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authorHeiko Carstens <heiko.carstens@de.ibm.com>2017-04-24 15:27:35 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2017-04-26 13:41:21 +0200
commit1366def38b6ab574dd0dbf95e308c7d115e73796 (patch)
treeba7b4a0e6b322678c76891a3c96e2d6896f5f75a /arch/s390
parent9b11c7912d00d0e5fe0d7f8973b77dac4f69d3df (diff)
downloadlinux-1366def38b6ab574dd0dbf95e308c7d115e73796.tar.bz2
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')
-rw-r--r--arch/s390/mm/pageattr.c10
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);
}