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| author | Alexander Gordeev <agordeev@linux.ibm.com> | 2020-03-19 13:44:50 +0100 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2020-03-28 12:46:12 +0100 |
| commit | 1058c163dc31b3335c9cf7c4fa42ccf87be73017 (patch) | |
| tree | 3951d9022fb7525320029fb9cb18593f6a2d31ba /arch/s390 | |
| parent | f75556081afe5a565c2ce200837406303a59ae2b (diff) | |
| download | lwn-1058c163dc31b3335c9cf7c4fa42ccf87be73017.tar.gz lwn-1058c163dc31b3335c9cf7c4fa42ccf87be73017.zip | |
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/s390')
| -rw-r--r-- | arch/s390/include/asm/mmu_context.h | 35 | ||||
| -rw-r--r-- | arch/s390/include/asm/pgalloc.h | 11 |
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, |