From: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
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>
---
arch/ia64/kernel/kprobes.c | 49 +++++++++++++++++++++++++++++++++++++++------
1 files changed, 43 insertions(+), 6 deletions(-)
diff -puN arch/ia64/kernel/kprobes.c~kprobes-temporary-disarming-of-reentrant-probe-for-ia64 arch/ia64/kernel/kprobes.c
--- 25/arch/ia64/kernel/kprobes.c~kprobes-temporary-disarming-of-reentrant-probe-for-ia64 2005-05-31 17:24:36.000000000 -0700
+++ 25-akpm/arch/ia64/kernel/kprobes.c 2005-05-31 17:24:36.000000000 -0700
@@ -41,8 +41,8 @@ extern void jprobe_inst_return(void);
#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};
@@ -81,6 +81,23 @@ static enum instruction_type bundle_enco
{ u, u, u }, /* 1F */
};
+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;
@@ -301,8 +318,18 @@ static int pre_kprobes_handler(struct di
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
@@ -325,7 +352,7 @@ static int pre_kprobes_handler(struct di
}
kprobe_status = KPROBE_HIT_ACTIVE;
- current_kprobe = p;
+ set_current_kprobe(p);
if (p->pre_handler && p->pre_handler(p, regs))
/*
@@ -350,12 +377,22 @@ static int post_kprobes_handler(struct p
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;
}
_