module_64.c

   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 <linux/kernel.h>
  18#include <asm/module.h>
  19#include <asm/firmware.h>
  20#include <asm/text-patching.h>
  21#include <linux/sort.h>
  22#include <asm/setup.h>
  23#include <asm/sections.h>
  24#include <asm/inst.h>
  25
  26/* FIXME: We don't do .init separately.  To do this, we'd need to have
  27   a separate r2 value in the init and core section, and stub between
  28   them, too.
  29
  30   Using a magic allocator which places modules within 32MB solves
  31   this, and makes other things simpler.  Anton?
  32   --RR.  */
  33
  34bool module_elf_check_arch(Elf_Ehdr *hdr)
  35{
  36	unsigned long abi_level = hdr->e_flags & 0x3;
  37
  38	if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2))
  39		return abi_level == 2;
  40	else
  41		return abi_level < 2;
  42}
  43
  44#ifdef CONFIG_PPC64_ELF_ABI_V2
  45
  46static func_desc_t func_desc(unsigned long addr)
  47{
  48	func_desc_t desc = {
  49		.addr = addr,
  50	};
  51
  52	return desc;
  53}
  54
  55/* PowerPC64 specific values for the Elf64_Sym st_other field.  */
  56#define STO_PPC64_LOCAL_BIT	5
  57#define STO_PPC64_LOCAL_MASK	(7 << STO_PPC64_LOCAL_BIT)
  58#define PPC64_LOCAL_ENTRY_OFFSET(other)					\
  59 (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
  60
  61static unsigned int local_entry_offset(const Elf64_Sym *sym)
  62{
  63	/* sym->st_other indicates offset to local entry point
  64	 * (otherwise it will assume r12 is the address of the start
  65	 * of function and try to derive r2 from it). */
  66	return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
  67}
  68#else
  69
  70static func_desc_t func_desc(unsigned long addr)
  71{
  72	return *(struct func_desc *)addr;
  73}
  74static unsigned int local_entry_offset(const Elf64_Sym *sym)
  75{
  76	return 0;
  77}
  78
  79void *dereference_module_function_descriptor(struct module *mod, void *ptr)
  80{
  81	if (ptr < (void *)mod->arch.start_opd ||
  82			ptr >= (void *)mod->arch.end_opd)
  83		return ptr;
  84
  85	return dereference_function_descriptor(ptr);
  86}
  87#endif
  88
  89static unsigned long func_addr(unsigned long addr)
  90{
  91	return func_desc(addr).addr;
  92}
  93
  94static unsigned long stub_func_addr(func_desc_t func)
  95{
  96	return func.addr;
  97}
  98
  99#define STUB_MAGIC 0x73747562 /* stub */
 100
 101/* Like PPC32, we need little trampolines to do > 24-bit jumps (into
 102   the kernel itself).  But on PPC64, these need to be used for every
 103   jump, actually, to reset r2 (TOC+0x8000). */
 104struct ppc64_stub_entry {
 105	/*
 106	 * 28 byte jump instruction sequence (7 instructions) that can
 107	 * hold ppc64_stub_insns or stub_insns. Must be 8-byte aligned
 108	 * with PCREL kernels that use prefix instructions in the stub.
 109	 */
 110	u32 jump[7];
 111	/* Used by ftrace to identify stubs */
 112	u32 magic;
 113	/* Data for the above code */
 114	func_desc_t funcdata;
 115} __aligned(8);
 116
 117struct ppc64_got_entry {
 118	u64 addr;
 119};
 120
 121/*
 122 * PPC64 uses 24 bit jumps, but we need to jump into other modules or
 123 * the kernel which may be further.  So we jump to a stub.
 124 *
 125 * Target address and TOC are loaded from function descriptor in the
 126 * ppc64_stub_entry.
 127 *
 128 * r12 is used to generate the target address, which is required for the
 129 * ELFv2 global entry point calling convention.
 130 *
 131 * TOC handling:
 132 * - PCREL does not have a TOC.
 133 * - ELFv2 non-PCREL just has to save r2, the callee is responsible for
 134 *   setting its own TOC pointer at the global entry address.
 135 * - ELFv1 must load the new TOC pointer from the function descriptor.
 136 */
 137static u32 ppc64_stub_insns[] = {
 138#ifdef CONFIG_PPC_KERNEL_PCREL
 139	/* pld r12,addr */
 140	PPC_PREFIX_8LS | __PPC_PRFX_R(1),
 141	PPC_INST_PLD | ___PPC_RT(_R12),
 142#else
 143	PPC_RAW_ADDIS(_R11, _R2, 0),
 144	PPC_RAW_ADDI(_R11, _R11, 0),
 145	/* Save current r2 value in magic place on the stack. */
 146	PPC_RAW_STD(_R2, _R1, R2_STACK_OFFSET),
 147	PPC_RAW_LD(_R12, _R11, 32),
 148#ifdef CONFIG_PPC64_ELF_ABI_V1
 149	/* Set up new r2 from function descriptor */
 150	PPC_RAW_LD(_R2, _R11, 40),
 151#endif
 152#endif
 153	PPC_RAW_MTCTR(_R12),
 154	PPC_RAW_BCTR(),
 155};
 156
 157/*
 158 * Count how many different r_type relocations (different symbol,
 159 * different addend).
 160 */
 161static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num,
 162				 unsigned long r_type)
 163{
 164	unsigned int i, r_info, r_addend, _count_relocs;
 165
 166	/* FIXME: Only count external ones --RR */
 167	_count_relocs = 0;
 168	r_info = 0;
 169	r_addend = 0;
 170	for (i = 0; i < num; i++)
 171		/* Only count r_type relocs, others don't need stubs */
 172		if (ELF64_R_TYPE(rela[i].r_info) == r_type &&
 173		    (r_info != ELF64_R_SYM(rela[i].r_info) ||
 174		     r_addend != rela[i].r_addend)) {
 175			_count_relocs++;
 176			r_info = ELF64_R_SYM(rela[i].r_info);
 177			r_addend = rela[i].r_addend;
 178		}
 179
 180	return _count_relocs;
 181}
 182
 183static int relacmp(const void *_x, const void *_y)
 184{
 185	const Elf64_Rela *x, *y;
 186
 187	y = (Elf64_Rela *)_x;
 188	x = (Elf64_Rela *)_y;
 189
 190	/* Compare the entire r_info (as opposed to ELF64_R_SYM(r_info) only) to
 191	 * make the comparison cheaper/faster. It won't affect the sorting or
 192	 * the counting algorithms' performance
 193	 */
 194	if (x->r_info < y->r_info)
 195		return -1;
 196	else if (x->r_info > y->r_info)
 197		return 1;
 198	else if (x->r_addend < y->r_addend)
 199		return -1;
 200	else if (x->r_addend > y->r_addend)
 201		return 1;
 202	else
 203		return 0;
 204}
 205
 206/* Get size of potential trampolines required. */
 207static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
 208				    const Elf64_Shdr *sechdrs,
 209				    char *secstrings,
 210				    struct module *me)
 211{
 212	unsigned long relocs = 0;
 213	unsigned i;
 214
 215	/* Every relocated section... */
 216	for (i = 1; i < hdr->e_shnum; i++) {
 217		if (sechdrs[i].sh_type == SHT_RELA) {
 218			pr_debug("Found relocations in section %u\n", i);
 219			pr_debug("Ptr: %p.  Number: %Lu\n",
 220			       (void *)sechdrs[i].sh_addr,
 221			       sechdrs[i].sh_size / sizeof(Elf64_Rela));
 222
 223			/* Sort the relocation information based on a symbol and
 224			 * addend key. This is a stable O(n*log n) complexity
 225			 * algorithm but it will reduce the complexity of
 226			 * count_relocs() to linear complexity O(n)
 227			 */
 228			sort((void *)sechdrs[i].sh_addr,
 229			     sechdrs[i].sh_size / sizeof(Elf64_Rela),
 230			     sizeof(Elf64_Rela), relacmp, NULL);
 231
 232			relocs += count_relocs((void *)sechdrs[i].sh_addr,
 233					       sechdrs[i].sh_size
 234					       / sizeof(Elf64_Rela),
 235					       R_PPC_REL24);
 236#ifdef CONFIG_PPC_KERNEL_PCREL
 237			relocs += count_relocs((void *)sechdrs[i].sh_addr,
 238					       sechdrs[i].sh_size
 239					       / sizeof(Elf64_Rela),
 240					       R_PPC64_REL24_NOTOC);
 241#endif
 242		}
 243	}
 244
 245	/* stubs for ftrace_caller and ftrace_regs_caller */
 246	relocs += IS_ENABLED(CONFIG_DYNAMIC_FTRACE) + IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS);
 247
 248#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
 249	/* stubs for the function tracer */
 250	for (i = 1; i < hdr->e_shnum; i++) {
 251		if (!strcmp(secstrings + sechdrs[i].sh_name, "__patchable_function_entries")) {
 252			me->arch.ool_stub_count = sechdrs[i].sh_size / sizeof(unsigned long);
 253			me->arch.ool_stub_index = 0;
 254			relocs += roundup(me->arch.ool_stub_count * sizeof(struct ftrace_ool_stub),
 255					  sizeof(struct ppc64_stub_entry)) /
 256				  sizeof(struct ppc64_stub_entry);
 257			break;
 258		}
 259	}
 260#endif
 261
 262	pr_debug("Looks like a total of %lu stubs, max\n", relocs);
 263	return relocs * sizeof(struct ppc64_stub_entry);
 264}
 265
 266#ifdef CONFIG_PPC_KERNEL_PCREL
 267static int count_pcpu_relocs(const Elf64_Shdr *sechdrs,
 268			     const Elf64_Rela *rela, unsigned int num,
 269			     unsigned int symindex, unsigned int pcpu)
 270{
 271	unsigned int i, r_info, r_addend, _count_relocs;
 272
 273	_count_relocs = 0;
 274	r_info = 0;
 275	r_addend = 0;
 276
 277	for (i = 0; i < num; i++) {
 278		Elf64_Sym *sym;
 279
 280		/* This is the symbol it is referring to */
 281		sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 282			+ ELF64_R_SYM(rela[i].r_info);
 283
 284		if (sym->st_shndx == pcpu &&
 285		    (r_info != ELF64_R_SYM(rela[i].r_info) ||
 286		     r_addend != rela[i].r_addend)) {
 287			_count_relocs++;
 288			r_info = ELF64_R_SYM(rela[i].r_info);
 289			r_addend = rela[i].r_addend;
 290		}
 291	}
 292
 293	return _count_relocs;
 294}
 295
 296/* Get size of potential GOT required. */
 297static unsigned long get_got_size(const Elf64_Ehdr *hdr,
 298				  const Elf64_Shdr *sechdrs,
 299				  struct module *me)
 300{
 301	/* One extra reloc so it's always 0-addr terminated */
 302	unsigned long relocs = 1;
 303	unsigned int i, symindex = 0;
 304
 305	for (i = 1; i < hdr->e_shnum; i++) {
 306		if (sechdrs[i].sh_type == SHT_SYMTAB) {
 307			symindex = i;
 308			break;
 309		}
 310	}
 311	WARN_ON_ONCE(!symindex);
 312
 313	/* Every relocated section... */
 314	for (i = 1; i < hdr->e_shnum; i++) {
 315		if (sechdrs[i].sh_type == SHT_RELA) {
 316			pr_debug("Found relocations in section %u\n", i);
 317			pr_debug("Ptr: %p.  Number: %llu\n", (void *)sechdrs[i].sh_addr,
 318				 sechdrs[i].sh_size / sizeof(Elf64_Rela));
 319
 320			/*
 321			 * Sort the relocation information based on a symbol and
 322			 * addend key. This is a stable O(n*log n) complexity
 323			 * algorithm but it will reduce the complexity of
 324			 * count_relocs() to linear complexity O(n)
 325			 */
 326			sort((void *)sechdrs[i].sh_addr,
 327			     sechdrs[i].sh_size / sizeof(Elf64_Rela),
 328			     sizeof(Elf64_Rela), relacmp, NULL);
 329
 330			relocs += count_relocs((void *)sechdrs[i].sh_addr,
 331					       sechdrs[i].sh_size
 332					       / sizeof(Elf64_Rela),
 333					       R_PPC64_GOT_PCREL34);
 334
 335			/*
 336			 * Percpu data access typically gets linked with
 337			 * REL34 relocations, but the percpu section gets
 338			 * moved at load time and requires that to be
 339			 * converted to GOT linkage.
 340			 */
 341			if (IS_ENABLED(CONFIG_SMP) && symindex)
 342				relocs += count_pcpu_relocs(sechdrs,
 343						(void *)sechdrs[i].sh_addr,
 344					       sechdrs[i].sh_size
 345					       / sizeof(Elf64_Rela),
 346					       symindex, me->arch.pcpu_section);
 347		}
 348	}
 349
 350	pr_debug("Looks like a total of %lu GOT entries, max\n", relocs);
 351	return relocs * sizeof(struct ppc64_got_entry);
 352}
 353#else /* CONFIG_PPC_KERNEL_PCREL */
 354
 355/* Still needed for ELFv2, for .TOC. */
 356static void dedotify_versions(struct modversion_info *vers,
 357			      unsigned long size)
 358{
 359	struct modversion_info *end;
 360
 361	for (end = (void *)vers + size; vers < end; vers++)
 362		if (vers->name[0] == '.') {
 363			memmove(vers->name, vers->name+1, strlen(vers->name));
 364		}
 365}
 366
 367/* Same as normal versions, remove a leading dot if present. */
 368static void dedotify_ext_version_names(char *str_seq, unsigned long size)
 369{
 370	unsigned long out = 0;
 371	unsigned long in;
 372	char last = '\0';
 373
 374	for (in = 0; in < size; in++) {
 375		/* Skip one leading dot */
 376		if (last == '\0' && str_seq[in] == '.')
 377			in++;
 378		last = str_seq[in];
 379		str_seq[out++] = last;
 380	}
 381	/* Zero the trailing portion of the names table for robustness */
 382	memset(&str_seq[out], 0, size - out);
 383}
 384
 385/*
 386 * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
 387 * seem to be defined (value set later).
 388 */
 389static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
 390{
 391	unsigned int i;
 392
 393	for (i = 1; i < numsyms; i++) {
 394		if (syms[i].st_shndx == SHN_UNDEF) {
 395			char *name = strtab + syms[i].st_name;
 396			if (name[0] == '.') {
 397				if (strcmp(name+1, "TOC.") == 0)
 398					syms[i].st_shndx = SHN_ABS;
 399				syms[i].st_name++;
 400			}
 401		}
 402	}
 403}
 404
 405static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
 406			       const char *strtab,
 407			       unsigned int symindex)
 408{
 409	unsigned int i, numsyms;
 410	Elf64_Sym *syms;
 411
 412	syms = (Elf64_Sym *)sechdrs[symindex].sh_addr;
 413	numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
 414
 415	for (i = 1; i < numsyms; i++) {
 416		if (syms[i].st_shndx == SHN_ABS
 417		    && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
 418			return &syms[i];
 419	}
 420	return NULL;
 421}
 422#endif /* CONFIG_PPC_KERNEL_PCREL */
 423
 424bool module_init_section(const char *name)
 425{
 426	/* We don't handle .init for the moment: always return false. */
 427	return false;
 428}
 429
 430int module_frob_arch_sections(Elf64_Ehdr *hdr,
 431			      Elf64_Shdr *sechdrs,
 432			      char *secstrings,
 433			      struct module *me)
 434{
 435	unsigned int i;
 436
 437	/* Find .toc and .stubs sections, symtab and strtab */
 438	for (i = 1; i < hdr->e_shnum; i++) {
 439		if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
 440			me->arch.stubs_section = i;
 441#ifdef CONFIG_PPC_KERNEL_PCREL
 442		else if (strcmp(secstrings + sechdrs[i].sh_name, ".data..percpu") == 0)
 443			me->arch.pcpu_section = i;
 444		else if (strcmp(secstrings + sechdrs[i].sh_name, ".mygot") == 0) {
 445			me->arch.got_section = i;
 446			if (sechdrs[i].sh_addralign < 8)
 447				sechdrs[i].sh_addralign = 8;
 448		}
 449#else
 450		else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) {
 451			me->arch.toc_section = i;
 452			if (sechdrs[i].sh_addralign < 8)
 453				sechdrs[i].sh_addralign = 8;
 454		} else if (strcmp(secstrings + sechdrs[i].sh_name, "__versions") == 0)
 455			dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
 456					  sechdrs[i].sh_size);
 457		else if (strcmp(secstrings + sechdrs[i].sh_name, "__version_ext_names") == 0)
 458			dedotify_ext_version_names((void *)hdr + sechdrs[i].sh_offset,
 459						   sechdrs[i].sh_size);
 460
 461		if (sechdrs[i].sh_type == SHT_SYMTAB)
 462			dedotify((void *)hdr + sechdrs[i].sh_offset,
 463				 sechdrs[i].sh_size / sizeof(Elf64_Sym),
 464				 (void *)hdr
 465				 + sechdrs[sechdrs[i].sh_link].sh_offset);
 466#endif
 467	}
 468
 469	if (!me->arch.stubs_section) {
 470		pr_err("%s: doesn't contain .stubs.\n", me->name);
 471		return -ENOEXEC;
 472	}
 473
 474#ifdef CONFIG_PPC_KERNEL_PCREL
 475	if (!me->arch.got_section) {
 476		pr_err("%s: doesn't contain .mygot.\n", me->name);
 477		return -ENOEXEC;
 478	}
 479
 480	/* Override the got size */
 481	sechdrs[me->arch.got_section].sh_size = get_got_size(hdr, sechdrs, me);
 482#else
 483	/* If we don't have a .toc, just use .stubs.  We need to set r2
 484	   to some reasonable value in case the module calls out to
 485	   other functions via a stub, or if a function pointer escapes
 486	   the module by some means.  */
 487	if (!me->arch.toc_section)
 488		me->arch.toc_section = me->arch.stubs_section;
 489#endif
 490
 491	/* Override the stubs size */
 492	sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs, secstrings, me);
 493
 494	return 0;
 495}
 496
 497#if defined(CONFIG_MPROFILE_KERNEL) || defined(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY)
 498
 499static u32 stub_insns[] = {
 500#ifdef CONFIG_PPC_KERNEL_PCREL
 501	PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernelbase)),
 502	PPC_RAW_NOP(), /* align the prefix insn */
 503	/* paddi r12,r12,addr */
 504	PPC_PREFIX_MLS | __PPC_PRFX_R(0),
 505	PPC_INST_PADDI | ___PPC_RT(_R12) | ___PPC_RA(_R12),
 506	PPC_RAW_MTCTR(_R12),
 507	PPC_RAW_BCTR(),
 508#else
 509	PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
 510	PPC_RAW_ADDIS(_R12, _R12, 0),
 511	PPC_RAW_ADDI(_R12, _R12, 0),
 512	PPC_RAW_MTCTR(_R12),
 513	PPC_RAW_BCTR(),
 514#endif
 515};
 516
 517/*
 518 * For mprofile-kernel we use a special stub for ftrace_caller() because we
 519 * can't rely on r2 containing this module's TOC when we enter the stub.
 520 *
 521 * That can happen if the function calling us didn't need to use the toc. In
 522 * that case it won't have setup r2, and the r2 value will be either the
 523 * kernel's toc, or possibly another modules toc.
 524 *
 525 * To deal with that this stub uses the kernel toc, which is always accessible
 526 * via the paca (in r13). The target (ftrace_caller()) is responsible for
 527 * saving and restoring the toc before returning.
 528 */
 529static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
 530					unsigned long addr,
 531					struct module *me)
 532{
 533	long reladdr;
 534
 535	if ((unsigned long)entry->jump % 8 != 0) {
 536		pr_err("%s: Address of stub entry is not 8-byte aligned\n", me->name);
 537		return 0;
 538	}
 539
 540	BUILD_BUG_ON(sizeof(stub_insns) > sizeof(entry->jump));
 541	memcpy(entry->jump, stub_insns, sizeof(stub_insns));
 542
 543	if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
 544		/* Stub uses address relative to kernel base (from the paca) */
 545		reladdr = addr - local_paca->kernelbase;
 546		if (reladdr > 0x1FFFFFFFFL || reladdr < -0x200000000L) {
 547			pr_err("%s: Address of %ps out of range of 34-bit relative address.\n",
 548				me->name, (void *)addr);
 549			return 0;
 550		}
 551
 552		entry->jump[2] |= IMM_H18(reladdr);
 553		entry->jump[3] |= IMM_L(reladdr);
 554	} else {
 555		/* Stub uses address relative to kernel toc (from the paca) */
 556		reladdr = addr - kernel_toc_addr();
 557		if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
 558			pr_err("%s: Address of %ps out of range of kernel_toc.\n",
 559				me->name, (void *)addr);
 560			return 0;
 561		}
 562
 563		entry->jump[1] |= PPC_HA(reladdr);
 564		entry->jump[2] |= PPC_LO(reladdr);
 565	}
 566
 567	/* Even though we don't use funcdata in the stub, it's needed elsewhere. */
 568	entry->funcdata = func_desc(addr);
 569	entry->magic = STUB_MAGIC;
 570
 571	return 1;
 572}
 573
 574static bool is_mprofile_ftrace_call(const char *name)
 575{
 576	if (!strcmp("_mcount", name))
 577		return true;
 578#ifdef CONFIG_DYNAMIC_FTRACE
 579	if (!strcmp("ftrace_caller", name))
 580		return true;
 581#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 582	if (!strcmp("ftrace_regs_caller", name))
 583		return true;
 584#endif
 585#endif
 586
 587	return false;
 588}
 589#else
 590static inline int create_ftrace_stub(struct ppc64_stub_entry *entry,
 591					unsigned long addr,
 592					struct module *me)
 593{
 594	return 0;
 595}
 596
 597static bool is_mprofile_ftrace_call(const char *name)
 598{
 599	return false;
 600}
 601#endif
 602
 603/*
 604 * r2 is the TOC pointer: it actually points 0x8000 into the TOC (this gives the
 605 * value maximum span in an instruction which uses a signed offset). Round down
 606 * to a 256 byte boundary for the odd case where we are setting up r2 without a
 607 * .toc section.
 608 */
 609static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
 610{
 611#ifndef CONFIG_PPC_KERNEL_PCREL
 612	return (sechdrs[me->arch.toc_section].sh_addr & ~0xfful) + 0x8000;
 613#else
 614	return -1;
 615#endif
 616}
 617
 618/* Patch stub to reference function and correct r2 value. */
 619static inline int create_stub(const Elf64_Shdr *sechdrs,
 620			      struct ppc64_stub_entry *entry,
 621			      unsigned long addr,
 622			      struct module *me,
 623			      const char *name)
 624{
 625	long reladdr;
 626	func_desc_t desc;
 627	int i;
 628
 629	if (is_mprofile_ftrace_call(name))
 630		return create_ftrace_stub(entry, addr, me);
 631
 632	if ((unsigned long)entry->jump % 8 != 0) {
 633		pr_err("%s: Address of stub entry is not 8-byte aligned\n", me->name);
 634		return 0;
 635	}
 636
 637	BUILD_BUG_ON(sizeof(ppc64_stub_insns) > sizeof(entry->jump));
 638	for (i = 0; i < ARRAY_SIZE(ppc64_stub_insns); i++) {
 639		if (patch_instruction(&entry->jump[i],
 640				      ppc_inst(ppc64_stub_insns[i])))
 641			return 0;
 642	}
 643
 644	if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
 645		/* Stub uses address relative to itself! */
 646		reladdr = 0 + offsetof(struct ppc64_stub_entry, funcdata);
 647		BUILD_BUG_ON(reladdr != 32);
 648		if (reladdr > 0x1FFFFFFFFL || reladdr < -0x200000000L) {
 649			pr_err("%s: Address of %p out of range of 34-bit relative address.\n",
 650				me->name, (void *)reladdr);
 651			return 0;
 652		}
 653		pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
 654
 655		/* May not even need this if we're relative to 0 */
 656		if (patch_instruction(&entry->jump[0],
 657		    ppc_inst_prefix(entry->jump[0] | IMM_H18(reladdr),
 658				    entry->jump[1] | IMM_L(reladdr))))
 659			return 0;
 660
 661	} else {
 662		/* Stub uses address relative to r2. */
 663		reladdr = (unsigned long)entry - my_r2(sechdrs, me);
 664		if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
 665			pr_err("%s: Address %p of stub out of range of %p.\n",
 666			       me->name, (void *)reladdr, (void *)my_r2);
 667			return 0;
 668		}
 669		pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
 670
 671		if (patch_instruction(&entry->jump[0],
 672				      ppc_inst(entry->jump[0] | PPC_HA(reladdr))))
 673			return 0;
 674
 675		if (patch_instruction(&entry->jump[1],
 676				      ppc_inst(entry->jump[1] | PPC_LO(reladdr))))
 677			return 0;
 678	}
 679
 680	// func_desc_t is 8 bytes if ABIv2, else 16 bytes
 681	desc = func_desc(addr);
 682	for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) {
 683		if (patch_u32(((u32 *)&entry->funcdata) + i, ((u32 *)&desc)[i]))
 684			return 0;
 685	}
 686
 687	if (patch_u32(&entry->magic, STUB_MAGIC))
 688		return 0;
 689
 690	return 1;
 691}
 692
 693/* Create stub to jump to function described in this OPD/ptr: we need the
 694   stub to set up the TOC ptr (r2) for the function. */
 695static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
 696				   unsigned long addr,
 697				   struct module *me,
 698				   const char *name)
 699{
 700	struct ppc64_stub_entry *stubs;
 701	unsigned int i, num_stubs;
 702
 703	num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
 704
 705	/* Find this stub, or if that fails, the next avail. entry */
 706	stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
 707	for (i = 0; i < me->arch.stub_count; i++) {
 708		if (WARN_ON(i >= num_stubs))
 709			return 0;
 710
 711		if (stub_func_addr(stubs[i].funcdata) == func_addr(addr))
 712			return (unsigned long)&stubs[i];
 713	}
 714
 715	if (!create_stub(sechdrs, &stubs[i], addr, me, name))
 716		return 0;
 717
 718	me->arch.stub_count++;
 719	return (unsigned long)&stubs[i];
 720}
 721
 722#ifdef CONFIG_PPC_KERNEL_PCREL
 723/* Create GOT to load the location described in this ptr */
 724static unsigned long got_for_addr(const Elf64_Shdr *sechdrs,
 725				  unsigned long addr,
 726				  struct module *me,
 727				  const char *name)
 728{
 729	struct ppc64_got_entry *got;
 730	unsigned int i, num_got;
 731
 732	if (!IS_ENABLED(CONFIG_PPC_KERNEL_PCREL))
 733		return addr;
 734
 735	num_got = sechdrs[me->arch.got_section].sh_size / sizeof(*got);
 736
 737	/* Find this stub, or if that fails, the next avail. entry */
 738	got = (void *)sechdrs[me->arch.got_section].sh_addr;
 739	for (i = 0; got[i].addr; i++) {
 740		if (WARN_ON(i >= num_got))
 741			return 0;
 742
 743		if (got[i].addr == addr)
 744			return (unsigned long)&got[i];
 745	}
 746
 747	got[i].addr = addr;
 748
 749	return (unsigned long)&got[i];
 750}
 751#endif
 752
 753/* We expect a noop next: if it is, replace it with instruction to
 754   restore r2. */
 755static int restore_r2(const char *name, u32 *instruction, struct module *me)
 756{
 757	u32 *prev_insn = instruction - 1;
 758	u32 insn_val = *instruction;
 759
 760	if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL))
 761		return 0;
 762
 763	if (is_mprofile_ftrace_call(name))
 764		return 0;
 765
 766	/*
 767	 * Make sure the branch isn't a sibling call.  Sibling calls aren't
 768	 * "link" branches and they don't return, so they don't need the r2
 769	 * restore afterwards.
 770	 */
 771	if (!instr_is_relative_link_branch(ppc_inst(*prev_insn)))
 772		return 0;
 773
 774	/*
 775	 * For livepatch, the restore r2 instruction might have already been
 776	 * written previously, if the referenced symbol is in a previously
 777	 * unloaded module which is now being loaded again.  In that case, skip
 778	 * the warning and the instruction write.
 779	 */
 780	if (insn_val == PPC_INST_LD_TOC)
 781		return 0;
 782
 783	if (insn_val != PPC_RAW_NOP()) {
 784		pr_err("%s: Expected nop after call, got %08x at %pS\n",
 785			me->name, insn_val, instruction);
 786		return -ENOEXEC;
 787	}
 788
 789	/* ld r2,R2_STACK_OFFSET(r1) */
 790	return patch_instruction(instruction, ppc_inst(PPC_INST_LD_TOC));
 791}
 792
 793int apply_relocate_add(Elf64_Shdr *sechdrs,
 794		       const char *strtab,
 795		       unsigned int symindex,
 796		       unsigned int relsec,
 797		       struct module *me)
 798{
 799	unsigned int i;
 800	Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
 801	Elf64_Sym *sym;
 802	unsigned long *location;
 803	unsigned long value;
 804
 805	pr_debug("Applying ADD relocate section %u to %u\n", relsec,
 806	       sechdrs[relsec].sh_info);
 807
 808#ifndef CONFIG_PPC_KERNEL_PCREL
 809	/* First time we're called, we can fix up .TOC. */
 810	if (!me->arch.toc_fixed) {
 811		sym = find_dot_toc(sechdrs, strtab, symindex);
 812		/* It's theoretically possible that a module doesn't want a
 813		 * .TOC. so don't fail it just for that. */
 814		if (sym)
 815			sym->st_value = my_r2(sechdrs, me);
 816		me->arch.toc_fixed = true;
 817	}
 818#endif
 819	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
 820		/* This is where to make the change */
 821		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 822			+ rela[i].r_offset;
 823		/* This is the symbol it is referring to */
 824		sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 825			+ ELF64_R_SYM(rela[i].r_info);
 826
 827		pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
 828		       location, (long)ELF64_R_TYPE(rela[i].r_info),
 829		       strtab + sym->st_name, (unsigned long)sym->st_value,
 830		       (long)rela[i].r_addend);
 831
 832		/* `Everything is relative'. */
 833		value = sym->st_value + rela[i].r_addend;
 834
 835		switch (ELF64_R_TYPE(rela[i].r_info)) {
 836		case R_PPC64_ADDR32:
 837			/* Simply set it */
 838			*(u32 *)location = value;
 839			break;
 840
 841		case R_PPC64_ADDR64:
 842			/* Simply set it */
 843			*(unsigned long *)location = value;
 844			break;
 845
 846#ifndef CONFIG_PPC_KERNEL_PCREL
 847		case R_PPC64_TOC:
 848			*(unsigned long *)location = my_r2(sechdrs, me);
 849			break;
 850
 851		case R_PPC64_TOC16:
 852			/* Subtract TOC pointer */
 853			value -= my_r2(sechdrs, me);
 854			if (value + 0x8000 > 0xffff) {
 855				pr_err("%s: bad TOC16 relocation (0x%lx)\n",
 856				       me->name, value);
 857				return -ENOEXEC;
 858			}
 859			*((uint16_t *) location)
 860				= (*((uint16_t *) location) & ~0xffff)
 861				| (value & 0xffff);
 862			break;
 863
 864		case R_PPC64_TOC16_LO:
 865			/* Subtract TOC pointer */
 866			value -= my_r2(sechdrs, me);
 867			*((uint16_t *) location)
 868				= (*((uint16_t *) location) & ~0xffff)
 869				| (value & 0xffff);
 870			break;
 871
 872		case R_PPC64_TOC16_DS:
 873			/* Subtract TOC pointer */
 874			value -= my_r2(sechdrs, me);
 875			if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
 876				pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
 877				       me->name, value);
 878				return -ENOEXEC;
 879			}
 880			*((uint16_t *) location)
 881				= (*((uint16_t *) location) & ~0xfffc)
 882				| (value & 0xfffc);
 883			break;
 884
 885		case R_PPC64_TOC16_LO_DS:
 886			/* Subtract TOC pointer */
 887			value -= my_r2(sechdrs, me);
 888			if ((value & 3) != 0) {
 889				pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
 890				       me->name, value);
 891				return -ENOEXEC;
 892			}
 893			*((uint16_t *) location)
 894				= (*((uint16_t *) location) & ~0xfffc)
 895				| (value & 0xfffc);
 896			break;
 897
 898		case R_PPC64_TOC16_HA:
 899			/* Subtract TOC pointer */
 900			value -= my_r2(sechdrs, me);
 901			value = ((value + 0x8000) >> 16);
 902			*((uint16_t *) location)
 903				= (*((uint16_t *) location) & ~0xffff)
 904				| (value & 0xffff);
 905			break;
 906#endif
 907
 908		case R_PPC_REL24:
 909#ifdef CONFIG_PPC_KERNEL_PCREL
 910		/* PCREL still generates REL24 for mcount */
 911		case R_PPC64_REL24_NOTOC:
 912#endif
 913			/* FIXME: Handle weak symbols here --RR */
 914			if (sym->st_shndx == SHN_UNDEF ||
 915			    sym->st_shndx == SHN_LIVEPATCH) {
 916				/* External: go via stub */
 917				value = stub_for_addr(sechdrs, value, me,
 918						strtab + sym->st_name);
 919				if (!value)
 920					return -ENOENT;
 921				if (restore_r2(strtab + sym->st_name,
 922					       (u32 *)location + 1, me))
 923					return -ENOEXEC;
 924			} else
 925				value += local_entry_offset(sym);
 926
 927			/* Convert value to relative */
 928			value -= (unsigned long)location;
 929			if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
 930				pr_err("%s: REL24 %li out of range!\n",
 931				       me->name, (long int)value);
 932				return -ENOEXEC;
 933			}
 934
 935			/* Only replace bits 2 through 26 */
 936			value = (*(uint32_t *)location & ~PPC_LI_MASK) | PPC_LI(value);
 937
 938			if (patch_instruction((u32 *)location, ppc_inst(value)))
 939				return -EFAULT;
 940
 941			break;
 942
 943		case R_PPC64_REL64:
 944			/* 64 bits relative (used by features fixups) */
 945			*location = value - (unsigned long)location;
 946			break;
 947
 948		case R_PPC64_REL32:
 949			/* 32 bits relative (used by relative exception tables) */
 950			/* Convert value to relative */
 951			value -= (unsigned long)location;
 952			if (value + 0x80000000 > 0xffffffff) {
 953				pr_err("%s: REL32 %li out of range!\n",
 954				       me->name, (long int)value);
 955				return -ENOEXEC;
 956			}
 957			*(u32 *)location = value;
 958			break;
 959
 960#ifdef CONFIG_PPC_KERNEL_PCREL
 961		case R_PPC64_PCREL34: {
 962			unsigned long absvalue = value;
 963
 964			/* Convert value to relative */
 965			value -= (unsigned long)location;
 966
 967			if (value + 0x200000000 > 0x3ffffffff) {
 968				if (sym->st_shndx != me->arch.pcpu_section) {
 969					pr_err("%s: REL34 %li out of range!\n",
 970					       me->name, (long)value);
 971					return -ENOEXEC;
 972				}
 973
 974				/*
 975				 * per-cpu section is special cased because
 976				 * it is moved during loading, so has to be
 977				 * converted to use GOT.
 978				 */
 979				value = got_for_addr(sechdrs, absvalue, me,
 980						     strtab + sym->st_name);
 981				if (!value)
 982					return -ENOENT;
 983				value -= (unsigned long)location;
 984
 985				/* Turn pla into pld */
 986				if (patch_instruction((u32 *)location,
 987				    ppc_inst_prefix((*(u32 *)location & ~0x02000000),
 988						    (*((u32 *)location + 1) & ~0xf8000000) | 0xe4000000)))
 989					return -EFAULT;
 990			}
 991
 992			if (patch_instruction((u32 *)location,
 993			    ppc_inst_prefix((*(u32 *)location & ~0x3ffff) | IMM_H18(value),
 994					    (*((u32 *)location + 1) & ~0xffff) | IMM_L(value))))
 995				return -EFAULT;
 996
 997			break;
 998		}
 999
1000#else
1001		case R_PPC64_TOCSAVE:
1002			/*
1003			 * Marker reloc indicates we don't have to save r2.
1004			 * That would only save us one instruction, so ignore
1005			 * it.
1006			 */
1007			break;
1008#endif
1009
1010		case R_PPC64_ENTRY:
1011			if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL))
1012				break;
1013
1014			/*
1015			 * Optimize ELFv2 large code model entry point if
1016			 * the TOC is within 2GB range of current location.
1017			 */
1018			value = my_r2(sechdrs, me) - (unsigned long)location;
1019			if (value + 0x80008000 > 0xffffffff)
1020				break;
1021			/*
1022			 * Check for the large code model prolog sequence:
1023		         *	ld r2, ...(r12)
1024			 *	add r2, r2, r12
1025			 */
1026			if ((((uint32_t *)location)[0] & ~0xfffc) != PPC_RAW_LD(_R2, _R12, 0))
1027				break;
1028			if (((uint32_t *)location)[1] != PPC_RAW_ADD(_R2, _R2, _R12))
1029				break;
1030			/*
1031			 * If found, replace it with:
1032			 *	addis r2, r12, (.TOC.-func)@ha
1033			 *	addi  r2,  r2, (.TOC.-func)@l
1034			 */
1035			((uint32_t *)location)[0] = PPC_RAW_ADDIS(_R2, _R12, PPC_HA(value));
1036			((uint32_t *)location)[1] = PPC_RAW_ADDI(_R2, _R2, PPC_LO(value));
1037			break;
1038
1039		case R_PPC64_REL16_HA:
1040			/* Subtract location pointer */
1041			value -= (unsigned long)location;
1042			value = ((value + 0x8000) >> 16);
1043			*((uint16_t *) location)
1044				= (*((uint16_t *) location) & ~0xffff)
1045				| (value & 0xffff);
1046			break;
1047
1048		case R_PPC64_REL16_LO:
1049			/* Subtract location pointer */
1050			value -= (unsigned long)location;
1051			*((uint16_t *) location)
1052				= (*((uint16_t *) location) & ~0xffff)
1053				| (value & 0xffff);
1054			break;
1055
1056#ifdef CONFIG_PPC_KERNEL_PCREL
1057		case R_PPC64_GOT_PCREL34:
1058			value = got_for_addr(sechdrs, value, me,
1059					     strtab + sym->st_name);
1060			if (!value)
1061				return -ENOENT;
1062			value -= (unsigned long)location;
1063			((uint32_t *)location)[0] = (((uint32_t *)location)[0] & ~0x3ffff) |
1064						    ((value >> 16) & 0x3ffff);
1065			((uint32_t *)location)[1] = (((uint32_t *)location)[1] & ~0xffff) |
1066						    (value & 0xffff);
1067			break;
1068#endif
1069
1070		default:
1071			pr_err("%s: Unknown ADD relocation: %lu\n",
1072			       me->name,
1073			       (unsigned long)ELF64_R_TYPE(rela[i].r_info));
1074			return -ENOEXEC;
1075		}
1076	}
1077
1078	return 0;
1079}
1080
1081#ifdef CONFIG_DYNAMIC_FTRACE
1082int module_trampoline_target(struct module *mod, unsigned long addr,
1083			     unsigned long *target)
1084{
1085	struct ppc64_stub_entry *stub;
1086	func_desc_t funcdata;
1087	u32 magic;
1088
1089	if (!within_module_core(addr, mod)) {
1090		pr_err("%s: stub %lx not in module %s\n", __func__, addr, mod->name);
1091		return -EFAULT;
1092	}
1093
1094	stub = (struct ppc64_stub_entry *)addr;
1095
1096	if (copy_from_kernel_nofault(&magic, &stub->magic,
1097			sizeof(magic))) {
1098		pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
1099		return -EFAULT;
1100	}
1101
1102	if (magic != STUB_MAGIC) {
1103		pr_err("%s: bad magic for stub %lx for %s\n", __func__, addr, mod->name);
1104		return -EFAULT;
1105	}
1106
1107	if (copy_from_kernel_nofault(&funcdata, &stub->funcdata,
1108			sizeof(funcdata))) {
1109		pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
1110                return -EFAULT;
1111	}
1112
1113	*target = stub_func_addr(funcdata);
1114
1115	return 0;
1116}
1117
1118static int setup_ftrace_ool_stubs(const Elf64_Shdr *sechdrs, unsigned long addr, struct module *me)
1119{
1120#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
1121	unsigned int total_stubs, num_stubs;
1122	struct ppc64_stub_entry *stub;
1123
1124	total_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stub);
1125	num_stubs = roundup(me->arch.ool_stub_count * sizeof(struct ftrace_ool_stub),
1126			    sizeof(struct ppc64_stub_entry)) / sizeof(struct ppc64_stub_entry);
1127
1128	if (WARN_ON(me->arch.stub_count + num_stubs > total_stubs))
1129		return -1;
1130
1131	stub = (void *)sechdrs[me->arch.stubs_section].sh_addr;
1132	me->arch.ool_stubs = (struct ftrace_ool_stub *)(stub + me->arch.stub_count);
1133	me->arch.stub_count += num_stubs;
1134#endif
1135
1136	return 0;
1137}
1138
1139int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
1140{
1141	mod->arch.tramp = stub_for_addr(sechdrs,
1142					(unsigned long)ftrace_caller,
1143					mod,
1144					"ftrace_caller");
1145#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
1146	mod->arch.tramp_regs = stub_for_addr(sechdrs,
1147					(unsigned long)ftrace_regs_caller,
1148					mod,
1149					"ftrace_regs_caller");
1150	if (!mod->arch.tramp_regs)
1151		return -ENOENT;
1152#endif
1153
1154	if (!mod->arch.tramp)
1155		return -ENOENT;
1156
1157	if (setup_ftrace_ool_stubs(sechdrs, mod->arch.tramp, mod))
1158		return -ENOENT;
1159
1160	return 0;
1161}
1162#endif