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authorRusty Lynch <rusty.lynch@intel.com>2005-06-27 15:17:12 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-27 15:23:53 -0700
commit9508dbfe39112813612085c00d55bacd398eddc6 (patch)
tree5f1cac16508284f54d7402f71bebf085c4bf2e7f /arch/ia64/kernel/process.c
parentba8af12f432c4f00ddb0bc1068b57b20aac93ecf (diff)
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[PATCH] Return probe redesign: ia64 specific implementation
The following patch implements function return probes for ia64 using the revised design. With this new design we no longer need to do some of the odd hacks previous required on the last ia64 return probe port that I sent out for comments. Note that this new implementation still does not resolve the problem noted by Keith Owens where backtrace data is lost after a return probe is hit. 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>
Diffstat (limited to 'arch/ia64/kernel/process.c')
-rw-r--r--arch/ia64/kernel/process.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index ebb71f3..6e35bff 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -27,6 +27,7 @@
#include <linux/efi.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
+#include <linux/kprobes.h>
#include <asm/cpu.h>
#include <asm/delay.h>
@@ -707,6 +708,13 @@ kernel_thread_helper (int (*fn)(void *), void *arg)
void
flush_thread (void)
{
+ /*
+ * Remove function-return probe instances associated with this task
+ * and put them back on the free list. Do not insert an exit probe for
+ * this function, it will be disabled by kprobe_flush_task if you do.
+ */
+ kprobe_flush_task(current);
+
/* drop floating-point and debug-register state if it exists: */
current->thread.flags &= ~(IA64_THREAD_FPH_VALID | IA64_THREAD_DBG_VALID);
ia64_drop_fpu(current);
@@ -721,6 +729,14 @@ flush_thread (void)
void
exit_thread (void)
{
+
+ /*
+ * Remove function-return probe instances associated with this task
+ * and put them back on the free list. Do not insert an exit probe for
+ * this function, it will be disabled by kprobe_flush_task if you do.
+ */
+ kprobe_flush_task(current);
+
ia64_drop_fpu(current);
#ifdef CONFIG_PERFMON
/* if needed, stop monitoring and flush state to perfmon context */