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1// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.02/******************************************************************************3 *4 * Module Name: utcksum - Support generating table checksums5 *6 * Copyright (C) 2000 - 2023, Intel Corp.7 *8 *****************************************************************************/9 10#include <acpi/acpi.h>11#include "accommon.h"12#include "acutils.h"13 14/* This module used for application-level code only */15 16#define _COMPONENT ACPI_CA_DISASSEMBLER17ACPI_MODULE_NAME("utcksum")18 19/*******************************************************************************20 *21 * FUNCTION: acpi_ut_verify_checksum22 *23 * PARAMETERS: table - ACPI table to verify24 * length - Length of entire table25 *26 * RETURN: Status27 *28 * DESCRIPTION: Verifies that the table checksums to zero. Optionally returns29 * exception on bad checksum.30 * Note: We don't have to check for a CDAT here, since CDAT is31 * not in the RSDT/XSDT, and the CDAT table is never installed32 * via ACPICA.33 *34 ******************************************************************************/35acpi_status acpi_ut_verify_checksum(struct acpi_table_header *table, u32 length)36{37 u8 checksum;38 39 /*40 * FACS/S3PT:41 * They are the odd tables, have no standard ACPI header and no checksum42 */43 if (ACPI_COMPARE_NAMESEG(table->signature, ACPI_SIG_S3PT) ||44 ACPI_COMPARE_NAMESEG(table->signature, ACPI_SIG_FACS)) {45 return (AE_OK);46 }47 48 /* Compute the checksum on the table */49 50 length = table->length;51 checksum =52 acpi_ut_generate_checksum(ACPI_CAST_PTR(u8, table), length,53 table->checksum);54 55 /* Computed checksum matches table? */56 57 if (checksum != table->checksum) {58 ACPI_BIOS_WARNING((AE_INFO,59 "Incorrect checksum in table [%4.4s] - 0x%2.2X, "60 "should be 0x%2.2X",61 table->signature, table->checksum,62 table->checksum - checksum));63 64#if (ACPI_CHECKSUM_ABORT)65 return (AE_BAD_CHECKSUM);66#endif67 }68 69 return (AE_OK);70}71 72/*******************************************************************************73 *74 * FUNCTION: acpi_ut_verify_cdat_checksum75 *76 * PARAMETERS: table - CDAT ACPI table to verify77 * length - Length of entire table78 *79 * RETURN: Status80 *81 * DESCRIPTION: Verifies that the CDAT table checksums to zero. Optionally82 * returns an exception on bad checksum.83 *84 ******************************************************************************/85 86acpi_status87acpi_ut_verify_cdat_checksum(struct acpi_table_cdat *cdat_table, u32 length)88{89 u8 checksum;90 91 /* Compute the checksum on the table */92 93 checksum = acpi_ut_generate_checksum(ACPI_CAST_PTR(u8, cdat_table),94 cdat_table->length,95 cdat_table->checksum);96 97 /* Computed checksum matches table? */98 99 if (checksum != cdat_table->checksum) {100 ACPI_BIOS_WARNING((AE_INFO,101 "Incorrect checksum in table [%4.4s] - 0x%2.2X, "102 "should be 0x%2.2X",103 acpi_gbl_CDAT, cdat_table->checksum,104 checksum));105 106#if (ACPI_CHECKSUM_ABORT)107 return (AE_BAD_CHECKSUM);108#endif109 }110 111 cdat_table->checksum = checksum;112 return (AE_OK);113}114 115/*******************************************************************************116 *117 * FUNCTION: acpi_ut_generate_checksum118 *119 * PARAMETERS: table - Pointer to table to be checksummed120 * length - Length of the table121 * original_checksum - Value of the checksum field122 *123 * RETURN: 8 bit checksum of buffer124 *125 * DESCRIPTION: Computes an 8 bit checksum of the table.126 *127 ******************************************************************************/128 129u8 acpi_ut_generate_checksum(void *table, u32 length, u8 original_checksum)130{131 u8 checksum;132 133 /* Sum the entire table as-is */134 135 checksum = acpi_ut_checksum((u8 *)table, length);136 137 /* Subtract off the existing checksum value in the table */138 139 checksum = (u8)(checksum - original_checksum);140 141 /* Compute and return the final checksum */142 143 checksum = (u8)(0 - checksum);144 return (checksum);145}146 147/*******************************************************************************148 *149 * FUNCTION: acpi_ut_checksum150 *151 * PARAMETERS: buffer - Pointer to memory region to be checked152 * length - Length of this memory region153 *154 * RETURN: Checksum (u8)155 *156 * DESCRIPTION: Calculates circular checksum of memory region.157 *158 ******************************************************************************/159 160u8 acpi_ut_checksum(u8 *buffer, u32 length)161{162 u8 sum = 0;163 u8 *end = buffer + length;164 165 while (buffer < end) {166 sum = (u8)(sum + *(buffer++));167 }168 169 return (sum);170}171