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Message-Id: <1356088596-17858-7-git-send-email-anton@redhat.com>
Date: Fri, 21 Dec 2012 12:16:36 +0100
From: Anton Arapov <anton@...hat.com>
To: Oleg Nesterov <oleg@...hat.com>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Josh Stone <jistone@...hat.com>,
Frank Eigler <fche@...hat.com>, Anton Arapov <anton@...hat.com>
Subject: [RFC PATCH 6/6] uretprobes: register() and unregister() implementation
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 <anton@...hat.com>
---
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
--
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