linux-kernel - [PATCH v4 05/13] selftests/sgx: Include memory clobber for inline asm in test enclave

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Message-Id: <20230825133252.9056-6-jo.vanbulck@cs.kuleuven.be>
Date:   Fri, 25 Aug 2023 15:32:44 +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 v4 05/13] selftests/sgx: Include memory clobber for inline asm in test enclave

Add the "memory" clobber to the EMODPE and EACCEPT asm blocks to tell the
compiler the assembly code accesses to the secinfo struct. This ensures
the compiler treats the asm block as a memory barrier and the write to
secinfo will be visible to ENCLU.

Signed-off-by: Jo Van Bulck <jo.vanbulck@...kuleuven.be>
Reviewed-by: Kai Huang <kai.huang@...el.com>
Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>
---
 tools/testing/selftests/sgx/test_encl.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/sgx/test_encl.c b/tools/testing/selftests/sgx/test_encl.c
index 706c1f7260ff..dfe531c5f560 100644
--- a/tools/testing/selftests/sgx/test_encl.c
+++ b/tools/testing/selftests/sgx/test_encl.c
@@ -24,10 +24,11 @@ static void do_encl_emodpe(void *_op)
 	secinfo.flags = op->flags;
 
 	asm volatile(".byte 0x0f, 0x01, 0xd7"
-				:
+				: /* no outputs */
 				: "a" (EMODPE),
 				  "b" (&secinfo),
-				  "c" (op->epc_addr));
+				  "c" (op->epc_addr)
+				: "memory" /* read from secinfo pointer */);
 }
 
 static void do_encl_eaccept(void *_op)
@@ -42,7 +43,8 @@ static void do_encl_eaccept(void *_op)
 				: "=a" (rax)
 				: "a" (EACCEPT),
 				  "b" (&secinfo),
-				  "c" (op->epc_addr));
+				  "c" (op->epc_addr)
+				: "memory" /* read from secinfo pointer */);
 
 	op->ret = rax;
 }
-- 
2.25.1