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From: Dave Martin <Dave.Martin@arm.com>
To: Amit Daniel Kachhap <amit.kachhap@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Brown <broonie@kernel.org>,
	James Morse <james.morse@arm.com>,
	Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 4/4] arm64: kprobe: clarify the comment of steppable hint instructions
Date: Wed, 29 Jul 2020 11:44:36 +0100	[thread overview]
Message-ID: <20200729104436.GE21941@arm.com> (raw)
In-Reply-To: <1594368010-4419-5-git-send-email-amit.kachhap@arm.com>

On Fri, Jul 10, 2020 at 01:30:10PM +0530, Amit Daniel Kachhap wrote:
> The existing comment about steppable hint instruction is not complete
> and only describes NOP instructions as steppable. As the function
> aarch64_insn_is_steppable_hint allows all white-listed instruction
> to be probed so the comment is updated to reflect this.
> 
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>

Reviewed-by: Dave Martin <Dave.Martin@arm.com>

> ---
> Changes since v3:
>  * New patch.
> 
>  arch/arm64/kernel/probes/decode-insn.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kernel/probes/decode-insn.c b/arch/arm64/kernel/probes/decode-insn.c
> index 263d5fba4c8a..3912a37cb117 100644
> --- a/arch/arm64/kernel/probes/decode-insn.c
> +++ b/arch/arm64/kernel/probes/decode-insn.c
> @@ -42,8 +42,10 @@ static bool __kprobes aarch64_insn_is_steppable(u32 insn)
>  			     != AARCH64_INSN_SPCLREG_DAIF;
>  
>  		/*
> -		 * The HINT instruction is is problematic when single-stepping,
> -		 * except for the NOP case.
> +		 * The HINT instruction is steppable only if it is in whitelist
> +		 * and the rest of other such instructions are blocked for
> +		 * single stepping as they may cause exception or other
> +		 * unintended behaviour.
>  		 */
>  		if (aarch64_insn_is_hint(insn))
>  			return aarch64_insn_is_steppable_hint(insn);
> -- 
> 2.17.1
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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      reply	other threads:[~2020-07-29 10:46 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-10  8:00 [PATCH v4 0/4] arm64: add Armv8.3 pointer authentication enhancements Amit Daniel Kachhap
2020-07-10  8:00 ` [PATCH v4 1/4] arm64: ptrauth: add Armv8.3 pointer authentication enhanced features Amit Daniel Kachhap
2020-07-29 11:07   ` Dave Martin
2020-08-03 10:13     ` Amit Kachhap
2020-07-10  8:00 ` [PATCH v4 2/4] arm64: cpufeature: Modify address authentication cpufeature to exact Amit Daniel Kachhap
2020-07-29 10:36   ` Dave Martin
2020-07-29 12:28     ` Suzuki K Poulose
2020-07-29 14:31       ` Dave Martin
2020-07-29 17:09         ` Suzuki K Poulose
2020-08-05  9:16           ` Amit Kachhap
2020-07-10  8:00 ` [PATCH v4 3/4] arm64: kprobe: disable probe of fault prone ptrauth instruction Amit Daniel Kachhap
2020-07-29 10:43   ` Dave Martin
2020-08-03 10:16     ` Amit Kachhap
2020-07-10  8:00 ` [PATCH v4 4/4] arm64: kprobe: clarify the comment of steppable hint instructions Amit Daniel Kachhap
2020-07-29 10:44   ` Dave Martin [this message]

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