On Mon, 2023-07-24 at 18:58 +0200, Jo Van Bulck wrote:
> Relocate encl_op_array entries at runtime relative to the enclave base to
> ensure correct function pointer when compiling the test enclave with -Os.
Putting aside whether we should consider building the selftests using "-Os", it
would be helpful to explain how can the "-Os" break the existing code, so that
we can review why this fix is reasonable. Perhaps it's obvious to others but
it's not obvious to me what can go wrong here.
>
> Signed-off-by: Jo Van Bulck <jo.vanbulck@xxxxxxxxxxxxxx>
> ---
> 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:
