Subject: Re: [PATCH v6 02/11] kselftest: arm64: mangle_pstate_invalid_compat_toggle and common utils

From: Cristian Marussi <[email-masked]>
Date: Thu, 26 Sep 2019 12:00:13 +0100

On 17/09/2019 17:05, Dave Martin wrote:
> On Tue, Sep 10, 2019 at 01:31:02pm +0100, 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.
>>
>> Signed-off-by: Cristian Marussi <[email-masked]>
>> ---
>> v5 --> v6
>> - fix commit msg
>> - feat_names is char const *const
>> - better supported options check and reporting
>> - removed critical asserts to avoid issues with NDEBUG
>> - more robust get_header
>> - fix validation for ESR_CONTEXT size
>> - add more explicit comment in GET_RESV_NEXT_HEAD() macro
>> - refactored default_handler()
>> - feats_ok() now public
>> - call always test_results() no matter the outcome of test_run()
> 
> [...]
> 
>> diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.c b/tools/testing/selftests/arm64/signal/test_signals_utils.c
> 
> [...]
> 
>> +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;
>> +		} else {
>> +			fprintf(stderr,
>> +				"HWCAP_CPUID NOT available. Mark ALL feats UNSUPPORTED.\n");
> 
> Nit: this message isn't strictly correct now: SSBS may still be detected
> even if HWCAP_CPUID isn't present.
> 
> For simplicity I suggest to drop this fprintf() (and the containing
> else { }, which is otherwise empty).
> 
> The following code reports what features are supported in any case, so
> the user will be able to see what was detected.
> 
> 
> The rest looks reasonable to me now, so with the above nit fixed:
> 
> Reviewed-by: Dave Martin <[email-masked]>

Thanks I'll do the above fixes in v7.

Cristian
> [...]
> Cheers
> ---Dave

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