Subject: Re: [PATCH v5 03/11] kselftest: arm64: mangle_pstate_invalid_daif_bits

From: Dave Martin <[email-masked]>
Date: Wed, 4 Sep 2019 12:48:03 +0100

On Mon, Sep 02, 2019 at 12:29:24pm +0100, Cristian Marussi wrote:
> Add a simple mangle testcase which messes with the ucontext_t from within
> the signal handler, trying to set PSTATE DAIF bits to an invalid value
> (masking everything). Expects SIGSEGV on test PASS.
> 
> Signed-off-by: Cristian Marussi <[email-masked]>

Reviewed-by: Dave Martin <[email-masked]>

> ---
> v3 --> v4
> - fixed commit message
> - added testcase comment description
> ---
>  .../mangle_pstate_invalid_daif_bits.c         | 35 +++++++++++++++++++
>  1 file changed, 35 insertions(+)
>  create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_daif_bits.c
> 
> diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_daif_bits.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_daif_bits.c
> new file mode 100644
> index 000000000000..434b82597007
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_daif_bits.c
> @@ -0,0 +1,35 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 ARM Limited
> + *
> + * Try to mangle the ucontext from inside a signal handler, mangling the
> + * DAIF bits in an illegal manner: this attempt must be spotted by Kernel
> + * and the test case is expected to be terminated via SEGV.
> + *
> + */
> +
> +#include "test_signals_utils.h"
> +#include "testcases.h"
> +
> +static int mangle_invalid_pstate_run(struct tdescr *td, siginfo_t *si,
> +				     ucontext_t *uc)
> +{
> +	ASSERT_GOOD_CONTEXT(uc);
> +
> +	/*
> +	 * This config should trigger a SIGSEGV by Kernel when it checks
> +	 * the sigframe consistency in valid_user_regs() routine.
> +	 */
> +	uc->uc_mcontext.pstate |= PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT;
> +
> +	return 1;
> +}
> +
> +struct tdescr tde = {
> +		.sanity_disabled = true,
> +		.name = "MANGLE_PSTATE_INVALID_DAIF_BITS",
> +		.descr = "Mangling uc_mcontext with INVALID DAIF_BITS",
> +		.sig_trig = SIGUSR1,
> +		.sig_ok = SIGSEGV,
> +		.run = mangle_invalid_pstate_run,
> +};
> -- 
> 2.17.1
> 
> 
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