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Subject[patch 1/5] [kprobes] Tweak to the function return probe design - take 2
This patch provides the architecture independant changes for the tweaks 
to the function return probe design.

--rusty

signed-off-by: Rusty Lynch <Rusty.lynch@intel.com>

include/linux/kprobes.h | 28 ++-----------------
kernel/kprobes.c | 69 +++++++++++++-----------------------------------
2 files changed, 22 insertions(+), 75 deletions(-)
Index: linux-2.6.12-rc6/include/linux/kprobes.h
===================================================================
--- linux-2.6.12-rc6.orig/include/linux/kprobes.h
+++ linux-2.6.12-rc6/include/linux/kprobes.h
@@ -104,33 +104,12 @@ struct jprobe {
};

#ifdef ARCH_SUPPORTS_KRETPROBES
-extern int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs);
-extern void trampoline_post_handler(struct kprobe *p, struct pt_regs *regs,
- unsigned long flags);
-extern struct task_struct *arch_get_kprobe_task(void *ptr);
extern void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs);
-extern void arch_kprobe_flush_task(struct task_struct *tk);
#else /* ARCH_SUPPORTS_KRETPROBES */
-static inline void kretprobe_trampoline(void)
-{
-}
-static inline int trampoline_probe_handler(struct kprobe *p,
- struct pt_regs *regs)
-{
- return 0;
-}
-static inline void trampoline_post_handler(struct kprobe *p,
- struct pt_regs *regs, unsigned long flags)
-{
-}
static inline void arch_prepare_kretprobe(struct kretprobe *rp,
struct pt_regs *regs)
{
}
-static inline void arch_kprobe_flush_task(struct task_struct *tk)
-{
-}
-#define arch_get_kprobe_task(ptr) ((struct task_struct *)NULL)
#endif /* ARCH_SUPPORTS_KRETPROBES */
/*
* Function-return probe -
@@ -155,8 +134,8 @@ struct kretprobe_instance {
struct hlist_node uflist; /* either on free list or used list */
struct hlist_node hlist;
struct kretprobe *rp;
- void *ret_addr;
- void *stack_addr;
+ kprobe_opcode_t *ret_addr;
+ struct task_struct *task;
};

#ifdef CONFIG_KPROBES
@@ -176,6 +155,7 @@ extern void arch_copy_kprobe(struct kpro
extern void arch_arm_kprobe(struct kprobe *p);
extern void arch_disarm_kprobe(struct kprobe *p);
extern void arch_remove_kprobe(struct kprobe *p);
+extern int arch_init(void);
extern void show_registers(struct pt_regs *regs);

/* Get the kprobe at this addr (if any). Must have called lock_kprobes */
@@ -194,8 +174,6 @@ int register_kretprobe(struct kretprobe
void unregister_kretprobe(struct kretprobe *rp);

struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp);
-struct kretprobe_instance *get_rp_inst(void *sara);
-struct kretprobe_instance *get_rp_inst_tsk(struct task_struct *tk);
void add_rp_inst(struct kretprobe_instance *ri);
void kprobe_flush_task(struct task_struct *tk);
void recycle_rp_inst(struct kretprobe_instance *ri);
Index: linux-2.6.12-rc6/kernel/kprobes.c
===================================================================
--- linux-2.6.12-rc6.orig/kernel/kprobes.c
+++ linux-2.6.12-rc6/kernel/kprobes.c
@@ -138,12 +138,6 @@ static int aggr_break_handler(struct kpr
return 0;
}

-struct kprobe trampoline_p = {
- .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
- .pre_handler = trampoline_probe_handler,
- .post_handler = trampoline_post_handler
-};
-
struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp)
{
struct hlist_node *node;
@@ -162,35 +156,18 @@ struct kretprobe_instance *get_used_rp_i
return NULL;
}

-struct kretprobe_instance *get_rp_inst(void *sara)
-{
- struct hlist_head *head;
- struct hlist_node *node;
- struct task_struct *tsk;
- struct kretprobe_instance *ri;
-
- tsk = arch_get_kprobe_task(sara);
- head = &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
- hlist_for_each_entry(ri, node, head, hlist) {
- if (ri->stack_addr == sara)
- return ri;
- }
- return NULL;
-}
-
void add_rp_inst(struct kretprobe_instance *ri)
{
- struct task_struct *tsk;
/*
* Remove rp inst off the free list -
* Add it back when probed function returns
*/
hlist_del(&ri->uflist);
- tsk = arch_get_kprobe_task(ri->stack_addr);
+
/* Add rp inst onto table */
INIT_HLIST_NODE(&ri->hlist);
hlist_add_head(&ri->hlist,
- &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]);
+ &kretprobe_inst_table[hash_ptr(ri->task, KPROBE_HASH_BITS)]);

/* Also add this rp inst to the used list. */
INIT_HLIST_NODE(&ri->uflist);
@@ -217,34 +194,25 @@ struct hlist_head * kretprobe_inst_table
return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
}

-struct kretprobe_instance *get_rp_inst_tsk(struct task_struct *tk)
-{
- struct task_struct *tsk;
- struct hlist_head *head;
- struct hlist_node *node;
- struct kretprobe_instance *ri;
-
- head = &kretprobe_inst_table[hash_ptr(tk, KPROBE_HASH_BITS)];
-
- hlist_for_each_entry(ri, node, head, hlist) {
- tsk = arch_get_kprobe_task(ri->stack_addr);
- if (tsk == tk)
- return ri;
- }
- return NULL;
-}
-
/*
- * This function is called from do_exit or do_execv when task tk's stack is
- * about to be recycled. Recycle any function-return probe instances
- * associated with this task. These represent probed functions that have
- * been called but may never return.
+ * This function is called from exit_thread or flush_thread when task tk's
+ * stack is being recycled so that we can recycle any function-return probe
+ * instances associated with this task. These left over instances represent
+ * probed functions that have been called but will never return.
*/
void kprobe_flush_task(struct task_struct *tk)
{
+ struct kretprobe_instance *ri;
+ struct hlist_head *head;
+ struct hlist_node *node, *tmp;
unsigned long flags = 0;
+
spin_lock_irqsave(&kprobe_lock, flags);
- arch_kprobe_flush_task(tk);
+ head = kretprobe_inst_table_head(current);
+ hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+ if (ri->task == tk)
+ recycle_rp_inst(ri);
+ }
spin_unlock_irqrestore(&kprobe_lock, flags);
}

@@ -504,9 +472,10 @@ static int __init init_kprobes(void)
INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
}

- err = register_die_notifier(&kprobe_exceptions_nb);
- /* Register the trampoline probe for return probe */
- register_kprobe(&trampoline_p);
+ err = arch_init();
+ if (!err)
+ err = register_die_notifier(&kprobe_exceptions_nb);
+
return err;
}

--
-
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