linux-kernel - Re: [PATCH v5 13/13] selftests/sgx: Remove incomplete ABI sanitization code in test enclave

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Message-Id: <CVAF8ZE299H1.UFFIVHH8YCM8@suppilovahvero>
Date:   Mon, 04 Sep 2023 23:39:37 +0300
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     "Jo Van Bulck" <jo.vanbulck@...kuleuven.be>, <kai.huang@...el.com>,
        <linux-sgx@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Cc:     <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v5 13/13] selftests/sgx: Remove incomplete ABI
 sanitization code in test enclave

On Thu Aug 31, 2023 at 4:41 PM EEST, Jo Van Bulck wrote:
> As the selftest enclave is *not* intended for production, simplify the
> code by not initializing CPU configuration registers as expected by the
> ABI on enclave entry or cleansing caller-save registers on enclave exit.
>
> Link: https://lore.kernel.org/all/da0cfb1e-e347-f7f2-ac72-aec0ee0d867d@intel.com/
> Signed-off-by: Jo Van Bulck <jo.vanbulck@...kuleuven.be>
> ---
>  .../testing/selftests/sgx/test_encl_bootstrap.S  | 16 +++-------------
>  1 file changed, 3 insertions(+), 13 deletions(-)
>
> diff --git a/tools/testing/selftests/sgx/test_encl_bootstrap.S b/tools/testing/selftests/sgx/test_encl_bootstrap.S
> index 28fe5d2ac0af..d8c4ac94e032 100644
> --- a/tools/testing/selftests/sgx/test_encl_bootstrap.S
> +++ b/tools/testing/selftests/sgx/test_encl_bootstrap.S
> @@ -59,21 +59,11 @@ encl_entry_core:
>  
>  	push	%rcx # push the address after EENTER
>  
> +	# NOTE: as the selftest enclave is *not* intended for production,
> +	# simplify the code by not initializing ABI registers on entry or
> +	# cleansing caller-save registers on exit.
>  	call	encl_body
>  
> -	/* Clear volatile GPRs, except RAX (EEXIT function). */
> -	xor     %rcx, %rcx
> -	xor     %rdx, %rdx
> -	xor     %rdi, %rdi
> -	xor     %rsi, %rsi
> -	xor     %r8, %r8
> -	xor     %r9, %r9
> -	xor     %r10, %r10
> -	xor     %r11, %r11
> -
> -	# Reset status flags.
> -	add     %rdx, %rdx # OF = SF = AF = CF = 0; ZF = PF = 1
> -
>  	# Prepare EEXIT target by popping the address of the instruction after
>  	# EENTER to RBX.
>  	pop	%rbx
> -- 
> 2.25.1

Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>

BR, Jarkko