A uretprobe is specified by a file:offset:handler. A uprobe is created at the offset specified. When this uprobe is hit a uretprobe instance created and a probe placed instead of the return address of the current function. The handler specified is invoked before replacing the return address. A uretprobe therefore places two probes, firstly a uprobe at offset, whose handler in turn places the second probe at the return address at task runtime.
Signed-off-by: Anton Arapov <[email protected]> --- include/linux/uprobes.h | 10 +++++ kernel/events/uprobes.c | 97 +++++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 91 insertions(+), 16 deletions(-) diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index 741cc77..ebf957f 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -104,6 +104,8 @@ extern int __weak set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, u 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 void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc); +extern int uretprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc); +extern void uretprobe_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); extern void uprobe_start_dup_mmap(void); @@ -130,6 +132,14 @@ static inline void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) { } +uretprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) +{ + return -ENOSYS; +} +static inline void +uretprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) +{ +} static inline int uprobe_mmap(struct vm_area_struct *vma) { return 0; diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index d4016282..d360077 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -486,6 +486,14 @@ static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) up_write(&uprobe->consumer_rwsem); } +static void return_consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) +{ + down_write(&uprobe->consumer_rwsem); + uc->next = uprobe->return_consumers; + uprobe->return_consumers = uc; + up_write(&uprobe->consumer_rwsem); +} + /* * For uprobe @uprobe, delete the consumer @uc. * Return true if the @uc is deleted successfully @@ -509,6 +517,24 @@ static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) return ret; } +static bool return_consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) +{ + struct uprobe_consumer **con; + bool ret = false; + + down_write(&uprobe->consumer_rwsem); + for (con = &uprobe->return_consumers; *con; con = &(*con)->next) { + if (*con == uc) { + *con = uc->next; + ret = true; + break; + } + } + up_write(&uprobe->consumer_rwsem); + + return ret; +} + static int __copy_insn(struct address_space *mapping, struct file *filp, char *insn, unsigned long nbytes, loff_t offset) @@ -831,30 +857,29 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) return err; } -static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) -{ - consumer_add(uprobe, uc); - return register_for_each_vma(uprobe, true); -} - -static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) +static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc, bool is_rp) { int err; - if (!consumer_del(uprobe, uc)) /* WARN? */ + if (is_rp) + err = return_consumer_del(uprobe, uc); + else + err = consumer_del(uprobe, uc); + if (!err) /* WARN? */ return; err = register_for_each_vma(uprobe, false); /* TODO : cant unregister? schedule a worker thread */ - if (!uprobe->consumers && !err) + if (!uprobe->consumers && !uprobe->return_consumers && !err) delete_uprobe(uprobe); } /* - * uprobe_register - register a probe + * __uprobe_register - register a probe * @inode: the file in which the probe has to be placed. * @offset: offset from the start of the file. - * @uc: information on howto handle the probe.. + * @uc: information on howto handle the probe. + * @is_rp: if true - return probe. * * Apart from the access refcount, uprobe_register() takes a creation * refcount (thro alloc_uprobe) if and only if this @uprobe is getting @@ -867,7 +892,7 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u * Return errno if it cannot successully install probes * else return 0 (success) */ -int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) +int __uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool is_rp) { struct uprobe *uprobe; int ret; @@ -887,9 +912,14 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer * down_write(&uprobe->register_rwsem); ret = -EAGAIN; if (likely(uprobe_is_active(uprobe))) { - ret = __uprobe_register(uprobe, uc); + if (is_rp) + return_consumer_add(uprobe, uc); + else + consumer_add(uprobe, uc); + + ret = register_for_each_vma(uprobe, true); if (ret) - __uprobe_unregister(uprobe, uc); + __uprobe_unregister(uprobe, uc, is_rp); } up_write(&uprobe->register_rwsem); put_uprobe(uprobe); @@ -900,7 +930,26 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer * } /* - * uprobe_unregister - unregister a already registered probe. + * u[ret]probe_register - register a probe + * @inode: the file in which the probe has to be placed. + * @offset: offset from the start of the file. + * @uc: information on howto handle the probe. + * + * Return errno if it cannot successully install probes + * else return 0 (success) + */ +int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) +{ + return __uprobe_register(inode, offset, uc, false); +} + +int uretprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) +{ + return __uprobe_register(inode, offset, uc, true); +} + +/* + * u[ret]probe_unregister - 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: identify which probe if multiple probes are colocated. @@ -914,8 +963,24 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume return; down_write(&uprobe->register_rwsem); - __uprobe_unregister(uprobe, uc); + __uprobe_unregister(uprobe, uc, false); up_write(&uprobe->register_rwsem); + + put_uprobe(uprobe); +} + +void uretprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) +{ + struct uprobe *uprobe; + + uprobe = find_uprobe(inode, offset); + if (!uprobe) + return; + + down_write(&uprobe->register_rwsem); + __uprobe_unregister(uprobe, uc, true); + up_write(&uprobe->register_rwsem); + put_uprobe(uprobe); } -- 1.8.0.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
