sw/device/tests/smc/smc_page_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/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"

#define CAUSE_USER_ECALL (0x8)
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)));
uint32_t user_l2pt[PAGE_SIZE / sizeof(uint32_t)]
    __attribute__((aligned(PAGE_SIZE)));

extern uint32_t __VIRTUAL_ROM;
extern uint32_t __virtual_start;
extern uint32_t __virtual_end;
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 uint32_t umode_custom_fn_addr = 0;

// Overrides the default supervisor ecall handler.
// From here, we will set the test pass.
void ottf_supervisor_ecall_handler(void) { test_status_set(kTestStatusPassed); }

// Function that will execute in S-mode.
// Passes a virtual function address to the U-mode trampoline.
static __attribute__((section(".super_virtual"))) void smode_fn(void) {
  user_trampoline((uint32_t)umode_custom_fn_addr);
}

// S-mode trap handler.
// We simply ecall into M-mode.
static __attribute__((section(".super_virtual")))
__attribute__((naked, aligned(256))) void
stvec(void) {
  asm volatile(
      ".option push \n"
      ".option norvc \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);
  }

  // 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, one set for user-mode and one set for
  // supervisor-mode.
  machine_map_region((uint32_t)&__VIRTUAL_ROM, (uint32_t)&__virtual_start,
                     (uint32_t)&__virtual_end, supervisor_l1pt, user_l2pt,
                     true);
  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 user-mode's
  // virtual space. We'll use the boundary between the two new pages to trigger
  // page table walks. NB: We add the new pages to the supervisor_l2pt since
  // they reside in the same 4MB segment.
  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, true);

  uint32_t unused_user_paddr =
      (uint32_t)&__SUPER_VIRTUAL_ROM + super_virtual_size_padded;
  uint32_t nop_code[] = {
      0x00000013,  // nop
      0x00000013,  // nop
      0x00000013,  // nop
      0x00000013,  // nop
      0x00000013,  // nop
      0x00000013,  // nop
      0x00000013,  // nop
      0x00000013,  // nop
      0x00000073,  // ecall
  };
  // Generate a target address that puts ~half of the code on each
  // side of the page boundary.
  uint32_t offset = PAGE_SIZE - (sizeof(nop_code) / 2);
  uint32_t target_paddr = unused_user_paddr + offset;
  memcpy((uint32_t *)target_paddr, nop_code, sizeof(nop_code));
  umode_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 U-mode ecalls to S-mode.
  uint32_t medeleg = (1 << CAUSE_USER_ECALL);

  // Execute smode_fn in supervisor mode, after enabling virtual memory.
  supervisor_trampoline((uint32_t)smode_fn, (uint32_t)satp, (uint32_t)medeleg,
                        (uint32_t)stvec, 0);
  __builtin_unreachable();
}