[PATCH] Kprobes/ia64: temporary disarming of reentrant probe
This patch includes IA64 architecture specific changes(ported form i386) to
support temporary disarming on reentrancy of probes.
In case of reentrancy we single step without calling user handler.
Signed-of-by: Anil S Keshavamurth <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 41e80b4..5978823 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -41,8 +41,8 @@
#define KPROBE_HIT_ACTIVE 0x00000001
#define KPROBE_HIT_SS 0x00000002
-static struct kprobe *current_kprobe;
-static unsigned long kprobe_status;
+static struct kprobe *current_kprobe, *kprobe_prev;
+static unsigned long kprobe_status, kprobe_status_prev;
static struct pt_regs jprobe_saved_regs;
enum instruction_type {A, I, M, F, B, L, X, u};
@@ -273,6 +273,23 @@
return 0;
}
+static inline void save_previous_kprobe(void)
+{
+ kprobe_prev = current_kprobe;
+ kprobe_status_prev = kprobe_status;
+}
+
+static inline void restore_previous_kprobe(void)
+{
+ current_kprobe = kprobe_prev;
+ kprobe_status = kprobe_status_prev;
+}
+
+static inline void set_current_kprobe(struct kprobe *p)
+{
+ current_kprobe = p;
+}
+
int arch_prepare_kprobe(struct kprobe *p)
{
unsigned long addr = (unsigned long) p->addr;
@@ -436,8 +453,18 @@
unlock_kprobes();
goto no_kprobe;
}
- arch_disarm_kprobe(p);
- ret = 1;
+ /* We have reentered the pre_kprobe_handler(), since
+ * another probe was hit while within the handler.
+ * We here save the original kprobes variables and
+ * just single step on the instruction of the new probe
+ * without calling any user handlers.
+ */
+ save_previous_kprobe();
+ set_current_kprobe(p);
+ p->nmissed++;
+ prepare_ss(p, regs);
+ kprobe_status = KPROBE_REENTER;
+ return 1;
} else if (args->err == __IA64_BREAK_JPROBE) {
/*
* jprobe instrumented function just completed
@@ -460,7 +487,7 @@
}
kprobe_status = KPROBE_HIT_ACTIVE;
- current_kprobe = p;
+ set_current_kprobe(p);
if (p->pre_handler && p->pre_handler(p, regs))
/*
@@ -485,12 +512,22 @@
if (!kprobe_running())
return 0;
- if (current_kprobe->post_handler)
+ if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
+ kprobe_status = KPROBE_HIT_SSDONE;
current_kprobe->post_handler(current_kprobe, regs, 0);
+ }
resume_execution(current_kprobe, regs);
+ /*Restore back the original saved kprobes variables and continue. */
+ if (kprobe_status == KPROBE_REENTER) {
+ restore_previous_kprobe();
+ goto out;
+ }
+
unlock_kprobes();
+
+out:
preempt_enable_no_resched();
return 1;
}