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