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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prev parent 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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