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Date: Sun, 15 Aug 2010 15:18:04 +0900 From: KUMANO Syuhei <kumano.prog@...il.com> To: linux-kernel@...r.kernel.org Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org, Frederic Weisbecker <fweisbec@...il.com>, Ananth N Mavinakayanahalli <ananth@...ibm.com>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>, Masami Hiramatsu <masami.hiramatsu.pt@...achi.com> Subject: [PATCH] kprobes/x86: Fix the return address of multiple kretprobes 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) Cc: Thomas Gleixner <tglx@...utronix.de> Cc: Ingo Molnar <mingo@...hat.com> Cc: "H. Peter Anvin" <hpa@...or.com> Cc: x86@...nel.org Cc: Frederic Weisbecker <fweisbec@...il.com> Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl> Cc: linux-kernel@...r.kernel.org Cc: YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com> Signed-off-by: KUMANO Syuhei <kumano.prog@...il.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) { -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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