// ################################################################################################# // # << NEORV32 - Physical Memory Protection Example Program >> # // # ********************************************************************************************* # // # BSD 3-Clause License # // # # // # Copyright (c) 2022, Stephan Nolting. All rights reserved. # // # # // # Redistribution and use in source and binary forms, with or without modification, are # // # permitted provided that the following conditions are met: # // # # // # 1. Redistributions of source code must retain the above copyright notice, this list of # // # conditions and the following disclaimer. # // # # // # 2. Redistributions in binary form must reproduce the above copyright notice, this list of # // # conditions and the following disclaimer in the documentation and/or other materials # // # provided with the distribution. # // # # // # 3. Neither the name of the copyright holder nor the names of its contributors may be used to # // # endorse or promote products derived from this software without specific prior written # // # permission. # // # # // # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS # // # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF # // # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE # // # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, # // # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE # // # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED # // # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING # // # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED # // # OF THE POSSIBILITY OF SUCH DAMAGE. # // # ********************************************************************************************* # // # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting # // ################################################################################################# /**********************************************************************//** * @file demo_pmp/main.c * @author Stephan Nolting * @brief Physical memory protection (PMP) example program. **************************************************************************/ #include /**********************************************************************//** * @name User configuration **************************************************************************/ /**@{*/ /** UART BAUD rate */ #define BAUD_RATE 19200 /**@}*/ /**********************************************************************//** * Example variable that will be protected by the PMP **************************************************************************/ uint32_t protected_var[4] = { 0x11223344, 0x55667788, 0x00CAFE00, 0xDEADC0DE }; /**********************************************************************//** * Main function * * @note This program requires the CPU PMP extension (with at least 2 regions) and UART0. * * @return 0 if execution was successful **************************************************************************/ int main() { // initialize NEORV32 run-time environment neorv32_rte_setup(); // setup UART0 at default baud rate, no parity bits, no HW flow control neorv32_uart0_setup(BAUD_RATE, PARITY_NONE, FLOW_CONTROL_NONE); // check if UART0 is implemented if (neorv32_uart0_available() == 0) { return 1; // UART0 not available, exit } // check if PMP is implemented at all if ((neorv32_cpu_csr_read(CSR_MXISA) & (1 << CSR_MXISA_PMP)) == 0) { neorv32_uart0_printf("ERROR! PMP CPU extension not implemented!\n"); return 1; } // intro neorv32_uart0_printf("\n<<< NEORV32 Physical Memory Protection (PMP) Example Program >>>\n\n"); neorv32_uart0_printf("NOTE: This program requires at least 2 PMP regions (PMP_NUM_REGIONS >= 2)\n" "and a minimal granularity of 4 bytes (PMP_MIN_GRANULARITY = 4).\n\n"); // show PMP configuration neorv32_uart0_printf("PMP hardware configuration:\n"); neorv32_uart0_printf("> Number of regions: %u\n", neorv32_cpu_pmp_get_num_regions()); neorv32_uart0_printf("> Min. granularity: %u bytes (minimal region size)\n\n", neorv32_cpu_pmp_get_granularity()); // PMP hardware configuration sufficient? uint32_t tmp; tmp = neorv32_cpu_pmp_get_num_regions(); if (tmp < 2) { neorv32_uart0_printf("ERROR! Insufficient PMP region! Regions required = 2; region available = %u\n", tmp); return 1; } tmp = neorv32_cpu_pmp_get_granularity(); if (tmp > 4) { neorv32_uart0_printf("ERROR! Insufficient PMP granularity! Granularity required = 4 bytes; granularity available = %u bytes\n", tmp); return 1; } neorv32_uart0_printf("NOTE: A 4-word array 'protected_var[4]' is created, which will be probed from\n" "machine-mode. The region provides the following access permissions:\n" "> !X - no execute permission\n" "> !W - no write permission\n" "> R - read permission\n" "> L - enforce access rights for machine-mode software\n\n"); // The "protected_var" variable will be protected: No execute and no write access, just allow read access // create protected region int pmp_status; uint8_t permissions; neorv32_uart0_printf("Creating protected regions (any access within [REGION_BEGIN <= address < REGION_END] will match the PMP rules)...\n"); // any access in "region_begin <= address < region_end" will match the PMP rule uint32_t region_begin = (uint32_t)(&protected_var[0]); uint32_t region_end = (uint32_t)(&protected_var[3]) + 4; neorv32_uart0_printf("REGION_BEGIN = 0x%x\n", region_begin); neorv32_uart0_printf("REGION_END = 0x%x\n", region_end); // base (region begin) permissions = PMP_OFF << PMPCFG_A_LSB; // mode = OFF neorv32_uart0_printf("> Region begin (PMP entry 0): Base = 0x%x, Mode = OFF (base of region) ", region_begin); pmp_status = neorv32_cpu_pmp_configure_region(0, region_begin, permissions); if (pmp_status) { neorv32_uart0_printf("[FAILED]\n"); } else { neorv32_uart0_printf("[ok]\n"); } // bound (region end) permissions = (PMP_TOR << PMPCFG_A_LSB) | // enable entry as TOR = top of region (0 << PMPCFG_X) | // no "execute" permission (0 << PMPCFG_W) | // no "write" permission (1 << PMPCFG_R) | // set "read" permission (1 << PMPCFG_L); // locked: enforce PMP rule for machine-mode software neorv32_uart0_printf("> Region end (PMP entry 1): Base = 0x%x, Mode = TOR (bound of region) ", region_end); pmp_status = neorv32_cpu_pmp_configure_region(1, region_end, permissions); if (pmp_status) { neorv32_uart0_printf("[FAILED]\n"); } else { neorv32_uart0_printf("[ok]\n"); } // test access neorv32_uart0_printf("\n\nTesting access to 'protected_var' - invalid accesses will raise an exception, which will be\n" "captured by the NEORV32 runtime environment's dummy/debug handlers (' ... ').\n\n"); neorv32_uart0_printf("Reading protected_var[0] @ 0x%x = 0x%x\n", (uint32_t)(&protected_var[0]), protected_var[0]); neorv32_uart0_printf("Reading protected_var[1] @ 0x%x = 0x%x\n", (uint32_t)(&protected_var[1]), protected_var[1]); neorv32_uart0_printf("Reading protected_var[2] @ 0x%x = 0x%x\n", (uint32_t)(&protected_var[2]), protected_var[2]); neorv32_uart0_printf("Reading protected_var[3] @ 0x%x = 0x%x\n\n", (uint32_t)(&protected_var[3]), protected_var[3]); neorv32_uart0_printf("Trying to write protected_var[0] @ 0x%x... \n", (uint32_t)(&protected_var[0])); protected_var[0] = 0; // should fail! neorv32_uart0_printf("Trying to write protected_var[1] @ 0x%x... \n", (uint32_t)(&protected_var[1])); protected_var[1] = 0; // should fail! neorv32_uart0_printf("Trying to write protected_var[2] @ 0x%x... \n", (uint32_t)(&protected_var[2])); protected_var[2] = 0; // should fail! neorv32_uart0_printf("Trying to write protected_var[3] @ 0x%x... \n", (uint32_t)(&protected_var[3])); protected_var[3] = 0; // should fail! neorv32_uart0_printf("\nReading again protected_var[0] @ 0x%x = 0x%x\n", (uint32_t)(&protected_var[0]), protected_var[0]); neorv32_uart0_printf("Reading again protected_var[1] @ 0x%x = 0x%x\n", (uint32_t)(&protected_var[1]), protected_var[1]); neorv32_uart0_printf("Reading again protected_var[2] @ 0x%x = 0x%x\n", (uint32_t)(&protected_var[2]), protected_var[2]); neorv32_uart0_printf("Reading again protected_var[3] @ 0x%x = 0x%x\n\n", (uint32_t)(&protected_var[3]), protected_var[3]); neorv32_uart0_printf("\nPMP demo program completed.\n"); return 0; }