From bdf8647c44766590ed02f9a84a450a796558b753 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 3 Feb 2013 19:21:12 +0100 Subject: [PATCH] uprobes: Introduce uprobe_apply() Currently it is not possible to change the filtering constraints after uprobe_register(), so a consumer can not, say, start to trace a task/mm which was previously filtered out, or remove the no longer needed bp's. Introduce uprobe_apply() which simply does register_for_each_vma() again to consult uprobe_consumer->filter() and install/remove the breakpoints. The only complication is that register_for_each_vma() can no longer assume that uprobe->consumers should be consulter if is_register == T, so we change it to accept "struct uprobe_consumer *new" instead. Unlike uprobe_register(), uprobe_apply(true) doesn't do "unregister" if register_for_each_vma() fails, it is up to caller to handle the error. Note: we probably need to cleanup the current interface, it is strange that uprobe_apply/unregister need inode/offset. We should either change uprobe_register() to return "struct uprobe *", or add a private ->uprobe member in uprobe_consumer. And in the long term uprobe_apply() should take a single argument, uprobe or consumer, even "bool add" should go away. Signed-off-by: Oleg Nesterov --- include/linux/uprobes.h | 6 ++++++ kernel/events/uprobes.c | 39 +++++++++++++++++++++++++++++++++++---- 2 files changed, 41 insertions(+), 4 deletions(-) diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index 95d0002efda5..02b83db8e2c5 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -101,6 +101,7 @@ extern int __weak set_swbp(struct arch_uprobe *aup, struct mm_struct *mm, unsign extern int __weak set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr); extern bool __weak is_swbp_insn(uprobe_opcode_t *insn); extern int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc); +extern int uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool); extern void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc); extern int uprobe_mmap(struct vm_area_struct *vma); extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end); @@ -124,6 +125,11 @@ uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) { return -ENOSYS; } +static inline int +uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool add) +{ + return -ENOSYS; +} static inline void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) { diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 221fc58f59e3..a567c8c7ef31 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -733,8 +733,10 @@ build_map_info(struct address_space *mapping, loff_t offset, bool is_register) return curr; } -static int register_for_each_vma(struct uprobe *uprobe, bool is_register) +static int +register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) { + bool is_register = !!new; struct map_info *info; int err = 0; @@ -765,7 +767,7 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) if (is_register) { /* consult only the "caller", new consumer. */ - if (consumer_filter(uprobe->consumers, + if (consumer_filter(new, UPROBE_FILTER_REGISTER, mm)) err = install_breakpoint(uprobe, mm, vma, info->vaddr); } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { @@ -788,7 +790,7 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) { consumer_add(uprobe, uc); - return register_for_each_vma(uprobe, true); + return register_for_each_vma(uprobe, uc); } static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) @@ -798,7 +800,7 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u if (!consumer_del(uprobe, uc)) /* WARN? */ return; - err = register_for_each_vma(uprobe, false); + err = register_for_each_vma(uprobe, NULL); /* TODO : cant unregister? schedule a worker thread */ if (!uprobe->consumers && !err) delete_uprobe(uprobe); @@ -854,6 +856,35 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer * } EXPORT_SYMBOL_GPL(uprobe_register); +/* + * uprobe_apply - unregister a already registered probe. + * @inode: the file in which the probe has to be removed. + * @offset: offset from the start of the file. + * @uc: consumer which wants to add more or remove some breakpoints + * @add: add or remove the breakpoints + */ +int uprobe_apply(struct inode *inode, loff_t offset, + struct uprobe_consumer *uc, bool add) +{ + struct uprobe *uprobe; + struct uprobe_consumer *con; + int ret = -ENOENT; + + uprobe = find_uprobe(inode, offset); + if (!uprobe) + return ret; + + down_write(&uprobe->register_rwsem); + for (con = uprobe->consumers; con && con != uc ; con = con->next) + ; + if (con) + ret = register_for_each_vma(uprobe, add ? uc : NULL); + up_write(&uprobe->register_rwsem); + put_uprobe(uprobe); + + return ret; +} + /* * uprobe_unregister - unregister a already registered probe. * @inode: the file in which the probe has to be removed. -- 2.30.2