[PATCH] kprobes: fix bug when probed on task and isr functions
This patch fixes a race condition where in system used to hang or sometime
crash within minutes when kprobes are inserted on ISR routine and a task
routine.
The fix has been stress tested on i386, ia64, pp64 and on x86_64. To
reproduce the problem insert kprobes on schedule() and do_IRQ() functions
and you should see hang or system crash.
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 4b1bd53..471086b 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -95,6 +95,17 @@
p->ainsn.inst_flag = 0;
p->ainsn.target_br_reg = 0;
+ /* Check for Break instruction
+ * Bits 37:40 Major opcode to be zero
+ * Bits 27:32 X6 to be zero
+ * Bits 32:35 X3 to be zero
+ */
+ if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
+ /* is a break instruction */
+ p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
+ return;
+ }
+
if (bundle_encoding[template][slot] == B) {
switch (major_opcode) {
case INDIRECT_CALL_OPCODE:
@@ -542,8 +553,11 @@
unsigned long bundle_addr = (unsigned long) &p->opcode.bundle;
unsigned long slot = (unsigned long)p->addr & 0xf;
- /* Update instruction pointer (IIP) and slot number (IPSR.ri) */
- regs->cr_iip = bundle_addr & ~0xFULL;
+ /* single step inline if break instruction */
+ if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
+ regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
+ else
+ regs->cr_iip = bundle_addr & ~0xFULL;
if (slot > 2)
slot = 0;
@@ -599,7 +613,9 @@
if (kprobe_running()) {
p = get_kprobe(addr);
if (p) {
- if (kprobe_status == KPROBE_HIT_SS) {
+ if ( (kprobe_status == KPROBE_HIT_SS) &&
+ (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
+ ia64_psr(regs)->ss = 0;
unlock_kprobes();
goto no_kprobe;
}