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Re: [PATCH 4/5] Kprobes: Temporary disarming of reentrant probe for ppc64
This patch includes ppc64 architecture specific changes to support temporary
disarming on reentrancy of probes.
Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
---
linux-2.6.12-rc4-mm2-prasanna/arch/ppc64/kernel/kprobes.c | 46 +++++++++++---
1 files changed, 38 insertions(+), 8 deletions(-)
diff -puN arch/ppc64/kernel/kprobes.c~kprobes-temporarily-disarm-ppc64 arch/ppc64/kernel/kprobes.c
--- linux-2.6.12-rc4-mm2/arch/ppc64/kernel/kprobes.c~kprobes-temporarily-disarm-ppc64 2005-05-19 15:43:06.000000000 +0530
+++ linux-2.6.12-rc4-mm2-prasanna/arch/ppc64/kernel/kprobes.c 2005-05-19 15:43:06.000000000 +0530
@@ -36,12 +36,10 @@
#include <asm/kdebug.h>
#include <asm/sstep.h>
-/* kprobe_status settings */
-#define KPROBE_HIT_ACTIVE 0x00000001
-#define KPROBE_HIT_SS 0x00000002
-
static struct kprobe *current_kprobe;
static unsigned long kprobe_status, kprobe_saved_msr;
+static struct kprobe *kprobe_prev;
+static unsigned long kprobe_status_prev, kprobe_saved_msr_prev;
static struct pt_regs jprobe_saved_regs;
int arch_prepare_kprobe(struct kprobe *p)
@@ -88,6 +86,20 @@ static inline void prepare_singlestep(st
regs->nip = (unsigned long)&p->ainsn.insn;
}
+static inline void save_previous_kprobe(void)
+{
+ kprobe_prev = current_kprobe;
+ kprobe_status_prev = kprobe_status;
+ kprobe_saved_msr_prev = kprobe_saved_msr;
+}
+
+static inline void restore_previous_kprobe(void)
+{
+ current_kprobe = kprobe_prev;
+ kprobe_status = kprobe_status_prev;
+ kprobe_saved_msr = kprobe_saved_msr_prev;
+}
+
static inline int kprobe_handler(struct pt_regs *regs)
{
struct kprobe *p;
@@ -106,9 +118,19 @@ static inline int kprobe_handler(struct
unlock_kprobes();
goto no_kprobe;
}
- arch_disarm_kprobe(p);
- regs->nip = (unsigned long)p->addr;
- ret = 1;
+ /* We have reentered the 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();
+ current_kprobe = p;
+ kprobe_saved_msr = regs->msr;
+ p->count_disarm++;
+ prepare_singlestep(p, regs);
+ kprobe_status = KPROBE_REENTER;
+ return 1;
} else {
p = current_kprobe;
if (p->break_handler && p->break_handler(p, regs)) {
@@ -192,13 +214,21 @@ static inline int post_kprobe_handler(st
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);
regs->msr |= kprobe_saved_msr;
+ /*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();
/*
_
--
Prasanna S Panchamukhi
Linux Technology Center
India Software Labs, IBM Bangalore
Ph: 91-80-25044636
<prasanna@in.ibm.com>