selftests/sgx: Add test for multiple TCS entry

Each thread executing in an enclave is associated with a Thread Control
Structure (TCS). The SGX test enclave contains two hardcoded TCS, thus
supporting two threads in the enclave.

Add a test to ensure it is possible to enter enclave at both entrypoints.

Signed-off-by: Reinette Chatre <[e-mail]>
Signed-off-by: Dave Hansen <[e-mail]>
Reviewed-by: Jarkko Sakkinen <[e-mail]>
Acked-by: Dave Hansen <[e-mail]>
Link: https://lkml.kernel.org/r/7be151a[e-mail]

tools/testing/selftests/sgx/defines.h

···
 	ENCL_OP_GET_FROM_BUFFER,
 	ENCL_OP_PUT_TO_ADDRESS,
 	ENCL_OP_GET_FROM_ADDRESS,
+	ENCL_OP_NOP,
 	ENCL_OP_MAX,
 };
 

tools/testing/selftests/sgx/main.c

···
 }
 
 /*
+ * Sanity check that it is possible to enter either of the two hardcoded TCS
+ */
+TEST_F(enclave, tcs_entry)
+{
+	struct encl_op_header op;
+
+	ASSERT_TRUE(setup_test_encl(ENCL_HEAP_SIZE_DEFAULT, &self->encl, _metadata));
+
+	memset(&self->run, 0, sizeof(self->run));
+	self->run.tcs = self->encl.encl_base;
+
+	op.type = ENCL_OP_NOP;
+
+	EXPECT_EQ(ENCL_CALL(&op, &self->run, true), 0);
+
+	EXPECT_EEXIT(&self->run);
+	EXPECT_EQ(self->run.exception_vector, 0);
+	EXPECT_EQ(self->run.exception_error_code, 0);
+	EXPECT_EQ(self->run.exception_addr, 0);
+
+	/* Move to the next TCS. */
+	self->run.tcs = self->encl.encl_base + PAGE_SIZE;
+
+	EXPECT_EQ(ENCL_CALL(&op, &self->run, true), 0);
+
+	EXPECT_EEXIT(&self->run);
+	EXPECT_EQ(self->run.exception_vector, 0);
+	EXPECT_EQ(self->run.exception_error_code, 0);
+	EXPECT_EQ(self->run.exception_addr, 0);
+}
+
+/*
  * Second page of .data segment is used to test changing PTE permissions.
  * This spans the local encl_buffer within the test enclave.
  *

tools/testing/selftests/sgx/test_encl.c

···
 	memcpy(&op->value, (void *)op->addr, 8);
 }
 
+static void do_encl_op_nop(void *_op)
+{
+
+}
+
 void encl_body(void *rdi,  void *rsi)
 {
 	const void (*encl_op_array[ENCL_OP_MAX])(void *) = {
···
 		do_encl_op_get_from_buf,
 		do_encl_op_put_to_addr,
 		do_encl_op_get_from_addr,
+		do_encl_op_nop,
 	};
 
 	struct encl_op_header *op = (struct encl_op_header *)rdi;