xref: /openbmc/linux/arch/s390/kernel/module.c (revision cabce92d)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  Kernel module help for s390.
4  *
5  *  S390 version
6  *    Copyright IBM Corp. 2002, 2003
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 #include <linux/module.h>
14 #include <linux/elf.h>
15 #include <linux/vmalloc.h>
16 #include <linux/fs.h>
17 #include <linux/ftrace.h>
18 #include <linux/string.h>
19 #include <linux/kernel.h>
20 #include <linux/kasan.h>
21 #include <linux/moduleloader.h>
22 #include <linux/bug.h>
23 #include <linux/memory.h>
24 #include <asm/alternative.h>
25 #include <asm/nospec-branch.h>
26 #include <asm/facility.h>
27 #include <asm/ftrace.lds.h>
28 #include <asm/set_memory.h>
29 #include <asm/setup.h>
30 
31 #if 0
32 #define DEBUGP printk
33 #else
34 #define DEBUGP(fmt , ...)
35 #endif
36 
37 #define PLT_ENTRY_SIZE 22
38 
39 static unsigned long get_module_load_offset(void)
40 {
41 	static DEFINE_MUTEX(module_kaslr_mutex);
42 	static unsigned long module_load_offset;
43 
44 	if (!kaslr_enabled())
45 		return 0;
46 	/*
47 	 * Calculate the module_load_offset the first time this code
48 	 * is called. Once calculated it stays the same until reboot.
49 	 */
50 	mutex_lock(&module_kaslr_mutex);
51 	if (!module_load_offset)
52 		module_load_offset = get_random_u32_inclusive(1, 1024) * PAGE_SIZE;
53 	mutex_unlock(&module_kaslr_mutex);
54 	return module_load_offset;
55 }
56 
57 void *module_alloc(unsigned long size)
58 {
59 	gfp_t gfp_mask = GFP_KERNEL;
60 	void *p;
61 
62 	if (PAGE_ALIGN(size) > MODULES_LEN)
63 		return NULL;
64 	p = __vmalloc_node_range(size, MODULE_ALIGN,
65 				 MODULES_VADDR + get_module_load_offset(),
66 				 MODULES_END, gfp_mask, PAGE_KERNEL,
67 				 VM_FLUSH_RESET_PERMS | VM_DEFER_KMEMLEAK,
68 				 NUMA_NO_NODE, __builtin_return_address(0));
69 	if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
70 		vfree(p);
71 		return NULL;
72 	}
73 	return p;
74 }
75 
76 #ifdef CONFIG_FUNCTION_TRACER
77 void module_arch_cleanup(struct module *mod)
78 {
79 	module_memfree(mod->arch.trampolines_start);
80 }
81 #endif
82 
83 void module_arch_freeing_init(struct module *mod)
84 {
85 	if (is_livepatch_module(mod) &&
86 	    mod->state == MODULE_STATE_LIVE)
87 		return;
88 
89 	vfree(mod->arch.syminfo);
90 	mod->arch.syminfo = NULL;
91 }
92 
93 static void check_rela(Elf_Rela *rela, struct module *me)
94 {
95 	struct mod_arch_syminfo *info;
96 
97 	info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
98 	switch (ELF_R_TYPE (rela->r_info)) {
99 	case R_390_GOT12:	/* 12 bit GOT offset.  */
100 	case R_390_GOT16:	/* 16 bit GOT offset.  */
101 	case R_390_GOT20:	/* 20 bit GOT offset.  */
102 	case R_390_GOT32:	/* 32 bit GOT offset.  */
103 	case R_390_GOT64:	/* 64 bit GOT offset.  */
104 	case R_390_GOTENT:	/* 32 bit PC rel. to GOT entry shifted by 1. */
105 	case R_390_GOTPLT12:	/* 12 bit offset to jump slot.	*/
106 	case R_390_GOTPLT16:	/* 16 bit offset to jump slot.  */
107 	case R_390_GOTPLT20:	/* 20 bit offset to jump slot.  */
108 	case R_390_GOTPLT32:	/* 32 bit offset to jump slot.  */
109 	case R_390_GOTPLT64:	/* 64 bit offset to jump slot.	*/
110 	case R_390_GOTPLTENT:	/* 32 bit rel. offset to jump slot >> 1. */
111 		if (info->got_offset == -1UL) {
112 			info->got_offset = me->arch.got_size;
113 			me->arch.got_size += sizeof(void*);
114 		}
115 		break;
116 	case R_390_PLT16DBL:	/* 16 bit PC rel. PLT shifted by 1.  */
117 	case R_390_PLT32DBL:	/* 32 bit PC rel. PLT shifted by 1.  */
118 	case R_390_PLT32:	/* 32 bit PC relative PLT address.  */
119 	case R_390_PLT64:	/* 64 bit PC relative PLT address.  */
120 	case R_390_PLTOFF16:	/* 16 bit offset from GOT to PLT. */
121 	case R_390_PLTOFF32:	/* 32 bit offset from GOT to PLT. */
122 	case R_390_PLTOFF64:	/* 16 bit offset from GOT to PLT. */
123 		if (info->plt_offset == -1UL) {
124 			info->plt_offset = me->arch.plt_size;
125 			me->arch.plt_size += PLT_ENTRY_SIZE;
126 		}
127 		break;
128 	case R_390_COPY:
129 	case R_390_GLOB_DAT:
130 	case R_390_JMP_SLOT:
131 	case R_390_RELATIVE:
132 		/* Only needed if we want to support loading of
133 		   modules linked with -shared. */
134 		break;
135 	}
136 }
137 
138 /*
139  * Account for GOT and PLT relocations. We can't add sections for
140  * got and plt but we can increase the core module size.
141  */
142 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
143 			      char *secstrings, struct module *me)
144 {
145 	Elf_Shdr *symtab;
146 	Elf_Sym *symbols;
147 	Elf_Rela *rela;
148 	char *strings;
149 	int nrela, i, j;
150 	struct module_memory *mod_mem;
151 
152 	/* Find symbol table and string table. */
153 	symtab = NULL;
154 	for (i = 0; i < hdr->e_shnum; i++)
155 		switch (sechdrs[i].sh_type) {
156 		case SHT_SYMTAB:
157 			symtab = sechdrs + i;
158 			break;
159 		}
160 	if (!symtab) {
161 		printk(KERN_ERR "module %s: no symbol table\n", me->name);
162 		return -ENOEXEC;
163 	}
164 
165 	/* Allocate one syminfo structure per symbol. */
166 	me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
167 	me->arch.syminfo = vmalloc(array_size(sizeof(struct mod_arch_syminfo),
168 					      me->arch.nsyms));
169 	if (!me->arch.syminfo)
170 		return -ENOMEM;
171 	symbols = (void *) hdr + symtab->sh_offset;
172 	strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
173 	for (i = 0; i < me->arch.nsyms; i++) {
174 		if (symbols[i].st_shndx == SHN_UNDEF &&
175 		    strcmp(strings + symbols[i].st_name,
176 			   "_GLOBAL_OFFSET_TABLE_") == 0)
177 			/* "Define" it as absolute. */
178 			symbols[i].st_shndx = SHN_ABS;
179 		me->arch.syminfo[i].got_offset = -1UL;
180 		me->arch.syminfo[i].plt_offset = -1UL;
181 		me->arch.syminfo[i].got_initialized = 0;
182 		me->arch.syminfo[i].plt_initialized = 0;
183 	}
184 
185 	/* Search for got/plt relocations. */
186 	me->arch.got_size = me->arch.plt_size = 0;
187 	for (i = 0; i < hdr->e_shnum; i++) {
188 		if (sechdrs[i].sh_type != SHT_RELA)
189 			continue;
190 		nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
191 		rela = (void *) hdr + sechdrs[i].sh_offset;
192 		for (j = 0; j < nrela; j++)
193 			check_rela(rela + j, me);
194 	}
195 
196 	/* Increase core size by size of got & plt and set start
197 	   offsets for got and plt. */
198 	mod_mem = &me->mem[MOD_TEXT];
199 	mod_mem->size = ALIGN(mod_mem->size, 4);
200 	me->arch.got_offset = mod_mem->size;
201 	mod_mem->size += me->arch.got_size;
202 	me->arch.plt_offset = mod_mem->size;
203 	if (me->arch.plt_size) {
204 		if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable)
205 			me->arch.plt_size += PLT_ENTRY_SIZE;
206 		mod_mem->size += me->arch.plt_size;
207 	}
208 	return 0;
209 }
210 
211 static int apply_rela_bits(Elf_Addr loc, Elf_Addr val,
212 			   int sign, int bits, int shift,
213 			   void *(*write)(void *dest, const void *src, size_t len))
214 {
215 	unsigned long umax;
216 	long min, max;
217 	void *dest = (void *)loc;
218 
219 	if (val & ((1UL << shift) - 1))
220 		return -ENOEXEC;
221 	if (sign) {
222 		val = (Elf_Addr)(((long) val) >> shift);
223 		min = -(1L << (bits - 1));
224 		max = (1L << (bits - 1)) - 1;
225 		if ((long) val < min || (long) val > max)
226 			return -ENOEXEC;
227 	} else {
228 		val >>= shift;
229 		umax = ((1UL << (bits - 1)) << 1) - 1;
230 		if ((unsigned long) val > umax)
231 			return -ENOEXEC;
232 	}
233 
234 	if (bits == 8) {
235 		unsigned char tmp = val;
236 		write(dest, &tmp, 1);
237 	} else if (bits == 12) {
238 		unsigned short tmp = (val & 0xfff) |
239 			(*(unsigned short *) loc & 0xf000);
240 		write(dest, &tmp, 2);
241 	} else if (bits == 16) {
242 		unsigned short tmp = val;
243 		write(dest, &tmp, 2);
244 	} else if (bits == 20) {
245 		unsigned int tmp = (val & 0xfff) << 16 |
246 			(val & 0xff000) >> 4 | (*(unsigned int *) loc & 0xf00000ff);
247 		write(dest, &tmp, 4);
248 	} else if (bits == 32) {
249 		unsigned int tmp = val;
250 		write(dest, &tmp, 4);
251 	} else if (bits == 64) {
252 		unsigned long tmp = val;
253 		write(dest, &tmp, 8);
254 	}
255 	return 0;
256 }
257 
258 static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
259 		      const char *strtab, struct module *me,
260 		      void *(*write)(void *dest, const void *src, size_t len))
261 {
262 	struct mod_arch_syminfo *info;
263 	Elf_Addr loc, val;
264 	int r_type, r_sym;
265 	int rc = -ENOEXEC;
266 
267 	/* This is where to make the change */
268 	loc = base + rela->r_offset;
269 	/* This is the symbol it is referring to.  Note that all
270 	   undefined symbols have been resolved.  */
271 	r_sym = ELF_R_SYM(rela->r_info);
272 	r_type = ELF_R_TYPE(rela->r_info);
273 	info = me->arch.syminfo + r_sym;
274 	val = symtab[r_sym].st_value;
275 
276 	switch (r_type) {
277 	case R_390_NONE:	/* No relocation.  */
278 		rc = 0;
279 		break;
280 	case R_390_8:		/* Direct 8 bit.   */
281 	case R_390_12:		/* Direct 12 bit.  */
282 	case R_390_16:		/* Direct 16 bit.  */
283 	case R_390_20:		/* Direct 20 bit.  */
284 	case R_390_32:		/* Direct 32 bit.  */
285 	case R_390_64:		/* Direct 64 bit.  */
286 		val += rela->r_addend;
287 		if (r_type == R_390_8)
288 			rc = apply_rela_bits(loc, val, 0, 8, 0, write);
289 		else if (r_type == R_390_12)
290 			rc = apply_rela_bits(loc, val, 0, 12, 0, write);
291 		else if (r_type == R_390_16)
292 			rc = apply_rela_bits(loc, val, 0, 16, 0, write);
293 		else if (r_type == R_390_20)
294 			rc = apply_rela_bits(loc, val, 1, 20, 0, write);
295 		else if (r_type == R_390_32)
296 			rc = apply_rela_bits(loc, val, 0, 32, 0, write);
297 		else if (r_type == R_390_64)
298 			rc = apply_rela_bits(loc, val, 0, 64, 0, write);
299 		break;
300 	case R_390_PC16:	/* PC relative 16 bit.  */
301 	case R_390_PC16DBL:	/* PC relative 16 bit shifted by 1.  */
302 	case R_390_PC32DBL:	/* PC relative 32 bit shifted by 1.  */
303 	case R_390_PC32:	/* PC relative 32 bit.  */
304 	case R_390_PC64:	/* PC relative 64 bit.	*/
305 		val += rela->r_addend - loc;
306 		if (r_type == R_390_PC16)
307 			rc = apply_rela_bits(loc, val, 1, 16, 0, write);
308 		else if (r_type == R_390_PC16DBL)
309 			rc = apply_rela_bits(loc, val, 1, 16, 1, write);
310 		else if (r_type == R_390_PC32DBL)
311 			rc = apply_rela_bits(loc, val, 1, 32, 1, write);
312 		else if (r_type == R_390_PC32)
313 			rc = apply_rela_bits(loc, val, 1, 32, 0, write);
314 		else if (r_type == R_390_PC64)
315 			rc = apply_rela_bits(loc, val, 1, 64, 0, write);
316 		break;
317 	case R_390_GOT12:	/* 12 bit GOT offset.  */
318 	case R_390_GOT16:	/* 16 bit GOT offset.  */
319 	case R_390_GOT20:	/* 20 bit GOT offset.  */
320 	case R_390_GOT32:	/* 32 bit GOT offset.  */
321 	case R_390_GOT64:	/* 64 bit GOT offset.  */
322 	case R_390_GOTENT:	/* 32 bit PC rel. to GOT entry shifted by 1. */
323 	case R_390_GOTPLT12:	/* 12 bit offset to jump slot.	*/
324 	case R_390_GOTPLT20:	/* 20 bit offset to jump slot.  */
325 	case R_390_GOTPLT16:	/* 16 bit offset to jump slot.  */
326 	case R_390_GOTPLT32:	/* 32 bit offset to jump slot.  */
327 	case R_390_GOTPLT64:	/* 64 bit offset to jump slot.	*/
328 	case R_390_GOTPLTENT:	/* 32 bit rel. offset to jump slot >> 1. */
329 		if (info->got_initialized == 0) {
330 			Elf_Addr *gotent = me->mem[MOD_TEXT].base +
331 					   me->arch.got_offset +
332 					   info->got_offset;
333 
334 			write(gotent, &val, sizeof(*gotent));
335 			info->got_initialized = 1;
336 		}
337 		val = info->got_offset + rela->r_addend;
338 		if (r_type == R_390_GOT12 ||
339 		    r_type == R_390_GOTPLT12)
340 			rc = apply_rela_bits(loc, val, 0, 12, 0, write);
341 		else if (r_type == R_390_GOT16 ||
342 			 r_type == R_390_GOTPLT16)
343 			rc = apply_rela_bits(loc, val, 0, 16, 0, write);
344 		else if (r_type == R_390_GOT20 ||
345 			 r_type == R_390_GOTPLT20)
346 			rc = apply_rela_bits(loc, val, 1, 20, 0, write);
347 		else if (r_type == R_390_GOT32 ||
348 			 r_type == R_390_GOTPLT32)
349 			rc = apply_rela_bits(loc, val, 0, 32, 0, write);
350 		else if (r_type == R_390_GOT64 ||
351 			 r_type == R_390_GOTPLT64)
352 			rc = apply_rela_bits(loc, val, 0, 64, 0, write);
353 		else if (r_type == R_390_GOTENT ||
354 			 r_type == R_390_GOTPLTENT) {
355 			val += (Elf_Addr)me->mem[MOD_TEXT].base +
356 				me->arch.got_offset - loc;
357 			rc = apply_rela_bits(loc, val, 1, 32, 1, write);
358 		}
359 		break;
360 	case R_390_PLT16DBL:	/* 16 bit PC rel. PLT shifted by 1.  */
361 	case R_390_PLT32DBL:	/* 32 bit PC rel. PLT shifted by 1.  */
362 	case R_390_PLT32:	/* 32 bit PC relative PLT address.  */
363 	case R_390_PLT64:	/* 64 bit PC relative PLT address.  */
364 	case R_390_PLTOFF16:	/* 16 bit offset from GOT to PLT. */
365 	case R_390_PLTOFF32:	/* 32 bit offset from GOT to PLT. */
366 	case R_390_PLTOFF64:	/* 16 bit offset from GOT to PLT. */
367 		if (info->plt_initialized == 0) {
368 			unsigned char insn[PLT_ENTRY_SIZE];
369 			char *plt_base;
370 			char *ip;
371 
372 			plt_base = me->mem[MOD_TEXT].base + me->arch.plt_offset;
373 			ip = plt_base + info->plt_offset;
374 			*(int *)insn = 0x0d10e310;	/* basr 1,0  */
375 			*(int *)&insn[4] = 0x100c0004;	/* lg	1,12(1) */
376 			if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
377 				char *jump_r1;
378 
379 				jump_r1 = plt_base + me->arch.plt_size -
380 					PLT_ENTRY_SIZE;
381 				/* brcl	0xf,__jump_r1 */
382 				*(short *)&insn[8] = 0xc0f4;
383 				*(int *)&insn[10] = (jump_r1 - (ip + 8)) / 2;
384 			} else {
385 				*(int *)&insn[8] = 0x07f10000;	/* br %r1 */
386 			}
387 			*(long *)&insn[14] = val;
388 
389 			write(ip, insn, sizeof(insn));
390 			info->plt_initialized = 1;
391 		}
392 		if (r_type == R_390_PLTOFF16 ||
393 		    r_type == R_390_PLTOFF32 ||
394 		    r_type == R_390_PLTOFF64)
395 			val = me->arch.plt_offset - me->arch.got_offset +
396 				info->plt_offset + rela->r_addend;
397 		else {
398 			if (!((r_type == R_390_PLT16DBL &&
399 			       val - loc + 0xffffUL < 0x1ffffeUL) ||
400 			      (r_type == R_390_PLT32DBL &&
401 			       val - loc + 0xffffffffULL < 0x1fffffffeULL)))
402 				val = (Elf_Addr) me->mem[MOD_TEXT].base +
403 					me->arch.plt_offset +
404 					info->plt_offset;
405 			val += rela->r_addend - loc;
406 		}
407 		if (r_type == R_390_PLT16DBL)
408 			rc = apply_rela_bits(loc, val, 1, 16, 1, write);
409 		else if (r_type == R_390_PLTOFF16)
410 			rc = apply_rela_bits(loc, val, 0, 16, 0, write);
411 		else if (r_type == R_390_PLT32DBL)
412 			rc = apply_rela_bits(loc, val, 1, 32, 1, write);
413 		else if (r_type == R_390_PLT32 ||
414 			 r_type == R_390_PLTOFF32)
415 			rc = apply_rela_bits(loc, val, 0, 32, 0, write);
416 		else if (r_type == R_390_PLT64 ||
417 			 r_type == R_390_PLTOFF64)
418 			rc = apply_rela_bits(loc, val, 0, 64, 0, write);
419 		break;
420 	case R_390_GOTOFF16:	/* 16 bit offset to GOT.  */
421 	case R_390_GOTOFF32:	/* 32 bit offset to GOT.  */
422 	case R_390_GOTOFF64:	/* 64 bit offset to GOT. */
423 		val = val + rela->r_addend -
424 			((Elf_Addr) me->mem[MOD_TEXT].base + me->arch.got_offset);
425 		if (r_type == R_390_GOTOFF16)
426 			rc = apply_rela_bits(loc, val, 0, 16, 0, write);
427 		else if (r_type == R_390_GOTOFF32)
428 			rc = apply_rela_bits(loc, val, 0, 32, 0, write);
429 		else if (r_type == R_390_GOTOFF64)
430 			rc = apply_rela_bits(loc, val, 0, 64, 0, write);
431 		break;
432 	case R_390_GOTPC:	/* 32 bit PC relative offset to GOT. */
433 	case R_390_GOTPCDBL:	/* 32 bit PC rel. off. to GOT shifted by 1. */
434 		val = (Elf_Addr) me->mem[MOD_TEXT].base + me->arch.got_offset +
435 			rela->r_addend - loc;
436 		if (r_type == R_390_GOTPC)
437 			rc = apply_rela_bits(loc, val, 1, 32, 0, write);
438 		else if (r_type == R_390_GOTPCDBL)
439 			rc = apply_rela_bits(loc, val, 1, 32, 1, write);
440 		break;
441 	case R_390_COPY:
442 	case R_390_GLOB_DAT:	/* Create GOT entry.  */
443 	case R_390_JMP_SLOT:	/* Create PLT entry.  */
444 	case R_390_RELATIVE:	/* Adjust by program base.  */
445 		/* Only needed if we want to support loading of
446 		   modules linked with -shared. */
447 		return -ENOEXEC;
448 	default:
449 		printk(KERN_ERR "module %s: unknown relocation: %u\n",
450 		       me->name, r_type);
451 		return -ENOEXEC;
452 	}
453 	if (rc) {
454 		printk(KERN_ERR "module %s: relocation error for symbol %s "
455 		       "(r_type %i, value 0x%lx)\n",
456 		       me->name, strtab + symtab[r_sym].st_name,
457 		       r_type, (unsigned long) val);
458 		return rc;
459 	}
460 	return 0;
461 }
462 
463 static int __apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
464 		       unsigned int symindex, unsigned int relsec,
465 		       struct module *me,
466 		       void *(*write)(void *dest, const void *src, size_t len))
467 {
468 	Elf_Addr base;
469 	Elf_Sym *symtab;
470 	Elf_Rela *rela;
471 	unsigned long i, n;
472 	int rc;
473 
474 	DEBUGP("Applying relocate section %u to %u\n",
475 	       relsec, sechdrs[relsec].sh_info);
476 	base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
477 	symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
478 	rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
479 	n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
480 
481 	for (i = 0; i < n; i++, rela++) {
482 		rc = apply_rela(rela, base, symtab, strtab, me, write);
483 		if (rc)
484 			return rc;
485 	}
486 	return 0;
487 }
488 
489 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
490 		       unsigned int symindex, unsigned int relsec,
491 		       struct module *me)
492 {
493 	bool early = me->state == MODULE_STATE_UNFORMED;
494 	void *(*write)(void *, const void *, size_t) = memcpy;
495 
496 	if (!early)
497 		write = s390_kernel_write;
498 
499 	return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
500 				    write);
501 }
502 
503 #ifdef CONFIG_FUNCTION_TRACER
504 static int module_alloc_ftrace_hotpatch_trampolines(struct module *me,
505 						    const Elf_Shdr *s)
506 {
507 	char *start, *end;
508 	int numpages;
509 	size_t size;
510 
511 	size = FTRACE_HOTPATCH_TRAMPOLINES_SIZE(s->sh_size);
512 	numpages = DIV_ROUND_UP(size, PAGE_SIZE);
513 	start = module_alloc(numpages * PAGE_SIZE);
514 	if (!start)
515 		return -ENOMEM;
516 	set_memory_rox((unsigned long)start, numpages);
517 	end = start + size;
518 
519 	me->arch.trampolines_start = (struct ftrace_hotpatch_trampoline *)start;
520 	me->arch.trampolines_end = (struct ftrace_hotpatch_trampoline *)end;
521 	me->arch.next_trampoline = me->arch.trampolines_start;
522 
523 	return 0;
524 }
525 #endif /* CONFIG_FUNCTION_TRACER */
526 
527 int module_finalize(const Elf_Ehdr *hdr,
528 		    const Elf_Shdr *sechdrs,
529 		    struct module *me)
530 {
531 	const Elf_Shdr *s;
532 	char *secstrings, *secname;
533 	void *aseg;
534 #ifdef CONFIG_FUNCTION_TRACER
535 	int ret;
536 #endif
537 
538 	if (IS_ENABLED(CONFIG_EXPOLINE) &&
539 	    !nospec_disable && me->arch.plt_size) {
540 		unsigned int *ij;
541 
542 		ij = me->mem[MOD_TEXT].base + me->arch.plt_offset +
543 			me->arch.plt_size - PLT_ENTRY_SIZE;
544 		ij[0] = 0xc6000000;	/* exrl	%r0,.+10	*/
545 		ij[1] = 0x0005a7f4;	/* j	.		*/
546 		ij[2] = 0x000007f1;	/* br	%r1		*/
547 	}
548 
549 	secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
550 	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
551 		aseg = (void *) s->sh_addr;
552 		secname = secstrings + s->sh_name;
553 
554 		if (!strcmp(".altinstructions", secname))
555 			/* patch .altinstructions */
556 			apply_alternatives(aseg, aseg + s->sh_size);
557 
558 		if (IS_ENABLED(CONFIG_EXPOLINE) &&
559 		    (str_has_prefix(secname, ".s390_indirect")))
560 			nospec_revert(aseg, aseg + s->sh_size);
561 
562 		if (IS_ENABLED(CONFIG_EXPOLINE) &&
563 		    (str_has_prefix(secname, ".s390_return")))
564 			nospec_revert(aseg, aseg + s->sh_size);
565 
566 #ifdef CONFIG_FUNCTION_TRACER
567 		if (!strcmp(FTRACE_CALLSITE_SECTION, secname)) {
568 			ret = module_alloc_ftrace_hotpatch_trampolines(me, s);
569 			if (ret < 0)
570 				return ret;
571 		}
572 #endif /* CONFIG_FUNCTION_TRACER */
573 	}
574 
575 	return 0;
576 }
577