mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-10-05 00:20:32 +00:00
Code Issues Releases Wiki Activity

[POWERPC] Disallow kprobes on emulate_step and branch_taken

Browse source 
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
Show stats Download patch file Download diff file Expand all files Collapse all files

5
arch/powerpc/lib/sstep.c
View file

@ -9,6 +9,7 @@
* 2 of the License, or (at your option) any later version. * 2 of the License, or (at your option) any later version.
*/ */
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h> #include <linux/ptrace.h>
#include <asm/sstep.h> #include <asm/sstep.h>
#include <asm/processor.h> #include <asm/processor.h>
@ -25,7 +26,7 @@ extern char system_call_common[];
/* /*
* Determine whether a conditional branch instruction would branch. * 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 bo = (instr >> 21) & 0x1f;
unsigned int bi; 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, * or -1 if the instruction is one that should not be stepped,
* such as an rfid, or a mtmsrd that would clear MSR_RI. * 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 int opcode, rd;
unsigned long int imm; unsigned long int imm;