kselftest: arm64: fake_sigreturn_missing_fpsimd

// 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);

		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,

};