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From: Will Deacon <will@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	"Naveen N . Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	Ananth N Mavinakayanahalli <ananth@linux.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	linux-kernel@vger.kernel.org, Sven Schnelle <svens@linux.ibm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Russell King <linux@armlinux.org.uk>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 4/8] arm64: kprobes: Make a frame pointer on __kretprobe_trampoline
Date: Wed, 13 Oct 2021 09:14:57 +0100	[thread overview]
Message-ID: <20211013081456.GE6701@willie-the-truck> (raw)
In-Reply-To: <163369612899.636038.6691283708565501775.stgit@devnote2>

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@kernel.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@kernel.org>

Will

  reply	other threads:[~2021-10-13  8:15 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-08 12:28 [PATCH 0/8] kprobes: Make KUnit and add stacktrace on kretprobe tests Masami Hiramatsu
2021-10-08 12:28 ` [PATCH 1/8] kprobes: convert tests to kunit Masami Hiramatsu
2021-10-08 12:28 ` [PATCH 2/8] kprobes: Add a test case for stacktrace from kretprobe handler Masami Hiramatsu
2021-10-08 12:28 ` [PATCH 3/8] arm64: kprobes: Record frame pointer with kretprobe instance Masami Hiramatsu
2021-10-13  8:14   ` Will Deacon
2021-10-13 10:01   ` Mark Rutland
2021-10-14  8:04     ` Masami Hiramatsu
2021-10-14  9:13       ` Mark Rutland
2021-10-14 10:01         ` Masami Hiramatsu
2021-10-14 10:27           ` Mark Rutland
2021-10-14 13:50             ` Masami Hiramatsu
2021-10-08 12:28 ` [PATCH 4/8] arm64: kprobes: Make a frame pointer on __kretprobe_trampoline Masami Hiramatsu
2021-10-13  8:14   ` Will Deacon [this message]
2021-10-08 12:28 ` [PATCH 5/8] arm64: Recover kretprobe modified return address in stacktrace Masami Hiramatsu
2021-10-13  8:14   ` Will Deacon
2021-10-14  8:05     ` Masami Hiramatsu
2021-10-13 10:13   ` Mark Rutland
2021-10-14  9:57     ` Masami Hiramatsu
2021-10-08 12:29 ` [PATCH 6/8] ARM: clang: Do not relay on lr register for stacktrace Masami Hiramatsu
2021-10-11 18:45   ` Nick Desaulniers
2021-10-12 14:18     ` Masami Hiramatsu
2021-10-13 19:54       ` Nick Desaulniers
2021-10-14 16:53   ` Russell King (Oracle)
2021-10-15  0:18     ` Masami Hiramatsu
2021-10-08 12:29 ` [PATCH 7/8] ARM: kprobes: Make a frame pointer on __kretprobe_trampoline Masami Hiramatsu
2021-10-11 19:06   ` Nick Desaulniers
2021-10-08 12:29 ` [PATCH 8/8] ARM: Recover kretprobe modified return address in stacktrace Masami Hiramatsu

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