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