.

With this lowcore might be mapped with 1MB / 2GB frames and only later
will be split. This way this mapping is handled like every other.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2022-09-05 14:18:27 +02:00 committed by Vasily Gorbik
parent bf2ce3855c
commit b193d2d4d0
1 changed files with 5 additions and 2 deletions
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7
arch/s390/mm/vmem.c
View File

@ -240,7 +240,7 @@ static int __ref modify_pmd_table(pud_t *pud, unsigned long addr,
} else if (pmd_none(*pmd)) {
if (IS_ALIGNED(addr, PMD_SIZE) &&
IS_ALIGNED(next, PMD_SIZE) &&
MACHINE_HAS_EDAT1 && addr && direct &&
MACHINE_HAS_EDAT1 && direct &&
!debug_pagealloc_enabled()) {
set_pmd(pmd, __pmd(__pa(addr) | prot));
pages++;
@ -336,7 +336,7 @@ static int modify_pud_table(p4d_t *p4d, unsigned long addr, unsigned long end,
} else if (pud_none(*pud)) {
if (IS_ALIGNED(addr, PUD_SIZE) &&
IS_ALIGNED(next, PUD_SIZE) &&
MACHINE_HAS_EDAT2 && addr && direct &&
MACHINE_HAS_EDAT2 && direct &&
!debug_pagealloc_enabled()) {
set_pud(pud, __pud(__pa(addr) | prot));
pages++;
@ -584,6 +584,9 @@ void __init vmem_map_init(void)
__set_memory(__stext_amode31, (__etext_amode31 - __stext_amode31) >> PAGE_SHIFT,
SET_MEMORY_RO | SET_MEMORY_X);
/* lowcore requires 4k mapping for real addresses / prefixing */
set_memory_4k(0, LC_PAGES);
/* lowcore must be executable for LPSWE */
if (!static_key_enabled(&cpu_has_bear))
set_memory_x(0, 1);