Re: [PATCH v5 08/11] kselftest: arm64: fake_sigreturn_missing_fpsimd

From: Cristian Marussi <cristian.marussi@arm.com>
To: Dave Martin <Dave.Martin@arm.com>
Cc: linux-kselftest@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, shuah@kernel.org,
	amit.kachhap@arm.com, andreyknvl@google.com
Subject: Re: [PATCH v5 08/11] kselftest: arm64: fake_sigreturn_missing_fpsimd
Date: Mon, 9 Sep 2019 18:51:20 +0100	[thread overview]
Message-ID: <8cabc8ff-fe9f-f476-a58b-0bf0fb71c499@arm.com> (raw)
In-Reply-To: <20190904114910.GY27757@arm.com>

On 04/09/2019 12:49, Dave Martin wrote:
> On Mon, Sep 02, 2019 at 12:29:29pm +0100, Cristian Marussi wrote:
>> Add a simple fake_sigreturn testcase which builds a ucontext_t without
>> the required fpsimd_context and place it onto the stack.
>> Expects a SIGSEGV on test PASS.
>>
>> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
>> ---
>> v3 --> v4
>> - fix commit
>> - added signal.h
>> - added test description
>> ---
>>  .../testcases/fake_sigreturn_missing_fpsimd.c | 50 +++++++++++++++++++
>>  1 file changed, 50 insertions(+)
>>  create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c
>>
>> diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c
>> new file mode 100644
>> index 000000000000..08ecd8073a1a
>> --- /dev/null
>> +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c
>> @@ -0,0 +1,50 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2019 ARM Limited
>> + *
>> + * Place a fake sigframe on the stack missing the mandatory FPSIMD
>> + * record: on sigreturn Kernel must spot this attempt and the test
>> + * case is expected to be terminated via SEGV.
>> + */
>> +
>> +#include <stdio.h>
>> +#include <signal.h>
>> +#include <ucontext.h>
>> +
>> +#include "test_signals_utils.h"
>> +#include "testcases.h"
>> +
>> +struct fake_sigframe sf;
>> +
>> +static int fake_sigreturn_missing_fpsimd_run(struct tdescr *td,
>> +					     siginfo_t *si, ucontext_t *uc)
>> +{
>> +	size_t resv_sz, offset;
>> +	struct _aarch64_ctx *head = GET_SF_RESV_HEAD(sf);
>> +
>> +	/* just to fill the ucontext_t with something real */
>> +	if (!get_current_context(td, &sf.uc))
>> +		return 1;
>> +
>> +	resv_sz = GET_SF_RESV_SIZE(sf);
>> +	head = get_header(head, FPSIMD_MAGIC, resv_sz, &offset);
>> +	if (head && resv_sz - offset >= HDR_SZ) {
>> +		fprintf(stderr, "Mangling template header. Spare space:%zd\n",
>> +			resv_sz - offset);
>> +		/* Just overwrite fpsmid_context */
>> +		write_terminator_record(head);
> 
> Strictly speaking, we may be throwing away more than just the
> fpsimd_context record here.
> 
> But I think the test works nonetheless.  fpsimd_context is the only
> record that's mandatory in any case.

Ok
> 
>> +
>> +		ASSERT_BAD_CONTEXT(&sf.uc);
>> +		fake_sigreturn(&sf, sizeof(sf), 0);
>> +	}
>> +
>> +	return 1;
>> +}
>> +
>> +struct tdescr tde = {
>> +		.name = "FAKE_SIGRETURN_MISSING_FPSIMD",
>> +		.descr = "Triggers a sigreturn with a missing fpsimd_context",
>> +		.sig_ok = SIGSEGV,
>> +		.timeout = 3,
>> +		.run = fake_sigreturn_missing_fpsimd_run,
>> +};
> 
> Assuming the comment I just posted on v3 of this patch makes sense to you,
> 
> Reviewed-by: Dave Martin <Dave.Martin@arm.com>
> 
Thanks

Cheers

Cristian