linux-kernel - [PATCH 2/5] selftests/sgx: Fix function pointer relocation in test enclave.

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Message-Id: <20230724165832.15797-3-jo.vanbulck@cs.kuleuven.be>
Date:   Mon, 24 Jul 2023 18:58:29 +0200
From:   Jo Van Bulck <jo.vanbulck@...kuleuven.be>
To:     jarkko@...nel.org, 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 2/5] selftests/sgx: Fix function pointer relocation in test enclave.

Relocate encl_op_array entries at runtime relative to the enclave base to
ensure correct function pointer when compiling the test enclave with -Os.

Signed-off-by: Jo Van Bulck <jo.vanbulck@...kuleuven.be>
---
 tools/testing/selftests/sgx/test_encl.c           | 6 ++++--
 tools/testing/selftests/sgx/test_encl.lds         | 1 +
 tools/testing/selftests/sgx/test_encl_bootstrap.S | 5 +++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/sgx/test_encl.c b/tools/testing/selftests/sgx/test_encl.c
index c0d6397295e3..4e31a6c3d673 100644
--- a/tools/testing/selftests/sgx/test_encl.c
+++ b/tools/testing/selftests/sgx/test_encl.c
@@ -119,9 +119,11 @@ static void do_encl_op_nop(void *_op)
 
 }
 
+uint64_t get_enclave_base(void);
+
 void encl_body(void *rdi,  void *rsi)
 {
-	const void (*encl_op_array[ENCL_OP_MAX])(void *) = {
+	static void (*encl_op_array[ENCL_OP_MAX])(void *) = {
 		do_encl_op_put_to_buf,
 		do_encl_op_get_from_buf,
 		do_encl_op_put_to_addr,
@@ -135,5 +137,5 @@ void encl_body(void *rdi,  void *rsi)
 	struct encl_op_header *op = (struct encl_op_header *)rdi;
 
 	if (op->type < ENCL_OP_MAX)
-		(*encl_op_array[op->type])(op);
+		(*(get_enclave_base() + encl_op_array[op->type]))(op);
 }
diff --git a/tools/testing/selftests/sgx/test_encl.lds b/tools/testing/selftests/sgx/test_encl.lds
index a1ec64f7d91f..ca659db2a534 100644
--- a/tools/testing/selftests/sgx/test_encl.lds
+++ b/tools/testing/selftests/sgx/test_encl.lds
@@ -10,6 +10,7 @@ PHDRS
 SECTIONS
 {
 	. = 0;
+        __enclave_base = .;
 	.tcs : {
 		*(.tcs*)
 	} : tcs
diff --git a/tools/testing/selftests/sgx/test_encl_bootstrap.S b/tools/testing/selftests/sgx/test_encl_bootstrap.S
index 03ae0f57e29d..6126dbd7ad1c 100644
--- a/tools/testing/selftests/sgx/test_encl_bootstrap.S
+++ b/tools/testing/selftests/sgx/test_encl_bootstrap.S
@@ -86,6 +86,11 @@ encl_entry_core:
 	mov	$4, %rax
 	enclu
 
+	.global get_enclave_base
+get_enclave_base:
+	lea __enclave_base(%rip), %rax
+	ret
+
 	.section ".data", "aw"
 
 encl_ssa_tcs1:
-- 
2.34.1