xref: /openbmc/linux/arch/s390/kernel/module.c (revision b627b4ed)
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 	/* FIXME: If module_region == mod->init_region, trim exception
60            table entries. */
61 }
62 
63 static void
64 check_rela(Elf_Rela *rela, struct module *me)
65 {
66 	struct mod_arch_syminfo *info;
67 
68 	info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
69 	switch (ELF_R_TYPE (rela->r_info)) {
70 	case R_390_GOT12:	/* 12 bit GOT offset.  */
71 	case R_390_GOT16:	/* 16 bit GOT offset.  */
72 	case R_390_GOT20:	/* 20 bit GOT offset.  */
73 	case R_390_GOT32:	/* 32 bit GOT offset.  */
74 	case R_390_GOT64:	/* 64 bit GOT offset.  */
75 	case R_390_GOTENT:	/* 32 bit PC rel. to GOT entry shifted by 1. */
76 	case R_390_GOTPLT12:	/* 12 bit offset to jump slot.	*/
77 	case R_390_GOTPLT16:	/* 16 bit offset to jump slot.  */
78 	case R_390_GOTPLT20:	/* 20 bit offset to jump slot.  */
79 	case R_390_GOTPLT32:	/* 32 bit offset to jump slot.  */
80 	case R_390_GOTPLT64:	/* 64 bit offset to jump slot.	*/
81 	case R_390_GOTPLTENT:	/* 32 bit rel. offset to jump slot >> 1. */
82 		if (info->got_offset == -1UL) {
83 			info->got_offset = me->arch.got_size;
84 			me->arch.got_size += sizeof(void*);
85 		}
86 		break;
87 	case R_390_PLT16DBL:	/* 16 bit PC rel. PLT shifted by 1.  */
88 	case R_390_PLT32DBL:	/* 32 bit PC rel. PLT shifted by 1.  */
89 	case R_390_PLT32:	/* 32 bit PC relative PLT address.  */
90 	case R_390_PLT64:	/* 64 bit PC relative PLT address.  */
91 	case R_390_PLTOFF16:	/* 16 bit offset from GOT to PLT. */
92 	case R_390_PLTOFF32:	/* 32 bit offset from GOT to PLT. */
93 	case R_390_PLTOFF64:	/* 16 bit offset from GOT to PLT. */
94 		if (info->plt_offset == -1UL) {
95 			info->plt_offset = me->arch.plt_size;
96 			me->arch.plt_size += PLT_ENTRY_SIZE;
97 		}
98 		break;
99 	case R_390_COPY:
100 	case R_390_GLOB_DAT:
101 	case R_390_JMP_SLOT:
102 	case R_390_RELATIVE:
103 		/* Only needed if we want to support loading of
104 		   modules linked with -shared. */
105 		break;
106 	}
107 }
108 
109 /*
110  * Account for GOT and PLT relocations. We can't add sections for
111  * got and plt but we can increase the core module size.
112  */
113 int
114 module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
115 			  char *secstrings, struct module *me)
116 {
117 	Elf_Shdr *symtab;
118 	Elf_Sym *symbols;
119 	Elf_Rela *rela;
120 	char *strings;
121 	int nrela, i, j;
122 
123 	/* Find symbol table and string table. */
124 	symtab = NULL;
125 	for (i = 0; i < hdr->e_shnum; i++)
126 		switch (sechdrs[i].sh_type) {
127 		case SHT_SYMTAB:
128 			symtab = sechdrs + i;
129 			break;
130 		}
131 	if (!symtab) {
132 		printk(KERN_ERR "module %s: no symbol table\n", me->name);
133 		return -ENOEXEC;
134 	}
135 
136 	/* Allocate one syminfo structure per symbol. */
137 	me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
138 	me->arch.syminfo = vmalloc(me->arch.nsyms *
139 				   sizeof(struct mod_arch_syminfo));
140 	if (!me->arch.syminfo)
141 		return -ENOMEM;
142 	symbols = (void *) hdr + symtab->sh_offset;
143 	strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
144 	for (i = 0; i < me->arch.nsyms; i++) {
145 		if (symbols[i].st_shndx == SHN_UNDEF &&
146 		    strcmp(strings + symbols[i].st_name,
147 			   "_GLOBAL_OFFSET_TABLE_") == 0)
148 			/* "Define" it as absolute. */
149 			symbols[i].st_shndx = SHN_ABS;
150 		me->arch.syminfo[i].got_offset = -1UL;
151 		me->arch.syminfo[i].plt_offset = -1UL;
152 		me->arch.syminfo[i].got_initialized = 0;
153 		me->arch.syminfo[i].plt_initialized = 0;
154 	}
155 
156 	/* Search for got/plt relocations. */
157 	me->arch.got_size = me->arch.plt_size = 0;
158 	for (i = 0; i < hdr->e_shnum; i++) {
159 		if (sechdrs[i].sh_type != SHT_RELA)
160 			continue;
161 		nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
162 		rela = (void *) hdr + sechdrs[i].sh_offset;
163 		for (j = 0; j < nrela; j++)
164 			check_rela(rela + j, me);
165 	}
166 
167 	/* Increase core size by size of got & plt and set start
168 	   offsets for got and plt. */
169 	me->core_size = ALIGN(me->core_size, 4);
170 	me->arch.got_offset = me->core_size;
171 	me->core_size += me->arch.got_size;
172 	me->arch.plt_offset = me->core_size;
173 	me->core_size += me->arch.plt_size;
174 	return 0;
175 }
176 
177 int
178 apply_relocate(Elf_Shdr *sechdrs, const char *strtab, unsigned int symindex,
179 	       unsigned int relsec, struct module *me)
180 {
181 	printk(KERN_ERR "module %s: RELOCATION unsupported\n",
182 	       me->name);
183 	return -ENOEXEC;
184 }
185 
186 static int
187 apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
188 	   struct module *me)
189 {
190 	struct mod_arch_syminfo *info;
191 	Elf_Addr loc, val;
192 	int r_type, r_sym;
193 
194 	/* This is where to make the change */
195 	loc = base + rela->r_offset;
196 	/* This is the symbol it is referring to.  Note that all
197 	   undefined symbols have been resolved.  */
198 	r_sym = ELF_R_SYM(rela->r_info);
199 	r_type = ELF_R_TYPE(rela->r_info);
200 	info = me->arch.syminfo + r_sym;
201 	val = symtab[r_sym].st_value;
202 
203 	switch (r_type) {
204 	case R_390_8:		/* Direct 8 bit.   */
205 	case R_390_12:		/* Direct 12 bit.  */
206 	case R_390_16:		/* Direct 16 bit.  */
207 	case R_390_20:		/* Direct 20 bit.  */
208 	case R_390_32:		/* Direct 32 bit.  */
209 	case R_390_64:		/* Direct 64 bit.  */
210 		val += rela->r_addend;
211 		if (r_type == R_390_8)
212 			*(unsigned char *) loc = val;
213 		else if (r_type == R_390_12)
214 			*(unsigned short *) loc = (val & 0xfff) |
215 				(*(unsigned short *) loc & 0xf000);
216 		else if (r_type == R_390_16)
217 			*(unsigned short *) loc = val;
218 		else if (r_type == R_390_20)
219 			*(unsigned int *) loc =
220 				(*(unsigned int *) loc & 0xf00000ff) |
221 				(val & 0xfff) << 16 | (val & 0xff000) >> 4;
222 		else if (r_type == R_390_32)
223 			*(unsigned int *) loc = val;
224 		else if (r_type == R_390_64)
225 			*(unsigned long *) loc = val;
226 		break;
227 	case R_390_PC16:	/* PC relative 16 bit.  */
228 	case R_390_PC16DBL:	/* PC relative 16 bit shifted by 1.  */
229 	case R_390_PC32DBL:	/* PC relative 32 bit shifted by 1.  */
230 	case R_390_PC32:	/* PC relative 32 bit.  */
231 	case R_390_PC64:	/* PC relative 64 bit.	*/
232 		val += rela->r_addend - loc;
233 		if (r_type == R_390_PC16)
234 			*(unsigned short *) loc = val;
235 		else if (r_type == R_390_PC16DBL)
236 			*(unsigned short *) loc = val >> 1;
237 		else if (r_type == R_390_PC32DBL)
238 			*(unsigned int *) loc = val >> 1;
239 		else if (r_type == R_390_PC32)
240 			*(unsigned int *) loc = val;
241 		else if (r_type == R_390_PC64)
242 			*(unsigned long *) loc = val;
243 		break;
244 	case R_390_GOT12:	/* 12 bit GOT offset.  */
245 	case R_390_GOT16:	/* 16 bit GOT offset.  */
246 	case R_390_GOT20:	/* 20 bit GOT offset.  */
247 	case R_390_GOT32:	/* 32 bit GOT offset.  */
248 	case R_390_GOT64:	/* 64 bit GOT offset.  */
249 	case R_390_GOTENT:	/* 32 bit PC rel. to GOT entry shifted by 1. */
250 	case R_390_GOTPLT12:	/* 12 bit offset to jump slot.	*/
251 	case R_390_GOTPLT20:	/* 20 bit offset to jump slot.  */
252 	case R_390_GOTPLT16:	/* 16 bit offset to jump slot.  */
253 	case R_390_GOTPLT32:	/* 32 bit offset to jump slot.  */
254 	case R_390_GOTPLT64:	/* 64 bit offset to jump slot.	*/
255 	case R_390_GOTPLTENT:	/* 32 bit rel. offset to jump slot >> 1. */
256 		if (info->got_initialized == 0) {
257 			Elf_Addr *gotent;
258 
259 			gotent = me->module_core + me->arch.got_offset +
260 				info->got_offset;
261 			*gotent = val;
262 			info->got_initialized = 1;
263 		}
264 		val = info->got_offset + rela->r_addend;
265 		if (r_type == R_390_GOT12 ||
266 		    r_type == R_390_GOTPLT12)
267 			*(unsigned short *) loc = (val & 0xfff) |
268 				(*(unsigned short *) loc & 0xf000);
269 		else if (r_type == R_390_GOT16 ||
270 			 r_type == R_390_GOTPLT16)
271 			*(unsigned short *) loc = val;
272 		else if (r_type == R_390_GOT20 ||
273 			 r_type == R_390_GOTPLT20)
274 			*(unsigned int *) loc =
275 				(*(unsigned int *) loc & 0xf00000ff) |
276 				(val & 0xfff) << 16 | (val & 0xff000) >> 4;
277 		else if (r_type == R_390_GOT32 ||
278 			 r_type == R_390_GOTPLT32)
279 			*(unsigned int *) loc = val;
280 		else if (r_type == R_390_GOTENT ||
281 			 r_type == R_390_GOTPLTENT)
282 			*(unsigned int *) loc =
283 				(val + (Elf_Addr) me->module_core - loc) >> 1;
284 		else if (r_type == R_390_GOT64 ||
285 			 r_type == R_390_GOTPLT64)
286 			*(unsigned long *) loc = val;
287 		break;
288 	case R_390_PLT16DBL:	/* 16 bit PC rel. PLT shifted by 1.  */
289 	case R_390_PLT32DBL:	/* 32 bit PC rel. PLT shifted by 1.  */
290 	case R_390_PLT32:	/* 32 bit PC relative PLT address.  */
291 	case R_390_PLT64:	/* 64 bit PC relative PLT address.  */
292 	case R_390_PLTOFF16:	/* 16 bit offset from GOT to PLT. */
293 	case R_390_PLTOFF32:	/* 32 bit offset from GOT to PLT. */
294 	case R_390_PLTOFF64:	/* 16 bit offset from GOT to PLT. */
295 		if (info->plt_initialized == 0) {
296 			unsigned int *ip;
297 			ip = me->module_core + me->arch.plt_offset +
298 				info->plt_offset;
299 #ifndef CONFIG_64BIT
300 			ip[0] = 0x0d105810; /* basr 1,0; l 1,6(1); br 1 */
301 			ip[1] = 0x100607f1;
302 			ip[2] = val;
303 #else /* CONFIG_64BIT */
304 			ip[0] = 0x0d10e310; /* basr 1,0; lg 1,10(1); br 1 */
305 			ip[1] = 0x100a0004;
306 			ip[2] = 0x07f10000;
307 			ip[3] = (unsigned int) (val >> 32);
308 			ip[4] = (unsigned int) val;
309 #endif /* CONFIG_64BIT */
310 			info->plt_initialized = 1;
311 		}
312 		if (r_type == R_390_PLTOFF16 ||
313 		    r_type == R_390_PLTOFF32 ||
314 		    r_type == R_390_PLTOFF64)
315 			val = me->arch.plt_offset - me->arch.got_offset +
316 				info->plt_offset + rela->r_addend;
317 		else {
318 			if (!((r_type == R_390_PLT16DBL &&
319 			       val - loc + 0xffffUL < 0x1ffffeUL) ||
320 			      (r_type == R_390_PLT32DBL &&
321 			       val - loc + 0xffffffffULL < 0x1fffffffeULL)))
322 				val = (Elf_Addr) me->module_core +
323 					me->arch.plt_offset +
324 					info->plt_offset;
325 			val += rela->r_addend - loc;
326 		}
327 		if (r_type == R_390_PLT16DBL)
328 			*(unsigned short *) loc = val >> 1;
329 		else if (r_type == R_390_PLTOFF16)
330 			*(unsigned short *) loc = val;
331 		else if (r_type == R_390_PLT32DBL)
332 			*(unsigned int *) loc = val >> 1;
333 		else if (r_type == R_390_PLT32 ||
334 			 r_type == R_390_PLTOFF32)
335 			*(unsigned int *) loc = val;
336 		else if (r_type == R_390_PLT64 ||
337 			 r_type == R_390_PLTOFF64)
338 			*(unsigned long *) loc = val;
339 		break;
340 	case R_390_GOTOFF16:	/* 16 bit offset to GOT.  */
341 	case R_390_GOTOFF32:	/* 32 bit offset to GOT.  */
342 	case R_390_GOTOFF64:	/* 64 bit offset to GOT. */
343 		val = val + rela->r_addend -
344 			((Elf_Addr) me->module_core + me->arch.got_offset);
345 		if (r_type == R_390_GOTOFF16)
346 			*(unsigned short *) loc = val;
347 		else if (r_type == R_390_GOTOFF32)
348 			*(unsigned int *) loc = val;
349 		else if (r_type == R_390_GOTOFF64)
350 			*(unsigned long *) loc = val;
351 		break;
352 	case R_390_GOTPC:	/* 32 bit PC relative offset to GOT. */
353 	case R_390_GOTPCDBL:	/* 32 bit PC rel. off. to GOT shifted by 1. */
354 		val = (Elf_Addr) me->module_core + me->arch.got_offset +
355 			rela->r_addend - loc;
356 		if (r_type == R_390_GOTPC)
357 			*(unsigned int *) loc = val;
358 		else if (r_type == R_390_GOTPCDBL)
359 			*(unsigned int *) loc = val >> 1;
360 		break;
361 	case R_390_COPY:
362 	case R_390_GLOB_DAT:	/* Create GOT entry.  */
363 	case R_390_JMP_SLOT:	/* Create PLT entry.  */
364 	case R_390_RELATIVE:	/* Adjust by program base.  */
365 		/* Only needed if we want to support loading of
366 		   modules linked with -shared. */
367 		break;
368 	default:
369 		printk(KERN_ERR "module %s: Unknown relocation: %u\n",
370 		       me->name, r_type);
371 		return -ENOEXEC;
372 	}
373 	return 0;
374 }
375 
376 int
377 apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
378 		   unsigned int symindex, unsigned int relsec,
379 		   struct module *me)
380 {
381 	Elf_Addr base;
382 	Elf_Sym *symtab;
383 	Elf_Rela *rela;
384 	unsigned long i, n;
385 	int rc;
386 
387 	DEBUGP("Applying relocate section %u to %u\n",
388 	       relsec, sechdrs[relsec].sh_info);
389 	base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
390 	symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
391 	rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
392 	n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
393 
394 	for (i = 0; i < n; i++, rela++) {
395 		rc = apply_rela(rela, base, symtab, me);
396 		if (rc)
397 			return rc;
398 	}
399 	return 0;
400 }
401 
402 int module_finalize(const Elf_Ehdr *hdr,
403 		    const Elf_Shdr *sechdrs,
404 		    struct module *me)
405 {
406 	vfree(me->arch.syminfo);
407 	return module_bug_finalize(hdr, sechdrs, me);
408 }
409 
410 void module_arch_cleanup(struct module *mod)
411 {
412 	module_bug_cleanup(mod);
413 }
414