Re: [PATCH 20/38] arm64: probes: Reject stepping over ALLINT

[Jinjie Ruan <ruanjinjie@huawei.com>]

在 2026/9/14 18:20, Vladimir Murzin 写道:
> ALLINT instructions are not safe for probing. Both the register and
> immediate forms of MSR for ALLINT are currently rejected because they
> match aarch64_insn_is_msr_{imm,reg}(). However, MRS instructions
> accessing ALLINT need to be rejected explicitly.
> 
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> ---
>  arch/arm64/include/asm/insn.h          |  1 +
>  arch/arm64/kernel/probes/decode-insn.c | 11 +++++++----
>  2 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
> index 1ce75a442638..0a81b5feb2ed 100644
> --- a/arch/arm64/include/asm/insn.h
> +++ b/arch/arm64/include/asm/insn.h
> @@ -118,6 +118,7 @@ enum aarch64_insn_special_register {
>  	AARCH64_INSN_SPCLREG_SP_EL0	= 0xC208,
>  	AARCH64_INSN_SPCLREG_SPSEL	= 0xC210,
>  	AARCH64_INSN_SPCLREG_CURRENTEL	= 0xC212,
> +	AARCH64_INSN_SPCLREG_ALLINT	= 0xC218,
>  	AARCH64_INSN_SPCLREG_DAIF	= 0xDA11,
>  	AARCH64_INSN_SPCLREG_NZCV	= 0xDA10,
>  	AARCH64_INSN_SPCLREG_FPCR	= 0xDA20,
> diff --git a/arch/arm64/kernel/probes/decode-insn.c b/arch/arm64/kernel/probes/decode-insn.c
> index 4137cc5ef031..a98d9d30fb4a 100644
> --- a/arch/arm64/kernel/probes/decode-insn.c
> +++ b/arch/arm64/kernel/probes/decode-insn.c
> @@ -36,11 +36,14 @@ static bool __kprobes aarch64_insn_is_steppable(u32 insn)
>  		/*
>  		 * The MRS instruction may not return a correct value when
>  		 * executing in the single-stepping environment. We do make one
> -		 * exception, for reading the DAIF bits.
> +		 * exception, for reading the DAIF and ALLINT bits.
>  		 */
> -		if (aarch64_insn_is_mrs(insn))
> -			return aarch64_insn_extract_system_reg(insn)
> -			     != AARCH64_INSN_SPCLREG_DAIF;
> +		if (aarch64_insn_is_mrs(insn)) {
> +			u32 sysreg = aarch64_insn_extract_system_reg(insn);
> +
> +			return (sysreg != AARCH64_INSN_SPCLREG_DAIF) &&
> +			       (sysreg != AARCH64_INSN_SPCLREG_ALLINT);

LGTM
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>

> +		}
>  
>  		/*
>  		 * The HINT instruction is steppable only if it is in whitelist