diff options
Diffstat (limited to 'drivers/acpi/acpica/utcksum.c')
| -rw-r--r-- | drivers/acpi/acpica/utcksum.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/drivers/acpi/acpica/utcksum.c b/drivers/acpi/acpica/utcksum.c new file mode 100644 index 000000000000..c166e4c05ab6 --- /dev/null +++ b/drivers/acpi/acpica/utcksum.c @@ -0,0 +1,170 @@ +// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 +/****************************************************************************** + * + * Module Name: utcksum - Support generating table checksums + * + * Copyright (C) 2000 - 2022, 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); +} |