linux-kernel - [PATCH v6 13/13] selftests/sgx: Remove incomplete ABI sanitization code in test enclave

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Message-Id: <20230921143604.6561-14-jo.vanbulck@cs.kuleuven.be>
Date:   Thu, 21 Sep 2023 16:36:04 +0200
From:   Jo Van Bulck <jo.vanbulck@...kuleuven.be>
To:     jarkko@...nel.org, kai.huang@...el.com, linux-sgx@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     dave.hansen@...ux.intel.com,
        Jo Van Bulck <jo.vanbulck@...kuleuven.be>
Subject: [PATCH v6 13/13] selftests/sgx: Remove incomplete ABI sanitization code in test enclave

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