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| author |   Heiko Carstens <heiko.carstens@de.ibm.com> | 2017-04-24 15:27:35 +0200 |
|---|---|---|
| committer |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-04-26 13:41:21 +0200 |
| commit | 1366def38b6ab574dd0dbf95e308c7d115e73796 (patch) | |
| tree | ba7b4a0e6b322678c76891a3c96e2d6896f5f75a /arch/s390/mm | |
| parent | s390/mm: simplify arch_get_unmapped_area[_topdown] (diff) | |
| download | linux-dev-1366def38b6ab574dd0dbf95e308c7d115e73796.tar.xz linux-dev-1366def38b6ab574dd0dbf95e308c7d115e73796.zip | |
s390/pageattr: avoid unnecessary page table splitting
The kernel page table splitting code will split page tables even for
features the CPU does not support. E.g. a CPU may not support the NX
feature.
In order to avoid this, remove those bits from the flags parameter
that correlate with unsupported CPU features within __set_memory(). In
addition add an early exit if the flags parameter does not have any
bits set afterwards.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/mm')
| -rw-r--r-- | arch/s390/mm/pageattr.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c index fc5dc33bb141..fc321c5ec30e 100644 --- a/arch/s390/mm/pageattr.c +++ b/arch/s390/mm/pageattr.c @@ -94,7 +94,7 @@ static int walk_pte_level(pmd_t *pmdp, unsigned long addr, unsigned long end, new = pte_wrprotect(new); else if (flags & SET_MEMORY_RW) new = pte_mkwrite(pte_mkdirty(new)); - if ((flags & SET_MEMORY_NX) && MACHINE_HAS_NX) + if (flags & SET_MEMORY_NX) pte_val(new) |= _PAGE_NOEXEC; else if (flags & SET_MEMORY_X) pte_val(new) &= ~_PAGE_NOEXEC; @@ -144,7 +144,7 @@ static void modify_pmd_page(pmd_t *pmdp, unsigned long addr, new = pmd_wrprotect(new); else if (flags & SET_MEMORY_RW) new = pmd_mkwrite(pmd_mkdirty(new)); - if ((flags & SET_MEMORY_NX) && MACHINE_HAS_NX) + if (flags & SET_MEMORY_NX) pmd_val(new) |= _SEGMENT_ENTRY_NOEXEC; else if (flags & SET_MEMORY_X) pmd_val(new) &= ~_SEGMENT_ENTRY_NOEXEC; @@ -221,7 +221,7 @@ static void modify_pud_page(pud_t *pudp, unsigned long addr, new = pud_wrprotect(new); else if (flags & SET_MEMORY_RW) new = pud_mkwrite(pud_mkdirty(new)); - if ((flags & SET_MEMORY_NX) && MACHINE_HAS_NX) + if (flags & SET_MEMORY_NX) pud_val(new) |= _REGION_ENTRY_NOEXEC; else if (flags & SET_MEMORY_X) pud_val(new) &= ~_REGION_ENTRY_NOEXEC; @@ -288,6 +288,10 @@ static int change_page_attr(unsigned long addr, unsigned long end, int __set_memory(unsigned long addr, int numpages, unsigned long flags) { + if (!MACHINE_HAS_NX) + flags &= ~(SET_MEMORY_NX | SET_MEMORY_X); + if (!flags) + return 0; addr &= PAGE_MASK; return change_page_attr(addr, addr + numpages * PAGE_SIZE, flags); } |