sw/device/tests/smc/smc_interrupt_boundary_test.c

/*
 * Copyright 2023 Google LLC
 * Copyright lowRISC contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "hw/top_matcha/sw/autogen/top_matcha.h"
#include "sw/device/lib/base/csr.h"
#include "sw/device/lib/dif/dif_rv_timer.h"
#include "sw/device/lib/runtime/log.h"
#include "sw/device/lib/runtime/print.h"
#include "sw/device/lib/testing/test_framework/check.h"
#include "sw/device/lib/testing/test_framework/ottf_test_config.h"
#include "sw/device/lib/testing/test_framework/status.h"
#include "sw/device/lib/testing/test_framework/test_util.h"
#include "sw/device/lib/virtual_memory.h"

uint32_t supervisor_l1pt[PAGE_SIZE / sizeof(uint32_t)]
    __attribute__((aligned(PAGE_SIZE)));
uint32_t supervisor_l2pt[PAGE_SIZE / sizeof(uint32_t)]
    __attribute__((aligned(PAGE_SIZE)));

extern uint32_t __SUPER_VIRTUAL_ROM;
extern uint32_t __super_virtual_start;
extern uint32_t __super_virtual_end;

OTTF_DEFINE_TEST_CONFIG();

static dif_uart_t smc_uart;
static dif_rv_timer_t rv_timer;
static uint32_t supervisor_custom_fn_addr = 0;

// Overrides the default supervisor ecall handler.
// In this test, any ecalls indicate that we took an unexpected interrupt,
// so fail the test.
void ottf_supervisor_ecall_handler(void) { test_status_set(kTestStatusFailed); }

// Function that will execute in S-mode.
// Triggers a test pass.
__attribute__((section(".super_virtual"))) void smode_fn(void) {
  test_status_set(kTestStatusPassed);
}

// S-mode trap handler.
// All entries are ecall, except the timer entry.
static __attribute__((section(".super_virtual")))
__attribute__((naked, aligned(256))) void
stvec(void) {
  asm volatile(
      ".option push \n"
      ".option norvc \n"
      "ecall \n"
      "ecall \n"
      "ecall \n"
      "ecall \n"
      "ecall \n"
      // Timer interrupt is index 5
      "j smode_fn \n"
      "ecall \n"
      "ecall \n"
      "ecall \n"
      "ecall \n"
      "ecall \n"
      "ecall \n"
      "ecall \n"
      "ecall \n"
      ".option pop \n");
}

void _ottf_main(void) {
  test_status_set(kTestStatusInTest);

  // Initialize the SMC UART to enable logging for non-DV simulation platforms.
  if (kDeviceType != kDeviceSimDV) {
    init_uart(TOP_MATCHA_SMC_UART_BASE_ADDR, &smc_uart);
  }

  dif_rv_timer_tick_params_t tick_params;
  CHECK_DIF_OK(dif_rv_timer_approximate_tick_params(kClockFreqPeripheralHz,
                                                    1000000, &tick_params));
  CHECK_DIF_OK(dif_rv_timer_init(
      mmio_region_from_addr(TOP_MATCHA_RV_TIMER_SMC_BASE_ADDR), &rv_timer));
  CHECK_DIF_OK(dif_rv_timer_set_tick_params(&rv_timer, 0, tick_params));
  CHECK_DIF_OK(dif_rv_timer_irq_set_enabled(
      &rv_timer, kDifRvTimerIrqTimerExpiredHart0Timer0, kDifToggleEnabled));
  uint64_t counter_start;
  CHECK_DIF_OK(dif_rv_timer_counter_read(&rv_timer, 0, &counter_start));
  CHECK_DIF_OK(dif_rv_timer_arm(&rv_timer, 0, 0, counter_start + 1000));
  CHECK_DIF_OK(
      dif_rv_timer_counter_set_enabled(&rv_timer, 0, kDifToggleEnabled));

  // Map our code space and UART peripheral.
  // Both are mapped such that the virtual addresses
  // and physical addresses are the same, but this still
  // causes address translation to happen.
  machine_map_megapage((void *)TOP_MATCHA_RAM_SMC_BASE_ADDR,
                       (void *)TOP_MATCHA_RAM_SMC_BASE_ADDR,
                       (uint32_t *)supervisor_l1pt);
  machine_map_megapage((void *)TOP_MATCHA_SMC_UART_BASE_ADDR,
                       (void *)TOP_MATCHA_SMC_UART_BASE_ADDR,
                       (uint32_t *)supervisor_l1pt);

  // Set up 2-level page tables for supervisor-mode
  machine_map_region(
      (uint32_t)&__SUPER_VIRTUAL_ROM, (uint32_t)&__super_virtual_start,
      (uint32_t)&__super_virtual_end, supervisor_l1pt, supervisor_l2pt, false);

  // Map the next two physical pages after supervisor's space into supervisor's
  // virtual memory space.
  uint32_t super_virtual_size = &__super_virtual_end - &__super_virtual_start;
  uint32_t super_virtual_size_padded =
      (super_virtual_size + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);
  machine_map_region(
      (uint32_t)&__SUPER_VIRTUAL_ROM + super_virtual_size_padded,
      (uint32_t)&__super_virtual_start + super_virtual_size_padded,
      (uint32_t)&__super_virtual_start + super_virtual_size_padded +
          (PAGE_SIZE * 2),
      supervisor_l1pt, supervisor_l2pt, false);

  uint32_t unused_supervisor_paddr =
      (uint32_t)&__SUPER_VIRTUAL_ROM + super_virtual_size_padded;
  // This code enables the timer interrupt, followed by an ecall.
  // When placed near a page boundary with the timer already expired,
  // this should cause an interrupt during a page table walk.
  uint32_t enable_isr_code[] = {
      0x02000513,  // li a0,32
      0x10452073,  // csrs sie,a0
      0x00000073,  // ecall
  };
  // Offset the code such that it straddles the page boundary.
  uint32_t offset = PAGE_SIZE - (sizeof(uint32_t) * 2);
  uint32_t target_paddr = unused_supervisor_paddr + offset;
  memcpy((uint32_t *)target_paddr, enable_isr_code, sizeof(enable_isr_code));
  supervisor_custom_fn_addr =
      (uint32_t)&__super_virtual_start + super_virtual_size_padded + offset;

  // Calculate the value of the SATP register.
  // We enable SV32 virtual memory, and store the page
  // containing our page tables.
  uint32_t satp = (uint32_t)(0x1llu << 31) | ((uint32_t)supervisor_l1pt >> 12);

  // Delegate the timer interrupt to supervisor mode.
  uint32_t mideleg = (1 << 5);

  // Wait until the timer interrupt 'expires'. That way, we will receive
  // it immediately upon enabling supervisor interrupts.
  dif_rv_timer_irq_state_snapshot_t snapshot = 0;
  do {
    CHECK_DIF_OK(dif_rv_timer_irq_get_state(&rv_timer, 0, &snapshot));
  } while (!snapshot);

  // Execute supervisor_custom_fn_addr_fn in supervisor mode, after enabling
  // virtual memory.
  supervisor_trampoline((uint32_t)supervisor_custom_fn_addr, (uint32_t)satp, 0,
                        (uint32_t)stvec | 1, (uint32_t)mideleg);
  __builtin_unreachable();
}