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1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*  Kernel module help for PPC64.
3     Copyright (C) 2001, 2003 Rusty Russell IBM Corporation.
4 
5 */
6 
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8 
9 #include <linux/module.h>
10 #include <linux/elf.h>
11 #include <linux/moduleloader.h>
12 #include <linux/err.h>
13 #include <linux/vmalloc.h>
14 #include <linux/ftrace.h>
15 #include <linux/bug.h>
16 #include <linux/uaccess.h>
17 #include <asm/module.h>
18 #include <asm/firmware.h>
19 #include <asm/code-patching.h>
20 #include <linux/sort.h>
21 #include <asm/setup.h>
22 #include <asm/sections.h>
23 #include <asm/inst.h>
24 
25 /* FIXME: We don't do .init separately.  To do this, we'd need to have
26    a separate r2 value in the init and core section, and stub between
27    them, too.
28 
29    Using a magic allocator which places modules within 32MB solves
30    this, and makes other things simpler.  Anton?
31    --RR.  */
32 
33 #ifdef PPC64_ELF_ABI_v2
34 
35 /* An address is simply the address of the function. */
36 typedef unsigned long func_desc_t;
37 
func_desc(unsigned long addr)38 static func_desc_t func_desc(unsigned long addr)
39 {
40 	return addr;
41 }
func_addr(unsigned long addr)42 static unsigned long func_addr(unsigned long addr)
43 {
44 	return addr;
45 }
stub_func_addr(func_desc_t func)46 static unsigned long stub_func_addr(func_desc_t func)
47 {
48 	return func;
49 }
50 
51 /* PowerPC64 specific values for the Elf64_Sym st_other field.  */
52 #define STO_PPC64_LOCAL_BIT	5
53 #define STO_PPC64_LOCAL_MASK	(7 << STO_PPC64_LOCAL_BIT)
54 #define PPC64_LOCAL_ENTRY_OFFSET(other)					\
55  (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
56 
local_entry_offset(const Elf64_Sym * sym)57 static unsigned int local_entry_offset(const Elf64_Sym *sym)
58 {
59 	/* sym->st_other indicates offset to local entry point
60 	 * (otherwise it will assume r12 is the address of the start
61 	 * of function and try to derive r2 from it). */
62 	return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
63 }
64 #else
65 
66 /* An address is address of the OPD entry, which contains address of fn. */
67 typedef struct ppc64_opd_entry func_desc_t;
68 
func_desc(unsigned long addr)69 static func_desc_t func_desc(unsigned long addr)
70 {
71 	return *(struct ppc64_opd_entry *)addr;
72 }
func_addr(unsigned long addr)73 static unsigned long func_addr(unsigned long addr)
74 {
75 	return func_desc(addr).funcaddr;
76 }
stub_func_addr(func_desc_t func)77 static unsigned long stub_func_addr(func_desc_t func)
78 {
79 	return func.funcaddr;
80 }
local_entry_offset(const Elf64_Sym * sym)81 static unsigned int local_entry_offset(const Elf64_Sym *sym)
82 {
83 	return 0;
84 }
85 
dereference_module_function_descriptor(struct module * mod,void * ptr)86 void *dereference_module_function_descriptor(struct module *mod, void *ptr)
87 {
88 	if (ptr < (void *)mod->arch.start_opd ||
89 			ptr >= (void *)mod->arch.end_opd)
90 		return ptr;
91 
92 	return dereference_function_descriptor(ptr);
93 }
94 #endif
95 
96 #define STUB_MAGIC 0x73747562 /* stub */
97 
98 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
99    the kernel itself).  But on PPC64, these need to be used for every
100    jump, actually, to reset r2 (TOC+0x8000). */
101 struct ppc64_stub_entry
102 {
103 	/* 28 byte jump instruction sequence (7 instructions). We only
104 	 * need 6 instructions on ABIv2 but we always allocate 7 so
105 	 * so we don't have to modify the trampoline load instruction. */
106 	u32 jump[7];
107 	/* Used by ftrace to identify stubs */
108 	u32 magic;
109 	/* Data for the above code */
110 	func_desc_t funcdata;
111 };
112 
113 /*
114  * PPC64 uses 24 bit jumps, but we need to jump into other modules or
115  * the kernel which may be further.  So we jump to a stub.
116  *
117  * For ELFv1 we need to use this to set up the new r2 value (aka TOC
118  * pointer).  For ELFv2 it's the callee's responsibility to set up the
119  * new r2, but for both we need to save the old r2.
120  *
121  * We could simply patch the new r2 value and function pointer into
122  * the stub, but it's significantly shorter to put these values at the
123  * end of the stub code, and patch the stub address (32-bits relative
124  * to the TOC ptr, r2) into the stub.
125  *
126  * addis   r11,r2, <high>
127  * addi    r11,r11, <low>
128  * std     r2,R2_STACK_OFFSET(r1)
129  * ld      r12,32(r11)
130  * ld      r2,40(r11)
131  * mtctr   r12
132  * bctr
133  */
134 static u32 ppc64_stub_insns[] = {
135 	PPC_INST_ADDIS | __PPC_RT(R11) | __PPC_RA(R2),
136 	PPC_INST_ADDI | __PPC_RT(R11) | __PPC_RA(R11),
137 	/* Save current r2 value in magic place on the stack. */
138 	PPC_INST_STD | __PPC_RS(R2) | __PPC_RA(R1) | R2_STACK_OFFSET,
139 	PPC_INST_LD | __PPC_RT(R12) | __PPC_RA(R11) | 32,
140 #ifdef PPC64_ELF_ABI_v1
141 	/* Set up new r2 from function descriptor */
142 	PPC_INST_LD | __PPC_RT(R2) | __PPC_RA(R11) | 40,
143 #endif
144 	PPC_INST_MTCTR | __PPC_RS(R12),
145 	PPC_INST_BCTR,
146 };
147 
148 /* Count how many different 24-bit relocations (different symbol,
149    different addend) */
count_relocs(const Elf64_Rela * rela,unsigned int num)150 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
151 {
152 	unsigned int i, r_info, r_addend, _count_relocs;
153 
154 	/* FIXME: Only count external ones --RR */
155 	_count_relocs = 0;
156 	r_info = 0;
157 	r_addend = 0;
158 	for (i = 0; i < num; i++)
159 		/* Only count 24-bit relocs, others don't need stubs */
160 		if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
161 		    (r_info != ELF64_R_SYM(rela[i].r_info) ||
162 		     r_addend != rela[i].r_addend)) {
163 			_count_relocs++;
164 			r_info = ELF64_R_SYM(rela[i].r_info);
165 			r_addend = rela[i].r_addend;
166 		}
167 
168 	return _count_relocs;
169 }
170 
relacmp(const void * _x,const void * _y)171 static int relacmp(const void *_x, const void *_y)
172 {
173 	const Elf64_Rela *x, *y;
174 
175 	y = (Elf64_Rela *)_x;
176 	x = (Elf64_Rela *)_y;
177 
178 	/* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
179 	 * make the comparison cheaper/faster. It won't affect the sorting or
180 	 * the counting algorithms' performance
181 	 */
182 	if (x->r_info < y->r_info)
183 		return -1;
184 	else if (x->r_info > y->r_info)
185 		return 1;
186 	else if (x->r_addend < y->r_addend)
187 		return -1;
188 	else if (x->r_addend > y->r_addend)
189 		return 1;
190 	else
191 		return 0;
192 }
193 
194 /* Get size of potential trampolines required. */
get_stubs_size(const Elf64_Ehdr * hdr,const Elf64_Shdr * sechdrs)195 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
196 				    const Elf64_Shdr *sechdrs)
197 {
198 	/* One extra reloc so it's always 0-funcaddr terminated */
199 	unsigned long relocs = 1;
200 	unsigned i;
201 
202 	/* Every relocated section... */
203 	for (i = 1; i < hdr->e_shnum; i++) {
204 		if (sechdrs[i].sh_type == SHT_RELA) {
205 			pr_debug("Found relocations in section %u\n", i);
206 			pr_debug("Ptr: %p.  Number: %Lu\n",
207 			       (void *)sechdrs[i].sh_addr,
208 			       sechdrs[i].sh_size / sizeof(Elf64_Rela));
209 
210 			/* Sort the relocation information based on a symbol and
211 			 * addend key. This is a stable O(n*log n) complexity
212 			 * alogrithm but it will reduce the complexity of
213 			 * count_relocs() to linear complexity O(n)
214 			 */
215 			sort((void *)sechdrs[i].sh_addr,
216 			     sechdrs[i].sh_size / sizeof(Elf64_Rela),
217 			     sizeof(Elf64_Rela), relacmp, NULL);
218 
219 			relocs += count_relocs((void *)sechdrs[i].sh_addr,
220 					       sechdrs[i].sh_size
221 					       / sizeof(Elf64_Rela));
222 		}
223 	}
224 
225 #ifdef CONFIG_DYNAMIC_FTRACE
226 	/* make the trampoline to the ftrace_caller */
227 	relocs++;
228 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
229 	/* an additional one for ftrace_regs_caller */
230 	relocs++;
231 #endif
232 #endif
233 
234 	pr_debug("Looks like a total of %lu stubs, max\n", relocs);
235 	return relocs * sizeof(struct ppc64_stub_entry);
236 }
237 
238 /* Still needed for ELFv2, for .TOC. */
dedotify_versions(struct modversion_info * vers,unsigned long size)239 static void dedotify_versions(struct modversion_info *vers,
240 			      unsigned long size)
241 {
242 	struct modversion_info *end;
243 
244 	for (end = (void *)vers + size; vers < end; vers++)
245 		if (vers->name[0] == '.') {
246 			memmove(vers->name, vers->name+1, strlen(vers->name));
247 		}
248 }
249 
250 /*
251  * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
252  * seem to be defined (value set later).
253  */
dedotify(Elf64_Sym * syms,unsigned int numsyms,char * strtab)254 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
255 {
256 	unsigned int i;
257 
258 	for (i = 1; i < numsyms; i++) {
259 		if (syms[i].st_shndx == SHN_UNDEF) {
260 			char *name = strtab + syms[i].st_name;
261 			if (name[0] == '.') {
262 				if (strcmp(name+1, "TOC.") == 0)
263 					syms[i].st_shndx = SHN_ABS;
264 				syms[i].st_name++;
265 			}
266 		}
267 	}
268 }
269 
find_dot_toc(Elf64_Shdr * sechdrs,const char * strtab,unsigned int symindex)270 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
271 			       const char *strtab,
272 			       unsigned int symindex)
273 {
274 	unsigned int i, numsyms;
275 	Elf64_Sym *syms;
276 
277 	syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
278 	numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
279 
280 	for (i = 1; i < numsyms; i++) {
281 		if (syms[i].st_shndx == SHN_ABS
282 		    && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
283 			return &syms[i];
284 	}
285 	return NULL;
286 }
287 
module_frob_arch_sections(Elf64_Ehdr * hdr,Elf64_Shdr * sechdrs,char * secstrings,struct module * me)288 int module_frob_arch_sections(Elf64_Ehdr *hdr,
289 			      Elf64_Shdr *sechdrs,
290 			      char *secstrings,
291 			      struct module *me)
292 {
293 	unsigned int i;
294 
295 	/* Find .toc and .stubs sections, symtab and strtab */
296 	for (i = 1; i < hdr->e_shnum; i++) {
297 		char *p;
298 		if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
299 			me->arch.stubs_section = i;
300 		else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) {
301 			me->arch.toc_section = i;
302 			if (sechdrs[i].sh_addralign < 8)
303 				sechdrs[i].sh_addralign = 8;
304 		}
305 		else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
306 			dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
307 					  sechdrs[i].sh_size);
308 
309 		/* We don't handle .init for the moment: rename to _init */
310 		while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
311 			p[0] = '_';
312 
313 		if (sechdrs[i].sh_type == SHT_SYMTAB)
314 			dedotify((void *)hdr + sechdrs[i].sh_offset,
315 				 sechdrs[i].sh_size / sizeof(Elf64_Sym),
316 				 (void *)hdr
317 				 + sechdrs[sechdrs[i].sh_link].sh_offset);
318 	}
319 
320 	if (!me->arch.stubs_section) {
321 		pr_err("%s: doesn't contain .stubs.\n", me->name);
322 		return -ENOEXEC;
323 	}
324 
325 	/* If we don't have a .toc, just use .stubs.  We need to set r2
326 	   to some reasonable value in case the module calls out to
327 	   other functions via a stub, or if a function pointer escapes
328 	   the module by some means.  */
329 	if (!me->arch.toc_section)
330 		me->arch.toc_section = me->arch.stubs_section;
331 
332 	/* Override the stubs size */
333 	sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
334 	return 0;
335 }
336 
337 #ifdef CONFIG_MPROFILE_KERNEL
338 
339 #define PACATOC offsetof(struct paca_struct, kernel_toc)
340 
341 /*
342  * ld      r12,PACATOC(r13)
343  * addis   r12,r12,<high>
344  * addi    r12,r12,<low>
345  * mtctr   r12
346  * bctr
347  */
348 static u32 stub_insns[] = {
349 	PPC_INST_LD | __PPC_RT(R12) | __PPC_RA(R13) | PACATOC,
350 	PPC_INST_ADDIS | __PPC_RT(R12) | __PPC_RA(R12),
351 	PPC_INST_ADDI | __PPC_RT(R12) | __PPC_RA(R12),
352 	PPC_INST_MTCTR | __PPC_RS(R12),
353 	PPC_INST_BCTR,
354 };
355 
356 /*
357  * For mprofile-kernel we use a special stub for ftrace_caller() because we
358  * can't rely on r2 containing this module's TOC when we enter the stub.
359  *
360  * That can happen if the function calling us didn't need to use the toc. In
361  * that case it won't have setup r2, and the r2 value will be either the
362  * kernel's toc, or possibly another modules toc.
363  *
364  * To deal with that this stub uses the kernel toc, which is always accessible
365  * via the paca (in r13). The target (ftrace_caller()) is responsible for
366  * saving and restoring the toc before returning.
367  */
create_ftrace_stub(struct ppc64_stub_entry * entry,unsigned long addr,struct module * me)368 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
369 					unsigned long addr,
370 					struct module *me)
371 {
372 	long reladdr;
373 
374 	memcpy(entry->jump, stub_insns, sizeof(stub_insns));
375 
376 	/* Stub uses address relative to kernel toc (from the paca) */
377 	reladdr = addr - kernel_toc_addr();
378 	if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
379 		pr_err("%s: Address of %ps out of range of kernel_toc.\n",
380 							me->name, (void *)addr);
381 		return 0;
382 	}
383 
384 	entry->jump[1] |= PPC_HA(reladdr);
385 	entry->jump[2] |= PPC_LO(reladdr);
386 
387 	/* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */
388 	entry->funcdata = func_desc(addr);
389 	entry->magic = STUB_MAGIC;
390 
391 	return 1;
392 }
393 
is_mprofile_ftrace_call(const char * name)394 static bool is_mprofile_ftrace_call(const char *name)
395 {
396 	if (!strcmp("_mcount", name))
397 		return true;
398 #ifdef CONFIG_DYNAMIC_FTRACE
399 	if (!strcmp("ftrace_caller", name))
400 		return true;
401 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
402 	if (!strcmp("ftrace_regs_caller", name))
403 		return true;
404 #endif
405 #endif
406 
407 	return false;
408 }
409 #else
create_ftrace_stub(struct ppc64_stub_entry * entry,unsigned long addr,struct module * me)410 static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
411 					unsigned long addr,
412 					struct module *me)
413 {
414 	return 0;
415 }
416 
is_mprofile_ftrace_call(const char * name)417 static bool is_mprofile_ftrace_call(const char *name)
418 {
419 	return false;
420 }
421 #endif
422 
423 /*
424  * r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the
425  * value maximum span in an instruction which uses a signed offset). Round down
426  * to a 256 byte boundary for the odd case where we are setting up r2 without a
427  * .toc section.
428  */
my_r2(const Elf64_Shdr * sechdrs,struct module * me)429 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
430 {
431 	return (sechdrs[me->arch.toc_section].sh_addr & ~0xfful) + 0x8000;
432 }
433 
434 /* Patch stub to reference function and correct r2 value. */
create_stub(const Elf64_Shdr * sechdrs,struct ppc64_stub_entry * entry,unsigned long addr,struct module * me,const char * name)435 static inline int create_stub(const Elf64_Shdr *sechdrs,
436 			      struct ppc64_stub_entry *entry,
437 			      unsigned long addr,
438 			      struct module *me,
439 			      const char *name)
440 {
441 	long reladdr;
442 
443 	if (is_mprofile_ftrace_call(name))
444 		return create_ftrace_stub(entry, addr, me);
445 
446 	memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns));
447 
448 	/* Stub uses address relative to r2. */
449 	reladdr = (unsigned long)entry - my_r2(sechdrs, me);
450 	if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
451 		pr_err("%s: Address %p of stub out of range of %p.\n",
452 		       me->name, (void *)reladdr, (void *)my_r2);
453 		return 0;
454 	}
455 	pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
456 
457 	entry->jump[0] |= PPC_HA(reladdr);
458 	entry->jump[1] |= PPC_LO(reladdr);
459 	entry->funcdata = func_desc(addr);
460 	entry->magic = STUB_MAGIC;
461 
462 	return 1;
463 }
464 
465 /* Create stub to jump to function described in this OPD/ptr: we need the
466    stub to set up the TOC ptr (r2) for the function. */
stub_for_addr(const Elf64_Shdr * sechdrs,unsigned long addr,struct module * me,const char * name)467 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
468 				   unsigned long addr,
469 				   struct module *me,
470 				   const char *name)
471 {
472 	struct ppc64_stub_entry *stubs;
473 	unsigned int i, num_stubs;
474 
475 	num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
476 
477 	/* Find this stub, or if that fails, the next avail. entry */
478 	stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
479 	for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
480 		if (WARN_ON(i >= num_stubs))
481 			return 0;
482 
483 		if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
484 			return (unsigned long)&stubs[i];
485 	}
486 
487 	if (!create_stub(sechdrs, &stubs[i], addr, me, name))
488 		return 0;
489 
490 	return (unsigned long)&stubs[i];
491 }
492 
493 /* We expect a noop next: if it is, replace it with instruction to
494    restore r2. */
restore_r2(const char * name,u32 * instruction,struct module * me)495 static int restore_r2(const char *name, u32 *instruction, struct module *me)
496 {
497 	u32 *prev_insn = instruction - 1;
498 
499 	if (is_mprofile_ftrace_call(name))
500 		return 1;
501 
502 	/*
503 	 * Make sure the branch isn't a sibling call.  Sibling calls aren't
504 	 * "link" branches and they don't return, so they don't need the r2
505 	 * restore afterwards.
506 	 */
507 	if (!instr_is_relative_link_branch(ppc_inst(*prev_insn)))
508 		return 1;
509 
510 	if (*instruction != PPC_INST_NOP) {
511 		pr_err("%s: Expected nop after call, got %08x at %pS\n",
512 			me->name, *instruction, instruction);
513 		return 0;
514 	}
515 	/* ld r2,R2_STACK_OFFSET(r1) */
516 	*instruction = PPC_INST_LD_TOC;
517 	return 1;
518 }
519 
apply_relocate_add(Elf64_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * me)520 int apply_relocate_add(Elf64_Shdr *sechdrs,
521 		       const char *strtab,
522 		       unsigned int symindex,
523 		       unsigned int relsec,
524 		       struct module *me)
525 {
526 	unsigned int i;
527 	Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
528 	Elf64_Sym *sym;
529 	unsigned long *location;
530 	unsigned long value;
531 
532 	pr_debug("Applying ADD relocate section %u to %u\n", relsec,
533 	       sechdrs[relsec].sh_info);
534 
535 	/* First time we're called, we can fix up .TOC. */
536 	if (!me->arch.toc_fixed) {
537 		sym = find_dot_toc(sechdrs, strtab, symindex);
538 		/* It's theoretically possible that a module doesn't want a
539 		 * .TOC. so don't fail it just for that. */
540 		if (sym)
541 			sym->st_value = my_r2(sechdrs, me);
542 		me->arch.toc_fixed = true;
543 	}
544 
545 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
546 		/* This is where to make the change */
547 		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
548 			+ rela[i].r_offset;
549 		/* This is the symbol it is referring to */
550 		sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
551 			+ ELF64_R_SYM(rela[i].r_info);
552 
553 		pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
554 		       location, (long)ELF64_R_TYPE(rela[i].r_info),
555 		       strtab + sym->st_name, (unsigned long)sym->st_value,
556 		       (long)rela[i].r_addend);
557 
558 		/* `Everything is relative'. */
559 		value = sym->st_value + rela[i].r_addend;
560 
561 		switch (ELF64_R_TYPE(rela[i].r_info)) {
562 		case R_PPC64_ADDR32:
563 			/* Simply set it */
564 			*(u32 *)location = value;
565 			break;
566 
567 		case R_PPC64_ADDR64:
568 			/* Simply set it */
569 			*(unsigned long *)location = value;
570 			break;
571 
572 		case R_PPC64_TOC:
573 			*(unsigned long *)location = my_r2(sechdrs, me);
574 			break;
575 
576 		case R_PPC64_TOC16:
577 			/* Subtract TOC pointer */
578 			value -= my_r2(sechdrs, me);
579 			if (value + 0x8000 > 0xffff) {
580 				pr_err("%s: bad TOC16 relocation (0x%lx)\n",
581 				       me->name, value);
582 				return -ENOEXEC;
583 			}
584 			*((uint16_t *) location)
585 				= (*((uint16_t *) location) & ~0xffff)
586 				| (value & 0xffff);
587 			break;
588 
589 		case R_PPC64_TOC16_LO:
590 			/* Subtract TOC pointer */
591 			value -= my_r2(sechdrs, me);
592 			*((uint16_t *) location)
593 				= (*((uint16_t *) location) & ~0xffff)
594 				| (value & 0xffff);
595 			break;
596 
597 		case R_PPC64_TOC16_DS:
598 			/* Subtract TOC pointer */
599 			value -= my_r2(sechdrs, me);
600 			if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
601 				pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
602 				       me->name, value);
603 				return -ENOEXEC;
604 			}
605 			*((uint16_t *) location)
606 				= (*((uint16_t *) location) & ~0xfffc)
607 				| (value & 0xfffc);
608 			break;
609 
610 		case R_PPC64_TOC16_LO_DS:
611 			/* Subtract TOC pointer */
612 			value -= my_r2(sechdrs, me);
613 			if ((value & 3) != 0) {
614 				pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
615 				       me->name, value);
616 				return -ENOEXEC;
617 			}
618 			*((uint16_t *) location)
619 				= (*((uint16_t *) location) & ~0xfffc)
620 				| (value & 0xfffc);
621 			break;
622 
623 		case R_PPC64_TOC16_HA:
624 			/* Subtract TOC pointer */
625 			value -= my_r2(sechdrs, me);
626 			value = ((value + 0x8000) >> 16);
627 			*((uint16_t *) location)
628 				= (*((uint16_t *) location) & ~0xffff)
629 				| (value & 0xffff);
630 			break;
631 
632 		case R_PPC_REL24:
633 			/* FIXME: Handle weak symbols here --RR */
634 			if (sym->st_shndx == SHN_UNDEF ||
635 			    sym->st_shndx == SHN_LIVEPATCH) {
636 				/* External: go via stub */
637 				value = stub_for_addr(sechdrs, value, me,
638 						strtab + sym->st_name);
639 				if (!value)
640 					return -ENOENT;
641 				if (!restore_r2(strtab + sym->st_name,
642 							(u32 *)location + 1, me))
643 					return -ENOEXEC;
644 			} else
645 				value += local_entry_offset(sym);
646 
647 			/* Convert value to relative */
648 			value -= (unsigned long)location;
649 			if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
650 				pr_err("%s: REL24 %li out of range!\n",
651 				       me->name, (long int)value);
652 				return -ENOEXEC;
653 			}
654 
655 			/* Only replace bits 2 through 26 */
656 			*(uint32_t *)location
657 				= (*(uint32_t *)location & ~0x03fffffc)
658 				| (value & 0x03fffffc);
659 			break;
660 
661 		case R_PPC64_REL64:
662 			/* 64 bits relative (used by features fixups) */
663 			*location = value - (unsigned long)location;
664 			break;
665 
666 		case R_PPC64_REL32:
667 			/* 32 bits relative (used by relative exception tables) */
668 			/* Convert value to relative */
669 			value -= (unsigned long)location;
670 			if (value + 0x80000000 > 0xffffffff) {
671 				pr_err("%s: REL32 %li out of range!\n",
672 				       me->name, (long int)value);
673 				return -ENOEXEC;
674 			}
675 			*(u32 *)location = value;
676 			break;
677 
678 		case R_PPC64_TOCSAVE:
679 			/*
680 			 * Marker reloc indicates we don't have to save r2.
681 			 * That would only save us one instruction, so ignore
682 			 * it.
683 			 */
684 			break;
685 
686 		case R_PPC64_ENTRY:
687 			/*
688 			 * Optimize ELFv2 large code model entry point if
689 			 * the TOC is within 2GB range of current location.
690 			 */
691 			value = my_r2(sechdrs, me) - (unsigned long)location;
692 			if (value + 0x80008000 > 0xffffffff)
693 				break;
694 			/*
695 			 * Check for the large code model prolog sequence:
696 		         *	ld r2, ...(r12)
697 			 *	add r2, r2, r12
698 			 */
699 			if ((((uint32_t *)location)[0] & ~0xfffc) !=
700 			    (PPC_INST_LD | __PPC_RT(R2) | __PPC_RA(R12)))
701 				break;
702 			if (((uint32_t *)location)[1] !=
703 			    (PPC_INST_ADD | __PPC_RT(R2) | __PPC_RA(R2) | __PPC_RB(R12)))
704 				break;
705 			/*
706 			 * If found, replace it with:
707 			 *	addis r2, r12, (.TOC.-func)@ha
708 			 *	addi  r2,  r2, (.TOC.-func)@l
709 			 */
710 			((uint32_t *)location)[0] = PPC_INST_ADDIS | __PPC_RT(R2) |
711 						    __PPC_RA(R12) | PPC_HA(value);
712 			((uint32_t *)location)[1] = PPC_INST_ADDI | __PPC_RT(R2) |
713 						    __PPC_RA(R2) | PPC_LO(value);
714 			break;
715 
716 		case R_PPC64_REL16_HA:
717 			/* Subtract location pointer */
718 			value -= (unsigned long)location;
719 			value = ((value + 0x8000) >> 16);
720 			*((uint16_t *) location)
721 				= (*((uint16_t *) location) & ~0xffff)
722 				| (value & 0xffff);
723 			break;
724 
725 		case R_PPC64_REL16_LO:
726 			/* Subtract location pointer */
727 			value -= (unsigned long)location;
728 			*((uint16_t *) location)
729 				= (*((uint16_t *) location) & ~0xffff)
730 				| (value & 0xffff);
731 			break;
732 
733 		default:
734 			pr_err("%s: Unknown ADD relocation: %lu\n",
735 			       me->name,
736 			       (unsigned long)ELF64_R_TYPE(rela[i].r_info));
737 			return -ENOEXEC;
738 		}
739 	}
740 
741 	return 0;
742 }
743 
744 #ifdef CONFIG_DYNAMIC_FTRACE
module_trampoline_target(struct module * mod,unsigned long addr,unsigned long * target)745 int module_trampoline_target(struct module *mod, unsigned long addr,
746 			     unsigned long *target)
747 {
748 	struct ppc64_stub_entry *stub;
749 	func_desc_t funcdata;
750 	u32 magic;
751 
752 	if (!within_module_core(addr, mod)) {
753 		pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name);
754 		return -EFAULT;
755 	}
756 
757 	stub = (struct ppc64_stub_entry *)addr;
758 
759 	if (copy_from_kernel_nofault(&magic, &stub->magic,
760 			sizeof(magic))) {
761 		pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
762 		return -EFAULT;
763 	}
764 
765 	if (magic != STUB_MAGIC) {
766 		pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name);
767 		return -EFAULT;
768 	}
769 
770 	if (copy_from_kernel_nofault(&funcdata, &stub->funcdata,
771 			sizeof(funcdata))) {
772 		pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
773                 return -EFAULT;
774 	}
775 
776 	*target = stub_func_addr(funcdata);
777 
778 	return 0;
779 }
780 
module_finalize_ftrace(struct module * mod,const Elf_Shdr * sechdrs)781 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
782 {
783 	mod->arch.tramp = stub_for_addr(sechdrs,
784 					(unsigned long)ftrace_caller,
785 					mod,
786 					"ftrace_caller");
787 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
788 	mod->arch.tramp_regs = stub_for_addr(sechdrs,
789 					(unsigned long)ftrace_regs_caller,
790 					mod,
791 					"ftrace_regs_caller");
792 	if (!mod->arch.tramp_regs)
793 		return -ENOENT;
794 #endif
795 
796 	if (!mod->arch.tramp)
797 		return -ENOENT;
798 
799 	return 0;
800 }
801 #endif
802