From: Masami Hiramatsu <mhiramat@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: 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 08/12] arm: kprobes: Make a space for regs->ARM_pc at kretprobe_trampoline
Date: Tue, 23 Mar 2021 09:04:29 +0900 [thread overview]
Message-ID: <20210323090429.da18461654ef9907581dab95@kernel.org> (raw)
In-Reply-To: <161639527851.895304.14313883616251450754.stgit@devnote2>
On Mon, 22 Mar 2021 15:41:18 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:
> Change kretprobe_trampoline to make a space for regs->ARM_pc so that
> kretprobe_trampoline_handler can call instruction_pointer_set()
> safely.
BTW, if kretprobe_trampoline is replaced with the assembly code,
I think it should fill all the regs as much as possible, because
originally it is written by a software break.
Thus the regs->sp should point the stack address at the entry of
kretprobe_trampoline, and also regs->lr and regs->pc will be
kretprobe_trampoline, so that user handler can access caller stack.
Thanks,
>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> arch/arm/probes/kprobes/core.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c
> index 1782b41df095..5f3c2b42787f 100644
> --- a/arch/arm/probes/kprobes/core.c
> +++ b/arch/arm/probes/kprobes/core.c
> @@ -397,11 +397,13 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
> void __naked __kprobes kretprobe_trampoline(void)
> {
> __asm__ __volatile__ (
> + "sub sp, sp, #16 \n\t"
> "stmdb sp!, {r0 - r11} \n\t"
> "mov r0, sp \n\t"
> "bl trampoline_handler \n\t"
> "mov lr, r0 \n\t"
> "ldmia sp!, {r0 - r11} \n\t"
> + "add sp, sp, #16 \n\t"
> #ifdef CONFIG_THUMB2_KERNEL
> "bx lr \n\t"
> #else
>
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2021-03-23 0:05 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 [this message]
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
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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