From: Masami Hiramatsu <mhiramat@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>, X86 ML <x86@kernel.org>,
Daniel Xu <dxu@dxuuu.xyz>,
linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
kuba@kernel.org, mingo@redhat.com, ast@kernel.org,
tglx@linutronix.de, kernel-team@fb.com, yhs@fb.com,
Josh Poimboeuf <jpoimboe@redhat.com>,
linux-ia64@vger.kernel.org,
Abhishek Sagar <sagar.abhishek@gmail.com>
Subject: Re: [PATCH -tip v4 10/12] x86/kprobes: Push a fake return address at kretprobe_trampoline
Date: Fri, 26 Mar 2021 21:03:49 +0900 [thread overview]
Message-ID: <20210326210349.22f6d34b229dd3a139a53686@kernel.org> (raw)
In-Reply-To: <20210326030503.7fa72da34e25ad35cf5ed3de@kernel.org>
On Fri, 26 Mar 2021 03:05:03 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:
> On Wed, 24 Mar 2021 10:40:58 +0900
> Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> > On Tue, 23 Mar 2021 23:30:07 +0100
> > Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > > On Mon, Mar 22, 2021 at 03:41:40PM +0900, Masami Hiramatsu wrote:
> > > > ".global kretprobe_trampoline\n"
> > > > ".type kretprobe_trampoline, @function\n"
> > > > "kretprobe_trampoline:\n"
> > > > #ifdef CONFIG_X86_64
> > >
> > > So what happens if we get an NMI here? That is, after the RET but before
> > > the push? Then our IP points into the trampoline but we've not done that
> > > push yet.
> >
> > Not only NMI, but also interrupts can happen. There is no cli/sti here.
> >
> > Anyway, thanks for pointing!
> > I think in UNWIND_HINT_TYPE_REGS and UNWIND_HINT_TYPE_REGS_PARTIAL cases
> > ORC unwinder also has to check the state->ip and if it is kretprobe_trampoline,
> > it should be recovered.
> > What about this?
>
> Hmm, this seems to intoduce another issue on stacktrace from kprobes.
>
> <...>-137 [003] d.Z. 17.250714: p_full_proxy_read_5: (full_proxy_read+0x5/0x80)
> <...>-137 [003] d.Z. 17.250737: <stack trace>
> => kprobe_trace_func+0x1d0/0x2c0
> => kprobe_dispatcher+0x39/0x60
> => aggr_pre_handler+0x4f/0x90
> => kprobe_int3_handler+0x152/0x1a0
> => exc_int3+0x47/0x140
> => asm_exc_int3+0x31/0x40
> => 0
> => 0
> => 0
> => 0
> => 0
> => 0
> => 0
>
> Let me check...
I confirmed this is not related to this series, but occurs when I build kernels with different
configs without cleanup.
Once I build kernel with CONFIG_UNWIND_GUESS=y (for testing), and after that,
I build kernel again with CONFIG_UNWIND_ORC=y (but without make clean), this
happened. In this case, I guess ORC data might be corrupted?
When I cleanup and rebuild, the stacktrace seems correct.
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2021-03-26 12:04 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 6:39 [PATCH -tip v4 00/12] kprobes: Fix stacktrace with kretprobes on x86 Masami Hiramatsu
2021-03-22 6:39 ` [PATCH -tip v4 01/12] ia64: kprobes: Fix to pass correct trampoline address to the handler Masami Hiramatsu
2021-03-22 6:40 ` [PATCH -tip v4 02/12] kprobes: treewide: Replace arch_deref_entry_point() with dereference_function_descriptor() Masami Hiramatsu
2021-03-22 6:40 ` [PATCH -tip v4 03/12] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() Masami Hiramatsu
2021-03-22 6:40 ` [PATCH -tip v4 04/12] kprobes: Add kretprobe_find_ret_addr() for searching return address Masami Hiramatsu
2021-03-22 6:40 ` [PATCH -tip v4 05/12] x86/kprobes: Add UNWIND_HINT_FUNC on kretprobe_trampoline code Masami Hiramatsu
2021-03-22 6:40 ` [PATCH -tip v4 06/12] ARC: Add instruction_pointer_set() API Masami Hiramatsu
2021-03-22 6:41 ` [PATCH -tip v4 07/12] ia64: " Masami Hiramatsu
2021-03-22 6:41 ` [PATCH -tip v4 08/12] arm: kprobes: Make a space for regs->ARM_pc at kretprobe_trampoline Masami Hiramatsu
2021-03-23 0:04 ` Masami Hiramatsu
2021-03-22 6:41 ` [PATCH -tip v4 09/12] kprobes: Setup instruction pointer in __kretprobe_trampoline_handler Masami Hiramatsu
2021-03-22 6:41 ` [PATCH -tip v4 10/12] x86/kprobes: Push a fake return address at kretprobe_trampoline Masami Hiramatsu
2021-03-23 22:30 ` Peter Zijlstra
2021-03-24 1:40 ` Masami Hiramatsu
2021-03-24 16:01 ` Josh Poimboeuf
2021-03-24 23:47 ` Masami Hiramatsu
2021-03-25 0:26 ` Steven Rostedt
2021-03-25 3:25 ` Masami Hiramatsu
2021-03-25 18:05 ` Masami Hiramatsu
2021-03-26 12:03 ` Masami Hiramatsu [this message]
2021-03-26 14:20 ` Steven Rostedt
2021-03-30 4:58 ` Josh Poimboeuf
2021-03-22 6:41 ` [PATCH -tip v4 11/12] x86/unwind: Recover kretprobe trampoline entry Masami Hiramatsu
2021-03-22 6:42 ` [PATCH -tip v4 12/12] tracing: Show kretprobe unknown indicator only for kretprobe_trampoline Masami Hiramatsu
2021-03-22 15:11 ` Steven Rostedt
2021-03-22 23:56 ` Masami Hiramatsu
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