Re: [PATCH v3 11/11] kselftest: arm64: fake_sigreturn_misaligned_sp

[Cristian Marussi <cristian.marussi@arm.com>]

On 02/08/2019 18:03, Cristian Marussi wrote:
> Added a simple fake_sigreturn testcase which places a valid
> sigframe on a non-16 bytes aligned SP.
> fake_sigretrun() helper function has been patched accordingly
> to support placing a sigframe on a non-16 bytes aligned address.
> Expects a SIGSEGV on test PASS.
> 
> Adds also a test TODO lists holding some further test ideas.
> 
> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
> ---
> Re-added this text after fixing the forced misaglinment procedure in
> fake_sigreturn() itself: require a ZERO alignment and you'll get
> your sigframe placed on a misaligned SP (2-bytes off the 16-align)
> ---
>  .../testing/selftests/arm64/signal/signals.S  | 21 +++++++++----
>  .../arm64/signal/testcases/TODO.readme        |  8 +++++
>  .../testcases/fake_sigreturn_misaligned_sp.c  | 30 +++++++++++++++++++
>  3 files changed, 53 insertions(+), 6 deletions(-)
>  create mode 100644 tools/testing/selftests/arm64/signal/testcases/TODO.readme
>  create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned_sp.c
> 

When this test was re-added in V3, the related .gitignore was missed.
It will go in V4

Cheers

Cristian
> diff --git a/tools/testing/selftests/arm64/signal/signals.S b/tools/testing/selftests/arm64/signal/signals.S
> index 6262b877400b..2099871176ed 100644
> --- a/tools/testing/selftests/arm64/signal/signals.S
> +++ b/tools/testing/selftests/arm64/signal/signals.S
> @@ -13,19 +13,28 @@ call_fmt:
>  
>  .globl fake_sigreturn
>  
> -/*	fake_sigreturn	x0:&sigframe,  x1:sigframe_size,  x2:alignment_SP */
> +/*	fake_sigreturn	x0:&sigframe, x1:sigframe_sz, x2:align */
>  fake_sigreturn:
> -	mov x20, x0
> -	mov x21, x1
> -	mov x22, x2
> -	mov x23, sp
>  
> -	/* create space on the stack for fake sigframe..."x22"-aligned */
> +	/* Save args and decide which aligment to enforce */
> +	mov 	x23, sp
> +	mov	x20, x0
> +	mov 	x21, x1
> +	/* x22 and x24 used for forcing alignment or misalignment */
> +	mov	x22, x2
> +	mov	x24, #0
> +	cbnz	x22, 1f
> +	mov	x22, #16
> +	mov	x24, #2
> +
> +1:	/* create space on the stack for fake sigframe..."x22"-aligned */
>  	mov x0, #0
>  	add x0, x21, x22
>  	sub x22, x22, #1
>  	bic x0, x0, x22
>  	sub x23, x23, x0
> +	/* force misaligned by x24 bytes if required alignment was zero */
> +	add x23, x23, x24
>  
>  	ldr x0, =call_fmt
>  	mov x1, x21
> diff --git a/tools/testing/selftests/arm64/signal/testcases/TODO.readme b/tools/testing/selftests/arm64/signal/testcases/TODO.readme
> new file mode 100644
> index 000000000000..5c949492e7ab
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/testcases/TODO.readme
> @@ -0,0 +1,8 @@
> +Some more possible ideas for signals tests:
> +
> +- fake_sigreturn_unmapped_sp
> +- fake_sigreturn_kernelspace_sp
> +- fake_sigreturn_sve_bad_extra_context
> +- mangle_sve_invalid_extra_context
> +- mangle_pstate_invalid_el for H modes (+ macroization ?)
> +- fake_sigreturn_overflow_reserved
> diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned_sp.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned_sp.c
> new file mode 100644
> index 000000000000..3ee8c500c7d1
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_misaligned_sp.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 fake_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), 0);
> +
> +	return 1;
> +}
> +
> +struct tdescr tde = {
> +		.name = "FAKE_SIGRETURN_MISALIGNED_SP",
> +		.descr = "Triggers a fake sigreturn with a misaligned sigframe on SP",
> +		.sig_ok = SIGSEGV,
> +		.timeout = 3,
> +		.run = fake_sigreturn_misaligned_run,
> +};
>