1 | // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 |
2 | /****************************************************************************** |
3 | * |
4 | * Module Name: utcksum - Support generating table checksums |
5 | * |
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_DISASSEMBLER |
17 | ACPI_MODULE_NAME("utcksum" ) |
18 | |
19 | /******************************************************************************* |
20 | * |
21 | * FUNCTION: acpi_ut_verify_checksum |
22 | * |
23 | * PARAMETERS: table - ACPI table to verify |
24 | * length - Length of entire table |
25 | * |
26 | * RETURN: Status |
27 | * |
28 | * DESCRIPTION: Verifies that the table checksums to zero. Optionally returns |
29 | * exception on bad checksum. |
30 | * Note: We don't have to check for a CDAT here, since CDAT is |
31 | * not in the RSDT/XSDT, and the CDAT table is never installed |
32 | * via ACPICA. |
33 | * |
34 | ******************************************************************************/ |
35 | acpi_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 checksum |
42 | */ |
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 | original_checksum: 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 | #endif |
67 | } |
68 | |
69 | return (AE_OK); |
70 | } |
71 | |
72 | /******************************************************************************* |
73 | * |
74 | * FUNCTION: acpi_ut_verify_cdat_checksum |
75 | * |
76 | * PARAMETERS: table - CDAT ACPI table to verify |
77 | * length - Length of entire table |
78 | * |
79 | * RETURN: Status |
80 | * |
81 | * DESCRIPTION: Verifies that the CDAT table checksums to zero. Optionally |
82 | * returns an exception on bad checksum. |
83 | * |
84 | ******************************************************************************/ |
85 | |
86 | acpi_status |
87 | acpi_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 | length: cdat_table->length, |
95 | original_checksum: 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 | #endif |
109 | } |
110 | |
111 | cdat_table->checksum = checksum; |
112 | return (AE_OK); |
113 | } |
114 | |
115 | /******************************************************************************* |
116 | * |
117 | * FUNCTION: acpi_ut_generate_checksum |
118 | * |
119 | * PARAMETERS: table - Pointer to table to be checksummed |
120 | * length - Length of the table |
121 | * original_checksum - Value of the checksum field |
122 | * |
123 | * RETURN: 8 bit checksum of buffer |
124 | * |
125 | * DESCRIPTION: Computes an 8 bit checksum of the table. |
126 | * |
127 | ******************************************************************************/ |
128 | |
129 | u8 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(buffer: (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_checksum |
150 | * |
151 | * PARAMETERS: buffer - Pointer to memory region to be checked |
152 | * length - Length of this memory region |
153 | * |
154 | * RETURN: Checksum (u8) |
155 | * |
156 | * DESCRIPTION: Calculates circular checksum of memory region. |
157 | * |
158 | ******************************************************************************/ |
159 | |
160 | u8 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 | |