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TOMOYO Linux Cross Reference
Linux/arch/powerpc/kernel/module_64.c

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  1 /*  Kernel module help for PPC64.
  2     Copyright (C) 2001, 2003 Rusty Russell IBM Corporation.
  3 
  4     This program is free software; you can redistribute it and/or modify
  5     it under the terms of the GNU General Public License as published by
  6     the Free Software Foundation; either version 2 of the License, or
  7     (at your option) any later version.
  8 
  9     This program is distributed in the hope that it will be useful,
 10     but WITHOUT ANY WARRANTY; without even the implied warranty of
 11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12     GNU General Public License for more details.
 13 
 14     You should have received a copy of the GNU General Public License
 15     along with this program; if not, write to the Free Software
 16     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 17 */
 18 
 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 20 
 21 #include <linux/module.h>
 22 #include <linux/elf.h>
 23 #include <linux/moduleloader.h>
 24 #include <linux/err.h>
 25 #include <linux/vmalloc.h>
 26 #include <linux/ftrace.h>
 27 #include <linux/bug.h>
 28 #include <linux/uaccess.h>
 29 #include <asm/module.h>
 30 #include <asm/firmware.h>
 31 #include <asm/code-patching.h>
 32 #include <linux/sort.h>
 33 #include <asm/setup.h>
 34 #include <asm/sections.h>
 35 
 36 /* FIXME: We don't do .init separately.  To do this, we'd need to have
 37    a separate r2 value in the init and core section, and stub between
 38    them, too.
 39 
 40    Using a magic allocator which places modules within 32MB solves
 41    this, and makes other things simpler.  Anton?
 42    --RR.  */
 43 
 44 #ifdef PPC64_ELF_ABI_v2
 45 
 46 /* An address is simply the address of the function. */
 47 typedef unsigned long func_desc_t;
 48 
 49 static func_desc_t func_desc(unsigned long addr)
 50 {
 51         return addr;
 52 }
 53 static unsigned long func_addr(unsigned long addr)
 54 {
 55         return addr;
 56 }
 57 static unsigned long stub_func_addr(func_desc_t func)
 58 {
 59         return func;
 60 }
 61 
 62 /* PowerPC64 specific values for the Elf64_Sym st_other field.  */
 63 #define STO_PPC64_LOCAL_BIT     5
 64 #define STO_PPC64_LOCAL_MASK    (7 << STO_PPC64_LOCAL_BIT)
 65 #define PPC64_LOCAL_ENTRY_OFFSET(other)                                 \
 66  (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
 67 
 68 static unsigned int local_entry_offset(const Elf64_Sym *sym)
 69 {
 70         /* sym->st_other indicates offset to local entry point
 71          * (otherwise it will assume r12 is the address of the start
 72          * of function and try to derive r2 from it). */
 73         return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
 74 }
 75 #else
 76 
 77 /* An address is address of the OPD entry, which contains address of fn. */
 78 typedef struct ppc64_opd_entry func_desc_t;
 79 
 80 static func_desc_t func_desc(unsigned long addr)
 81 {
 82         return *(struct ppc64_opd_entry *)addr;
 83 }
 84 static unsigned long func_addr(unsigned long addr)
 85 {
 86         return func_desc(addr).funcaddr;
 87 }
 88 static unsigned long stub_func_addr(func_desc_t func)
 89 {
 90         return func.funcaddr;
 91 }
 92 static unsigned int local_entry_offset(const Elf64_Sym *sym)
 93 {
 94         return 0;
 95 }
 96 #endif
 97 
 98 #define STUB_MAGIC 0x73747562 /* stub */
 99 
100 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
101    the kernel itself).  But on PPC64, these need to be used for every
102    jump, actually, to reset r2 (TOC+0x8000). */
103 struct ppc64_stub_entry
104 {
105         /* 28 byte jump instruction sequence (7 instructions). We only
106          * need 6 instructions on ABIv2 but we always allocate 7 so
107          * so we don't have to modify the trampoline load instruction. */
108         u32 jump[7];
109         /* Used by ftrace to identify stubs */
110         u32 magic;
111         /* Data for the above code */
112         func_desc_t funcdata;
113 };
114 
115 /*
116  * PPC64 uses 24 bit jumps, but we need to jump into other modules or
117  * the kernel which may be further.  So we jump to a stub.
118  *
119  * For ELFv1 we need to use this to set up the new r2 value (aka TOC
120  * pointer).  For ELFv2 it's the callee's responsibility to set up the
121  * new r2, but for both we need to save the old r2.
122  *
123  * We could simply patch the new r2 value and function pointer into
124  * the stub, but it's significantly shorter to put these values at the
125  * end of the stub code, and patch the stub address (32-bits relative
126  * to the TOC ptr, r2) into the stub.
127  */
128 
129 static u32 ppc64_stub_insns[] = {
130         0x3d620000,                     /* addis   r11,r2, <high> */
131         0x396b0000,                     /* addi    r11,r11, <low> */
132         /* Save current r2 value in magic place on the stack. */
133         0xf8410000|R2_STACK_OFFSET,     /* std     r2,R2_STACK_OFFSET(r1) */
134         0xe98b0020,                     /* ld      r12,32(r11) */
135 #ifdef PPC64_ELF_ABI_v1
136         /* Set up new r2 from function descriptor */
137         0xe84b0028,                     /* ld      r2,40(r11) */
138 #endif
139         0x7d8903a6,                     /* mtctr   r12 */
140         0x4e800420                      /* bctr */
141 };
142 
143 #ifdef CONFIG_DYNAMIC_FTRACE
144 int module_trampoline_target(struct module *mod, unsigned long addr,
145                              unsigned long *target)
146 {
147         struct ppc64_stub_entry *stub;
148         func_desc_t funcdata;
149         u32 magic;
150 
151         if (!within_module_core(addr, mod)) {
152                 pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name);
153                 return -EFAULT;
154         }
155 
156         stub = (struct ppc64_stub_entry *)addr;
157 
158         if (probe_kernel_read(&magic, &stub->magic, sizeof(magic))) {
159                 pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
160                 return -EFAULT;
161         }
162 
163         if (magic != STUB_MAGIC) {
164                 pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name);
165                 return -EFAULT;
166         }
167 
168         if (probe_kernel_read(&funcdata, &stub->funcdata, sizeof(funcdata))) {
169                 pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
170                 return -EFAULT;
171         }
172 
173         *target = stub_func_addr(funcdata);
174 
175         return 0;
176 }
177 #endif
178 
179 /* Count how many different 24-bit relocations (different symbol,
180    different addend) */
181 static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num)
182 {
183         unsigned int i, r_info, r_addend, _count_relocs;
184 
185         /* FIXME: Only count external ones --RR */
186         _count_relocs = 0;
187         r_info = 0;
188         r_addend = 0;
189         for (i = 0; i < num; i++)
190                 /* Only count 24-bit relocs, others don't need stubs */
191                 if (ELF64_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
192                     (r_info != ELF64_R_SYM(rela[i].r_info) ||
193                      r_addend != rela[i].r_addend)) {
194                         _count_relocs++;
195                         r_info = ELF64_R_SYM(rela[i].r_info);
196                         r_addend = rela[i].r_addend;
197                 }
198 
199         return _count_relocs;
200 }
201 
202 static int relacmp(const void *_x, const void *_y)
203 {
204         const Elf64_Rela *x, *y;
205 
206         y = (Elf64_Rela *)_x;
207         x = (Elf64_Rela *)_y;
208 
209         /* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
210          * make the comparison cheaper/faster. It won't affect the sorting or
211          * the counting algorithms' performance
212          */
213         if (x->r_info < y->r_info)
214                 return -1;
215         else if (x->r_info > y->r_info)
216                 return 1;
217         else if (x->r_addend < y->r_addend)
218                 return -1;
219         else if (x->r_addend > y->r_addend)
220                 return 1;
221         else
222                 return 0;
223 }
224 
225 static void relaswap(void *_x, void *_y, int size)
226 {
227         uint64_t *x, *y, tmp;
228         int i;
229 
230         y = (uint64_t *)_x;
231         x = (uint64_t *)_y;
232 
233         for (i = 0; i < sizeof(Elf64_Rela) / sizeof(uint64_t); i++) {
234                 tmp = x[i];
235                 x[i] = y[i];
236                 y[i] = tmp;
237         }
238 }
239 
240 /* Get size of potential trampolines required. */
241 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
242                                     const Elf64_Shdr *sechdrs)
243 {
244         /* One extra reloc so it's always 0-funcaddr terminated */
245         unsigned long relocs = 1;
246         unsigned i;
247 
248         /* Every relocated section... */
249         for (i = 1; i < hdr->e_shnum; i++) {
250                 if (sechdrs[i].sh_type == SHT_RELA) {
251                         pr_debug("Found relocations in section %u\n", i);
252                         pr_debug("Ptr: %p.  Number: %Lu\n",
253                                (void *)sechdrs[i].sh_addr,
254                                sechdrs[i].sh_size / sizeof(Elf64_Rela));
255 
256                         /* Sort the relocation information based on a symbol and
257                          * addend key. This is a stable O(n*log n) complexity
258                          * alogrithm but it will reduce the complexity of
259                          * count_relocs() to linear complexity O(n)
260                          */
261                         sort((void *)sechdrs[i].sh_addr,
262                              sechdrs[i].sh_size / sizeof(Elf64_Rela),
263                              sizeof(Elf64_Rela), relacmp, relaswap);
264 
265                         relocs += count_relocs((void *)sechdrs[i].sh_addr,
266                                                sechdrs[i].sh_size
267                                                / sizeof(Elf64_Rela));
268                 }
269         }
270 
271 #ifdef CONFIG_DYNAMIC_FTRACE
272         /* make the trampoline to the ftrace_caller */
273         relocs++;
274 #endif
275 
276         pr_debug("Looks like a total of %lu stubs, max\n", relocs);
277         return relocs * sizeof(struct ppc64_stub_entry);
278 }
279 
280 /* Still needed for ELFv2, for .TOC. */
281 static void dedotify_versions(struct modversion_info *vers,
282                               unsigned long size)
283 {
284         struct modversion_info *end;
285 
286         for (end = (void *)vers + size; vers < end; vers++)
287                 if (vers->name[0] == '.') {
288                         memmove(vers->name, vers->name+1, strlen(vers->name));
289                 }
290 }
291 
292 /*
293  * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
294  * seem to be defined (value set later).
295  */
296 static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
297 {
298         unsigned int i;
299 
300         for (i = 1; i < numsyms; i++) {
301                 if (syms[i].st_shndx == SHN_UNDEF) {
302                         char *name = strtab + syms[i].st_name;
303                         if (name[0] == '.') {
304                                 if (strcmp(name+1, "TOC.") == 0)
305                                         syms[i].st_shndx = SHN_ABS;
306                                 syms[i].st_name++;
307                         }
308                 }
309         }
310 }
311 
312 static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
313                                const char *strtab,
314                                unsigned int symindex)
315 {
316         unsigned int i, numsyms;
317         Elf64_Sym *syms;
318 
319         syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
320         numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
321 
322         for (i = 1; i < numsyms; i++) {
323                 if (syms[i].st_shndx == SHN_ABS
324                     && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
325                         return &syms[i];
326         }
327         return NULL;
328 }
329 
330 int module_frob_arch_sections(Elf64_Ehdr *hdr,
331                               Elf64_Shdr *sechdrs,
332                               char *secstrings,
333                               struct module *me)
334 {
335         unsigned int i;
336 
337         /* Find .toc and .stubs sections, symtab and strtab */
338         for (i = 1; i < hdr->e_shnum; i++) {
339                 char *p;
340                 if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
341                         me->arch.stubs_section = i;
342                 else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0)
343                         me->arch.toc_section = i;
344                 else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
345                         dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
346                                           sechdrs[i].sh_size);
347 
348                 /* We don't handle .init for the moment: rename to _init */
349                 while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
350                         p[0] = '_';
351 
352                 if (sechdrs[i].sh_type == SHT_SYMTAB)
353                         dedotify((void *)hdr + sechdrs[i].sh_offset,
354                                  sechdrs[i].sh_size / sizeof(Elf64_Sym),
355                                  (void *)hdr
356                                  + sechdrs[sechdrs[i].sh_link].sh_offset);
357         }
358 
359         if (!me->arch.stubs_section) {
360                 pr_err("%s: doesn't contain .stubs.\n", me->name);
361                 return -ENOEXEC;
362         }
363 
364         /* If we don't have a .toc, just use .stubs.  We need to set r2
365            to some reasonable value in case the module calls out to
366            other functions via a stub, or if a function pointer escapes
367            the module by some means.  */
368         if (!me->arch.toc_section)
369                 me->arch.toc_section = me->arch.stubs_section;
370 
371         /* Override the stubs size */
372         sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
373         return 0;
374 }
375 
376 /* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this
377    gives the value maximum span in an instruction which uses a signed
378    offset) */
379 static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
380 {
381         return sechdrs[me->arch.toc_section].sh_addr + 0x8000;
382 }
383 
384 /* Both low and high 16 bits are added as SIGNED additions, so if low
385    16 bits has high bit set, high 16 bits must be adjusted.  These
386    macros do that (stolen from binutils). */
387 #define PPC_LO(v) ((v) & 0xffff)
388 #define PPC_HI(v) (((v) >> 16) & 0xffff)
389 #define PPC_HA(v) PPC_HI ((v) + 0x8000)
390 
391 /* Patch stub to reference function and correct r2 value. */
392 static inline int create_stub(const Elf64_Shdr *sechdrs,
393                               struct ppc64_stub_entry *entry,
394                               unsigned long addr,
395                               struct module *me)
396 {
397         long reladdr;
398 
399         memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns));
400 
401         /* Stub uses address relative to r2. */
402         reladdr = (unsigned long)entry - my_r2(sechdrs, me);
403         if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
404                 pr_err("%s: Address %p of stub out of range of %p.\n",
405                        me->name, (void *)reladdr, (void *)my_r2);
406                 return 0;
407         }
408         pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
409 
410         entry->jump[0] |= PPC_HA(reladdr);
411         entry->jump[1] |= PPC_LO(reladdr);
412         entry->funcdata = func_desc(addr);
413         entry->magic = STUB_MAGIC;
414 
415         return 1;
416 }
417 
418 /* Create stub to jump to function described in this OPD/ptr: we need the
419    stub to set up the TOC ptr (r2) for the function. */
420 static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
421                                    unsigned long addr,
422                                    struct module *me)
423 {
424         struct ppc64_stub_entry *stubs;
425         unsigned int i, num_stubs;
426 
427         num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
428 
429         /* Find this stub, or if that fails, the next avail. entry */
430         stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
431         for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
432                 if (WARN_ON(i >= num_stubs))
433                         return 0;
434 
435                 if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
436                         return (unsigned long)&stubs[i];
437         }
438 
439         if (!create_stub(sechdrs, &stubs[i], addr, me))
440                 return 0;
441 
442         return (unsigned long)&stubs[i];
443 }
444 
445 #ifdef CC_USING_MPROFILE_KERNEL
446 static bool is_early_mcount_callsite(u32 *instruction)
447 {
448         /*
449          * Check if this is one of the -mprofile-kernel sequences.
450          */
451         if (instruction[-1] == PPC_INST_STD_LR &&
452             instruction[-2] == PPC_INST_MFLR)
453                 return true;
454 
455         if (instruction[-1] == PPC_INST_MFLR)
456                 return true;
457 
458         return false;
459 }
460 
461 /*
462  * In case of _mcount calls, do not save the current callee's TOC (in r2) into
463  * the original caller's stack frame. If we did we would clobber the saved TOC
464  * value of the original caller.
465  */
466 static void squash_toc_save_inst(const char *name, unsigned long addr)
467 {
468         struct ppc64_stub_entry *stub = (struct ppc64_stub_entry *)addr;
469 
470         /* Only for calls to _mcount */
471         if (strcmp("_mcount", name) != 0)
472                 return;
473 
474         stub->jump[2] = PPC_INST_NOP;
475 }
476 #else
477 static void squash_toc_save_inst(const char *name, unsigned long addr) { }
478 
479 /* without -mprofile-kernel, mcount calls are never early */
480 static bool is_early_mcount_callsite(u32 *instruction)
481 {
482         return false;
483 }
484 #endif
485 
486 /* We expect a noop next: if it is, replace it with instruction to
487    restore r2. */
488 static int restore_r2(u32 *instruction, struct module *me)
489 {
490         u32 *prev_insn = instruction - 1;
491 
492         if (is_early_mcount_callsite(prev_insn))
493                 return 1;
494 
495         /*
496          * Make sure the branch isn't a sibling call.  Sibling calls aren't
497          * "link" branches and they don't return, so they don't need the r2
498          * restore afterwards.
499          */
500         if (!instr_is_relative_link_branch(*prev_insn))
501                 return 1;
502 
503         if (*instruction != PPC_INST_NOP) {
504                 pr_err("%s: Expect noop after relocate, got %08x\n",
505                        me->name, *instruction);
506                 return 0;
507         }
508         /* ld r2,R2_STACK_OFFSET(r1) */
509         *instruction = PPC_INST_LD_TOC;
510         return 1;
511 }
512 
513 int apply_relocate_add(Elf64_Shdr *sechdrs,
514                        const char *strtab,
515                        unsigned int symindex,
516                        unsigned int relsec,
517                        struct module *me)
518 {
519         unsigned int i;
520         Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
521         Elf64_Sym *sym;
522         unsigned long *location;
523         unsigned long value;
524 
525         pr_debug("Applying ADD relocate section %u to %u\n", relsec,
526                sechdrs[relsec].sh_info);
527 
528         /* First time we're called, we can fix up .TOC. */
529         if (!me->arch.toc_fixed) {
530                 sym = find_dot_toc(sechdrs, strtab, symindex);
531                 /* It's theoretically possible that a module doesn't want a
532                  * .TOC. so don't fail it just for that. */
533                 if (sym)
534                         sym->st_value = my_r2(sechdrs, me);
535                 me->arch.toc_fixed = true;
536         }
537 
538         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
539                 /* This is where to make the change */
540                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
541                         + rela[i].r_offset;
542                 /* This is the symbol it is referring to */
543                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
544                         + ELF64_R_SYM(rela[i].r_info);
545 
546                 pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
547                        location, (long)ELF64_R_TYPE(rela[i].r_info),
548                        strtab + sym->st_name, (unsigned long)sym->st_value,
549                        (long)rela[i].r_addend);
550 
551                 /* `Everything is relative'. */
552                 value = sym->st_value + rela[i].r_addend;
553 
554                 switch (ELF64_R_TYPE(rela[i].r_info)) {
555                 case R_PPC64_ADDR32:
556                         /* Simply set it */
557                         *(u32 *)location = value;
558                         break;
559 
560                 case R_PPC64_ADDR64:
561                         /* Simply set it */
562                         *(unsigned long *)location = value;
563                         break;
564 
565                 case R_PPC64_TOC:
566                         *(unsigned long *)location = my_r2(sechdrs, me);
567                         break;
568 
569                 case R_PPC64_TOC16:
570                         /* Subtract TOC pointer */
571                         value -= my_r2(sechdrs, me);
572                         if (value + 0x8000 > 0xffff) {
573                                 pr_err("%s: bad TOC16 relocation (0x%lx)\n",
574                                        me->name, value);
575                                 return -ENOEXEC;
576                         }
577                         *((uint16_t *) location)
578                                 = (*((uint16_t *) location) & ~0xffff)
579                                 | (value & 0xffff);
580                         break;
581 
582                 case R_PPC64_TOC16_LO:
583                         /* Subtract TOC pointer */
584                         value -= my_r2(sechdrs, me);
585                         *((uint16_t *) location)
586                                 = (*((uint16_t *) location) & ~0xffff)
587                                 | (value & 0xffff);
588                         break;
589 
590                 case R_PPC64_TOC16_DS:
591                         /* Subtract TOC pointer */
592                         value -= my_r2(sechdrs, me);
593                         if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
594                                 pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
595                                        me->name, value);
596                                 return -ENOEXEC;
597                         }
598                         *((uint16_t *) location)
599                                 = (*((uint16_t *) location) & ~0xfffc)
600                                 | (value & 0xfffc);
601                         break;
602 
603                 case R_PPC64_TOC16_LO_DS:
604                         /* Subtract TOC pointer */
605                         value -= my_r2(sechdrs, me);
606                         if ((value & 3) != 0) {
607                                 pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
608                                        me->name, value);
609                                 return -ENOEXEC;
610                         }
611                         *((uint16_t *) location)
612                                 = (*((uint16_t *) location) & ~0xfffc)
613                                 | (value & 0xfffc);
614                         break;
615 
616                 case R_PPC64_TOC16_HA:
617                         /* Subtract TOC pointer */
618                         value -= my_r2(sechdrs, me);
619                         value = ((value + 0x8000) >> 16);
620                         *((uint16_t *) location)
621                                 = (*((uint16_t *) location) & ~0xffff)
622                                 | (value & 0xffff);
623                         break;
624 
625                 case R_PPC_REL24:
626                         /* FIXME: Handle weak symbols here --RR */
627                         if (sym->st_shndx == SHN_UNDEF) {
628                                 /* External: go via stub */
629                                 value = stub_for_addr(sechdrs, value, me);
630                                 if (!value)
631                                         return -ENOENT;
632                                 if (!restore_r2((u32 *)location + 1, me))
633                                         return -ENOEXEC;
634 
635                                 squash_toc_save_inst(strtab + sym->st_name, value);
636                         } else
637                                 value += local_entry_offset(sym);
638 
639                         /* Convert value to relative */
640                         value -= (unsigned long)location;
641                         if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
642                                 pr_err("%s: REL24 %li out of range!\n",
643                                        me->name, (long int)value);
644                                 return -ENOEXEC;
645                         }
646 
647                         /* Only replace bits 2 through 26 */
648                         *(uint32_t *)location
649                                 = (*(uint32_t *)location & ~0x03fffffc)
650                                 | (value & 0x03fffffc);
651                         break;
652 
653                 case R_PPC64_REL64:
654                         /* 64 bits relative (used by features fixups) */
655                         *location = value - (unsigned long)location;
656                         break;
657 
658                 case R_PPC64_REL32:
659                         /* 32 bits relative (used by relative exception tables) */
660                         *(u32 *)location = value - (unsigned long)location;
661                         break;
662 
663                 case R_PPC64_TOCSAVE:
664                         /*
665                          * Marker reloc indicates we don't have to save r2.
666                          * That would only save us one instruction, so ignore
667                          * it.
668                          */
669                         break;
670 
671                 case R_PPC64_ENTRY:
672                         /*
673                          * Optimize ELFv2 large code model entry point if
674                          * the TOC is within 2GB range of current location.
675                          */
676                         value = my_r2(sechdrs, me) - (unsigned long)location;
677                         if (value + 0x80008000 > 0xffffffff)
678                                 break;
679                         /*
680                          * Check for the large code model prolog sequence:
681                          *      ld r2, ...(r12)
682                          *      add r2, r2, r12
683                          */
684                         if ((((uint32_t *)location)[0] & ~0xfffc)
685                             != 0xe84c0000)
686                                 break;
687                         if (((uint32_t *)location)[1] != 0x7c426214)
688                                 break;
689                         /*
690                          * If found, replace it with:
691                          *      addis r2, r12, (.TOC.-func)@ha
692                          *      addi r2, r12, (.TOC.-func)@l
693                          */
694                         ((uint32_t *)location)[0] = 0x3c4c0000 + PPC_HA(value);
695                         ((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value);
696                         break;
697 
698                 case R_PPC64_REL16_HA:
699                         /* Subtract location pointer */
700                         value -= (unsigned long)location;
701                         value = ((value + 0x8000) >> 16);
702                         *((uint16_t *) location)
703                                 = (*((uint16_t *) location) & ~0xffff)
704                                 | (value & 0xffff);
705                         break;
706 
707                 case R_PPC64_REL16_LO:
708                         /* Subtract location pointer */
709                         value -= (unsigned long)location;
710                         *((uint16_t *) location)
711                                 = (*((uint16_t *) location) & ~0xffff)
712                                 | (value & 0xffff);
713                         break;
714 
715                 default:
716                         pr_err("%s: Unknown ADD relocation: %lu\n",
717                                me->name,
718                                (unsigned long)ELF64_R_TYPE(rela[i].r_info));
719                         return -ENOEXEC;
720                 }
721         }
722 
723         return 0;
724 }
725 
726 #ifdef CONFIG_DYNAMIC_FTRACE
727 
728 #ifdef CC_USING_MPROFILE_KERNEL
729 
730 #define PACATOC offsetof(struct paca_struct, kernel_toc)
731 
732 /*
733  * For mprofile-kernel we use a special stub for ftrace_caller() because we
734  * can't rely on r2 containing this module's TOC when we enter the stub.
735  *
736  * That can happen if the function calling us didn't need to use the toc. In
737  * that case it won't have setup r2, and the r2 value will be either the
738  * kernel's toc, or possibly another modules toc.
739  *
740  * To deal with that this stub uses the kernel toc, which is always accessible
741  * via the paca (in r13). The target (ftrace_caller()) is responsible for
742  * saving and restoring the toc before returning.
743  */
744 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me)
745 {
746         struct ppc64_stub_entry *entry;
747         unsigned int i, num_stubs;
748         static u32 stub_insns[] = {
749                 0xe98d0000 | PACATOC,   /* ld      r12,PACATOC(r13)     */
750                 0x3d8c0000,             /* addis   r12,r12,<high>       */
751                 0x398c0000,             /* addi    r12,r12,<low>        */
752                 0x7d8903a6,             /* mtctr   r12                  */
753                 0x4e800420,             /* bctr                         */
754         };
755         long reladdr;
756 
757         num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*entry);
758 
759         /* Find the next available stub entry */
760         entry = (void *)sechdrs[me->arch.stubs_section].sh_addr;
761         for (i = 0; i < num_stubs && stub_func_addr(entry->funcdata); i++, entry++);
762 
763         if (i >= num_stubs) {
764                 pr_err("%s: Unable to find a free slot for ftrace stub.\n", me->name);
765                 return 0;
766         }
767 
768         memcpy(entry->jump, stub_insns, sizeof(stub_insns));
769 
770         /* Stub uses address relative to kernel toc (from the paca) */
771         reladdr = (unsigned long)ftrace_caller - kernel_toc_addr();
772         if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
773                 pr_err("%s: Address of ftrace_caller out of range of kernel_toc.\n", me->name);
774                 return 0;
775         }
776 
777         entry->jump[1] |= PPC_HA(reladdr);
778         entry->jump[2] |= PPC_LO(reladdr);
779 
780         /* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */
781         entry->funcdata = func_desc((unsigned long)ftrace_caller);
782         entry->magic = STUB_MAGIC;
783 
784         return (unsigned long)entry;
785 }
786 #else
787 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me)
788 {
789         return stub_for_addr(sechdrs, (unsigned long)ftrace_caller, me);
790 }
791 #endif
792 
793 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
794 {
795         mod->arch.toc = my_r2(sechdrs, mod);
796         mod->arch.tramp = create_ftrace_stub(sechdrs, mod);
797 
798         if (!mod->arch.tramp)
799                 return -ENOENT;
800 
801         return 0;
802 }
803 #endif
804 

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