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authorAlexander Gordeev <agordeev@linux.ibm.com>2020-03-19 13:44:50 +0100
committerVasily Gorbik <gor@linux.ibm.com>2020-03-28 12:46:12 +0100
commit1058c163dc31b3335c9cf7c4fa42ccf87be73017 (patch)
tree3951d9022fb7525320029fb9cb18593f6a2d31ba /arch
parentf75556081afe5a565c2ce200837406303a59ae2b (diff)
s390/mm: cleanup init_new_context() callback
The set of values asce_limit may be assigned with is TASK_SIZE_MAX, _REGION1_SIZE, _REGION2_SIZE and 0 as a special case if the callback was called from execve(). Do VM_BUG_ON() if asce_limit is something else. Save few CPU cycles by removing unnecessary asce_limit re-assignment in case of 3-level task and redundant PGD entry type reconstruction. Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/s390/include/asm/mmu_context.h35
-rw-r--r--arch/s390/include/asm/pgalloc.h11
2 files changed, 21 insertions, 25 deletions
diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index 248d51cdcad9..844396b3735e 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -18,6 +18,8 @@
static inline int init_new_context(struct task_struct *tsk,
struct mm_struct *mm)
{
+ unsigned long asce_type, init_entry;
+
spin_lock_init(&mm->context.lock);
INIT_LIST_HEAD(&mm->context.pgtable_list);
INIT_LIST_HEAD(&mm->context.gmap_list);
@@ -35,29 +37,34 @@ static inline int init_new_context(struct task_struct *tsk,
mm->context.allow_gmap_hpage_1m = 0;
#endif
switch (mm->context.asce_limit) {
- case _REGION2_SIZE:
+ default:
/*
- * forked 3-level task, fall through to set new asce with new
- * mm->pgd
+ * context created by exec, the value of asce_limit can
+ * only be zero in this case
*/
- case 0:
- /* context created by exec, set asce limit to 4TB */
+ VM_BUG_ON(mm->context.asce_limit);
+ /* continue as 3-level task */
mm->context.asce_limit = _REGION2_SIZE;
- mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
- _ASCE_USER_BITS | _ASCE_TYPE_REGION3;
+ fallthrough;
+ case _REGION2_SIZE:
+ /* forked 3-level task */
+ init_entry = _REGION3_ENTRY_EMPTY;
+ asce_type = _ASCE_TYPE_REGION3;
break;
case TASK_SIZE_MAX:
- /* forked 5-level task, set new asce with new_mm->pgd */
- mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
- _ASCE_USER_BITS | _ASCE_TYPE_REGION1;
+ /* forked 5-level task */
+ init_entry = _REGION1_ENTRY_EMPTY;
+ asce_type = _ASCE_TYPE_REGION1;
break;
case _REGION1_SIZE:
- /* forked 4-level task, set new asce with new mm->pgd */
- mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
- _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
+ /* forked 4-level task */
+ init_entry = _REGION2_ENTRY_EMPTY;
+ asce_type = _ASCE_TYPE_REGION2;
break;
}
- crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
+ mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
+ _ASCE_USER_BITS | asce_type;
+ crst_table_init((unsigned long *) mm->pgd, init_entry);
return 0;
}
diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index 5e3ff9f7a586..74a352f8c0d1 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -34,17 +34,6 @@ static inline void crst_table_init(unsigned long *crst, unsigned long entry)
memset64((u64 *)crst, entry, _CRST_ENTRIES);
}
-static inline unsigned long pgd_entry_type(struct mm_struct *mm)
-{
- if (mm_pmd_folded(mm))
- return _SEGMENT_ENTRY_EMPTY;
- if (mm_pud_folded(mm))
- return _REGION3_ENTRY_EMPTY;
- if (mm_p4d_folded(mm))
- return _REGION2_ENTRY_EMPTY;
- return _REGION1_ENTRY_EMPTY;
-}
-
int crst_table_upgrade(struct mm_struct *mm, unsigned long limit);
static inline unsigned long check_asce_limit(struct mm_struct *mm, unsigned long addr,