Re: [PATCH 5/5] Kprobes: Temporary disarming of reentrant probe for sparc64
From: Prasanna S Panchamukhi
Date: Tue May 24 2005 - 05:38:08 EST
This patch includes sparc64 architecture specific changes to support temporary
disarming on reentrancy of probes.
Signed-of-by: Prasanna S Panchamukhi <prasanna@xxxxxxxxxx>
---
---
linux-2.6.12-rc4-mm2-prasanna/arch/sparc64/kernel/kprobes.c | 62 +++++++++---
1 files changed, 49 insertions(+), 13 deletions(-)
diff -puN arch/sparc64/kernel/kprobes.c~kprobes-temporary-disarming-on-reentrancy-sparc64 arch/sparc64/kernel/kprobes.c
--- linux-2.6.12-rc4-mm2/arch/sparc64/kernel/kprobes.c~kprobes-temporary-disarming-on-reentrancy-sparc64 2005-05-24 15:30:47.000000000 +0530
+++ linux-2.6.12-rc4-mm2-prasanna/arch/sparc64/kernel/kprobes.c 2005-05-24 15:30:47.000000000 +0530
@@ -65,19 +65,40 @@ void arch_remove_kprobe(struct kprobe *p
{
}
-/* kprobe_status settings */
-#define KPROBE_HIT_ACTIVE 0x00000001
-#define KPROBE_HIT_SS 0x00000002
-
static struct kprobe *current_kprobe;
static unsigned long current_kprobe_orig_tnpc;
static unsigned long current_kprobe_orig_tstate_pil;
static unsigned int kprobe_status;
+static struct kprobe *kprobe_prev;
+static unsigned long kprobe_orig_tnpc_prev;
+static unsigned long kprobe_orig_tstate_pil_prev;
+static unsigned int kprobe_status_prev;
-static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+static inline void save_previous_kprobe(void)
+{
+ kprobe_status_prev = kprobe_status;
+ kprobe_orig_tnpc_prev = current_kprobe_orig_tnpc;
+ kprobe_orig_tstate_pil_prev = current_kprobe_orig_tstate_pil;
+ kprobe_prev = current_kprobe;
+}
+
+static inline void restore_previous_kprobe(void)
+{
+ kprobe_status = kprobe_status_prev;
+ current_kprobe_orig_tnpc = kprobe_orig_tnpc_prev;
+ current_kprobe_orig_tstate_pil = kprobe_orig_tstate_pil_prev;
+ current_kprobe = kprobe_prev;
+}
+
+static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs)
{
current_kprobe_orig_tnpc = regs->tnpc;
current_kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
+ current_kprobe = p;
+}
+
+static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
regs->tstate |= TSTATE_PIL;
/*single step inline, if it a breakpoint instruction*/
@@ -110,12 +131,18 @@ static int kprobe_handler(struct pt_regs
unlock_kprobes();
goto no_kprobe;
}
- arch_disarm_kprobe(p);
- regs->tpc = (unsigned long) p->addr;
- regs->tnpc = current_kprobe_orig_tnpc;
- regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
- current_kprobe_orig_tstate_pil);
- 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();
+ set_current_kprobe(p, regs);
+ p->nmissed++;
+ kprobe_status = KPROBE_REENTER;
+ prepare_singlestep(p, regs);
+ return 1;
} else {
p = current_kprobe;
if (p->break_handler && p->break_handler(p, regs))
@@ -143,8 +170,8 @@ static int kprobe_handler(struct pt_regs
goto no_kprobe;
}
+ set_current_kprobe(p, regs);
kprobe_status = KPROBE_HIT_ACTIVE;
- current_kprobe = p;
if (p->pre_handler && p->pre_handler(p, regs))
return 1;
@@ -250,12 +277,20 @@ 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);
+ /*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;
@@ -397,3 +432,4 @@ int longjmp_break_handler(struct kprobe
}
return 0;
}
+
_
--
Prasanna S Panchamukhi
Linux Technology Center
India Software Labs, IBM Bangalore
Ph: 91-80-25044636
<prasanna@xxxxxxxxxx>
-
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