1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   4 * Copyright (C) 2002-2006 Novell, Inc.
   5 *	Jan Beulich <jbeulich@novell.com>
   6 *
   7 * A simple API for unwinding kernel stacks.  This is used for
   8 * debugging and error reporting purposes.  The kernel doesn't need
   9 * full-blown stack unwinding with all the bells and whistles, so there
  10 * is not much point in implementing the full Dwarf2 unwind API.
  11 */
  12
  13#include <linux/sched.h>
  14#include <linux/module.h>
  15#include <linux/memblock.h>
  16#include <linux/sort.h>
  17#include <linux/slab.h>
  18#include <linux/stop_machine.h>
  19#include <linux/uaccess.h>
  20#include <linux/ptrace.h>
  21#include <asm/sections.h>
  22#include <linux/unaligned.h>
  23#include <asm/unwind.h>
  24
  25extern char __start_unwind[], __end_unwind[];
  26/* extern const u8 __start_unwind_hdr[], __end_unwind_hdr[];*/
  27
  28/* #define UNWIND_DEBUG */
  29
  30#ifdef UNWIND_DEBUG
  31int dbg_unw;
  32#define unw_debug(fmt, ...)			\
  33do {						\
  34	if (dbg_unw)				\
  35		pr_info(fmt, ##__VA_ARGS__);	\
  36} while (0);
  37#else
  38#define unw_debug(fmt, ...)
  39#endif
  40
  41#define MAX_STACK_DEPTH 8
  42
  43#define EXTRA_INFO(f) { \
  44		BUILD_BUG_ON_ZERO(offsetof(struct unwind_frame_info, f) \
  45				% sizeof_field(struct unwind_frame_info, f)) \
  46				+ offsetof(struct unwind_frame_info, f) \
  47				/ sizeof_field(struct unwind_frame_info, f), \
  48				sizeof_field(struct unwind_frame_info, f) \
  49	}
  50#define PTREGS_INFO(f) EXTRA_INFO(regs.f)
  51
  52static const struct {
  53	unsigned offs:BITS_PER_LONG / 2;
  54	unsigned width:BITS_PER_LONG / 2;
  55} reg_info[] = {
  56UNW_REGISTER_INFO};
  57
  58#undef PTREGS_INFO
  59#undef EXTRA_INFO
  60
  61#ifndef REG_INVALID
  62#define REG_INVALID(r) (reg_info[r].width == 0)
  63#endif
  64
  65#define DW_CFA_nop                          0x00
  66#define DW_CFA_set_loc                      0x01
  67#define DW_CFA_advance_loc1                 0x02
  68#define DW_CFA_advance_loc2                 0x03
  69#define DW_CFA_advance_loc4                 0x04
  70#define DW_CFA_offset_extended              0x05
  71#define DW_CFA_restore_extended             0x06
  72#define DW_CFA_undefined                    0x07
  73#define DW_CFA_same_value                   0x08
  74#define DW_CFA_register                     0x09
  75#define DW_CFA_remember_state               0x0a
  76#define DW_CFA_restore_state                0x0b
  77#define DW_CFA_def_cfa                      0x0c
  78#define DW_CFA_def_cfa_register             0x0d
  79#define DW_CFA_def_cfa_offset               0x0e
  80#define DW_CFA_def_cfa_expression           0x0f
  81#define DW_CFA_expression                   0x10
  82#define DW_CFA_offset_extended_sf           0x11
  83#define DW_CFA_def_cfa_sf                   0x12
  84#define DW_CFA_def_cfa_offset_sf            0x13
  85#define DW_CFA_val_offset                   0x14
  86#define DW_CFA_val_offset_sf                0x15
  87#define DW_CFA_val_expression               0x16
  88#define DW_CFA_lo_user                      0x1c
  89#define DW_CFA_GNU_window_save              0x2d
  90#define DW_CFA_GNU_args_size                0x2e
  91#define DW_CFA_GNU_negative_offset_extended 0x2f
  92#define DW_CFA_hi_user                      0x3f
  93
  94#define DW_EH_PE_FORM     0x07
  95#define DW_EH_PE_native   0x00
  96#define DW_EH_PE_leb128   0x01
  97#define DW_EH_PE_data2    0x02
  98#define DW_EH_PE_data4    0x03
  99#define DW_EH_PE_data8    0x04
 100#define DW_EH_PE_signed   0x08
 101#define DW_EH_PE_ADJUST   0x70
 102#define DW_EH_PE_abs      0x00
 103#define DW_EH_PE_pcrel    0x10
 104#define DW_EH_PE_textrel  0x20
 105#define DW_EH_PE_datarel  0x30
 106#define DW_EH_PE_funcrel  0x40
 107#define DW_EH_PE_aligned  0x50
 108#define DW_EH_PE_indirect 0x80
 109#define DW_EH_PE_omit     0xff
 110
 111#define CIE_ID	0
 112
 113typedef unsigned long uleb128_t;
 114typedef signed long sleb128_t;
 115
 116static struct unwind_table {
 117	struct {
 118		unsigned long pc;
 119		unsigned long range;
 120	} core, init;
 121	const void *address;
 122	unsigned long size;
 123	const unsigned char *header;
 124	unsigned long hdrsz;
 125	struct unwind_table *link;
 126	const char *name;
 127} root_table;
 128
 129struct unwind_item {
 130	enum item_location {
 131		Nowhere,
 132		Memory,
 133		Register,
 134		Value
 135	} where;
 136	uleb128_t value;
 137};
 138
 139struct unwind_state {
 140	uleb128_t loc, org;
 141	const u8 *cieStart, *cieEnd;
 142	uleb128_t codeAlign;
 143	sleb128_t dataAlign;
 144	struct cfa {
 145		uleb128_t reg, offs;
 146	} cfa;
 147	struct unwind_item regs[ARRAY_SIZE(reg_info)];
 148	unsigned stackDepth:8;
 149	unsigned version:8;
 150	const u8 *label;
 151	const u8 *stack[MAX_STACK_DEPTH];
 152};
 153
 154static const struct cfa badCFA = { ARRAY_SIZE(reg_info), 1 };
 155
 156static struct unwind_table *find_table(unsigned long pc)
 157{
 158	struct unwind_table *table;
 159
 160	for (table = &root_table; table; table = table->link)
 161		if ((pc >= table->core.pc
 162		     && pc < table->core.pc + table->core.range)
 163		    || (pc >= table->init.pc
 164			&& pc < table->init.pc + table->init.range))
 165			break;
 166
 167	return table;
 168}
 169
 170static unsigned long read_pointer(const u8 **pLoc,
 171				  const void *end, signed ptrType);
 172static void init_unwind_hdr(struct unwind_table *table,
 173			    void *(*alloc) (unsigned long));
 174
 175/*
 176 * wrappers for header alloc (vs. calling one vs. other at call site)
 177 * to elide section mismatches warnings
 178 */
 179static void *__init unw_hdr_alloc_early(unsigned long sz)
 180{
 181	return memblock_alloc_from(sz, sizeof(unsigned int), MAX_DMA_ADDRESS);
 182}
 183
 184static void init_unwind_table(struct unwind_table *table, const char *name,
 185			      const void *core_start, unsigned long core_size,
 186			      const void *init_start, unsigned long init_size,
 187			      const void *table_start, unsigned long table_size,
 188			      const u8 *header_start, unsigned long header_size)
 189{
 190	table->core.pc = (unsigned long)core_start;
 191	table->core.range = core_size;
 192	table->init.pc = (unsigned long)init_start;
 193	table->init.range = init_size;
 194	table->address = table_start;
 195	table->size = table_size;
 196	/* To avoid the pointer addition with NULL pointer.*/
 197	if (header_start != NULL) {
 198		const u8 *ptr = header_start + 4;
 199		const u8 *end = header_start + header_size;
 200		/* See if the linker provided table looks valid. */
 201		if (header_size <= 4
 202		|| header_start[0] != 1
 203		|| (void *)read_pointer(&ptr, end, header_start[1])
 204				!= table_start
 205		|| header_start[2] == DW_EH_PE_omit
 206		|| read_pointer(&ptr, end, header_start[2]) <= 0
 207		|| header_start[3] == DW_EH_PE_omit)
 208			header_start = NULL;
 209	}
 210	table->hdrsz = header_size;
 211	smp_wmb();
 212	table->header = header_start;
 213	table->link = NULL;
 214	table->name = name;
 215}
 216
 217void __init arc_unwind_init(void)
 218{
 219	init_unwind_table(&root_table, "kernel", _text, _end - _text, NULL, 0,
 220			  __start_unwind, __end_unwind - __start_unwind,
 221			  NULL, 0);
 222	  /*__start_unwind_hdr, __end_unwind_hdr - __start_unwind_hdr);*/
 223
 224	init_unwind_hdr(&root_table, unw_hdr_alloc_early);
 225}
 226
 227static const u32 bad_cie, not_fde;
 228static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *);
 229static const u32 *__cie_for_fde(const u32 *fde);
 230static signed fde_pointer_type(const u32 *cie);
 231
 232struct eh_frame_hdr_table_entry {
 233	unsigned long start, fde;
 234};
 235
 236static int cmp_eh_frame_hdr_table_entries(const void *p1, const void *p2)
 237{
 238	const struct eh_frame_hdr_table_entry *e1 = p1;
 239	const struct eh_frame_hdr_table_entry *e2 = p2;
 240
 241	return (e1->start > e2->start) - (e1->start < e2->start);
 242}
 243
 244static void swap_eh_frame_hdr_table_entries(void *p1, void *p2, int size)
 245{
 246	struct eh_frame_hdr_table_entry *e1 = p1;
 247	struct eh_frame_hdr_table_entry *e2 = p2;
 248
 249	swap(e1->start, e2->start);
 250	swap(e1->fde, e2->fde);
 251}
 252
 253static void init_unwind_hdr(struct unwind_table *table,
 254			    void *(*alloc) (unsigned long))
 255{
 256	const u8 *ptr;
 257	unsigned long tableSize = table->size, hdrSize;
 258	unsigned int n;
 259	const u32 *fde;
 260	struct {
 261		u8 version;
 262		u8 eh_frame_ptr_enc;
 263		u8 fde_count_enc;
 264		u8 table_enc;
 265		unsigned long eh_frame_ptr;
 266		unsigned int fde_count;
 267		struct eh_frame_hdr_table_entry table[];
 268	} __attribute__ ((__packed__)) *header;
 269
 270	if (table->header)
 271		return;
 272
 273	if (table->hdrsz)
 274		pr_warn(".eh_frame_hdr for '%s' present but unusable\n",
 275			table->name);
 276
 277	if (tableSize & (sizeof(*fde) - 1))
 278		return;
 279
 280	for (fde = table->address, n = 0;
 281	     tableSize > sizeof(*fde) && tableSize - sizeof(*fde) >= *fde;
 282	     tableSize -= sizeof(*fde) + *fde, fde += 1 + *fde / sizeof(*fde)) {
 283		const u32 *cie = cie_for_fde(fde, table);
 284		signed ptrType;
 285
 286		if (cie == &not_fde)
 287			continue;
 288		if (cie == NULL || cie == &bad_cie)
 289			goto ret_err;
 290		ptrType = fde_pointer_type(cie);
 291		if (ptrType < 0)
 292			goto ret_err;
 293
 294		ptr = (const u8 *)(fde + 2);
 295		if (!read_pointer(&ptr, (const u8 *)(fde + 1) + *fde,
 296								ptrType)) {
 297			/* FIXME_Rajesh We have 4 instances of null addresses
 298			 * instead of the initial loc addr
 299			 * return;
 300			 */
 301			WARN(1, "unwinder: FDE->initial_location NULL %p\n",
 302				(const u8 *)(fde + 1) + *fde);
 303		}
 304		++n;
 305	}
 306
 307	if (tableSize || !n)
 308		goto ret_err;
 309
 310	hdrSize = 4 + sizeof(unsigned long) + sizeof(unsigned int)
 311	    + 2 * n * sizeof(unsigned long);
 312
 313	header = alloc(hdrSize);
 314	if (!header)
 315		goto ret_err;
 316
 317	header->version = 1;
 318	header->eh_frame_ptr_enc = DW_EH_PE_abs | DW_EH_PE_native;
 319	header->fde_count_enc = DW_EH_PE_abs | DW_EH_PE_data4;
 320	header->table_enc = DW_EH_PE_abs | DW_EH_PE_native;
 321	put_unaligned((unsigned long)table->address, &header->eh_frame_ptr);
 322	BUILD_BUG_ON(offsetof(typeof(*header), fde_count)
 323		     % __alignof(typeof(header->fde_count)));
 324	header->fde_count = n;
 325
 326	BUILD_BUG_ON(offsetof(typeof(*header), table)
 327		     % __alignof(typeof(*header->table)));
 328	for (fde = table->address, tableSize = table->size, n = 0;
 329	     tableSize;
 330	     tableSize -= sizeof(*fde) + *fde, fde += 1 + *fde / sizeof(*fde)) {
 331		const u32 *cie = __cie_for_fde(fde);
 332
 333		if (fde[1] == CIE_ID)
 334			continue;	/* this is a CIE */
 335		ptr = (const u8 *)(fde + 2);
 336		header->table[n].start = read_pointer(&ptr,
 337						      (const u8 *)(fde + 1) +
 338						      *fde,
 339						      fde_pointer_type(cie));
 340		header->table[n].fde = (unsigned long)fde;
 341		++n;
 342	}
 343	WARN_ON(n != header->fde_count);
 344
 345	sort(header->table,
 346	     n,
 347	     sizeof(*header->table),
 348	     cmp_eh_frame_hdr_table_entries, swap_eh_frame_hdr_table_entries);
 349
 350	table->hdrsz = hdrSize;
 351	smp_wmb();
 352	table->header = (const void *)header;
 353	return;
 354
 355ret_err:
 356	panic("Attention !!! Dwarf FDE parsing errors\n");
 357}
 358
 359#ifdef CONFIG_MODULES
 360static void *unw_hdr_alloc(unsigned long sz)
 361{
 362	return kmalloc(sz, GFP_KERNEL);
 363}
 364
 365static struct unwind_table *last_table;
 366
 367/* Must be called with module_mutex held. */
 368void *unwind_add_table(struct module *module, const void *table_start,
 369		       unsigned long table_size)
 370{
 371	struct unwind_table *table;
 372	struct module_memory *core_text;
 373	struct module_memory *init_text;
 374
 375	if (table_size <= 0)
 376		return NULL;
 377
 378	table = kmalloc(sizeof(*table), GFP_KERNEL);
 379	if (!table)
 380		return NULL;
 381
 382	core_text = &module->mem[MOD_TEXT];
 383	init_text = &module->mem[MOD_INIT_TEXT];
 384
 385	init_unwind_table(table, module->name, core_text->base, core_text->size,
 386			  init_text->base, init_text->size, table_start, table_size, NULL, 0);
 387
 388	init_unwind_hdr(table, unw_hdr_alloc);
 389
 390#ifdef UNWIND_DEBUG
 391	unw_debug("Table added for [%s] %lx %lx\n",
 392		module->name, table->core.pc, table->core.range);
 393#endif
 394	if (last_table)
 395		last_table->link = table;
 396	else
 397		root_table.link = table;
 398	last_table = table;
 399
 400	return table;
 401}
 402
 403struct unlink_table_info {
 404	struct unwind_table *table;
 405	int init_only;
 406};
 407
 408static int unlink_table(void *arg)
 409{
 410	struct unlink_table_info *info = arg;
 411	struct unwind_table *table = info->table, *prev;
 412
 413	for (prev = &root_table; prev->link && prev->link != table;
 414	     prev = prev->link)
 415		;
 416
 417	if (prev->link) {
 418		if (info->init_only) {
 419			table->init.pc = 0;
 420			table->init.range = 0;
 421			info->table = NULL;
 422		} else {
 423			prev->link = table->link;
 424			if (!prev->link)
 425				last_table = prev;
 426		}
 427	} else
 428		info->table = NULL;
 429
 430	return 0;
 431}
 432
 433/* Must be called with module_mutex held. */
 434void unwind_remove_table(void *handle, int init_only)
 435{
 436	struct unwind_table *table = handle;
 437	struct unlink_table_info info;
 438
 439	if (!table || table == &root_table)
 440		return;
 441
 442	if (init_only && table == last_table) {
 443		table->init.pc = 0;
 444		table->init.range = 0;
 445		return;
 446	}
 447
 448	info.table = table;
 449	info.init_only = init_only;
 450
 451	unlink_table(&info); /* XXX: SMP */
 452	kfree(table->header);
 453	kfree(table);
 454}
 455
 456#endif /* CONFIG_MODULES */
 457
 458static uleb128_t get_uleb128(const u8 **pcur, const u8 *end)
 459{
 460	const u8 *cur = *pcur;
 461	uleb128_t value;
 462	unsigned int shift;
 463
 464	for (shift = 0, value = 0; cur < end; shift += 7) {
 465		if (shift + 7 > 8 * sizeof(value)
 466		    && (*cur & 0x7fU) >= (1U << (8 * sizeof(value) - shift))) {
 467			cur = end + 1;
 468			break;
 469		}
 470		value |= (uleb128_t) (*cur & 0x7f) << shift;
 471		if (!(*cur++ & 0x80))
 472			break;
 473	}
 474	*pcur = cur;
 475
 476	return value;
 477}
 478
 479static sleb128_t get_sleb128(const u8 **pcur, const u8 *end)
 480{
 481	const u8 *cur = *pcur;
 482	sleb128_t value;
 483	unsigned int shift;
 484
 485	for (shift = 0, value = 0; cur < end; shift += 7) {
 486		if (shift + 7 > 8 * sizeof(value)
 487		    && (*cur & 0x7fU) >= (1U << (8 * sizeof(value) - shift))) {
 488			cur = end + 1;
 489			break;
 490		}
 491		value |= (sleb128_t) (*cur & 0x7f) << shift;
 492		if (!(*cur & 0x80)) {
 493			value |= -(*cur++ & 0x40) << shift;
 494			break;
 495		}
 496	}
 497	*pcur = cur;
 498
 499	return value;
 500}
 501
 502static const u32 *__cie_for_fde(const u32 *fde)
 503{
 504	const u32 *cie;
 505
 506	cie = fde + 1 - fde[1] / sizeof(*fde);
 507
 508	return cie;
 509}
 510
 511static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *table)
 512{
 513	const u32 *cie;
 514
 515	if (!*fde || (*fde & (sizeof(*fde) - 1)))
 516		return &bad_cie;
 517
 518	if (fde[1] == CIE_ID)
 519		return &not_fde;	/* this is a CIE */
 520
 521	if ((fde[1] & (sizeof(*fde) - 1)))
 522/* || fde[1] > (unsigned long)(fde + 1) - (unsigned long)table->address) */
 523		return NULL;	/* this is not a valid FDE */
 524
 525	cie = __cie_for_fde(fde);
 526
 527	if (*cie <= sizeof(*cie) + 4 || *cie >= fde[1] - sizeof(*fde)
 528	    || (*cie & (sizeof(*cie) - 1))
 529	    || (cie[1] != CIE_ID))
 530		return NULL;	/* this is not a (valid) CIE */
 531	return cie;
 532}
 533
 534static unsigned long read_pointer(const u8 **pLoc, const void *end,
 535				  signed ptrType)
 536{
 537	unsigned long value = 0;
 538	union {
 539		const u8 *p8;
 540		const u16 *p16u;
 541		const s16 *p16s;
 542		const u32 *p32u;
 543		const s32 *p32s;
 544		const unsigned long *pul;
 545	} ptr;
 546
 547	if (ptrType < 0 || ptrType == DW_EH_PE_omit)
 548		return 0;
 549	ptr.p8 = *pLoc;
 550	switch (ptrType & DW_EH_PE_FORM) {
 551	case DW_EH_PE_data2:
 552		if (end < (const void *)(ptr.p16u + 1))
 553			return 0;
 554		if (ptrType & DW_EH_PE_signed)
 555			value = get_unaligned((u16 *) ptr.p16s++);
 556		else
 557			value = get_unaligned((u16 *) ptr.p16u++);
 558		break;
 559	case DW_EH_PE_data4:
 560#ifdef CONFIG_64BIT
 561		if (end < (const void *)(ptr.p32u + 1))
 562			return 0;
 563		if (ptrType & DW_EH_PE_signed)
 564			value = get_unaligned(ptr.p32s++);
 565		else
 566			value = get_unaligned(ptr.p32u++);
 567		break;
 568	case DW_EH_PE_data8:
 569		BUILD_BUG_ON(sizeof(u64) != sizeof(value));
 570#else
 571		BUILD_BUG_ON(sizeof(u32) != sizeof(value));
 572#endif
 573		fallthrough;
 574	case DW_EH_PE_native:
 575		if (end < (const void *)(ptr.pul + 1))
 576			return 0;
 577		value = get_unaligned((unsigned long *)ptr.pul++);
 578		break;
 579	case DW_EH_PE_leb128:
 580		BUILD_BUG_ON(sizeof(uleb128_t) > sizeof(value));
 581		value = ptrType & DW_EH_PE_signed ? get_sleb128(&ptr.p8, end)
 582		    : get_uleb128(&ptr.p8, end);
 583		if ((const void *)ptr.p8 > end)
 584			return 0;
 585		break;
 586	default:
 587		return 0;
 588	}
 589	switch (ptrType & DW_EH_PE_ADJUST) {
 590	case DW_EH_PE_abs:
 591		break;
 592	case DW_EH_PE_pcrel:
 593		value += (unsigned long)*pLoc;
 594		break;
 595	default:
 596		return 0;
 597	}
 598	if ((ptrType & DW_EH_PE_indirect)
 599	    && __get_user(value, (unsigned long __user *)value))
 600		return 0;
 601	*pLoc = ptr.p8;
 602
 603	return value;
 604}
 605
 606static signed fde_pointer_type(const u32 *cie)
 607{
 608	const u8 *ptr = (const u8 *)(cie + 2);
 609	unsigned int version = *ptr;
 610
 611	if (*++ptr) {
 612		const char *aug;
 613		const u8 *end = (const u8 *)(cie + 1) + *cie;
 614		uleb128_t len;
 615
 616		/* check if augmentation size is first (and thus present) */
 617		if (*ptr != 'z')
 618			return -1;
 619
 620		/* check if augmentation string is nul-terminated */
 621		aug = (const void *)ptr;
 622		ptr = memchr(aug, 0, end - ptr);
 623		if (ptr == NULL)
 624			return -1;
 625
 626		++ptr;		/* skip terminator */
 627		get_uleb128(&ptr, end);	/* skip code alignment */
 628		get_sleb128(&ptr, end);	/* skip data alignment */
 629		/* skip return address column */
 630		version <= 1 ? (void) ++ptr : (void)get_uleb128(&ptr, end);
 631		len = get_uleb128(&ptr, end);	/* augmentation length */
 632
 633		if (ptr + len < ptr || ptr + len > end)
 634			return -1;
 635
 636		end = ptr + len;
 637		while (*++aug) {
 638			if (ptr >= end)
 639				return -1;
 640			switch (*aug) {
 641			case 'L':
 642				++ptr;
 643				break;
 644			case 'P':{
 645					signed ptrType = *ptr++;
 646
 647					if (!read_pointer(&ptr, end, ptrType)
 648					    || ptr > end)
 649						return -1;
 650				}
 651				break;
 652			case 'R':
 653				return *ptr;
 654			default:
 655				return -1;
 656			}
 657		}
 658	}
 659	return DW_EH_PE_native | DW_EH_PE_abs;
 660}
 661
 662static int advance_loc(unsigned long delta, struct unwind_state *state)
 663{
 664	state->loc += delta * state->codeAlign;
 665
 666	/* FIXME_Rajesh: Probably we are defining for the initial range as well;
 667	   return delta > 0;
 668	 */
 669	unw_debug("delta %3lu => loc 0x%lx: ", delta, state->loc);
 670	return 1;
 671}
 672
 673static void set_rule(uleb128_t reg, enum item_location where, uleb128_t value,
 674		     struct unwind_state *state)
 675{
 676	if (reg < ARRAY_SIZE(state->regs)) {
 677		state->regs[reg].where = where;
 678		state->regs[reg].value = value;
 679
 680#ifdef UNWIND_DEBUG
 681		unw_debug("r%lu: ", reg);
 682		switch (where) {
 683		case Nowhere:
 684			unw_debug("s ");
 685			break;
 686		case Memory:
 687			unw_debug("c(%lu) ", value);
 688			break;
 689		case Register:
 690			unw_debug("r(%lu) ", value);
 691			break;
 692		case Value:
 693			unw_debug("v(%lu) ", value);
 694			break;
 695		default:
 696			break;
 697		}
 698#endif
 699	}
 700}
 701
 702static int processCFI(const u8 *start, const u8 *end, unsigned long targetLoc,
 703		      signed ptrType, struct unwind_state *state)
 704{
 705	union {
 706		const u8 *p8;
 707		const u16 *p16;
 708		const u32 *p32;
 709	} ptr;
 710	int result = 1;
 711	u8 opcode;
 712
 713	if (start != state->cieStart) {
 714		state->loc = state->org;
 715		result =
 716		    processCFI(state->cieStart, state->cieEnd, 0, ptrType,
 717			       state);
 718		if (targetLoc == 0 && state->label == NULL)
 719			return result;
 720	}
 721	for (ptr.p8 = start; result && ptr.p8 < end;) {
 722		switch (*ptr.p8 >> 6) {
 723			uleb128_t value;
 724
 725		case 0:
 726			opcode = *ptr.p8++;
 727
 728			switch (opcode) {
 729			case DW_CFA_nop:
 730				unw_debug("cfa nop ");
 731				break;
 732			case DW_CFA_set_loc:
 733				state->loc = read_pointer(&ptr.p8, end,
 734							  ptrType);
 735				if (state->loc == 0)
 736					result = 0;
 737				unw_debug("cfa_set_loc: 0x%lx ", state->loc);
 738				break;
 739			case DW_CFA_advance_loc1:
 740				unw_debug("\ncfa advance loc1:");
 741				result = ptr.p8 < end
 742				    && advance_loc(*ptr.p8++, state);
 743				break;
 744			case DW_CFA_advance_loc2:
 745				value = *ptr.p8++;
 746				value += *ptr.p8++ << 8;
 747				unw_debug("\ncfa advance loc2:");
 748				result = ptr.p8 <= end + 2
 749				    /* && advance_loc(*ptr.p16++, state); */
 750				    && advance_loc(value, state);
 751				break;
 752			case DW_CFA_advance_loc4:
 753				unw_debug("\ncfa advance loc4:");
 754				result = ptr.p8 <= end + 4
 755				    && advance_loc(*ptr.p32++, state);
 756				break;
 757			case DW_CFA_offset_extended:
 758				value = get_uleb128(&ptr.p8, end);
 759				unw_debug("cfa_offset_extended: ");
 760				set_rule(value, Memory,
 761					 get_uleb128(&ptr.p8, end), state);
 762				break;
 763			case DW_CFA_val_offset:
 764				value = get_uleb128(&ptr.p8, end);
 765				set_rule(value, Value,
 766					 get_uleb128(&ptr.p8, end), state);
 767				break;
 768			case DW_CFA_offset_extended_sf:
 769				value = get_uleb128(&ptr.p8, end);
 770				set_rule(value, Memory,
 771					 get_sleb128(&ptr.p8, end), state);
 772				break;
 773			case DW_CFA_val_offset_sf:
 774				value = get_uleb128(&ptr.p8, end);
 775				set_rule(value, Value,
 776					 get_sleb128(&ptr.p8, end), state);
 777				break;
 778			case DW_CFA_restore_extended:
 779				unw_debug("cfa_restore_extended: ");
 780			case DW_CFA_undefined:
 781				unw_debug("cfa_undefined: ");
 782			case DW_CFA_same_value:
 783				unw_debug("cfa_same_value: ");
 784				set_rule(get_uleb128(&ptr.p8, end), Nowhere, 0,
 785					 state);
 786				break;
 787			case DW_CFA_register:
 788				unw_debug("cfa_register: ");
 789				value = get_uleb128(&ptr.p8, end);
 790				set_rule(value,
 791					 Register,
 792					 get_uleb128(&ptr.p8, end), state);
 793				break;
 794			case DW_CFA_remember_state:
 795				unw_debug("cfa_remember_state: ");
 796				if (ptr.p8 == state->label) {
 797					state->label = NULL;
 798					return 1;
 799				}
 800				if (state->stackDepth >= MAX_STACK_DEPTH)
 801					return 0;
 802				state->stack[state->stackDepth++] = ptr.p8;
 803				break;
 804			case DW_CFA_restore_state:
 805				unw_debug("cfa_restore_state: ");
 806				if (state->stackDepth) {
 807					const uleb128_t loc = state->loc;
 808					const u8 *label = state->label;
 809
 810					state->label =
 811					    state->stack[state->stackDepth - 1];
 812					memcpy(&state->cfa, &badCFA,
 813					       sizeof(state->cfa));
 814					memset(state->regs, 0,
 815					       sizeof(state->regs));
 816					state->stackDepth = 0;
 817					result =
 818					    processCFI(start, end, 0, ptrType,
 819						       state);
 820					state->loc = loc;
 821					state->label = label;
 822				} else
 823					return 0;
 824				break;
 825			case DW_CFA_def_cfa:
 826				state->cfa.reg = get_uleb128(&ptr.p8, end);
 827				unw_debug("cfa_def_cfa: r%lu ", state->cfa.reg);
 828				fallthrough;
 829			case DW_CFA_def_cfa_offset:
 830				state->cfa.offs = get_uleb128(&ptr.p8, end);
 831				unw_debug("cfa_def_cfa_offset: 0x%lx ",
 832					  state->cfa.offs);
 833				break;
 834			case DW_CFA_def_cfa_sf:
 835				state->cfa.reg = get_uleb128(&ptr.p8, end);
 836				fallthrough;
 837			case DW_CFA_def_cfa_offset_sf:
 838				state->cfa.offs = get_sleb128(&ptr.p8, end)
 839				    * state->dataAlign;
 840				break;
 841			case DW_CFA_def_cfa_register:
 842				unw_debug("cfa_def_cfa_register: ");
 843				state->cfa.reg = get_uleb128(&ptr.p8, end);
 844				break;
 845				/*todo case DW_CFA_def_cfa_expression: */
 846				/*todo case DW_CFA_expression: */
 847				/*todo case DW_CFA_val_expression: */
 848			case DW_CFA_GNU_args_size:
 849				get_uleb128(&ptr.p8, end);
 850				break;
 851			case DW_CFA_GNU_negative_offset_extended:
 852				value = get_uleb128(&ptr.p8, end);
 853				set_rule(value,
 854					 Memory,
 855					 (uleb128_t) 0 - get_uleb128(&ptr.p8,
 856								     end),
 857					 state);
 858				break;
 859			case DW_CFA_GNU_window_save:
 860			default:
 861				unw_debug("UNKNOWN OPCODE 0x%x\n", opcode);
 862				result = 0;
 863				break;
 864			}
 865			break;
 866		case 1:
 867			unw_debug("\ncfa_adv_loc: ");
 868			result = advance_loc(*ptr.p8++ & 0x3f, state);
 869			break;
 870		case 2:
 871			unw_debug("cfa_offset: ");
 872			value = *ptr.p8++ & 0x3f;
 873			set_rule(value, Memory, get_uleb128(&ptr.p8, end),
 874				 state);
 875			break;
 876		case 3:
 877			unw_debug("cfa_restore: ");
 878			set_rule(*ptr.p8++ & 0x3f, Nowhere, 0, state);
 879			break;
 880		}
 881
 882		if (ptr.p8 > end)
 883			result = 0;
 884		if (result && targetLoc != 0 && targetLoc < state->loc)
 885			return 1;
 886	}
 887
 888	return result && ptr.p8 == end && (targetLoc == 0 || (
 889		/*todo While in theory this should apply, gcc in practice omits
 890		  everything past the function prolog, and hence the location
 891		  never reaches the end of the function.
 892		targetLoc < state->loc && */  state->label == NULL));
 893}
 894
 895/* Unwind to previous to frame.  Returns 0 if successful, negative
 896 * number in case of an error. */
 897int arc_unwind(struct unwind_frame_info *frame)
 898{
 899#define FRAME_REG(r, t) (((t *)frame)[reg_info[r].offs])
 900	const u32 *fde = NULL, *cie = NULL;
 901	const u8 *ptr = NULL, *end = NULL;
 902	unsigned long pc = UNW_PC(frame) - frame->call_frame;
 903	unsigned long startLoc = 0, endLoc = 0, cfa;
 904	unsigned int i;
 905	signed ptrType = -1;
 906	uleb128_t retAddrReg = 0;
 907	const struct unwind_table *table;
 908	struct unwind_state state;
 909	unsigned long *fptr;
 910	unsigned long addr;
 911
 912	unw_debug("\n\nUNWIND FRAME:\n");
 913	unw_debug("PC: 0x%lx BLINK: 0x%lx, SP: 0x%lx, FP: 0x%x\n",
 914		  UNW_PC(frame), UNW_BLINK(frame), UNW_SP(frame),
 915		  UNW_FP(frame));
 916
 917	if (UNW_PC(frame) == 0)
 918		return -EINVAL;
 919
 920#ifdef UNWIND_DEBUG
 921	{
 922		unsigned long *sptr = (unsigned long *)UNW_SP(frame);
 923		unw_debug("\nStack Dump:\n");
 924		for (i = 0; i < 20; i++, sptr++)
 925			unw_debug("0x%p:  0x%lx\n", sptr, *sptr);
 926		unw_debug("\n");
 927	}
 928#endif
 929
 930	table = find_table(pc);
 931	if (table != NULL
 932	    && !(table->size & (sizeof(*fde) - 1))) {
 933		const u8 *hdr = table->header;
 934		unsigned long tableSize;
 935
 936		smp_rmb();
 937		if (hdr && hdr[0] == 1) {
 938			switch (hdr[3] & DW_EH_PE_FORM) {
 939			case DW_EH_PE_native:
 940				tableSize = sizeof(unsigned long);
 941				break;
 942			case DW_EH_PE_data2:
 943				tableSize = 2;
 944				break;
 945			case DW_EH_PE_data4:
 946				tableSize = 4;
 947				break;
 948			case DW_EH_PE_data8:
 949				tableSize = 8;
 950				break;
 951			default:
 952				tableSize = 0;
 953				break;
 954			}
 955			ptr = hdr + 4;
 956			end = hdr + table->hdrsz;
 957			if (tableSize && read_pointer(&ptr, end, hdr[1])
 958			    == (unsigned long)table->address
 959			    && (i = read_pointer(&ptr, end, hdr[2])) > 0
 960			    && i == (end - ptr) / (2 * tableSize)
 961			    && !((end - ptr) % (2 * tableSize))) {
 962				do {
 963					const u8 *cur =
 964					    ptr + (i / 2) * (2 * tableSize);
 965
 966					startLoc = read_pointer(&cur,
 967								cur + tableSize,
 968								hdr[3]);
 969					if (pc < startLoc)
 970						i /= 2;
 971					else {
 972						ptr = cur - tableSize;
 973						i = (i + 1) / 2;
 974					}
 975				} while (startLoc && i > 1);
 976				if (i == 1
 977				    && (startLoc = read_pointer(&ptr,
 978								ptr + tableSize,
 979								hdr[3])) != 0
 980				    && pc >= startLoc)
 981					fde = (void *)read_pointer(&ptr,
 982								   ptr +
 983								   tableSize,
 984								   hdr[3]);
 985			}
 986		}
 987
 988		if (fde != NULL) {
 989			cie = cie_for_fde(fde, table);
 990			ptr = (const u8 *)(fde + 2);
 991			if (cie != NULL
 992			    && cie != &bad_cie
 993			    && cie != &not_fde
 994			    && (ptrType = fde_pointer_type(cie)) >= 0
 995			    && read_pointer(&ptr,
 996					    (const u8 *)(fde + 1) + *fde,
 997					    ptrType) == startLoc) {
 998				if (!(ptrType & DW_EH_PE_indirect))
 999					ptrType &=
1000					    DW_EH_PE_FORM | DW_EH_PE_signed;
1001				endLoc =
1002				    startLoc + read_pointer(&ptr,
1003							    (const u8 *)(fde +
1004									 1) +
1005							    *fde, ptrType);
1006				if (pc >= endLoc) {
1007					fde = NULL;
1008					cie = NULL;
1009				}
1010			} else {
1011				fde = NULL;
1012				cie = NULL;
1013			}
1014		}
1015	}
1016	if (cie != NULL) {
1017		memset(&state, 0, sizeof(state));
1018		state.cieEnd = ptr;	/* keep here temporarily */
1019		ptr = (const u8 *)(cie + 2);
1020		end = (const u8 *)(cie + 1) + *cie;
1021		frame->call_frame = 1;
1022		if (*++ptr) {
1023			/* check if augmentation size is first (thus present) */
1024			if (*ptr == 'z') {
1025				while (++ptr < end && *ptr) {
1026					switch (*ptr) {
1027					/* chk for ignorable or already handled
1028					 * nul-terminated augmentation string */
1029					case 'L':
1030					case 'P':
1031					case 'R':
1032						continue;
1033					case 'S':
1034						frame->call_frame = 0;
1035						continue;
1036					default:
1037						break;
1038					}
1039					break;
1040				}
1041			}
1042			if (ptr >= end || *ptr)
1043				cie = NULL;
1044		}
1045		++ptr;
1046	}
1047	if (cie != NULL) {
1048		/* get code alignment factor */
1049		state.codeAlign = get_uleb128(&ptr, end);
1050		/* get data alignment factor */
1051		state.dataAlign = get_sleb128(&ptr, end);
1052		if (state.codeAlign == 0 || state.dataAlign == 0 || ptr >= end)
1053			cie = NULL;
1054		else {
1055			retAddrReg =
1056			    state.version <= 1 ? *ptr++ : get_uleb128(&ptr,
1057								      end);
1058			unw_debug("CIE Frame Info:\n");
1059			unw_debug("return Address register 0x%lx\n",
1060				  retAddrReg);
1061			unw_debug("data Align: %ld\n", state.dataAlign);
1062			unw_debug("code Align: %lu\n", state.codeAlign);
1063			/* skip augmentation */
1064			if (((const char *)(cie + 2))[1] == 'z') {
1065				uleb128_t augSize = get_uleb128(&ptr, end);
1066
1067				ptr += augSize;
1068			}
1069			if (ptr > end || retAddrReg >= ARRAY_SIZE(reg_info)
1070			    || REG_INVALID(retAddrReg)
1071			    || reg_info[retAddrReg].width !=
1072			    sizeof(unsigned long))
1073				cie = NULL;
1074		}
1075	}
1076	if (cie != NULL) {
1077		state.cieStart = ptr;
1078		ptr = state.cieEnd;
1079		state.cieEnd = end;
1080		end = (const u8 *)(fde + 1) + *fde;
1081		/* skip augmentation */
1082		if (((const char *)(cie + 2))[1] == 'z') {
1083			uleb128_t augSize = get_uleb128(&ptr, end);
1084
1085			if ((ptr += augSize) > end)
1086				fde = NULL;
1087		}
1088	}
1089	if (cie == NULL || fde == NULL) {
1090#ifdef CONFIG_FRAME_POINTER
1091		unsigned long top, bottom;
1092
1093		top = STACK_TOP_UNW(frame->task);
1094		bottom = STACK_BOTTOM_UNW(frame->task);
1095#if FRAME_RETADDR_OFFSET < 0
1096		if (UNW_SP(frame) < top && UNW_FP(frame) <= UNW_SP(frame)
1097		    && bottom < UNW_FP(frame)
1098#else
1099		if (UNW_SP(frame) > top && UNW_FP(frame) >= UNW_SP(frame)
1100		    && bottom > UNW_FP(frame)
1101#endif
1102		    && !((UNW_SP(frame) | UNW_FP(frame))
1103			 & (sizeof(unsigned long) - 1))) {
1104			unsigned long link;
1105
1106			if (!__get_user(link, (unsigned long *)
1107					(UNW_FP(frame) + FRAME_LINK_OFFSET))
1108#if FRAME_RETADDR_OFFSET < 0
1109			    && link > bottom && link < UNW_FP(frame)
1110#else
1111			    && link > UNW_FP(frame) && link < bottom
1112#endif
1113			    && !(link & (sizeof(link) - 1))
1114			    && !__get_user(UNW_PC(frame),
1115					   (unsigned long *)(UNW_FP(frame)
1116						+ FRAME_RETADDR_OFFSET)))
1117			{
1118				UNW_SP(frame) =
1119				    UNW_FP(frame) + FRAME_RETADDR_OFFSET
1120#if FRAME_RETADDR_OFFSET < 0
1121				    -
1122#else
1123				    +
1124#endif
1125				    sizeof(UNW_PC(frame));
1126				UNW_FP(frame) = link;
1127				return 0;
1128			}
1129		}
1130#endif
1131		return -ENXIO;
1132	}
1133	state.org = startLoc;
1134	memcpy(&state.cfa, &badCFA, sizeof(state.cfa));
1135
1136	unw_debug("\nProcess instructions\n");
1137
1138	/* process instructions
1139	 * For ARC, we optimize by having blink(retAddrReg) with
1140	 * the sameValue in the leaf function, so we should not check
1141	 * state.regs[retAddrReg].where == Nowhere
1142	 */
1143	if (!processCFI(ptr, end, pc, ptrType, &state)
1144	    || state.loc > endLoc
1145/*	   || state.regs[retAddrReg].where == Nowhere */
1146	    || state.cfa.reg >= ARRAY_SIZE(reg_info)
1147	    || reg_info[state.cfa.reg].width != sizeof(unsigned long)
1148	    || state.cfa.offs % sizeof(unsigned long))
1149		return -EIO;
1150
1151#ifdef UNWIND_DEBUG
1152	unw_debug("\n");
1153
1154	unw_debug("\nRegister State Based on the rules parsed from FDE:\n");
1155	for (i = 0; i < ARRAY_SIZE(state.regs); ++i) {
1156
1157		if (REG_INVALID(i))
1158			continue;
1159
1160		switch (state.regs[i].where) {
1161		case Nowhere:
1162			break;
1163		case Memory:
1164			unw_debug(" r%d: c(%lu),", i, state.regs[i].value);
1165			break;
1166		case Register:
1167			unw_debug(" r%d: r(%lu),", i, state.regs[i].value);
1168			break;
1169		case Value:
1170			unw_debug(" r%d: v(%lu),", i, state.regs[i].value);
1171			break;
1172		}
1173	}
1174
1175	unw_debug("\n");
1176#endif
1177
1178	/* update frame */
1179	if (frame->call_frame
1180	    && !UNW_DEFAULT_RA(state.regs[retAddrReg], state.dataAlign))
1181		frame->call_frame = 0;
1182	cfa = FRAME_REG(state.cfa.reg, unsigned long) + state.cfa.offs;
1183	startLoc = min_t(unsigned long, UNW_SP(frame), cfa);
1184	endLoc = max_t(unsigned long, UNW_SP(frame), cfa);
1185	if (STACK_LIMIT(startLoc) != STACK_LIMIT(endLoc)) {
1186		startLoc = min(STACK_LIMIT(cfa), cfa);
1187		endLoc = max(STACK_LIMIT(cfa), cfa);
1188	}
1189
1190	unw_debug("\nCFA reg: 0x%lx, offset: 0x%lx =>  0x%lx\n",
1191		  state.cfa.reg, state.cfa.offs, cfa);
1192
1193	for (i = 0; i < ARRAY_SIZE(state.regs); ++i) {
1194		if (REG_INVALID(i)) {
1195			if (state.regs[i].where == Nowhere)
1196				continue;
1197			return -EIO;
1198		}
1199		switch (state.regs[i].where) {
1200		default:
1201			break;
1202		case Register:
1203			if (state.regs[i].value >= ARRAY_SIZE(reg_info)
1204			    || REG_INVALID(state.regs[i].value)
1205			    || reg_info[i].width >
1206			    reg_info[state.regs[i].value].width)
1207				return -EIO;
1208			switch (reg_info[state.regs[i].value].width) {
1209			case sizeof(u8):
1210				state.regs[i].value =
1211				FRAME_REG(state.regs[i].value, const u8);
1212				break;
1213			case sizeof(u16):
1214				state.regs[i].value =
1215				FRAME_REG(state.regs[i].value, const u16);
1216				break;
1217			case sizeof(u32):
1218				state.regs[i].value =
1219				FRAME_REG(state.regs[i].value, const u32);
1220				break;
1221#ifdef CONFIG_64BIT
1222			case sizeof(u64):
1223				state.regs[i].value =
1224				FRAME_REG(state.regs[i].value, const u64);
1225				break;
1226#endif
1227			default:
1228				return -EIO;
1229			}
1230			break;
1231		}
1232	}
1233
1234	unw_debug("\nRegister state after evaluation with realtime Stack:\n");
1235	fptr = (unsigned long *)(&frame->regs);
1236	for (i = 0; i < ARRAY_SIZE(state.regs); ++i, fptr++) {
1237
1238		if (REG_INVALID(i))
1239			continue;
1240		switch (state.regs[i].where) {
1241		case Nowhere:
1242			if (reg_info[i].width != sizeof(UNW_SP(frame))
1243			    || &FRAME_REG(i, __typeof__(UNW_SP(frame)))
1244			    != &UNW_SP(frame))
1245				continue;
1246			UNW_SP(frame) = cfa;
1247			break;
1248		case Register:
1249			switch (reg_info[i].width) {
1250			case sizeof(u8):
1251				FRAME_REG(i, u8) = state.regs[i].value;
1252				break;
1253			case sizeof(u16):
1254				FRAME_REG(i, u16) = state.regs[i].value;
1255				break;
1256			case sizeof(u32):
1257				FRAME_REG(i, u32) = state.regs[i].value;
1258				break;
1259#ifdef CONFIG_64BIT
1260			case sizeof(u64):
1261				FRAME_REG(i, u64) = state.regs[i].value;
1262				break;
1263#endif
1264			default:
1265				return -EIO;
1266			}
1267			break;
1268		case Value:
1269			if (reg_info[i].width != sizeof(unsigned long))
1270				return -EIO;
1271			FRAME_REG(i, unsigned long) = cfa + state.regs[i].value
1272			    * state.dataAlign;
1273			break;
1274		case Memory:
1275			addr = cfa + state.regs[i].value * state.dataAlign;
1276
1277			if ((state.regs[i].value * state.dataAlign)
1278			    % sizeof(unsigned long)
1279			    || addr < startLoc
1280			    || addr + sizeof(unsigned long) < addr
1281			    || addr + sizeof(unsigned long) > endLoc)
1282					return -EIO;
1283
1284			switch (reg_info[i].width) {
1285			case sizeof(u8):
1286				__get_user(FRAME_REG(i, u8),
1287					   (u8 __user *)addr);
1288				break;
1289			case sizeof(u16):
1290				__get_user(FRAME_REG(i, u16),
1291					   (u16 __user *)addr);
1292				break;
1293			case sizeof(u32):
1294				__get_user(FRAME_REG(i, u32),
1295					   (u32 __user *)addr);
1296				break;
1297#ifdef CONFIG_64BIT
1298			case sizeof(u64):
1299				__get_user(FRAME_REG(i, u64),
1300					   (u64 __user *)addr);
1301				break;
1302#endif
1303			default:
1304				return -EIO;
1305			}
1306
1307			break;
1308		}
1309		unw_debug("r%d: 0x%lx ", i, *fptr);
1310	}
1311
1312	return 0;
1313#undef FRAME_REG
1314}
1315EXPORT_SYMBOL(arc_unwind);