linux-kernel - Re: [PATCH 4/8] arm64: kprobes: Make a frame pointer on __kretprobe

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20211013081456.GE6701@willie-the-truck>
Date:   Wed, 13 Oct 2021 09:14:57 +0100
From:   Will Deacon <will@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        "Naveen N . Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Ananth N Mavinakayanahalli <ananth@...ux.ibm.com>,
        Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
        Sven Schnelle <svens@...ux.ibm.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Russell King <linux@...linux.org.uk>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 4/8] arm64: kprobes: Make a frame pointer on
 __kretprobe_trampoline

On Fri, Oct 08, 2021 at 09:28:49PM +0900, Masami Hiramatsu wrote:
> Make a frame pointer (make the x29 register points the
> address of pt_regs->regs[29]) on __kretprobe_trampoline.
> 
> This frame pointer will be used by the stacktracer when it is
> called from the kretprobe handlers. In this case, the stack
> tracer will unwind stack to trampoline_probe_handler() and
> find the next frame pointer in the stack frame of the
> __kretprobe_trampoline().
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> ---
>  arch/arm64/kernel/probes/kprobes_trampoline.S |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/arm64/kernel/probes/kprobes_trampoline.S b/arch/arm64/kernel/probes/kprobes_trampoline.S
> index 520ee8711db1..9a6499bed58b 100644
> --- a/arch/arm64/kernel/probes/kprobes_trampoline.S
> +++ b/arch/arm64/kernel/probes/kprobes_trampoline.S
> @@ -66,6 +66,9 @@ SYM_CODE_START(__kretprobe_trampoline)
>  
>  	save_all_base_regs
>  
> +	/* Setup a frame pointer. */
> +	add x29, sp, #S_FP
> +
>  	mov x0, sp
>  	bl trampoline_probe_handler
>  	/*
> @@ -74,6 +77,7 @@ SYM_CODE_START(__kretprobe_trampoline)
>  	 */
>  	mov lr, x0
>  
> +	/* The frame pointer (x29) is restored with other registers. */
>  	restore_all_base_regs
>  
>  	add sp, sp, #PT_REGS_SIZE

Acked-by: Will Deacon <will@...nel.org>

Will