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[PATCH] kprobes: fix single-step out of line
- From: Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>
- To: linuxppc64-dev at ozlabs dot org
- Cc: anton at samba dot org, paulus at samba dot org, systemtap at sources dot redhat dot com
- Date: Wed, 25 May 2005 13:01:59 -0400
- Subject: [PATCH] kprobes: fix single-step out of line
- Reply-to: ananth at in dot ibm dot com
Hi,
On Power4 and above, single-step out of line when the instruction copy
is on a kmalloc'ed memory area, fails with an Instruction Access
exception. Here is a patch that fixes it.
Thanks,
Ananth
The single-step out of line fails with an Trap 0x400 (Instruction Access)
if the copy of the instruction is in a kmalloced memory area. Fix that.
While we are there, correct the case of a kprobe on a trap variant.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
arch/ppc64/kernel/kprobes.c | 10 +++++++---
1 files changed, 7 insertions(+), 3 deletions(-)
Index: linux-2.6.12-rc5/arch/ppc64/kernel/kprobes.c
===================================================================
--- linux-2.6.12-rc5.orig/arch/ppc64/kernel/kprobes.c 2005-05-24 23:31:20.000000000 -0400
+++ linux-2.6.12-rc5/arch/ppc64/kernel/kprobes.c 2005-05-25 12:47:33.000000000 -0400
@@ -42,6 +42,7 @@
static struct kprobe *current_kprobe;
static unsigned long kprobe_status, kprobe_saved_msr;
static struct pt_regs jprobe_saved_regs;
+static kprobe_opcode_t stepped_insn;
int arch_prepare_kprobe(struct kprobe *p)
{
@@ -71,11 +72,14 @@ static inline void disarm_kprobe(struct
static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
regs->msr |= MSR_SE;
- /*single step inline if it a breakpoint instruction*/
- if (p->opcode == BREAKPOINT_INSTRUCTION)
+ stepped_insn = *p->ainsn.insn;
+
+ /* single step inline if it is a trap variant */
+ if (IS_TW(stepped_insn) || IS_TD(stepped_insn) ||
+ IS_TWI(stepped_insn) || IS_TDI(stepped_insn))
regs->nip = (unsigned long)p->addr;
else
- regs->nip = (unsigned long)&p->ainsn.insn;
+ regs->nip = (unsigned long)&stepped_insn;
}
static inline int kprobe_handler(struct pt_regs *regs)