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From: Dave Martin <Dave.Martin@arm.com>
To: Cristian Marussi <cristian.marussi@arm.com>
Cc: linux-kselftest@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, shuah@kernel.org,
	andreyknvl@google.com
Subject: Re: [PATCH v3 11/11] kselftest: arm64: fake_sigreturn_misaligned_sp
Date: Tue, 13 Aug 2019 17:27:56 +0100
Message-ID: <20190813162756.GI10425@arm.com> (raw)
In-Reply-To: <20190802170300.20662-12-cristian.marussi@arm.com>

On Fri, Aug 02, 2019 at 06:03:00PM +0100, Cristian Marussi wrote:
> Added a simple fake_sigreturn testcase which places a valid

Add

> 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.

Adds -> Also add
lists -> list

> 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
> 
> 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

Would it be simpler for the third argument to specify a number of bytes
to subtract from SP after allocating 16-byte aligned storage to
accommodate sigframe_sz?

Then 0 gives an aligned frame, 1 gives a frame misaligned by 1 byte,
etc.


Also if all this is a fix to the original fake_sigreturn, can we merge
it into the original patch instead?

> 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

This seems a reasonable list, but it occurs to me that it will tend to
go out of sync as tests get added.  So maybe just put this list in the
cover letter instead of including it in the patch.

We should probably have a one-line description of each proposed test,
since the names are a bit cryptic.

> 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 */
> +

signal.h?

> +#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;
> +}

[...]

Cheers
---Dave

  parent reply index

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-02 17:02 [PATCH v3 00/11] Add arm64/signal initial kselftest support Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 01/11] kselftest: arm64: introduce new boilerplate code Cristian Marussi
2019-08-13 16:23   ` Dave Martin
2019-08-27 12:14     ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 02/11] kselftest: arm64: adds first test and common utils Cristian Marussi
2019-08-06 15:50   ` Cristian Marussi
2019-08-07 15:42   ` Cristian Marussi
2019-08-09 10:54   ` Cristian Marussi
2019-08-09 11:16     ` Dave Martin
2019-08-09 12:20       ` Cristian Marussi
2019-08-09 12:32         ` Dave Martin
2019-08-12 12:43   ` Amit Kachhap
2019-08-13 13:22     ` Cristian Marussi
2019-08-14 10:22       ` Amit Kachhap
2019-08-27 14:24         ` Cristian Marussi
2019-08-13 16:24   ` Dave Martin
2019-08-28 17:34     ` Cristian Marussi
2019-09-03 15:34       ` Dave Martin
2019-09-03 16:08         ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 03/11] kselftest: arm64: mangle_pstate_invalid_daif_bits Cristian Marussi
2019-08-13 16:24   ` Dave Martin
2019-08-29 10:19     ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 04/11] kselftest: arm64: mangle_pstate_invalid_mode_el Cristian Marussi
2019-08-13 16:24   ` Dave Martin
2019-08-29 11:50     ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 05/11] kselftest: arm64: mangle_pstate_ssbs_regs Cristian Marussi
2019-08-13 16:25   ` Dave Martin
2019-08-29 15:35     ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 06/11] kselftest: arm64: fake_sigreturn_bad_magic Cristian Marussi
2019-08-13 16:25   ` Dave Martin
2019-08-30 14:29     ` Cristian Marussi
2019-09-04 10:05       ` Dave Martin
2019-09-04 10:37         ` Cristian Marussi
2019-09-04 10:47           ` Dave Martin
2019-08-02 17:02 ` [PATCH v3 07/11] kselftest: arm64: fake_sigreturn_bad_size_for_magic0 Cristian Marussi
2019-08-13 16:25   ` Dave Martin
2019-08-30 14:49     ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 08/11] kselftest: arm64: fake_sigreturn_missing_fpsimd Cristian Marussi
2019-08-13 16:26   ` Dave Martin
2019-08-30 14:55     ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 09/11] kselftest: arm64: fake_sigreturn_duplicated_fpsimd Cristian Marussi
2019-08-13 16:26   ` Dave Martin
2019-08-30 15:11     ` Cristian Marussi
2019-08-02 17:02 ` [PATCH v3 10/11] kselftest: arm64: fake_sigreturn_bad_size Cristian Marussi
2019-08-13 16:26   ` Dave Martin
2019-08-30 15:21     ` Cristian Marussi
2019-08-02 17:03 ` [PATCH v3 11/11] kselftest: arm64: fake_sigreturn_misaligned_sp Cristian Marussi
2019-08-07 16:04   ` Cristian Marussi
2019-08-13 16:28     ` Dave Martin
2019-08-30 15:22       ` Cristian Marussi
2019-08-13 16:27   ` Dave Martin [this message]
2019-08-30 16:33     ` Cristian Marussi
2019-08-13 16:22 ` [PATCH v3 00/11] Add arm64/signal initial kselftest support Dave Martin
2019-08-30 16:40   ` Cristian Marussi
2019-09-02 10:53     ` Dave Martin
2019-09-02 11:30       ` Cristian Marussi

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