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[PATCH][kprobe]disallow kprobes on emulate_step function
- From: "Gui,Jian" <guij at cn dot ibm dot com>
- To: ananth at in dot ibm dot com, prasanna at in dot ibm dot com, systemtap at sources dot redhat dot com
- Date: Tue, 31 Oct 2006 17:13:19 +0800
- Subject: [PATCH][kprobe]disallow kprobes on emulate_step function
Probing on emulate_step function will crash 2.6.18.1 when it is
triggered. This problem is powerpc dependent.
When kprobe is triggered, emulate_step is on its kernel path and
will cause recursive kprobe fault. This patch can disallow
kprobes on emulate_step function.
diff -Nur linux-2.6.18.1/arch/powerpc/lib/sstep.c
new/arch/powerpc/lib/sstep.c
--- linux-2.6.18.1/arch/powerpc/lib/sstep.c 2006-10-13
23:34:03.000000000 -0400
+++ new/arch/powerpc/lib/sstep.c 2006-10-31 06:14:44.000000000
-0500
@@ -9,6 +9,7 @@
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
+#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <asm/sstep.h>
#include <asm/processor.h>
@@ -51,7 +52,7 @@
* or -1 if the instruction is one that should not be stepped,
* such as an rfid, or a mtmsrd that would clear MSR_RI.
*/
-int emulate_step(struct pt_regs *regs, unsigned int instr)
+int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
{
unsigned int opcode, rd;
unsigned long int imm;