| From | Greg Kroah-Hartman <> | Subject | [ 057/122] s390/mm: downgrade page table after fork of a 31 bit process | Date | Tue, 7 Aug 2012 15:25:45 -0700 |
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From: Greg KH <gregkh@linuxfoundation.org>
3.5-stable review patch. If anyone has any objections, please let me know.
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From: Martin Schwidefsky <schwidefsky@de.ibm.com>
commit 0f6f281b731d20bfe75c13f85d33f3f05b440222 upstream.
The downgrade of the 4 level page table created by init_new_context is currently done only in start_thread31. If a 31 bit process forks the new mm uses a 4 level page table, including the task size of 2<<42 that goes along with it. This is incorrect as now a 31 bit process can map memory beyond 2GB. Define arch_dup_mmap to do the downgrade after fork.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/s390/include/asm/mmu_context.h | 14 +++++++++++++- arch/s390/include/asm/processor.h | 2 ++ arch/s390/mm/mmap.c | 12 ++++++++++-- arch/s390/mm/pgtable.c | 5 ----- 4 files changed, 25 insertions(+), 8 deletions(-)
--- a/arch/s390/include/asm/mmu_context.h +++ b/arch/s390/include/asm/mmu_context.h @@ -13,7 +13,6 @@ #include <asm/uaccess.h> #include <asm/tlbflush.h> #include <asm/ctl_reg.h> -#include <asm-generic/mm_hooks.h> static inline int init_new_context(struct task_struct *tsk, struct mm_struct *mm) @@ -93,4 +92,17 @@ static inline void activate_mm(struct mm switch_mm(prev, next, current); } +static inline void arch_dup_mmap(struct mm_struct *oldmm, + struct mm_struct *mm) +{ +#ifdef CONFIG_64BIT + if (oldmm->context.asce_limit < mm->context.asce_limit) + crst_table_downgrade(mm, oldmm->context.asce_limit); +#endif +} + +static inline void arch_exit_mmap(struct mm_struct *mm) +{ +} + #endif /* __S390_MMU_CONTEXT_H */ --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -122,7 +122,9 @@ struct stack_frame { regs->psw.mask = psw_user_bits | PSW_MASK_BA; \ regs->psw.addr = new_psw | PSW_ADDR_AMODE; \ regs->gprs[15] = new_stackp; \ + __tlb_flush_mm(current->mm); \ crst_table_downgrade(current->mm, 1UL << 31); \ + update_mm(current->mm, current); \ } while (0) /* Forward declaration, a strange C thing */ --- a/arch/s390/mm/mmap.c +++ b/arch/s390/mm/mmap.c @@ -105,9 +105,15 @@ void arch_pick_mmap_layout(struct mm_str int s390_mmap_check(unsigned long addr, unsigned long len) { + int rc; + if (!is_compat_task() && - len >= TASK_SIZE && TASK_SIZE < (1UL << 53)) - return crst_table_upgrade(current->mm, 1UL << 53); + len >= TASK_SIZE && TASK_SIZE < (1UL << 53)) { + rc = crst_table_upgrade(current->mm, 1UL << 53); + if (rc) + return rc; + update_mm(current->mm, current); + } return 0; } @@ -127,6 +133,7 @@ s390_get_unmapped_area(struct file *filp rc = crst_table_upgrade(mm, 1UL << 53); if (rc) return (unsigned long) rc; + update_mm(mm, current); area = arch_get_unmapped_area(filp, addr, len, pgoff, flags); } return area; @@ -149,6 +156,7 @@ s390_get_unmapped_area_topdown(struct fi rc = crst_table_upgrade(mm, 1UL << 53); if (rc) return (unsigned long) rc; + update_mm(mm, current); area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags); } --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -85,7 +85,6 @@ repeat: crst_table_free(mm, table); if (mm->context.asce_limit < limit) goto repeat; - update_mm(mm, current); return 0; } @@ -93,9 +92,6 @@ void crst_table_downgrade(struct mm_stru { pgd_t *pgd; - if (mm->context.asce_limit <= limit) - return; - __tlb_flush_mm(mm); while (mm->context.asce_limit > limit) { pgd = mm->pgd; switch (pgd_val(*pgd) & _REGION_ENTRY_TYPE_MASK) { @@ -118,7 +114,6 @@ void crst_table_downgrade(struct mm_stru mm->task_size = mm->context.asce_limit; crst_table_free(mm, (unsigned long *) pgd); } - update_mm(mm, current); } #endif
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