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From: Mark Rutland <mark.rutland@arm.com>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 4/4] arm64: insn: Report PAC and BTI instructions as skippable
Date: Mon, 4 May 2020 14:43:33 +0100	[thread overview]
Message-ID: <20200504134333.GD73375@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20200504131326.18290-5-broonie@kernel.org>

On Mon, May 04, 2020 at 02:13:26PM +0100, Mark Brown wrote:
> The PAC and BTI instructions can be safely skipped so report them as
> such, allowing them to be probed.
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>

These all look safe to step in a XOL area, so:

Acked-by: Mark Rutland <mark.rutland@arm.com>

> ---
>  arch/arm64/kernel/insn.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
> index 15c3f0643e3b..6439af794ec4 100644
> --- a/arch/arm64/kernel/insn.c
> +++ b/arch/arm64/kernel/insn.c
> @@ -57,6 +57,23 @@ bool __kprobes aarch64_insn_is_steppable_hint(u32 insn)
>  		return false;
>  
>  	switch (insn & 0xFE0) {
> +	case AARCH64_INSN_HINT_XPACLRI:
> +	case AARCH64_INSN_HINT_PACIA_1716:
> +	case AARCH64_INSN_HINT_PACIB_1716:
> +	case AARCH64_INSN_HINT_AUTIA_1716:
> +	case AARCH64_INSN_HINT_AUTIB_1716:
> +	case AARCH64_INSN_HINT_PACIAZ:
> +	case AARCH64_INSN_HINT_PACIASP:
> +	case AARCH64_INSN_HINT_PACIBZ:
> +	case AARCH64_INSN_HINT_PACIBSP:
> +	case AARCH64_INSN_HINT_AUTIAZ:
> +	case AARCH64_INSN_HINT_AUTIASP:
> +	case AARCH64_INSN_HINT_AUTIBZ:
> +	case AARCH64_INSN_HINT_AUTIBSP:
> +	case AARCH64_INSN_HINT_BTI:
> +	case AARCH64_INSN_HINT_BTIC:
> +	case AARCH64_INSN_HINT_BTIJ:
> +	case AARCH64_INSN_HINT_BTIJC:

Just to check -- do we set the GP flag when creating/mapping the XOL
area? If that's PAGE_KERNEL_EXEC, presumably we do.

Mark.

>  	case AARCH64_INSN_HINT_NOP:
>  		return true;
>  	default:
> -- 
> 2.20.1
> 

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  reply	other threads:[~2020-05-04 13:43 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-04 13:13 [PATCH v4 0/4] arm64: Make NOP handling a whitelist Mark Brown
2020-05-04 13:13 ` [PATCH v4 1/4] arm64: insn: Add constants for new HINT instruction decode Mark Brown
2020-05-04 14:05   ` Mark Rutland
2020-05-04 13:13 ` [PATCH v4 2/4] arm64: insn: Provide a better name for aarch64_insn_is_nop() Mark Brown
2020-05-04 13:40   ` Mark Rutland
2020-05-04 13:13 ` [PATCH v4 3/4] arm64: insn: Don't assume unrecognized HINTs are skippable Mark Brown
2020-05-04 13:44   ` Mark Rutland
2020-05-04 13:13 ` [PATCH v4 4/4] arm64: insn: Report PAC and BTI instructions as skippable Mark Brown
2020-05-04 13:43   ` Mark Rutland [this message]
2020-05-04 15:33 ` [PATCH v4 0/4] arm64: Make NOP handling a whitelist Will Deacon

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