tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#include <stdio.h>
2#include <stdlib.h>
3#include <netinet/in.h>
4#include <unistd.h>
5#include <sys/types.h>
6#include <sys/stat.h>
7#include <string.h>
8
9#define ElfHeaderSize (64 * 1024)
10#define ElfPages (ElfHeaderSize / 4096)
11#define KERNELBASE (0xc0000000)
12
13void get4k(FILE *file, char *buf )
14{
15 unsigned j;
16 unsigned num = fread(buf, 1, 4096, file);
17 for ( j=num; j<4096; ++j )
18 buf[j] = 0;
19}
20
21void put4k(FILE *file, char *buf )
22{
23 fwrite(buf, 1, 4096, file);
24}
25
26void death(const char *msg, FILE *fdesc, const char *fname)
27{
28 printf(msg);
29 fclose(fdesc);
30 unlink(fname);
31 exit(1);
32}
33
34int main(int argc, char **argv)
35{
36 char inbuf[4096];
37 FILE *ramDisk = NULL;
38 FILE *inputVmlinux = NULL;
39 FILE *outputVmlinux = NULL;
40 unsigned i = 0;
41 u_int32_t ramFileLen = 0;
42 u_int32_t ramLen = 0;
43 u_int32_t roundR = 0;
44 u_int32_t kernelLen = 0;
45 u_int32_t actualKernelLen = 0;
46 u_int32_t round = 0;
47 u_int32_t roundedKernelLen = 0;
48 u_int32_t ramStartOffs = 0;
49 u_int32_t ramPages = 0;
50 u_int32_t roundedKernelPages = 0;
51 u_int32_t hvReleaseData = 0;
52 u_int32_t eyeCatcher = 0xc8a5d9c4;
53 u_int32_t naca = 0;
54 u_int32_t xRamDisk = 0;
55 u_int32_t xRamDiskSize = 0;
56 if ( argc < 2 ) {
57 printf("Name of RAM disk file missing.\n");
58 exit(1);
59 }
60
61 if ( argc < 3 ) {
62 printf("Name of vmlinux file missing.\n");
63 exit(1);
64 }
65
66 if ( argc < 4 ) {
67 printf("Name of vmlinux output file missing.\n");
68 exit(1);
69 }
70
71 ramDisk = fopen(argv[1], "r");
72 if ( ! ramDisk ) {
73 printf("RAM disk file \"%s\" failed to open.\n", argv[1]);
74 exit(1);
75 }
76 inputVmlinux = fopen(argv[2], "r");
77 if ( ! inputVmlinux ) {
78 printf("vmlinux file \"%s\" failed to open.\n", argv[2]);
79 exit(1);
80 }
81 outputVmlinux = fopen(argv[3], "w+");
82 if ( ! outputVmlinux ) {
83 printf("output vmlinux file \"%s\" failed to open.\n", argv[3]);
84 exit(1);
85 }
86 fseek(ramDisk, 0, SEEK_END);
87 ramFileLen = ftell(ramDisk);
88 fseek(ramDisk, 0, SEEK_SET);
89 printf("%s file size = %d\n", argv[1], ramFileLen);
90
91 ramLen = ramFileLen;
92
93 roundR = 4096 - (ramLen % 4096);
94 if ( roundR ) {
95 printf("Rounding RAM disk file up to a multiple of 4096, adding %d\n", roundR);
96 ramLen += roundR;
97 }
98
99 printf("Rounded RAM disk size is %d\n", ramLen);
100 fseek(inputVmlinux, 0, SEEK_END);
101 kernelLen = ftell(inputVmlinux);
102 fseek(inputVmlinux, 0, SEEK_SET);
103 printf("kernel file size = %d\n", kernelLen);
104 if ( kernelLen == 0 ) {
105 printf("You must have a linux kernel specified as argv[2]\n");
106 exit(1);
107 }
108
109 actualKernelLen = kernelLen - ElfHeaderSize;
110
111 printf("actual kernel length (minus ELF header) = %d\n", actualKernelLen);
112
113 round = actualKernelLen % 4096;
114 roundedKernelLen = actualKernelLen;
115 if ( round )
116 roundedKernelLen += (4096 - round);
117
118 printf("actual kernel length rounded up to a 4k multiple = %d\n", roundedKernelLen);
119
120 ramStartOffs = roundedKernelLen;
121 ramPages = ramLen / 4096;
122
123 printf("RAM disk pages to copy = %d\n", ramPages);
124
125 // Copy 64K ELF header
126 for (i=0; i<(ElfPages); ++i) {
127 get4k( inputVmlinux, inbuf );
128 put4k( outputVmlinux, inbuf );
129 }
130
131 roundedKernelPages = roundedKernelLen / 4096;
132
133 fseek(inputVmlinux, ElfHeaderSize, SEEK_SET);
134
135 for ( i=0; i<roundedKernelPages; ++i ) {
136 get4k( inputVmlinux, inbuf );
137 put4k( outputVmlinux, inbuf );
138 }
139
140 for ( i=0; i<ramPages; ++i ) {
141 get4k( ramDisk, inbuf );
142 put4k( outputVmlinux, inbuf );
143 }
144
145 /* Close the input files */
146 fclose(ramDisk);
147 fclose(inputVmlinux);
148 /* And flush the written output file */
149 fflush(outputVmlinux);
150
151 /* fseek to the hvReleaseData pointer */
152 fseek(outputVmlinux, ElfHeaderSize + 0x24, SEEK_SET);
153 if (fread(&hvReleaseData, 4, 1, outputVmlinux) != 1) {
154 death("Could not read hvReleaseData pointer\n", outputVmlinux, argv[3]);
155 }
156 hvReleaseData = ntohl(hvReleaseData); /* Convert to native int */
157 printf("hvReleaseData is at %08x\n", hvReleaseData);
158
159 /* fseek to the hvReleaseData */
160 fseek(outputVmlinux, ElfHeaderSize + hvReleaseData, SEEK_SET);
161 if (fread(inbuf, 0x40, 1, outputVmlinux) != 1) {
162 death("Could not read hvReleaseData\n", outputVmlinux, argv[3]);
163 }
164 /* Check hvReleaseData sanity */
165 if (memcmp(inbuf, &eyeCatcher, 4) != 0) {
166 death("hvReleaseData is invalid\n", outputVmlinux, argv[3]);
167 }
168 /* Get the naca pointer */
169 naca = ntohl(*((u_int32_t *) &inbuf[0x0c])) - KERNELBASE;
170 printf("naca is at %08x\n", naca);
171
172 /* fseek to the naca */
173 fseek(outputVmlinux, ElfHeaderSize + naca, SEEK_SET);
174 if (fread(inbuf, 0x18, 1, outputVmlinux) != 1) {
175 death("Could not read naca\n", outputVmlinux, argv[3]);
176 }
177 xRamDisk = ntohl(*((u_int32_t *) &inbuf[0x0c]));
178 xRamDiskSize = ntohl(*((u_int32_t *) &inbuf[0x14]));
179 /* Make sure a RAM disk isn't already present */
180 if ((xRamDisk != 0) || (xRamDiskSize != 0)) {
181 death("RAM disk is already attached to this kernel\n", outputVmlinux, argv[3]);
182 }
183 /* Fill in the values */
184 *((u_int32_t *) &inbuf[0x0c]) = htonl(ramStartOffs);
185 *((u_int32_t *) &inbuf[0x14]) = htonl(ramPages);
186
187 /* Write out the new naca */
188 fflush(outputVmlinux);
189 fseek(outputVmlinux, ElfHeaderSize + naca, SEEK_SET);
190 if (fwrite(inbuf, 0x18, 1, outputVmlinux) != 1) {
191 death("Could not write naca\n", outputVmlinux, argv[3]);
192 }
193 printf("RAM Disk of 0x%x pages size is attached to the kernel at offset 0x%08x\n",
194 ramPages, ramStartOffs);
195
196 /* Done */
197 fclose(outputVmlinux);
198 /* Set permission to executable */
199 chmod(argv[3], S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
200
201 return 0;
202}
203