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[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>
This commit is contained in:
Keshavamurthy Anil S 2005-09-06 15:19:35 -07:00 committed by Linus Torvalds
parent bce0649417
commit deac66ae45
7 changed files with 55 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/i386/kernel/kprobes.c
View File

@ -177,7 +177,8 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
Disarm the probe we just hit, and ignore it. */
p = get_kprobe(addr);
if (p) {
if (kprobe_status == KPROBE_HIT_SS) {
if (kprobe_status == KPROBE_HIT_SS &&
*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
regs->eflags &= ~TF_MASK;
regs->eflags |= kprobe_saved_eflags;
unlock_kprobes();

22
arch/ia64/kernel/kprobes.c
View File

@ -95,6 +95,17 @@ static void __kprobes update_kprobe_inst_flag(uint template, uint slot,
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 @@ static void __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
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 @@ static int __kprobes pre_kprobes_handler(struct die_args *args)
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;
}

11
arch/ppc64/kernel/kprobes.c
View File

@ -102,7 +102,7 @@ static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
regs->msr |= MSR_SE;
/* single step inline if it is a trap variant */
if (IS_TW(insn) || IS_TD(insn) || IS_TWI(insn) || IS_TDI(insn))
if (is_trap(insn))
regs->nip = (unsigned long)p->addr;
else
regs->nip = (unsigned long)p->ainsn.insn;
@ -152,7 +152,9 @@ static inline int kprobe_handler(struct pt_regs *regs)
Disarm the probe we just hit, and ignore it. */
p = get_kprobe(addr);
if (p) {
if (kprobe_status == KPROBE_HIT_SS) {
kprobe_opcode_t insn = *p->ainsn.insn;
if (kprobe_status == KPROBE_HIT_SS &&
is_trap(insn)) {
regs->msr &= ~MSR_SE;
regs->msr |= kprobe_saved_msr;
unlock_kprobes();
@ -192,8 +194,7 @@ static inline int kprobe_handler(struct pt_regs *regs)
* trap variant, it could belong to someone else
*/
kprobe_opcode_t cur_insn = *addr;
if (IS_TW(cur_insn) || IS_TD(cur_insn) ||
IS_TWI(cur_insn) || IS_TDI(cur_insn))
if (is_trap(cur_insn))
goto no_kprobe;
/*
* The breakpoint instruction was removed right
@ -403,7 +404,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
default:
break;
}
preempt_enable();
preempt_enable_no_resched();
return ret;
}

3
arch/x86_64/kernel/kprobes.c
View File

@ -311,7 +311,8 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
Disarm the probe we just hit, and ignore it. */
p = get_kprobe(addr);
if (p) {
if (kprobe_status == KPROBE_HIT_SS) {
if (kprobe_status == KPROBE_HIT_SS &&
*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
regs->eflags &= ~TF_MASK;
regs->eflags |= kprobe_saved_rflags;
unlock_kprobes();

1
include/asm-ia64/kprobes.h
View File

@ -92,6 +92,7 @@ struct arch_specific_insn {
kprobe_opcode_t insn;
#define INST_FLAG_FIX_RELATIVE_IP_ADDR 1
#define INST_FLAG_FIX_BRANCH_REG 2
#define INST_FLAG_BREAK_INST 4
unsigned long inst_flag;
unsigned short target_br_reg;
};

3
include/asm-ppc64/kprobes.h
View File

@ -42,6 +42,9 @@ typedef unsigned int kprobe_opcode_t;
#define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)((func_descr_t *)pentry)
#define is_trap(instr) (IS_TW(instr) || IS_TD(instr) || \
IS_TWI(instr) || IS_TDI(instr))
#define ARCH_SUPPORTS_KRETPROBES
void kretprobe_trampoline(void);

22
kernel/kprobes.c
View File

@ -155,14 +155,36 @@ void __kprobes free_insn_slot(kprobe_opcode_t *slot)
/* Locks kprobe: irqs must be disabled */
void __kprobes lock_kprobes(void)
{
unsigned long flags = 0;
/* Avoiding local interrupts to happen right after we take the kprobe_lock
* and before we get a chance to update kprobe_cpu, this to prevent
* deadlock when we have a kprobe on ISR routine and a kprobe on task
* routine
*/
local_irq_save(flags);
spin_lock(&kprobe_lock);
kprobe_cpu = smp_processor_id();
local_irq_restore(flags);
}
void __kprobes unlock_kprobes(void)
{
unsigned long flags = 0;
/* Avoiding local interrupts to happen right after we update
* kprobe_cpu and before we get a a chance to release kprobe_lock,
* this to prevent deadlock when we have a kprobe on ISR routine and
* a kprobe on task routine
*/
local_irq_save(flags);
kprobe_cpu = NR_CPUS;
spin_unlock(&kprobe_lock);
local_irq_restore(flags);
}
/* You have to be holding the kprobe_lock */