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);
+}