tests: arch: riscv: make sure that `gp` reg can't be corrupted

# SPDX-License-Identifier: Apache-2.0

cmake_minimum_required(VERSION 3.20.0)

find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})

project(riscv_gp)

FILE(GLOB app_sources src/*.c)

target_sources(app PRIVATE ${app_sources})

CONFIG_ZTEST=y

CONFIG_RISCV_GP=y

CONFIG_TEST_USERSPACE=y

/*

 * Copyright (c) 2024 Meta Platforms

 *

 * SPDX-License-Identifier: Apache-2.0

 */

#include <stdio.h>

#include <zephyr/arch/riscv/reg.h>

#include <zephyr/kernel.h>

#include <zephyr/ztest.h>

#define ROGUE_USER_STACK_SZ 2048

static struct k_thread rogue_user_thread;

static K_THREAD_STACK_DEFINE(rogue_user_stack, ROGUE_USER_STACK_SZ);

static void rogue_user_fn(void *p1, void *p2, void *p3)

{

	zassert_true(k_is_user_context());

	reg_write(gp, 0xbad);

	zassert_equal(reg_read(gp), 0xbad);

}

ZTEST_USER(riscv_gp, test_gp_value)

{

	uintptr_t gp_val = reg_read(gp);

	k_tid_t th;

	zassert_not_equal(gp_val, 0);

	th = k_thread_create(&rogue_user_thread, rogue_user_stack, ROGUE_USER_STACK_SZ,

			     rogue_user_fn, NULL, NULL, NULL, -1, K_USER, K_NO_WAIT);

	zassert_ok(k_thread_join(th, K_FOREVER));

	zassert_equal(reg_read(gp), gp_val, "`gp` corrupted by user thread");

}

static void *userspace_setup(void)

{

	k_thread_access_grant(k_current_get(), &rogue_user_thread, &rogue_user_stack);

	return NULL;

}

ZTEST_SUITE(riscv_gp, NULL, userspace_setup, NULL, NULL, NULL);

common:

  ignore_faults: true

  ignore_qemu_crash: true

  tags: kernel riscv

  platform_allow:

    - qemu_riscv64

tests:

  arch.riscv64.riscv_gp: {}