summaryrefslogtreecommitdiffstats
path: root/arch/s390/kernel/module.c
blob: 5a83be955c70ed8f9a378ec6a47c61933c2968d9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
// SPDX-License-Identifier: GPL-2.0+
/*
 *  Kernel module help for s390.
 *
 *  S390 version
 *    Copyright IBM Corp. 2002, 2003
 *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
 *		 Martin Schwidefsky (schwidefsky@de.ibm.com)
 *
 *  based on i386 version
 *    Copyright (C) 2001 Rusty Russell.
 */
#include <linux/module.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/moduleloader.h>
#include <linux/bug.h>
#include <asm/alternative.h>
#include <asm/nospec-branch.h>
#include <asm/facility.h>

#if 0
#define DEBUGP printk
#else
#define DEBUGP(fmt , ...)
#endif

#define PLT_ENTRY_SIZE 20

void *module_alloc(unsigned long size)
{
	if (PAGE_ALIGN(size) > MODULES_LEN)
		return NULL;
	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
				    GFP_KERNEL, PAGE_KERNEL_EXEC,
				    0, NUMA_NO_NODE,
				    __builtin_return_address(0));
}

void module_arch_freeing_init(struct module *mod)
{
	if (is_livepatch_module(mod) &&
	    mod->state == MODULE_STATE_LIVE)
		return;

	vfree(mod->arch.syminfo);
	mod->arch.syminfo = NULL;
}

static void check_rela(Elf_Rela *rela, struct module *me)
{
	struct mod_arch_syminfo *info;

	info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
	switch (ELF_R_TYPE (rela->r_info)) {
	case R_390_GOT12:	/* 12 bit GOT offset.  */
	case R_390_GOT16:	/* 16 bit GOT offset.  */
	case R_390_GOT20:	/* 20 bit GOT offset.  */
	case R_390_GOT32:	/* 32 bit GOT offset.  */
	case R_390_GOT64:	/* 64 bit GOT offset.  */
	case R_390_GOTENT:	/* 32 bit PC rel. to GOT entry shifted by 1. */
	case R_390_GOTPLT12:	/* 12 bit offset to jump slot.	*/
	case R_390_GOTPLT16:	/* 16 bit offset to jump slot.  */
	case R_390_GOTPLT20:	/* 20 bit offset to jump slot.  */
	case R_390_GOTPLT32:	/* 32 bit offset to jump slot.  */
	case R_390_GOTPLT64:	/* 64 bit offset to jump slot.	*/
	case R_390_GOTPLTENT:	/* 32 bit rel. offset to jump slot >> 1. */
		if (info->got_offset == -1UL) {
			info->got_offset = me->arch.got_size;
			me->arch.got_size += sizeof(void*);
		}
		break;
	case R_390_PLT16DBL:	/* 16 bit PC rel. PLT shifted by 1.  */
	case R_390_PLT32DBL:	/* 32 bit PC rel. PLT shifted by 1.  */
	case R_390_PLT32:	/* 32 bit PC relative PLT address.  */
	case R_390_PLT64:	/* 64 bit PC relative PLT address.  */
	case R_390_PLTOFF16:	/* 16 bit offset from GOT to PLT. */
	case R_390_PLTOFF32:	/* 32 bit offset from GOT to PLT. */
	case R_390_PLTOFF64:	/* 16 bit offset from GOT to PLT. */
		if (info->plt_offset == -1UL) {
			info->plt_offset = me->arch.plt_size;
			me->arch.plt_size += PLT_ENTRY_SIZE;
		}
		break;
	case R_390_COPY:
	case R_390_GLOB_DAT:
	case R_390_JMP_SLOT:
	case R_390_RELATIVE:
		/* Only needed if we want to support loading of 
		   modules linked with -shared. */
		break;
	}
}

/*
 * Account for GOT and PLT relocations. We can't add sections for
 * got and plt but we can increase the core module size.
 */
int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
			      char *secstrings, struct module *me)
{
	Elf_Shdr *symtab;
	Elf_Sym *symbols;
	Elf_Rela *rela;
	char *strings;
	int nrela, i, j;

	/* Find symbol table and string table. */
	symtab = NULL;
	for (i = 0; i < hdr->e_shnum; i++)
		switch (sechdrs[i].sh_type) {
		case SHT_SYMTAB:
			symtab = sechdrs + i;
			break;
		}
	if (!symtab) {
		printk(KERN_ERR "module %s: no symbol table\n", me->name);
		return -ENOEXEC;
	}

	/* Allocate one syminfo structure per symbol. */
	me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
	me->arch.syminfo = vmalloc(me->arch.nsyms *
				   sizeof(struct mod_arch_syminfo));
	if (!me->arch.syminfo)
		return -ENOMEM;
	symbols = (void *) hdr + symtab->sh_offset;
	strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
	for (i = 0; i < me->arch.nsyms; i++) {
		if (symbols[i].st_shndx == SHN_UNDEF &&
		    strcmp(strings + symbols[i].st_name,
			   "_GLOBAL_OFFSET_TABLE_") == 0)
			/* "Define" it as absolute. */
			symbols[i].st_shndx = SHN_ABS;
		me->arch.syminfo[i].got_offset = -1UL;
		me->arch.syminfo[i].plt_offset = -1UL;
		me->arch.syminfo[i].got_initialized = 0;
		me->arch.syminfo[i].plt_initialized = 0;
	}

	/* Search for got/plt relocations. */
	me->arch.got_size = me->arch.plt_size = 0;
	for (i = 0; i < hdr->e_shnum; i++) {
		if (sechdrs[i].sh_type != SHT_RELA)
			continue;
		nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
		rela = (void *) hdr + sechdrs[i].sh_offset;
		for (j = 0; j < nrela; j++)
			check_rela(rela + j, me);
	}

	/* Increase core size by size of got & plt and set start
	   offsets for got and plt. */
	me->core_layout.size = ALIGN(me->core_layout.size, 4);
	me->arch.got_offset = me->core_layout.size;
	me->core_layout.size += me->arch.got_size;
	me->arch.plt_offset = me->core_layout.size;
	if (me->arch.plt_size) {
		if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable)
			me->arch.plt_size += PLT_ENTRY_SIZE;
		me->core_layout.size += me->arch.plt_size;
	}
	return 0;
}

static int apply_rela_bits(Elf_Addr loc, Elf_Addr val,
			   int sign, int bits, int shift)
{
	unsigned long umax;
	long min, max;

	if (val & ((1UL << shift) - 1))
		return -ENOEXEC;
	if (sign) {
		val = (Elf_Addr)(((long) val) >> shift);
		min = -(1L << (bits - 1));
		max = (1L << (bits - 1)) - 1;
		if ((long) val < min || (long) val > max)
			return -ENOEXEC;
	} else {
		val >>= shift;
		umax = ((1UL << (bits - 1)) << 1) - 1;
		if ((unsigned long) val > umax)
			return -ENOEXEC;
	}

	if (bits == 8)
		*(unsigned char *) loc = val;
	else if (bits == 12)
		*(unsigned short *) loc = (val & 0xfff) |
			(*(unsigned short *) loc & 0xf000);
	else if (bits == 16)
		*(unsigned short *) loc = val;
	else if (bits == 20)
		*(unsigned int *) loc = (val & 0xfff) << 16 |
			(val & 0xff000) >> 4 |
			(*(unsigned int *) loc & 0xf00000ff);
	else if (bits == 32)
		*(unsigned int *) loc = val;
	else if (bits == 64)
		*(unsigned long *) loc = val;
	return 0;
}

static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
		      const char *strtab, struct module *me)
{
	struct mod_arch_syminfo *info;
	Elf_Addr loc, val;
	int r_type, r_sym;
	int rc = -ENOEXEC;

	/* This is where to make the change */
	loc = base + rela->r_offset;
	/* This is the symbol it is referring to.  Note that all
	   undefined symbols have been resolved.  */
	r_sym = ELF_R_SYM(rela->r_info);
	r_type = ELF_R_TYPE(rela->r_info);
	info = me->arch.syminfo + r_sym;
	val = symtab[r_sym].st_value;

	switch (r_type) {
	case R_390_NONE:	/* No relocation.  */
		rc = 0;
		break;
	case R_390_8:		/* Direct 8 bit.   */
	case R_390_12:		/* Direct 12 bit.  */
	case R_390_16:		/* Direct 16 bit.  */
	case R_390_20:		/* Direct 20 bit.  */
	case R_390_32:		/* Direct 32 bit.  */
	case R_390_64:		/* Direct 64 bit.  */
		val += rela->r_addend;
		if (r_type == R_390_8)
			rc = apply_rela_bits(loc, val, 0, 8, 0);
		else if (r_type == R_390_12)
			rc = apply_rela_bits(loc, val, 0, 12, 0);
		else if (r_type == R_390_16)
			rc = apply_rela_bits(loc, val, 0, 16, 0);
		else if (r_type == R_390_20)
			rc = apply_rela_bits(loc, val, 1, 20, 0);
		else if (r_type == R_390_32)
			rc = apply_rela_bits(loc, val, 0, 32, 0);
		else if (r_type == R_390_64)
			rc = apply_rela_bits(loc, val, 0, 64, 0);
		break;
	case R_390_PC16:	/* PC relative 16 bit.  */
	case R_390_PC16DBL:	/* PC relative 16 bit shifted by 1.  */
	case R_390_PC32DBL:	/* PC relative 32 bit shifted by 1.  */
	case R_390_PC32:	/* PC relative 32 bit.  */
	case R_390_PC64:	/* PC relative 64 bit.	*/
		val += rela->r_addend - loc;
		if (r_type == R_390_PC16)
			rc = apply_rela_bits(loc, val, 1, 16, 0);
		else if (r_type == R_390_PC16DBL)
			rc = apply_rela_bits(loc, val, 1, 16, 1);
		else if (r_type == R_390_PC32DBL)
			rc = apply_rela_bits(loc, val, 1, 32, 1);
		else if (r_type == R_390_PC32)
			rc = apply_rela_bits(loc, val, 1, 32, 0);
		else if (r_type == R_390_PC64)
			rc = apply_rela_bits(loc, val, 1, 64, 0);
		break;
	case R_390_GOT12:	/* 12 bit GOT offset.  */
	case R_390_GOT16:	/* 16 bit GOT offset.  */
	case R_390_GOT20:	/* 20 bit GOT offset.  */
	case R_390_GOT32:	/* 32 bit GOT offset.  */
	case R_390_GOT64:	/* 64 bit GOT offset.  */
	case R_390_GOTENT:	/* 32 bit PC rel. to GOT entry shifted by 1. */
	case R_390_GOTPLT12:	/* 12 bit offset to jump slot.	*/
	case R_390_GOTPLT20:	/* 20 bit offset to jump slot.  */
	case R_390_GOTPLT16:	/* 16 bit offset to jump slot.  */
	case R_390_GOTPLT32:	/* 32 bit offset to jump slot.  */
	case R_390_GOTPLT64:	/* 64 bit offset to jump slot.	*/
	case R_390_GOTPLTENT:	/* 32 bit rel. offset to jump slot >> 1. */
		if (info->got_initialized == 0) {
			Elf_Addr *gotent;

			gotent = me->core_layout.base + me->arch.got_offset +
				info->got_offset;
			*gotent = val;
			info->got_initialized = 1;
		}
		val = info->got_offset + rela->r_addend;
		if (r_type == R_390_GOT12 ||
		    r_type == R_390_GOTPLT12)
			rc = apply_rela_bits(loc, val, 0, 12, 0);
		else if (r_type == R_390_GOT16 ||
			 r_type == R_390_GOTPLT16)
			rc = apply_rela_bits(loc, val, 0, 16, 0);
		else if (r_type == R_390_GOT20 ||
			 r_type == R_390_GOTPLT20)
			rc = apply_rela_bits(loc, val, 1, 20, 0);
		else if (r_type == R_390_GOT32 ||
			 r_type == R_390_GOTPLT32)
			rc = apply_rela_bits(loc, val, 0, 32, 0);
		else if (r_type == R_390_GOT64 ||
			 r_type == R_390_GOTPLT64)
			rc = apply_rela_bits(loc, val, 0, 64, 0);
		else if (r_type == R_390_GOTENT ||
			 r_type == R_390_GOTPLTENT) {
			val += (Elf_Addr) me->core_layout.base - loc;
			rc = apply_rela_bits(loc, val, 1, 32, 1);
		}
		break;
	case R_390_PLT16DBL:	/* 16 bit PC rel. PLT shifted by 1.  */
	case R_390_PLT32DBL:	/* 32 bit PC rel. PLT shifted by 1.  */
	case R_390_PLT32:	/* 32 bit PC relative PLT address.  */
	case R_390_PLT64:	/* 64 bit PC relative PLT address.  */
	case R_390_PLTOFF16:	/* 16 bit offset from GOT to PLT. */
	case R_390_PLTOFF32:	/* 32 bit offset from GOT to PLT. */
	case R_390_PLTOFF64:	/* 16 bit offset from GOT to PLT. */
		if (info->plt_initialized == 0) {
			unsigned int *ip;
			ip = me->core_layout.base + me->arch.plt_offset +
				info->plt_offset;
			ip[0] = 0x0d10e310;	/* basr 1,0  */
			ip[1] = 0x100a0004;	/* lg	1,10(1) */
			if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
				unsigned int *ij;
				ij = me->core_layout.base +
					me->arch.plt_offset +
					me->arch.plt_size - PLT_ENTRY_SIZE;
				ip[2] = 0xa7f40000 +	/* j __jump_r1 */
					(unsigned int)(u16)
					(((unsigned long) ij - 8 -
					  (unsigned long) ip) / 2);
			} else {
				ip[2] = 0x07f10000;	/* br %r1 */
			}
			ip[3] = (unsigned int) (val >> 32);
			ip[4] = (unsigned int) val;
			info->plt_initialized = 1;
		}
		if (r_type == R_390_PLTOFF16 ||
		    r_type == R_390_PLTOFF32 ||
		    r_type == R_390_PLTOFF64)
			val = me->arch.plt_offset - me->arch.got_offset +
				info->plt_offset + rela->r_addend;
		else {
			if (!((r_type == R_390_PLT16DBL &&
			       val - loc + 0xffffUL < 0x1ffffeUL) ||
			      (r_type == R_390_PLT32DBL &&
			       val - loc + 0xffffffffULL < 0x1fffffffeULL)))
				val = (Elf_Addr) me->core_layout.base +
					me->arch.plt_offset +
					info->plt_offset;
			val += rela->r_addend - loc;
		}
		if (r_type == R_390_PLT16DBL)
			rc = apply_rela_bits(loc, val, 1, 16, 1);
		else if (r_type == R_390_PLTOFF16)
			rc = apply_rela_bits(loc, val, 0, 16, 0);
		else if (r_type == R_390_PLT32DBL)
			rc = apply_rela_bits(loc, val, 1, 32, 1);
		else if (r_type == R_390_PLT32 ||
			 r_type == R_390_PLTOFF32)
			rc = apply_rela_bits(loc, val, 0, 32, 0);
		else if (r_type == R_390_PLT64 ||
			 r_type == R_390_PLTOFF64)
			rc = apply_rela_bits(loc, val, 0, 64, 0);
		break;
	case R_390_GOTOFF16:	/* 16 bit offset to GOT.  */
	case R_390_GOTOFF32:	/* 32 bit offset to GOT.  */
	case R_390_GOTOFF64:	/* 64 bit offset to GOT. */
		val = val + rela->r_addend -
			((Elf_Addr) me->core_layout.base + me->arch.got_offset);
		if (r_type == R_390_GOTOFF16)
			rc = apply_rela_bits(loc, val, 0, 16, 0);
		else if (r_type == R_390_GOTOFF32)
			rc = apply_rela_bits(loc, val, 0, 32, 0);
		else if (r_type == R_390_GOTOFF64)
			rc = apply_rela_bits(loc, val, 0, 64, 0);
		break;
	case R_390_GOTPC:	/* 32 bit PC relative offset to GOT. */
	case R_390_GOTPCDBL:	/* 32 bit PC rel. off. to GOT shifted by 1. */
		val = (Elf_Addr) me->core_layout.base + me->arch.got_offset +
			rela->r_addend - loc;
		if (r_type == R_390_GOTPC)
			rc = apply_rela_bits(loc, val, 1, 32, 0);
		else if (r_type == R_390_GOTPCDBL)
			rc = apply_rela_bits(loc, val, 1, 32, 1);
		break;
	case R_390_COPY:
	case R_390_GLOB_DAT:	/* Create GOT entry.  */
	case R_390_JMP_SLOT:	/* Create PLT entry.  */
	case R_390_RELATIVE:	/* Adjust by program base.  */
		/* Only needed if we want to support loading of 
		   modules linked with -shared. */
		return -ENOEXEC;
	default:
		printk(KERN_ERR "module %s: unknown relocation: %u\n",
		       me->name, r_type);
		return -ENOEXEC;
	}
	if (rc) {
		printk(KERN_ERR "module %s: relocation error for symbol %s "
		       "(r_type %i, value 0x%lx)\n",
		       me->name, strtab + symtab[r_sym].st_name,
		       r_type, (unsigned long) val);
		return rc;
	}
	return 0;
}

int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
		       unsigned int symindex, unsigned int relsec,
		       struct module *me)
{
	Elf_Addr base;
	Elf_Sym *symtab;
	Elf_Rela *rela;
	unsigned long i, n;
	int rc;

	DEBUGP("Applying relocate section %u to %u\n",
	       relsec, sechdrs[relsec].sh_info);
	base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
	symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
	rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
	n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);

	for (i = 0; i < n; i++, rela++) {
		rc = apply_rela(rela, base, symtab, strtab, me);
		if (rc)
			return rc;
	}
	return 0;
}

int module_finalize(const Elf_Ehdr *hdr,
		    const Elf_Shdr *sechdrs,
		    struct module *me)
{
	const Elf_Shdr *s;
	char *secstrings, *secname;
	void *aseg;

	if (IS_ENABLED(CONFIG_EXPOLINE) &&
	    !nospec_disable && me->arch.plt_size) {
		unsigned int *ij;

		ij = me->core_layout.base + me->arch.plt_offset +
			me->arch.plt_size - PLT_ENTRY_SIZE;
		if (test_facility(35)) {
			ij[0] = 0xc6000000;	/* exrl	%r0,.+10	*/
			ij[1] = 0x0005a7f4;	/* j	.		*/
			ij[2] = 0x000007f1;	/* br	%r1		*/
		} else {
			ij[0] = 0x44000000 | (unsigned int)
				offsetof(struct lowcore, br_r1_trampoline);
			ij[1] = 0xa7f40000;	/* j	.		*/
		}
	}

	secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
		aseg = (void *) s->sh_addr;
		secname = secstrings + s->sh_name;

		if (!strcmp(".altinstructions", secname))
			/* patch .altinstructions */
			apply_alternatives(aseg, aseg + s->sh_size);

		if (IS_ENABLED(CONFIG_EXPOLINE) &&
		    (!strcmp(".nospec_call_table", secname)))
			nospec_revert(aseg, aseg + s->sh_size);

		if (IS_ENABLED(CONFIG_EXPOLINE) &&
		    (!strcmp(".nospec_return_table", secname)))
			nospec_revert(aseg, aseg + s->sh_size);
	}

	jump_label_apply_nops(me);
	return 0;
}