diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/uprobes.c | 66 |
1 files changed, 51 insertions, 15 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 84fa00497c49..648f47553bff 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -143,10 +143,12 @@ static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) * * @vma: vma that holds the pte pointing to page * @addr: address the old @page is mapped at - * @page: the cowed page we are replacing by kpage - * @kpage: the modified page we replace page by + * @old_page: the page we are replacing by new_page + * @new_page: the modified page we replace page by * - * Returns 0 on success, -EFAULT on failure. + * If @new_page is NULL, only unmap @old_page. + * + * Returns 0 on success, negative error code otherwise. */ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, struct page *old_page, struct page *new_page) @@ -166,10 +168,12 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, VM_BUG_ON_PAGE(PageTransHuge(old_page), old_page); - err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, &memcg, - false); - if (err) - return err; + if (new_page) { + err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, + &memcg, false); + if (err) + return err; + } /* For try_to_free_swap() and munlock_vma_page() below */ lock_page(old_page); @@ -177,15 +181,20 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, mmu_notifier_invalidate_range_start(&range); err = -EAGAIN; if (!page_vma_mapped_walk(&pvmw)) { - mem_cgroup_cancel_charge(new_page, memcg, false); + if (new_page) + mem_cgroup_cancel_charge(new_page, memcg, false); goto unlock; } VM_BUG_ON_PAGE(addr != pvmw.address, old_page); - get_page(new_page); - page_add_new_anon_rmap(new_page, vma, addr, false); - mem_cgroup_commit_charge(new_page, memcg, false, false); - lru_cache_add_active_or_unevictable(new_page, vma); + if (new_page) { + get_page(new_page); + page_add_new_anon_rmap(new_page, vma, addr, false); + mem_cgroup_commit_charge(new_page, memcg, false, false); + lru_cache_add_active_or_unevictable(new_page, vma); + } else + /* no new page, just dec_mm_counter for old_page */ + dec_mm_counter(mm, MM_ANONPAGES); if (!PageAnon(old_page)) { dec_mm_counter(mm, mm_counter_file(old_page)); @@ -194,8 +203,9 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, flush_cache_page(vma, addr, pte_pfn(*pvmw.pte)); ptep_clear_flush_notify(vma, addr, pvmw.pte); - set_pte_at_notify(mm, addr, pvmw.pte, - mk_pte(new_page, vma->vm_page_prot)); + if (new_page) + set_pte_at_notify(mm, addr, pvmw.pte, + mk_pte(new_page, vma->vm_page_prot)); page_remove_rmap(old_page, false); if (!page_mapped(old_page)) @@ -488,6 +498,10 @@ retry: ref_ctr_updated = 1; } + ret = 0; + if (!is_register && !PageAnon(old_page)) + goto put_old; + ret = anon_vma_prepare(vma); if (ret) goto put_old; @@ -501,8 +515,30 @@ retry: copy_highpage(new_page, old_page); copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); + if (!is_register) { + struct page *orig_page; + pgoff_t index; + + VM_BUG_ON_PAGE(!PageAnon(old_page), old_page); + + index = vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT; + orig_page = find_get_page(vma->vm_file->f_inode->i_mapping, + index); + + if (orig_page) { + if (PageUptodate(orig_page) && + pages_identical(new_page, orig_page)) { + /* let go new_page */ + put_page(new_page); + new_page = NULL; + } + put_page(orig_page); + } + } + ret = __replace_page(vma, vaddr, old_page, new_page); - put_page(new_page); + if (new_page) + put_page(new_page); put_old: put_page(old_page); |