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| author | Heiko Carstens <hca@linux.ibm.com> | 2023-08-25 14:29:50 +0200 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2023-08-30 11:03:27 +0200 |
| commit | a6e49f10f4411ec87f16ccb1b0ce5ea7e4a04a95 (patch) | |
| tree | 4c3517ef04721f2b9d76afed2d0b0f7543c8363c /arch/s390 | |
| parent | 3eeb07788ff05b30e2ddad39561d53495563e63a (diff) | |
s390/mm: improve description of mapping permissions of prefix pages
Slightly improve the description which explains why the first prefix
page must be mapped executable when the BEAR-enhancement facility is
not installed.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/mm/vmem.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c index 9b31dc565bc5..a1e01542790b 100644 --- a/arch/s390/mm/vmem.c +++ b/arch/s390/mm/vmem.c @@ -659,8 +659,11 @@ void __init vmem_map_init(void) (unsigned long)(_einittext - _sinittext) >> PAGE_SHIFT); set_memory_rox((unsigned long)__stext_amode31, (unsigned long)(__etext_amode31 - __stext_amode31) >> PAGE_SHIFT); - - /* lowcore must be executable for LPSWE */ + /* + * If the BEAR-enhancement facility is not installed the first + * prefix page is used to return to the previous context with + * an LPSWE instruction and therefore must be executable. + */ if (!static_key_enabled(&cpu_has_bear)) set_memory_x(0, 1); if (debug_pagealloc_enabled()) { |