xref: /openbmc/linux/arch/s390/kernel/module.c (revision fd589a8f)
1 /*
2  *  arch/s390/kernel/module.c - Kernel module help for s390.
3  *
4  *  S390 version
5  *    Copyright (C) 2002, 2003 IBM Deutschland Entwicklung GmbH,
6  *			       IBM Corporation
7  *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
8  *		 Martin Schwidefsky (schwidefsky@de.ibm.com)
9  *
10  *  based on i386 version
11  *    Copyright (C) 2001 Rusty Russell.
12  *
13  *  This program is free software; you can redistribute it and/or modify
14  *  it under the terms of the GNU General Public License as published by
15  *  the Free Software Foundation; either version 2 of the License, or
16  *  (at your option) any later version.
17  *
18  *  This program is distributed in the hope that it will be useful,
19  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
20  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
21  *  GNU General Public License for more details.
22  *
23  *  You should have received a copy of the GNU General Public License
24  *  along with this program; if not, write to the Free Software
25  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
26  */
27 #include <linux/module.h>
28 #include <linux/elf.h>
29 #include <linux/vmalloc.h>
30 #include <linux/fs.h>
31 #include <linux/string.h>
32 #include <linux/kernel.h>
33 #include <linux/moduleloader.h>
34 #include <linux/bug.h>
35 
36 #if 0
37 #define DEBUGP printk
38 #else
39 #define DEBUGP(fmt , ...)
40 #endif
41 
42 #ifndef CONFIG_64BIT
43 #define PLT_ENTRY_SIZE 12
44 #else /* CONFIG_64BIT */
45 #define PLT_ENTRY_SIZE 20
46 #endif /* CONFIG_64BIT */
47 
48 void *module_alloc(unsigned long size)
49 {
50 	if (size == 0)
51 		return NULL;
52 	return vmalloc(size);
53 }
54 
55 /* Free memory returned from module_alloc */
56 void module_free(struct module *mod, void *module_region)
57 {
58 	vfree(module_region);
59 }
60 
61 static void
62 check_rela(Elf_Rela *rela, struct module *me)
63 {
64 	struct mod_arch_syminfo *info;
65 
66 	info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
67 	switch (ELF_R_TYPE (rela->r_info)) {
68 	case R_390_GOT12:	/* 12 bit GOT offset.  */
69 	case R_390_GOT16:	/* 16 bit GOT offset.  */
70 	case R_390_GOT20:	/* 20 bit GOT offset.  */
71 	case R_390_GOT32:	/* 32 bit GOT offset.  */
72 	case R_390_GOT64:	/* 64 bit GOT offset.  */
73 	case R_390_GOTENT:	/* 32 bit PC rel. to GOT entry shifted by 1. */
74 	case R_390_GOTPLT12:	/* 12 bit offset to jump slot.	*/
75 	case R_390_GOTPLT16:	/* 16 bit offset to jump slot.  */
76 	case R_390_GOTPLT20:	/* 20 bit offset to jump slot.  */
77 	case R_390_GOTPLT32:	/* 32 bit offset to jump slot.  */
78 	case R_390_GOTPLT64:	/* 64 bit offset to jump slot.	*/
79 	case R_390_GOTPLTENT:	/* 32 bit rel. offset to jump slot >> 1. */
80 		if (info->got_offset == -1UL) {
81 			info->got_offset = me->arch.got_size;
82 			me->arch.got_size += sizeof(void*);
83 		}
84 		break;
85 	case R_390_PLT16DBL:	/* 16 bit PC rel. PLT shifted by 1.  */
86 	case R_390_PLT32DBL:	/* 32 bit PC rel. PLT shifted by 1.  */
87 	case R_390_PLT32:	/* 32 bit PC relative PLT address.  */
88 	case R_390_PLT64:	/* 64 bit PC relative PLT address.  */
89 	case R_390_PLTOFF16:	/* 16 bit offset from GOT to PLT. */
90 	case R_390_PLTOFF32:	/* 32 bit offset from GOT to PLT. */
91 	case R_390_PLTOFF64:	/* 16 bit offset from GOT to PLT. */
92 		if (info->plt_offset == -1UL) {
93 			info->plt_offset = me->arch.plt_size;
94 			me->arch.plt_size += PLT_ENTRY_SIZE;
95 		}
96 		break;
97 	case R_390_COPY:
98 	case R_390_GLOB_DAT:
99 	case R_390_JMP_SLOT:
100 	case R_390_RELATIVE:
101 		/* Only needed if we want to support loading of
102 		   modules linked with -shared. */
103 		break;
104 	}
105 }
106 
107 /*
108  * Account for GOT and PLT relocations. We can't add sections for
109  * got and plt but we can increase the core module size.
110  */
111 int
112 module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
113 			  char *secstrings, struct module *me)
114 {
115 	Elf_Shdr *symtab;
116 	Elf_Sym *symbols;
117 	Elf_Rela *rela;
118 	char *strings;
119 	int nrela, i, j;
120 
121 	/* Find symbol table and string table. */
122 	symtab = NULL;
123 	for (i = 0; i < hdr->e_shnum; i++)
124 		switch (sechdrs[i].sh_type) {
125 		case SHT_SYMTAB:
126 			symtab = sechdrs + i;
127 			break;
128 		}
129 	if (!symtab) {
130 		printk(KERN_ERR "module %s: no symbol table\n", me->name);
131 		return -ENOEXEC;
132 	}
133 
134 	/* Allocate one syminfo structure per symbol. */
135 	me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
136 	me->arch.syminfo = vmalloc(me->arch.nsyms *
137 				   sizeof(struct mod_arch_syminfo));
138 	if (!me->arch.syminfo)
139 		return -ENOMEM;
140 	symbols = (void *) hdr + symtab->sh_offset;
141 	strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
142 	for (i = 0; i < me->arch.nsyms; i++) {
143 		if (symbols[i].st_shndx == SHN_UNDEF &&
144 		    strcmp(strings + symbols[i].st_name,
145 			   "_GLOBAL_OFFSET_TABLE_") == 0)
146 			/* "Define" it as absolute. */
147 			symbols[i].st_shndx = SHN_ABS;
148 		me->arch.syminfo[i].got_offset = -1UL;
149 		me->arch.syminfo[i].plt_offset = -1UL;
150 		me->arch.syminfo[i].got_initialized = 0;
151 		me->arch.syminfo[i].plt_initialized = 0;
152 	}
153 
154 	/* Search for got/plt relocations. */
155 	me->arch.got_size = me->arch.plt_size = 0;
156 	for (i = 0; i < hdr->e_shnum; i++) {
157 		if (sechdrs[i].sh_type != SHT_RELA)
158 			continue;
159 		nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
160 		rela = (void *) hdr + sechdrs[i].sh_offset;
161 		for (j = 0; j < nrela; j++)
162 			check_rela(rela + j, me);
163 	}
164 
165 	/* Increase core size by size of got & plt and set start
166 	   offsets for got and plt. */
167 	me->core_size = ALIGN(me->core_size, 4);
168 	me->arch.got_offset = me->core_size;
169 	me->core_size += me->arch.got_size;
170 	me->arch.plt_offset = me->core_size;
171 	me->core_size += me->arch.plt_size;
172 	return 0;
173 }
174 
175 int
176 apply_relocate(Elf_Shdr *sechdrs, const char *strtab, unsigned int symindex,
177 	       unsigned int relsec, struct module *me)
178 {
179 	printk(KERN_ERR "module %s: RELOCATION unsupported\n",
180 	       me->name);
181 	return -ENOEXEC;
182 }
183 
184 static int
185 apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
186 	   struct module *me)
187 {
188 	struct mod_arch_syminfo *info;
189 	Elf_Addr loc, val;
190 	int r_type, r_sym;
191 
192 	/* This is where to make the change */
193 	loc = base + rela->r_offset;
194 	/* This is the symbol it is referring to.  Note that all
195 	   undefined symbols have been resolved.  */
196 	r_sym = ELF_R_SYM(rela->r_info);
197 	r_type = ELF_R_TYPE(rela->r_info);
198 	info = me->arch.syminfo + r_sym;
199 	val = symtab[r_sym].st_value;
200 
201 	switch (r_type) {
202 	case R_390_8:		/* Direct 8 bit.   */
203 	case R_390_12:		/* Direct 12 bit.  */
204 	case R_390_16:		/* Direct 16 bit.  */
205 	case R_390_20:		/* Direct 20 bit.  */
206 	case R_390_32:		/* Direct 32 bit.  */
207 	case R_390_64:		/* Direct 64 bit.  */
208 		val += rela->r_addend;
209 		if (r_type == R_390_8)
210 			*(unsigned char *) loc = val;
211 		else if (r_type == R_390_12)
212 			*(unsigned short *) loc = (val & 0xfff) |
213 				(*(unsigned short *) loc & 0xf000);
214 		else if (r_type == R_390_16)
215 			*(unsigned short *) loc = val;
216 		else if (r_type == R_390_20)
217 			*(unsigned int *) loc =
218 				(*(unsigned int *) loc & 0xf00000ff) |
219 				(val & 0xfff) << 16 | (val & 0xff000) >> 4;
220 		else if (r_type == R_390_32)
221 			*(unsigned int *) loc = val;
222 		else if (r_type == R_390_64)
223 			*(unsigned long *) loc = val;
224 		break;
225 	case R_390_PC16:	/* PC relative 16 bit.  */
226 	case R_390_PC16DBL:	/* PC relative 16 bit shifted by 1.  */
227 	case R_390_PC32DBL:	/* PC relative 32 bit shifted by 1.  */
228 	case R_390_PC32:	/* PC relative 32 bit.  */
229 	case R_390_PC64:	/* PC relative 64 bit.	*/
230 		val += rela->r_addend - loc;
231 		if (r_type == R_390_PC16)
232 			*(unsigned short *) loc = val;
233 		else if (r_type == R_390_PC16DBL)
234 			*(unsigned short *) loc = val >> 1;
235 		else if (r_type == R_390_PC32DBL)
236 			*(unsigned int *) loc = val >> 1;
237 		else if (r_type == R_390_PC32)
238 			*(unsigned int *) loc = val;
239 		else if (r_type == R_390_PC64)
240 			*(unsigned long *) loc = val;
241 		break;
242 	case R_390_GOT12:	/* 12 bit GOT offset.  */
243 	case R_390_GOT16:	/* 16 bit GOT offset.  */
244 	case R_390_GOT20:	/* 20 bit GOT offset.  */
245 	case R_390_GOT32:	/* 32 bit GOT offset.  */
246 	case R_390_GOT64:	/* 64 bit GOT offset.  */
247 	case R_390_GOTENT:	/* 32 bit PC rel. to GOT entry shifted by 1. */
248 	case R_390_GOTPLT12:	/* 12 bit offset to jump slot.	*/
249 	case R_390_GOTPLT20:	/* 20 bit offset to jump slot.  */
250 	case R_390_GOTPLT16:	/* 16 bit offset to jump slot.  */
251 	case R_390_GOTPLT32:	/* 32 bit offset to jump slot.  */
252 	case R_390_GOTPLT64:	/* 64 bit offset to jump slot.	*/
253 	case R_390_GOTPLTENT:	/* 32 bit rel. offset to jump slot >> 1. */
254 		if (info->got_initialized == 0) {
255 			Elf_Addr *gotent;
256 
257 			gotent = me->module_core + me->arch.got_offset +
258 				info->got_offset;
259 			*gotent = val;
260 			info->got_initialized = 1;
261 		}
262 		val = info->got_offset + rela->r_addend;
263 		if (r_type == R_390_GOT12 ||
264 		    r_type == R_390_GOTPLT12)
265 			*(unsigned short *) loc = (val & 0xfff) |
266 				(*(unsigned short *) loc & 0xf000);
267 		else if (r_type == R_390_GOT16 ||
268 			 r_type == R_390_GOTPLT16)
269 			*(unsigned short *) loc = val;
270 		else if (r_type == R_390_GOT20 ||
271 			 r_type == R_390_GOTPLT20)
272 			*(unsigned int *) loc =
273 				(*(unsigned int *) loc & 0xf00000ff) |
274 				(val & 0xfff) << 16 | (val & 0xff000) >> 4;
275 		else if (r_type == R_390_GOT32 ||
276 			 r_type == R_390_GOTPLT32)
277 			*(unsigned int *) loc = val;
278 		else if (r_type == R_390_GOTENT ||
279 			 r_type == R_390_GOTPLTENT)
280 			*(unsigned int *) loc =
281 				(val + (Elf_Addr) me->module_core - loc) >> 1;
282 		else if (r_type == R_390_GOT64 ||
283 			 r_type == R_390_GOTPLT64)
284 			*(unsigned long *) loc = val;
285 		break;
286 	case R_390_PLT16DBL:	/* 16 bit PC rel. PLT shifted by 1.  */
287 	case R_390_PLT32DBL:	/* 32 bit PC rel. PLT shifted by 1.  */
288 	case R_390_PLT32:	/* 32 bit PC relative PLT address.  */
289 	case R_390_PLT64:	/* 64 bit PC relative PLT address.  */
290 	case R_390_PLTOFF16:	/* 16 bit offset from GOT to PLT. */
291 	case R_390_PLTOFF32:	/* 32 bit offset from GOT to PLT. */
292 	case R_390_PLTOFF64:	/* 16 bit offset from GOT to PLT. */
293 		if (info->plt_initialized == 0) {
294 			unsigned int *ip;
295 			ip = me->module_core + me->arch.plt_offset +
296 				info->plt_offset;
297 #ifndef CONFIG_64BIT
298 			ip[0] = 0x0d105810; /* basr 1,0; l 1,6(1); br 1 */
299 			ip[1] = 0x100607f1;
300 			ip[2] = val;
301 #else /* CONFIG_64BIT */
302 			ip[0] = 0x0d10e310; /* basr 1,0; lg 1,10(1); br 1 */
303 			ip[1] = 0x100a0004;
304 			ip[2] = 0x07f10000;
305 			ip[3] = (unsigned int) (val >> 32);
306 			ip[4] = (unsigned int) val;
307 #endif /* CONFIG_64BIT */
308 			info->plt_initialized = 1;
309 		}
310 		if (r_type == R_390_PLTOFF16 ||
311 		    r_type == R_390_PLTOFF32 ||
312 		    r_type == R_390_PLTOFF64)
313 			val = me->arch.plt_offset - me->arch.got_offset +
314 				info->plt_offset + rela->r_addend;
315 		else {
316 			if (!((r_type == R_390_PLT16DBL &&
317 			       val - loc + 0xffffUL < 0x1ffffeUL) ||
318 			      (r_type == R_390_PLT32DBL &&
319 			       val - loc + 0xffffffffULL < 0x1fffffffeULL)))
320 				val = (Elf_Addr) me->module_core +
321 					me->arch.plt_offset +
322 					info->plt_offset;
323 			val += rela->r_addend - loc;
324 		}
325 		if (r_type == R_390_PLT16DBL)
326 			*(unsigned short *) loc = val >> 1;
327 		else if (r_type == R_390_PLTOFF16)
328 			*(unsigned short *) loc = val;
329 		else if (r_type == R_390_PLT32DBL)
330 			*(unsigned int *) loc = val >> 1;
331 		else if (r_type == R_390_PLT32 ||
332 			 r_type == R_390_PLTOFF32)
333 			*(unsigned int *) loc = val;
334 		else if (r_type == R_390_PLT64 ||
335 			 r_type == R_390_PLTOFF64)
336 			*(unsigned long *) loc = val;
337 		break;
338 	case R_390_GOTOFF16:	/* 16 bit offset to GOT.  */
339 	case R_390_GOTOFF32:	/* 32 bit offset to GOT.  */
340 	case R_390_GOTOFF64:	/* 64 bit offset to GOT. */
341 		val = val + rela->r_addend -
342 			((Elf_Addr) me->module_core + me->arch.got_offset);
343 		if (r_type == R_390_GOTOFF16)
344 			*(unsigned short *) loc = val;
345 		else if (r_type == R_390_GOTOFF32)
346 			*(unsigned int *) loc = val;
347 		else if (r_type == R_390_GOTOFF64)
348 			*(unsigned long *) loc = val;
349 		break;
350 	case R_390_GOTPC:	/* 32 bit PC relative offset to GOT. */
351 	case R_390_GOTPCDBL:	/* 32 bit PC rel. off. to GOT shifted by 1. */
352 		val = (Elf_Addr) me->module_core + me->arch.got_offset +
353 			rela->r_addend - loc;
354 		if (r_type == R_390_GOTPC)
355 			*(unsigned int *) loc = val;
356 		else if (r_type == R_390_GOTPCDBL)
357 			*(unsigned int *) loc = val >> 1;
358 		break;
359 	case R_390_COPY:
360 	case R_390_GLOB_DAT:	/* Create GOT entry.  */
361 	case R_390_JMP_SLOT:	/* Create PLT entry.  */
362 	case R_390_RELATIVE:	/* Adjust by program base.  */
363 		/* Only needed if we want to support loading of
364 		   modules linked with -shared. */
365 		break;
366 	default:
367 		printk(KERN_ERR "module %s: Unknown relocation: %u\n",
368 		       me->name, r_type);
369 		return -ENOEXEC;
370 	}
371 	return 0;
372 }
373 
374 int
375 apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
376 		   unsigned int symindex, unsigned int relsec,
377 		   struct module *me)
378 {
379 	Elf_Addr base;
380 	Elf_Sym *symtab;
381 	Elf_Rela *rela;
382 	unsigned long i, n;
383 	int rc;
384 
385 	DEBUGP("Applying relocate section %u to %u\n",
386 	       relsec, sechdrs[relsec].sh_info);
387 	base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
388 	symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
389 	rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
390 	n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
391 
392 	for (i = 0; i < n; i++, rela++) {
393 		rc = apply_rela(rela, base, symtab, me);
394 		if (rc)
395 			return rc;
396 	}
397 	return 0;
398 }
399 
400 int module_finalize(const Elf_Ehdr *hdr,
401 		    const Elf_Shdr *sechdrs,
402 		    struct module *me)
403 {
404 	vfree(me->arch.syminfo);
405 	return module_bug_finalize(hdr, sechdrs, me);
406 }
407 
408 void module_arch_cleanup(struct module *mod)
409 {
410 	module_bug_cleanup(mod);
411 }
412