plat/arm/common/arm_nor_psci_mem_protect.c

   1 /*
   2  * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
   3  *
   4  * SPDX-License-Identifier: BSD-3-Clause
   5  */
   6
   7 #include <platform_def.h>
   8
   9 #include <common/debug.h>
  10 #include <drivers/cfi/v2m_flash.h>
  11 #include <lib/psci/psci.h>
  12 #include <lib/mmio.h>
  13 #include <lib/utils.h>
  14 #include <plat/arm/common/plat_arm.h>
  15
  16 /*
  17  * DRAM1 is used also to load the NS boot loader. For this reason we
  18  * cannot clear the full DRAM1, because in that case we would clear
  19  * the NS images (especially for RESET_TO_BL31 and RESET_TO_SPMIN cases).
  20  * For this reason we reserve 64 MB for the NS images and protect the RAM
  21  * until the end of DRAM1.
  22  * We limit the size of DRAM2 to 1 GB to avoid big delays while booting
  23  */
  24 #define DRAM1_NS_IMAGE_LIMIT  (PLAT_ARM_NS_IMAGE_BASE + (32 << TWO_MB_SHIFT))
  25 #define DRAM1_PROTECTED_SIZE  (ARM_NS_DRAM1_END+1u - DRAM1_NS_IMAGE_LIMIT)
  26
  27 static mem_region_t arm_ram_ranges[] = {
  28         {DRAM1_NS_IMAGE_LIMIT, DRAM1_PROTECTED_SIZE},
  29 #ifdef AARCH64
  30         {ARM_DRAM2_BASE, 1u << ONE_GB_SHIFT},
  31 #endif
  32 };
  33
  34 /*******************************************************************************
  35  * Function that reads the content of the memory protect variable that
  36  * enables clearing of non secure memory when system boots. This variable
  37  * should be stored in a secure NVRAM.
  38  ******************************************************************************/
  39 int arm_psci_read_mem_protect(int *enabled)
  40 {
  41         int tmp;
  42
  43         tmp = *(int *) PLAT_ARM_MEM_PROT_ADDR;
  44         *enabled = (tmp == 1) ? 1 : 0;
  45         return 0;
  46 }
  47
  48 /*******************************************************************************
  49  * Function that writes the content of the memory protect variable that
  50  * enables overwritten of non secure memory when system boots.
  51  ******************************************************************************/
  52 int arm_nor_psci_write_mem_protect(int val)
  53 {
  54         unsigned long enable = (val != 0) ? 1UL : 0UL;
  55
  56         if (nor_unlock(PLAT_ARM_MEM_PROT_ADDR) != 0) {
  57                 ERROR("unlocking memory protect variable\n");
  58                 return -1;
  59         }
  60
  61         if (enable == 1UL) {
  62                 /*
  63                  * If we want to write a value different than 0
  64                  * then we have to erase the full block because
  65                  * otherwise we cannot ensure that the value programmed
  66                  * into the flash is going to be the same than the value
  67                  * requested by the caller
  68                  */
  69                 if (nor_erase(PLAT_ARM_MEM_PROT_ADDR) != 0) {
  70                         ERROR("erasing block containing memory protect variable\n");
  71                         return -1;
  72                 }
  73         }
  74
  75         if (nor_word_program(PLAT_ARM_MEM_PROT_ADDR, enable) != 0) {
  76                 ERROR("programming memory protection variable\n");
  77                 return -1;
  78         }
  79         return 0;
  80 }
  81
  82 /*******************************************************************************
  83  * Function used for required psci operations performed when
  84  * system boots
  85  ******************************************************************************/
  86 /*
  87  * PLAT_MEM_PROTECT_VA_FRAME is a address specifically
  88  * selected in a way that is not needed an additional
  89  * translation table for memprotect. It happens because
  90  * we use a chunk of size 2MB and it means that it can
  91  * be mapped in a level 2 table and the level 2 table
  92  * for 0xc0000000 is already used and the entry for
  93  * 0xc0000000 is not used.
  94  */
  95 #if defined(PLAT_XLAT_TABLES_DYNAMIC)
  96 void arm_nor_psci_do_dyn_mem_protect(void)
  97 {
  98         int enable;
  99
 100         arm_psci_read_mem_protect(&enable);
 101         if (enable == 0)
 102                 return;
 103
 104         INFO("PSCI: Overwriting non secure memory\n");
 105         clear_map_dyn_mem_regions(arm_ram_ranges,
 106                                   ARRAY_SIZE(arm_ram_ranges),
 107                                   PLAT_ARM_MEM_PROTEC_VA_FRAME,
 108                                   1 << TWO_MB_SHIFT);
 109 }
 110 #endif
 111
 112 /*******************************************************************************
 113  * Function used for required psci operations performed when
 114  * system boots and dynamic memory is not used.
 115  ******************************************************************************/
 116 void arm_nor_psci_do_static_mem_protect(void)
 117 {
 118         int enable;
 119
 120         (void) arm_psci_read_mem_protect(&enable);
 121         if (enable == 0)
 122                 return;
 123
 124         INFO("PSCI: Overwriting non secure memory\n");
 125         clear_mem_regions(arm_ram_ranges,
 126                           ARRAY_SIZE(arm_ram_ranges));
 127         (void) arm_nor_psci_write_mem_protect(0);
 128 }
 129
 130 /*******************************************************************************
 131  * Function that checks if a region is protected by the memory protect
 132  * mechanism
 133  ******************************************************************************/
 134 int arm_psci_mem_protect_chk(uintptr_t base, u_register_t length)
 135 {
 136         return mem_region_in_array_chk(arm_ram_ranges,
 137                                        ARRAY_SIZE(arm_ram_ranges),
 138                                        base, length);
 139 }