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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 | // SPDX-License-Identifier: GPL-2.0-only /* * SMI methods for use with dell-smbios * * Copyright (c) Red Hat <mjg@redhat.com> * Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com> * Copyright (c) 2014 Pali Rohár <pali@kernel.org> * Copyright (c) 2017 Dell Inc. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/dmi.h> #include <linux/gfp.h> #include <linux/io.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/platform_device.h> #include "dcdbas.h" #include "dell-smbios.h" static int da_command_address; static int da_command_code; static struct smi_buffer smi_buf; static struct calling_interface_buffer *buffer; static struct platform_device *platform_device; static DEFINE_MUTEX(smm_mutex); static void parse_da_table(const struct dmi_header *dm) { struct calling_interface_structure *table = container_of(dm, struct calling_interface_structure, header); /* 4 bytes of table header, plus 7 bytes of Dell header, plus at least * 6 bytes of entry */ if (dm->length < 17) return; da_command_address = table->cmdIOAddress; da_command_code = table->cmdIOCode; } static void find_cmd_address(const struct dmi_header *dm, void *dummy) { switch (dm->type) { case 0xda: /* Calling interface */ parse_da_table(dm); break; } } static int dell_smbios_smm_call(struct calling_interface_buffer *input) { struct smi_cmd command; size_t size; size = sizeof(struct calling_interface_buffer); command.magic = SMI_CMD_MAGIC; command.command_address = da_command_address; command.command_code = da_command_code; command.ebx = smi_buf.dma; command.ecx = 0x42534931; mutex_lock(&smm_mutex); memcpy(buffer, input, size); dcdbas_smi_request(&command); memcpy(input, buffer, size); mutex_unlock(&smm_mutex); return 0; } /* When enabled this indicates that SMM won't work */ static bool test_wsmt_enabled(void) { struct calling_interface_token *wsmt; /* if token doesn't exist, SMM will work */ wsmt = dell_smbios_find_token(WSMT_EN_TOKEN); if (!wsmt) return false; /* If token exists, try to access over SMM but set a dummy return. * - If WSMT disabled it will be overwritten by SMM * - If WSMT enabled then dummy value will remain */ buffer->cmd_class = CLASS_TOKEN_READ; buffer->cmd_select = SELECT_TOKEN_STD; memset(buffer, 0, sizeof(struct calling_interface_buffer)); buffer->input[0] = wsmt->location; buffer->output[0] = 99; dell_smbios_smm_call(buffer); if (buffer->output[0] == 99) return true; return false; } int init_dell_smbios_smm(void) { int ret; /* * Allocate buffer below 4GB for SMI data--only 32-bit physical addr * is passed to SMI handler. */ ret = dcdbas_smi_alloc(&smi_buf, PAGE_SIZE); if (ret) return ret; buffer = (void *)smi_buf.virt; dmi_walk(find_cmd_address, NULL); if (test_wsmt_enabled()) { pr_debug("Disabling due to WSMT enabled\n"); ret = -ENODEV; goto fail_wsmt; } platform_device = platform_device_alloc("dell-smbios", 1); if (!platform_device) { ret = -ENOMEM; goto fail_platform_device_alloc; } ret = platform_device_add(platform_device); if (ret) goto fail_platform_device_add; ret = dell_smbios_register_device(&platform_device->dev, &dell_smbios_smm_call); if (ret) goto fail_register; return 0; fail_register: platform_device_del(platform_device); fail_platform_device_add: platform_device_put(platform_device); fail_wsmt: fail_platform_device_alloc: dcdbas_smi_free(&smi_buf); return ret; } void exit_dell_smbios_smm(void) { if (platform_device) { dell_smbios_unregister_device(&platform_device->dev); platform_device_unregister(platform_device); dcdbas_smi_free(&smi_buf); } } |