2022-10-28 01:58:36 +08:00
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// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
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/******************************************************************************
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*
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* Module Name: utcksum - Support generating table checksums
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*
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2023-04-05 21:38:21 +08:00
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* Copyright (C) 2000 - 2023, Intel Corp.
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2022-10-28 01:58:36 +08:00
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*
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*****************************************************************************/
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#include <acpi/acpi.h>
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#include "accommon.h"
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#include "acutils.h"
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/* This module used for application-level code only */
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#define _COMPONENT ACPI_CA_DISASSEMBLER
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ACPI_MODULE_NAME("utcksum")
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/*******************************************************************************
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*
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* FUNCTION: acpi_ut_verify_checksum
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*
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* PARAMETERS: table - ACPI table to verify
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* length - Length of entire table
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*
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* RETURN: Status
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*
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* DESCRIPTION: Verifies that the table checksums to zero. Optionally returns
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* exception on bad checksum.
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* Note: We don't have to check for a CDAT here, since CDAT is
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* not in the RSDT/XSDT, and the CDAT table is never installed
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* via ACPICA.
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*
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******************************************************************************/
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acpi_status acpi_ut_verify_checksum(struct acpi_table_header *table, u32 length)
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{
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u8 checksum;
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/*
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* FACS/S3PT:
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* They are the odd tables, have no standard ACPI header and no checksum
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*/
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if (ACPI_COMPARE_NAMESEG(table->signature, ACPI_SIG_S3PT) ||
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ACPI_COMPARE_NAMESEG(table->signature, ACPI_SIG_FACS)) {
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return (AE_OK);
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}
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/* Compute the checksum on the table */
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length = table->length;
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checksum =
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acpi_ut_generate_checksum(ACPI_CAST_PTR(u8, table), length,
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table->checksum);
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/* Computed checksum matches table? */
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if (checksum != table->checksum) {
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ACPI_BIOS_WARNING((AE_INFO,
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"Incorrect checksum in table [%4.4s] - 0x%2.2X, "
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"should be 0x%2.2X",
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table->signature, table->checksum,
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table->checksum - checksum));
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#if (ACPI_CHECKSUM_ABORT)
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return (AE_BAD_CHECKSUM);
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#endif
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}
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return (AE_OK);
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}
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/*******************************************************************************
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*
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* FUNCTION: acpi_ut_verify_cdat_checksum
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*
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* PARAMETERS: table - CDAT ACPI table to verify
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* length - Length of entire table
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*
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* RETURN: Status
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*
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* DESCRIPTION: Verifies that the CDAT table checksums to zero. Optionally
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* returns an exception on bad checksum.
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*
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******************************************************************************/
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acpi_status
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acpi_ut_verify_cdat_checksum(struct acpi_table_cdat *cdat_table, u32 length)
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{
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u8 checksum;
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/* Compute the checksum on the table */
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checksum = acpi_ut_generate_checksum(ACPI_CAST_PTR(u8, cdat_table),
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cdat_table->length,
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cdat_table->checksum);
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/* Computed checksum matches table? */
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if (checksum != cdat_table->checksum) {
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ACPI_BIOS_WARNING((AE_INFO,
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"Incorrect checksum in table [%4.4s] - 0x%2.2X, "
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"should be 0x%2.2X",
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acpi_gbl_CDAT, cdat_table->checksum,
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checksum));
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#if (ACPI_CHECKSUM_ABORT)
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return (AE_BAD_CHECKSUM);
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#endif
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}
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cdat_table->checksum = checksum;
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return (AE_OK);
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}
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/*******************************************************************************
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*
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* FUNCTION: acpi_ut_generate_checksum
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*
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* PARAMETERS: table - Pointer to table to be checksummed
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* length - Length of the table
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* original_checksum - Value of the checksum field
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*
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* RETURN: 8 bit checksum of buffer
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*
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* DESCRIPTION: Computes an 8 bit checksum of the table.
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*
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******************************************************************************/
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u8 acpi_ut_generate_checksum(void *table, u32 length, u8 original_checksum)
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{
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u8 checksum;
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/* Sum the entire table as-is */
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checksum = acpi_ut_checksum((u8 *)table, length);
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/* Subtract off the existing checksum value in the table */
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checksum = (u8)(checksum - original_checksum);
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/* Compute and return the final checksum */
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checksum = (u8)(0 - checksum);
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return (checksum);
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}
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/*******************************************************************************
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*
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* FUNCTION: acpi_ut_checksum
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*
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* PARAMETERS: buffer - Pointer to memory region to be checked
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* length - Length of this memory region
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*
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* RETURN: Checksum (u8)
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*
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* DESCRIPTION: Calculates circular checksum of memory region.
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*
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******************************************************************************/
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u8 acpi_ut_checksum(u8 *buffer, u32 length)
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{
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u8 sum = 0;
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u8 *end = buffer + length;
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while (buffer < end) {
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sum = (u8)(sum + *(buffer++));
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}
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return (sum);
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}
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