On Thu, Jun 13, 2019 at 12:13:31PM +0100, Cristian Marussi wrote:
> Added a simple fake_sigreturn testcase which builds a good
> ucontext_t and tries to place it onto the stack in a misaligned way.
> Expects a SIGSEGV on test PASS.
>
> Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> ---
> .../arm64/signal/testcases/.gitignore | 1 +
> .../testcases/fake_sigreturn_misaligned.c | 30 +++++++++++++++++++
> 2 files changed, 31 insertions(+)
> create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned.c
>
> diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore
> index c2972c3f33ca..3e6b26be6727 100644
> --- a/tools/testing/selftests/arm64/signal/testcases/.gitignore
> +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore
> @@ -6,3 +6,4 @@ mangle_pstate_invalid_mode_el1
> mangle_pstate_invalid_mode_el2
> mangle_pstate_invalid_mode_el3
> mangle_pstate_ssbs_regs
> +fake_sigreturn_misaligned
> diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned.c
> new file mode 100644
> index 000000000000..d551858dd9dd
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned.c
> @@ -0,0 +1,30 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (C) 2019 ARM Limited */
> +
> +#include <ucontext.h>
> +
> +#include "test_signals_utils.h"
> +#include "testcases.h"
> +
> +struct a_sigframe sf;
> +
> +static int fake_sigreturn_misaligned_run(struct tdescr *td,
> + siginfo_t *si, ucontext_t *uc)
> +{
> + /* just to fill the ucontext_t with something real */
> + if (!get_current_context(td, &sf.uc))
> + return 1;
> +
> + /* Forcing sigframe on misaligned (=!16) SP */
> + fake_sigreturn(&sf, sizeof(sf), 8);
Does this do the right thing? From the asm code, it looks like
fake_sigreturn will ensure that SP % 8 == 0, but that may still be fine
(i.e., SP % 16 == 0 and SP % 8 == 0 can both be true, depending on the
precise value of sizeof(sf)).
Maybe I misunderstood what fake_sigreturn is doing.
Instead, do we want to ensure that SP % 16 != 0 here?
[...]
Cheers
---Dave
