From f1a45d023193f7d8e55e384090b645d609325393 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 6 Aug 2012 14:13:23 +0200 Subject: uprobes: Kill dup_mmap()->uprobe_mmap(), simplify uprobe_mmap/munmap 1. Kill dup_mmap()->uprobe_mmap(), it was only needed to calculate new_mm->uprobes_state.count removed by the previous patch. If the forking process has a pending uprobe (int3) in vma, it will be copied by copy_page_range(), note that it checks vma->anon_vma so "Don't copy ptes" is not possible after install_breakpoint() which does anon_vma_prepare(). 2. Remove is_swbp_at_addr() and "int count" in uprobe_mmap(). Again, this was needed for uprobes_state.count. As a side effect this fixes the bug pointed out by Srikar, this code lacked the necessary put_uprobe(). 3. uprobe_munmap() becomes a nop after the previous patch. Remove the meaningless code but do not remove the helper, we will need it. Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju --- kernel/fork.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index 2c8857e12855..912b6f6fe5b8 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -454,9 +454,6 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) if (retval) goto out; - - if (file) - uprobe_mmap(tmp); } /* a new mm has just been created */ arch_dup_mmap(oldmm, mm); -- cgit v1.2.3 From f8ac4ec9c064b330dcc49e03c450fe74298c4622 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 8 Aug 2012 17:11:42 +0200 Subject: uprobes: Introduce MMF_HAS_UPROBES Add the new MMF_HAS_UPROBES flag. It is set by install_breakpoint() and it is copied by dup_mmap(), uprobe_pre_sstep_notifier() checks it to avoid the slow path if the task was never probed. Perhaps it makes sense to check it in valid_vma(is_register => false) as well. This needs the new dup_mmap()->uprobe_dup_mmap() hook. We can't use uprobe_reset_state() or put MMF_HAS_UPROBES into MMF_INIT_MASK, we need oldmm->mmap_sem to avoid the race with uprobe_register() or mmap() from another thread. Currently we never clear this bit, it can be false-positive after uprobe_unregister() or uprobe_munmap() or if dup_mmap() hits the probed VM_DONTCOPY vma. But this is fine correctness-wise and has no effect unless the task hits the non-uprobe breakpoint. Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju --- kernel/fork.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index 912b6f6fe5b8..cbb5f9fcd3e8 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -353,6 +353,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) down_write(&oldmm->mmap_sem); flush_cache_dup_mm(oldmm); + uprobe_dup_mmap(oldmm, mm); /* * Not linked in yet - no deadlock potential: */ -- cgit v1.2.3 From 61559a8165da2b6bab7621ac36379c6280efacb6 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 8 Aug 2012 17:17:46 +0200 Subject: uprobes: Fold uprobe_reset_state() into uprobe_dup_mmap() Now that we have uprobe_dup_mmap() we can fold uprobe_reset_state() into the new hook and remove it. mmput()->uprobe_clear_state() can't be called before dup_mmap(). Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju --- kernel/fork.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index cbb5f9fcd3e8..2343c9eaaaf4 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -837,8 +837,6 @@ struct mm_struct *dup_mm(struct task_struct *tsk) #ifdef CONFIG_TRANSPARENT_HUGEPAGE mm->pmd_huge_pte = NULL; #endif - uprobe_reset_state(mm); - if (!mm_init(mm, tsk)) goto fail_nomem; -- cgit v1.2.3