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From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: cristian.marussi@arm.com, linux-kselftest@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, shuah@kernel.org
Cc: amit.kachhap@arm.com, andreyknvl@google.com, dave.martin@arm.com
Subject: Re: [PATCH v9 02/12] kselftest: arm64: mangle_pstate_invalid_compat_toggle and common utils
Date: Thu, 24 Oct 2019 23:41:50 +0100	[thread overview]
Message-ID: <dde06d83-4c3b-0be4-db98-e740a1dd327e@arm.com> (raw)
In-Reply-To: <20191009120459.21805-3-cristian.marussi@arm.com>

Hi Cristian,

On 10/09/2019 01:04 PM, Cristian Marussi wrote:
> Add some arm64/signal specific boilerplate and utility code to help
> further testcases' development.
> 
> Introduce also one simple testcase mangle_pstate_invalid_compat_toggle
> and some related helpers: it is a simple mangle testcase which messes
> with the ucontext_t from within the signal handler, trying to toggle
> PSTATE state bits to switch the system between 32bit/64bit execution
> state. Expects SIGSEGV on test PASS.
> 
> Reviewed-by: Dave Martin <Dave.Martin@arm.com>
> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>

[...]

> +
> +#define get_regval(regname, out)			\
> +{							\
> +	asm volatile("mrs %0, " __stringify(regname)	\
> +	: "=r" (out)					\
> +	:						\
> +	: "memory");					\
> +}
> +
> +/* Regs encoding and masks naming copied in from sysreg.h */
> +#define SYS_ID_AA64MMFR1_EL1	S3_0_C0_C7_1	/* MRS Emulated */
> +#define SYS_ID_AA64MMFR2_EL1	S3_0_C0_C7_2	/* MRS Emulated */
> +#define ID_AA64MMFR1_PAN_SHIFT	20
> +#define ID_AA64MMFR2_UAO_SHIFT	4
> +
> +/* Local Helpers */
> +#define ID_AA64MMFR1_EL1_PAN_SUPPORTED(val) \
> +	(!!((val) & (0xfUL << ID_AA64MMFR1_PAN_SHIFT)))
> +#define ID_AA64MMFR2_EL1_UAO_SUPPORTED(val) \
> +	(!!((val) & (0xfUL << ID_AA64MMFR2_UAO_SHIFT)))
> +
> +/*
> + * Feature flags used in tdescr.feats_required to specify
> + * any feature by the test
> + */
> +enum {
> +	FSSBS_BIT,
> +	FPAN_BIT,
> +	FUAO_BIT,
> +	FMAX_END
> +};
> +
> +#define FEAT_SSBS		(1UL << FSSBS_BIT)
> +#define FEAT_PAN		(1UL << FPAN_BIT)
> +#define FEAT_UAO		(1UL << FUAO_BIT)
> +

[...]

> +static int test_init(struct tdescr *td)
> +{
> +	td->minsigstksz = getauxval(AT_MINSIGSTKSZ);
> +	if (!td->minsigstksz)
> +		td->minsigstksz = MINSIGSTKSZ;
> +	fprintf(stderr, "Detected MINSTKSIGSZ:%d\n", td->minsigstksz);
> +
> +	if (td->feats_required) {
> +		td->feats_supported = 0;
> +		/*
> +		 * Checking for CPU required features using both the
> +		 * auxval and the arm64 MRS Emulation to read sysregs.
> +		 */
> +		if (getauxval(AT_HWCAP) & HWCAP_SSBS)
> +			td->feats_supported |= FEAT_SSBS;
> +		if (getauxval(AT_HWCAP) & HWCAP_CPUID) {
> +			uint64_t val = 0;
> +
> +			/* Uses MRS emulation to check capability */
> +			get_regval(SYS_ID_AA64MMFR1_EL1, val);
> +			if (ID_AA64MMFR1_EL1_PAN_SUPPORTED(val))
> +				td->feats_supported |= FEAT_PAN;
> +			/* Uses MRS emulation to check capability */
> +			get_regval(SYS_ID_AA64MMFR2_EL1, val);
> +			if (ID_AA64MMFR2_EL1_UAO_SUPPORTED(val))
> +				td->feats_supported |= FEAT_UAO;

As discussed, these fields are never exposed to userspace via mrs. So
you may as well drop these features.

Cheers
Suzuki

  reply	other threads:[~2019-10-24 22:38 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-09 12:04 [PATCH v9 00/12] Add arm64/signal initial kselftest support Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 01/12] kselftest: arm64: extend toplevel skeleton Makefile Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 02/12] kselftest: arm64: mangle_pstate_invalid_compat_toggle and common utils Cristian Marussi
2019-10-24 22:41   ` Suzuki K Poulose [this message]
2019-10-25  9:56     ` Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 03/12] kselftest: arm64: mangle_pstate_invalid_daif_bits Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 04/12] kselftest: arm64: mangle_pstate_invalid_mode_el[123][ht] Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 05/12] kselftest: arm64: extend test_init functionalities Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 06/12] kselftest: arm64: add helper get_current_context Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 07/12] kselftest: arm64: fake_sigreturn_bad_magic Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 08/12] kselftest: arm64: fake_sigreturn_bad_size_for_magic0 Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 09/12] kselftest: arm64: fake_sigreturn_missing_fpsimd Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 10/12] kselftest: arm64: fake_sigreturn_duplicated_fpsimd Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 11/12] kselftest: arm64: fake_sigreturn_bad_size Cristian Marussi
2019-10-09 12:04 ` [PATCH v9 12/12] kselftest: arm64: fake_sigreturn_misaligned_sp Cristian Marussi

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