[PATCH] Return probe redesign: ppc64 specific implementation
The following is a patch provided by Ananth Mavinakayanahalli that implements
the new PPC64 specific parts of the new function return probe design.
NOTE: Since getting Ananth's patch, I changed trampoline_probe_handler()
to consume each of the outstanding return probem instances (feedback
on my original RFC after Ananth cut a patch), and also added the
arch_init() function (adding arch specific initialization.) I have
cross compiled but have not testing this on a PPC64 machine.
Changes include:
* Addition of kretprobe_trampoline to act as a dummy function for instrumented
functions to return to, and for the return probe infrastructure to place
a kprobe on on, gaining control so that the return probe handler
can be called, and so that the instruction pointer can be moved back
to the original return address.
* Addition of arch_init(), allowing a kprobe to be registered on
kretprobe_trampoline
* Addition of trampoline_probe_handler() which is used as the pre_handler
for the kprobe inserted on kretprobe_implementation. This is the function
that handles the details for calling the return probe handler function
and returning control back at the original return address
* Addition of arch_prepare_kretprobe() which is setup as the pre_handler
for a kprobe registered at the beginning of the target function by
kernel/kprobes.c so that a return probe instance can be setup when
a caller enters the target function. (A return probe instance contains
all the needed information for trampoline_probe_handler to do it's job.)
* Hooks added to the exit path of a task so that we can cleanup any left-over
return probe instances (i.e. if a task dies while inside a targeted function
then the return probe instance was reserved at the beginning of the function
but the function never returns so we need to mark the instance as unused.)
Signed-off-by: Rusty Lynch <rusty.lynch@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/ppc64/kernel/process.c b/arch/ppc64/kernel/process.c
index aba8955..f7cae05 100644
--- a/arch/ppc64/kernel/process.c
+++ b/arch/ppc64/kernel/process.c
@@ -36,6 +36,7 @@
#include <linux/kallsyms.h>
#include <linux/interrupt.h>
#include <linux/utsname.h>
+#include <linux/kprobes.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
@@ -307,6 +308,8 @@
void exit_thread(void)
{
+ kprobe_flush_task(current);
+
#ifndef CONFIG_SMP
if (last_task_used_math == current)
last_task_used_math = NULL;
@@ -321,6 +324,7 @@
{
struct thread_info *t = current_thread_info();
+ kprobe_flush_task(current);
if (t->flags & _TIF_ABI_PENDING)
t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);