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[POWERPC] Disallow kprobes on emulate_step and branch_taken 

On powerpc, probing on emulate_step function will crash 2.6.18.1 when
it is triggered.

When kprobe is triggered, emulate_step() is on its kernel path and
will cause recursive kprobe fault.  And branch_taken() is called
in emulate_step().  This disallows kprobes on both of them.

Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Gui,Jian 2006-11-01 10:50:15 +08:00 committed by Paul Mackerras
parent 292f86f005
commit 0d69a052d4
1 changed files with 3 additions and 2 deletions
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5
arch/powerpc/lib/sstep.c
View File

@ -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>
@ -25,7 +26,7 @@ extern char system_call_common[];
/*
* Determine whether a conditional branch instruction would branch.
*/
static int branch_taken(unsigned int instr, struct pt_regs *regs)
static int __kprobes branch_taken(unsigned int instr, struct pt_regs *regs)
{
unsigned int bo = (instr >> 21) & 0x1f;
unsigned int bi;
@ -51,7 +52,7 @@ static int branch_taken(unsigned int instr, struct pt_regs *regs)
* 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;