Messages in this thread | | | Date | Wed, 18 Aug 2010 00:10:06 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH] kprobes/x86: Fix the return address of multiple kretprobes |
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KUMANO Syuhei wrote: > Fix the return address of subsequent kretprobes when multiple > kretprobes are set on the same function. > > For example: > # cd /sys/kernel/debug/tracing > # echo "r:event1 sys_symlink" > kprobe_events > # echo "r:event2 sys_symlink" >> kprobe_events > # echo 1 > events/kprobes/enable > # ln -s /tmp/foo /tmp/bar > (without this patch) > # cat trace > ln-897 [000] 20404.133727: event1: (kretprobe_trampoline+0x0/0x4c <- sys_symlink) > ln-897 [000] 20404.133747: event2: (system_call_fastpath+0x16/0x1b <- sys_symlink) > (with this patch) > # cat trace > ln-740 [000] 13799.491076: event1: (system_call_fastpath+0x16/0x1b <- sys_symlink) > ln-740 [000] 13799.491096: event2: (system_call_fastpath+0x16/0x1b <- sys_symlink) >
Yeah, I'm OK for this fix.
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Ingo, could you pull this on your x86/bugfix tree?
Thank you,
> Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: x86@kernel.org > Cc: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> > Cc: linux-kernel@vger.kernel.org > Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> > Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> > Signed-off-by: KUMANO Syuhei <kumano.prog@gmail.com> > --- > arch/x86/kernel/kprobes.c | 25 ++++++++++++++++++++++--- > 1 files changed, 22 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c > index 675879b..5220e14 100644 > --- a/arch/x86/kernel/kprobes.c > +++ b/arch/x86/kernel/kprobes.c > @@ -707,6 +707,7 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs) > struct hlist_node *node, *tmp; > unsigned long flags, orig_ret_address = 0; > unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; > + kprobe_opcode_t *correct_ret_addr = NULL; > > INIT_HLIST_HEAD(&empty_rp); > kretprobe_hash_lock(current, &head, &flags); > @@ -738,14 +739,34 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs) > /* another task is sharing our hash bucket */ > continue; > > + orig_ret_address = (unsigned long)ri->ret_addr; > + > + if (orig_ret_address != trampoline_address) > + /* > + * This is the real return address. Any other > + * instances associated with this task are for > + * other calls deeper on the call stack > + */ > + break; > + } > + > + kretprobe_assert(ri, orig_ret_address, trampoline_address); > + > + correct_ret_addr = ri->ret_addr; > + hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { > + if (ri->task != current) > + /* another task is sharing our hash bucket */ > + continue; > + > + orig_ret_address = (unsigned long)ri->ret_addr; > if (ri->rp && ri->rp->handler) { > __get_cpu_var(current_kprobe) = &ri->rp->kp; > get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; > + ri->ret_addr = correct_ret_addr; > ri->rp->handler(ri, regs); > __get_cpu_var(current_kprobe) = NULL; > } > > - orig_ret_address = (unsigned long)ri->ret_addr; > recycle_rp_inst(ri, &empty_rp); > > if (orig_ret_address != trampoline_address) > @@ -757,8 +778,6 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs) > break; > } > > - kretprobe_assert(ri, orig_ret_address, trampoline_address); > - > kretprobe_hash_unlock(current, &flags); > > hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
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