unwind.c 30.8 KB
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/*
 * Copyright (C) 2002-2006 Novell, Inc.
 *	Jan Beulich <jbeulich@novell.com>
 * This code is released under version 2 of the GNU GPL.
 *
 * A simple API for unwinding kernel stacks.  This is used for
 * debugging and error reporting purposes.  The kernel doesn't need
 * full-blown stack unwinding with all the bells and whistles, so there
 * is not much point in implementing the full Dwarf2 unwind API.
 */

#include <linux/unwind.h>
#include <linux/module.h>
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#include <linux/bootmem.h>
#include <linux/sort.h>
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#include <linux/stop_machine.h>
#include <asm/sections.h>
#include <asm/uaccess.h>
#include <asm/unaligned.h>

extern char __start_unwind[], __end_unwind[];
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extern const u8 __start_unwind_hdr[], __end_unwind_hdr[];
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#define MAX_STACK_DEPTH 8

#define EXTRA_INFO(f) { \
		BUILD_BUG_ON_ZERO(offsetof(struct unwind_frame_info, f) \
		                  % FIELD_SIZEOF(struct unwind_frame_info, f)) \
		+ offsetof(struct unwind_frame_info, f) \
		  / FIELD_SIZEOF(struct unwind_frame_info, f), \
		FIELD_SIZEOF(struct unwind_frame_info, f) \
	}
#define PTREGS_INFO(f) EXTRA_INFO(regs.f)

static const struct {
	unsigned offs:BITS_PER_LONG / 2;
	unsigned width:BITS_PER_LONG / 2;
} reg_info[] = {
	UNW_REGISTER_INFO
};

#undef PTREGS_INFO
#undef EXTRA_INFO

#ifndef REG_INVALID
#define REG_INVALID(r) (reg_info[r].width == 0)
#endif

#define DW_CFA_nop                          0x00
#define DW_CFA_set_loc                      0x01
#define DW_CFA_advance_loc1                 0x02
#define DW_CFA_advance_loc2                 0x03
#define DW_CFA_advance_loc4                 0x04
#define DW_CFA_offset_extended              0x05
#define DW_CFA_restore_extended             0x06
#define DW_CFA_undefined                    0x07
#define DW_CFA_same_value                   0x08
#define DW_CFA_register                     0x09
#define DW_CFA_remember_state               0x0a
#define DW_CFA_restore_state                0x0b
#define DW_CFA_def_cfa                      0x0c
#define DW_CFA_def_cfa_register             0x0d
#define DW_CFA_def_cfa_offset               0x0e
#define DW_CFA_def_cfa_expression           0x0f
#define DW_CFA_expression                   0x10
#define DW_CFA_offset_extended_sf           0x11
#define DW_CFA_def_cfa_sf                   0x12
#define DW_CFA_def_cfa_offset_sf            0x13
#define DW_CFA_val_offset                   0x14
#define DW_CFA_val_offset_sf                0x15
#define DW_CFA_val_expression               0x16
#define DW_CFA_lo_user                      0x1c
#define DW_CFA_GNU_window_save              0x2d
#define DW_CFA_GNU_args_size                0x2e
#define DW_CFA_GNU_negative_offset_extended 0x2f
#define DW_CFA_hi_user                      0x3f

#define DW_EH_PE_FORM     0x07
#define DW_EH_PE_native   0x00
#define DW_EH_PE_leb128   0x01
#define DW_EH_PE_data2    0x02
#define DW_EH_PE_data4    0x03
#define DW_EH_PE_data8    0x04
#define DW_EH_PE_signed   0x08
#define DW_EH_PE_ADJUST   0x70
#define DW_EH_PE_abs      0x00
#define DW_EH_PE_pcrel    0x10
#define DW_EH_PE_textrel  0x20
#define DW_EH_PE_datarel  0x30
#define DW_EH_PE_funcrel  0x40
#define DW_EH_PE_aligned  0x50
#define DW_EH_PE_indirect 0x80
#define DW_EH_PE_omit     0xff

typedef unsigned long uleb128_t;
typedef   signed long sleb128_t;

static struct unwind_table {
	struct {
		unsigned long pc;
		unsigned long range;
	} core, init;
	const void *address;
	unsigned long size;
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	const unsigned char *header;
	unsigned long hdrsz;
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	struct unwind_table *link;
	const char *name;
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} root_table;
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struct unwind_item {
	enum item_location {
		Nowhere,
		Memory,
		Register,
		Value
	} where;
	uleb128_t value;
};

struct unwind_state {
	uleb128_t loc, org;
	const u8 *cieStart, *cieEnd;
	uleb128_t codeAlign;
	sleb128_t dataAlign;
	struct cfa {
		uleb128_t reg, offs;
	} cfa;
	struct unwind_item regs[ARRAY_SIZE(reg_info)];
	unsigned stackDepth:8;
	unsigned version:8;
	const u8 *label;
	const u8 *stack[MAX_STACK_DEPTH];
};

static const struct cfa badCFA = { ARRAY_SIZE(reg_info), 1 };

static struct unwind_table *find_table(unsigned long pc)
{
	struct unwind_table *table;

	for (table = &root_table; table; table = table->link)
		if ((pc >= table->core.pc
		     && pc < table->core.pc + table->core.range)
		    || (pc >= table->init.pc
		        && pc < table->init.pc + table->init.range))
			break;

	return table;
}

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static unsigned long read_pointer(const u8 **pLoc,
                                  const void *end,
                                  signed ptrType);

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static void init_unwind_table(struct unwind_table *table,
                              const char *name,
                              const void *core_start,
                              unsigned long core_size,
                              const void *init_start,
                              unsigned long init_size,
                              const void *table_start,
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                              unsigned long table_size,
                              const u8 *header_start,
                              unsigned long header_size)
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{
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	const u8 *ptr = header_start + 4;
	const u8 *end = header_start + header_size;

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	table->core.pc = (unsigned long)core_start;
	table->core.range = core_size;
	table->init.pc = (unsigned long)init_start;
	table->init.range = init_size;
	table->address = table_start;
	table->size = table_size;
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	/* See if the linker provided table looks valid. */
	if (header_size <= 4
	    || header_start[0] != 1
	    || (void *)read_pointer(&ptr, end, header_start[1]) != table_start
	    || header_start[2] == DW_EH_PE_omit
	    || read_pointer(&ptr, end, header_start[2]) <= 0
	    || header_start[3] == DW_EH_PE_omit)
		header_start = NULL;
	table->hdrsz = header_size;
	smp_wmb();
	table->header = header_start;
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	table->link = NULL;
	table->name = name;
}

void __init unwind_init(void)
{
	init_unwind_table(&root_table, "kernel",
	                  _text, _end - _text,
	                  NULL, 0,
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	                  __start_unwind, __end_unwind - __start_unwind,
	                  __start_unwind_hdr, __end_unwind_hdr - __start_unwind_hdr);
}

static const u32 bad_cie, not_fde;
static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *);
static signed fde_pointer_type(const u32 *cie);

struct eh_frame_hdr_table_entry {
	unsigned long start, fde;
};

static int cmp_eh_frame_hdr_table_entries(const void *p1, const void *p2)
{
	const struct eh_frame_hdr_table_entry *e1 = p1;
	const struct eh_frame_hdr_table_entry *e2 = p2;

	return (e1->start > e2->start) - (e1->start < e2->start);
}

static void swap_eh_frame_hdr_table_entries(void *p1, void *p2, int size)
{
	struct eh_frame_hdr_table_entry *e1 = p1;
	struct eh_frame_hdr_table_entry *e2 = p2;
	unsigned long v;

	v = e1->start;
	e1->start = e2->start;
	e2->start = v;
	v = e1->fde;
	e1->fde = e2->fde;
	e2->fde = v;
}

static void __init setup_unwind_table(struct unwind_table *table,
					void *(*alloc)(unsigned long))
{
	const u8 *ptr;
	unsigned long tableSize = table->size, hdrSize;
	unsigned n;
	const u32 *fde;
	struct {
		u8 version;
		u8 eh_frame_ptr_enc;
		u8 fde_count_enc;
		u8 table_enc;
		unsigned long eh_frame_ptr;
		unsigned int fde_count;
		struct eh_frame_hdr_table_entry table[];
	} __attribute__((__packed__)) *header;

	if (table->header)
		return;

	if (table->hdrsz)
		printk(KERN_WARNING ".eh_frame_hdr for '%s' present but unusable\n",
		       table->name);

	if (tableSize & (sizeof(*fde) - 1))
		return;

	for (fde = table->address, n = 0;
	     tableSize > sizeof(*fde) && tableSize - sizeof(*fde) >= *fde;
	     tableSize -= sizeof(*fde) + *fde, fde += 1 + *fde / sizeof(*fde)) {
		const u32 *cie = cie_for_fde(fde, table);
		signed ptrType;

		if (cie == &not_fde)
			continue;
		if (cie == NULL
		    || cie == &bad_cie
		    || (ptrType = fde_pointer_type(cie)) < 0)
			return;
		ptr = (const u8 *)(fde + 2);
		if (!read_pointer(&ptr,
		                  (const u8 *)(fde + 1) + *fde,
		                  ptrType))
			return;
		++n;
	}

	if (tableSize || !n)
		return;

	hdrSize = 4 + sizeof(unsigned long) + sizeof(unsigned int)
	        + 2 * n * sizeof(unsigned long);
	header = alloc(hdrSize);
	if (!header)
		return;
	header->version          = 1;
	header->eh_frame_ptr_enc = DW_EH_PE_abs|DW_EH_PE_native;
	header->fde_count_enc    = DW_EH_PE_abs|DW_EH_PE_data4;
	header->table_enc        = DW_EH_PE_abs|DW_EH_PE_native;
	put_unaligned((unsigned long)table->address, &header->eh_frame_ptr);
	BUILD_BUG_ON(offsetof(typeof(*header), fde_count)
	             % __alignof(typeof(header->fde_count)));
	header->fde_count        = n;

	BUILD_BUG_ON(offsetof(typeof(*header), table)
	             % __alignof(typeof(*header->table)));
	for (fde = table->address, tableSize = table->size, n = 0;
	     tableSize;
	     tableSize -= sizeof(*fde) + *fde, fde += 1 + *fde / sizeof(*fde)) {
		const u32 *cie = fde + 1 - fde[1] / sizeof(*fde);

		if (!fde[1])
			continue; /* this is a CIE */
		ptr = (const u8 *)(fde + 2);
		header->table[n].start = read_pointer(&ptr,
		                                      (const u8 *)(fde + 1) + *fde,
		                                      fde_pointer_type(cie));
		header->table[n].fde = (unsigned long)fde;
		++n;
	}
	WARN_ON(n != header->fde_count);

	sort(header->table,
	     n,
	     sizeof(*header->table),
	     cmp_eh_frame_hdr_table_entries,
	     swap_eh_frame_hdr_table_entries);

	table->hdrsz = hdrSize;
	smp_wmb();
	table->header = (const void *)header;
}

static void *__init balloc(unsigned long sz)
{
	return __alloc_bootmem_nopanic(sz,
	                               sizeof(unsigned int),
	                               __pa(MAX_DMA_ADDRESS));
}

void __init unwind_setup(void)
{
	setup_unwind_table(&root_table, balloc);
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}

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#ifdef CONFIG_MODULES

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static struct unwind_table *last_table;

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/* Must be called with module_mutex held. */
void *unwind_add_table(struct module *module,
                       const void *table_start,
                       unsigned long table_size)
{
	struct unwind_table *table;

	if (table_size <= 0)
		return NULL;

	table = kmalloc(sizeof(*table), GFP_KERNEL);
	if (!table)
		return NULL;

	init_unwind_table(table, module->name,
	                  module->module_core, module->core_size,
	                  module->module_init, module->init_size,
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	                  table_start, table_size,
	                  NULL, 0);
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	if (last_table)
		last_table->link = table;
	else
		root_table.link = table;
	last_table = table;

	return table;
}

struct unlink_table_info
{
	struct unwind_table *table;
	int init_only;
};

static int unlink_table(void *arg)
{
	struct unlink_table_info *info = arg;
	struct unwind_table *table = info->table, *prev;

	for (prev = &root_table; prev->link && prev->link != table; prev = prev->link)
		;

	if (prev->link) {
		if (info->init_only) {
			table->init.pc = 0;
			table->init.range = 0;
			info->table = NULL;
		} else {
			prev->link = table->link;
			if (!prev->link)
				last_table = prev;
		}
	} else
		info->table = NULL;

	return 0;
}

/* Must be called with module_mutex held. */
void unwind_remove_table(void *handle, int init_only)
{
	struct unwind_table *table = handle;
	struct unlink_table_info info;

	if (!table || table == &root_table)
		return;

	if (init_only && table == last_table) {
		table->init.pc = 0;
		table->init.range = 0;
		return;
	}

	info.table = table;
	info.init_only = init_only;
	stop_machine_run(unlink_table, &info, NR_CPUS);

	if (info.table)
		kfree(table);
}

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#endif /* CONFIG_MODULES */

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static uleb128_t get_uleb128(const u8 **pcur, const u8 *end)
{
	const u8 *cur = *pcur;
	uleb128_t value;
	unsigned shift;

	for (shift = 0, value = 0; cur < end; shift += 7) {
		if (shift + 7 > 8 * sizeof(value)
		    && (*cur & 0x7fU) >= (1U << (8 * sizeof(value) - shift))) {
			cur = end + 1;
			break;
		}
		value |= (uleb128_t)(*cur & 0x7f) << shift;
		if (!(*cur++ & 0x80))
			break;
	}
	*pcur = cur;

	return value;
}

static sleb128_t get_sleb128(const u8 **pcur, const u8 *end)
{
	const u8 *cur = *pcur;
	sleb128_t value;
	unsigned shift;

	for (shift = 0, value = 0; cur < end; shift += 7) {
		if (shift + 7 > 8 * sizeof(value)
		    && (*cur & 0x7fU) >= (1U << (8 * sizeof(value) - shift))) {
			cur = end + 1;
			break;
		}
		value |= (sleb128_t)(*cur & 0x7f) << shift;
		if (!(*cur & 0x80)) {
			value |= -(*cur++ & 0x40) << shift;
			break;
		}
	}
	*pcur = cur;

	return value;
}

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static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *table)
{
	const u32 *cie;

	if (!*fde || (*fde & (sizeof(*fde) - 1)))
		return &bad_cie;
	if (!fde[1])
		return &not_fde; /* this is a CIE */
	if ((fde[1] & (sizeof(*fde) - 1))
	    || fde[1] > (unsigned long)(fde + 1) - (unsigned long)table->address)
		return NULL; /* this is not a valid FDE */
	cie = fde + 1 - fde[1] / sizeof(*fde);
	if (*cie <= sizeof(*cie) + 4
	    || *cie >= fde[1] - sizeof(*fde)
	    || (*cie & (sizeof(*cie) - 1))
	    || cie[1])
		return NULL; /* this is not a (valid) CIE */
	return cie;
}

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static unsigned long read_pointer(const u8 **pLoc,
                                  const void *end,
                                  signed ptrType)
{
	unsigned long value = 0;
	union {
		const u8 *p8;
		const u16 *p16u;
		const s16 *p16s;
		const u32 *p32u;
		const s32 *p32s;
		const unsigned long *pul;
	} ptr;

	if (ptrType < 0 || ptrType == DW_EH_PE_omit)
		return 0;
	ptr.p8 = *pLoc;
	switch(ptrType & DW_EH_PE_FORM) {
	case DW_EH_PE_data2:
		if (end < (const void *)(ptr.p16u + 1))
			return 0;
		if(ptrType & DW_EH_PE_signed)
			value = get_unaligned(ptr.p16s++);
		else
			value = get_unaligned(ptr.p16u++);
		break;
	case DW_EH_PE_data4:
#ifdef CONFIG_64BIT
		if (end < (const void *)(ptr.p32u + 1))
			return 0;
		if(ptrType & DW_EH_PE_signed)
			value = get_unaligned(ptr.p32s++);
		else
			value = get_unaligned(ptr.p32u++);
		break;
	case DW_EH_PE_data8:
		BUILD_BUG_ON(sizeof(u64) != sizeof(value));
#else
		BUILD_BUG_ON(sizeof(u32) != sizeof(value));
#endif
	case DW_EH_PE_native:
		if (end < (const void *)(ptr.pul + 1))
			return 0;
		value = get_unaligned(ptr.pul++);
		break;
	case DW_EH_PE_leb128:
		BUILD_BUG_ON(sizeof(uleb128_t) > sizeof(value));
		value = ptrType & DW_EH_PE_signed
		        ? get_sleb128(&ptr.p8, end)
		        : get_uleb128(&ptr.p8, end);
		if ((const void *)ptr.p8 > end)
			return 0;
		break;
	default:
		return 0;
	}
	switch(ptrType & DW_EH_PE_ADJUST) {
	case DW_EH_PE_abs:
		break;
	case DW_EH_PE_pcrel:
		value += (unsigned long)*pLoc;
		break;
	default:
		return 0;
	}
	if ((ptrType & DW_EH_PE_indirect)
	    && __get_user(value, (unsigned long *)value))
		return 0;
	*pLoc = ptr.p8;

	return value;
}

static signed fde_pointer_type(const u32 *cie)
{
	const u8 *ptr = (const u8 *)(cie + 2);
	unsigned version = *ptr;

	if (version != 1)
		return -1; /* unsupported */
	if (*++ptr) {
		const char *aug;
		const u8 *end = (const u8 *)(cie + 1) + *cie;
		uleb128_t len;

		/* check if augmentation size is first (and thus present) */
		if (*ptr != 'z')
			return -1;
		/* check if augmentation string is nul-terminated */
		if ((ptr = memchr(aug = (const void *)ptr, 0, end - ptr)) == NULL)
			return -1;
		++ptr; /* skip terminator */
		get_uleb128(&ptr, end); /* skip code alignment */
		get_sleb128(&ptr, end); /* skip data alignment */
		/* skip return address column */
		version <= 1 ? (void)++ptr : (void)get_uleb128(&ptr, end);
		len = get_uleb128(&ptr, end); /* augmentation length */
		if (ptr + len < ptr || ptr + len > end)
			return -1;
		end = ptr + len;
		while (*++aug) {
			if (ptr >= end)
				return -1;
			switch(*aug) {
			case 'L':
				++ptr;
				break;
			case 'P': {
					signed ptrType = *ptr++;

					if (!read_pointer(&ptr, end, ptrType) || ptr > end)
						return -1;
				}
				break;
			case 'R':
				return *ptr;
			default:
				return -1;
			}
		}
	}
	return DW_EH_PE_native|DW_EH_PE_abs;
}

static int advance_loc(unsigned long delta, struct unwind_state *state)
{
	state->loc += delta * state->codeAlign;

	return delta > 0;
}

static void set_rule(uleb128_t reg,
                     enum item_location where,
                     uleb128_t value,
                     struct unwind_state *state)
{
	if (reg < ARRAY_SIZE(state->regs)) {
		state->regs[reg].where = where;
		state->regs[reg].value = value;
	}
}

static int processCFI(const u8 *start,
                      const u8 *end,
                      unsigned long targetLoc,
                      signed ptrType,
                      struct unwind_state *state)
{
	union {
		const u8 *p8;
		const u16 *p16;
		const u32 *p32;
	} ptr;
	int result = 1;

	if (start != state->cieStart) {
		state->loc = state->org;
		result = processCFI(state->cieStart, state->cieEnd, 0, ptrType, state);
		if (targetLoc == 0 && state->label == NULL)
			return result;
	}
	for (ptr.p8 = start; result && ptr.p8 < end; ) {
		switch(*ptr.p8 >> 6) {
			uleb128_t value;

		case 0:
			switch(*ptr.p8++) {
			case DW_CFA_nop:
				break;
			case DW_CFA_set_loc:
				if ((state->loc = read_pointer(&ptr.p8, end, ptrType)) == 0)
					result = 0;
				break;
			case DW_CFA_advance_loc1:
				result = ptr.p8 < end && advance_loc(*ptr.p8++, state);
				break;
			case DW_CFA_advance_loc2:
				result = ptr.p8 <= end + 2
				         && advance_loc(*ptr.p16++, state);
				break;
			case DW_CFA_advance_loc4:
				result = ptr.p8 <= end + 4
				         && advance_loc(*ptr.p32++, state);
				break;
			case DW_CFA_offset_extended:
				value = get_uleb128(&ptr.p8, end);
				set_rule(value, Memory, get_uleb128(&ptr.p8, end), state);
				break;
			case DW_CFA_val_offset:
				value = get_uleb128(&ptr.p8, end);
				set_rule(value, Value, get_uleb128(&ptr.p8, end), state);
				break;
			case DW_CFA_offset_extended_sf:
				value = get_uleb128(&ptr.p8, end);
				set_rule(value, Memory, get_sleb128(&ptr.p8, end), state);
				break;
			case DW_CFA_val_offset_sf:
				value = get_uleb128(&ptr.p8, end);
				set_rule(value, Value, get_sleb128(&ptr.p8, end), state);
				break;
			case DW_CFA_restore_extended:
			case DW_CFA_undefined:
			case DW_CFA_same_value:
				set_rule(get_uleb128(&ptr.p8, end), Nowhere, 0, state);
				break;
			case DW_CFA_register:
				value = get_uleb128(&ptr.p8, end);
				set_rule(value,
				         Register,
				         get_uleb128(&ptr.p8, end), state);
				break;
			case DW_CFA_remember_state:
				if (ptr.p8 == state->label) {
					state->label = NULL;
					return 1;
				}
				if (state->stackDepth >= MAX_STACK_DEPTH)
					return 0;
				state->stack[state->stackDepth++] = ptr.p8;
				break;
			case DW_CFA_restore_state:
				if (state->stackDepth) {
					const uleb128_t loc = state->loc;
					const u8 *label = state->label;

					state->label = state->stack[state->stackDepth - 1];
					memcpy(&state->cfa, &badCFA, sizeof(state->cfa));
					memset(state->regs, 0, sizeof(state->regs));
					state->stackDepth = 0;
					result = processCFI(start, end, 0, ptrType, state);
					state->loc = loc;
					state->label = label;
				} else
					return 0;
				break;
			case DW_CFA_def_cfa:
				state->cfa.reg = get_uleb128(&ptr.p8, end);
				/*nobreak*/
			case DW_CFA_def_cfa_offset:
				state->cfa.offs = get_uleb128(&ptr.p8, end);
				break;
			case DW_CFA_def_cfa_sf:
				state->cfa.reg = get_uleb128(&ptr.p8, end);
				/*nobreak*/
			case DW_CFA_def_cfa_offset_sf:
				state->cfa.offs = get_sleb128(&ptr.p8, end)
				                  * state->dataAlign;
				break;
			case DW_CFA_def_cfa_register:
				state->cfa.reg = get_uleb128(&ptr.p8, end);
				break;
			/*todo case DW_CFA_def_cfa_expression: */
			/*todo case DW_CFA_expression: */
			/*todo case DW_CFA_val_expression: */
			case DW_CFA_GNU_args_size:
				get_uleb128(&ptr.p8, end);
				break;
			case DW_CFA_GNU_negative_offset_extended:
				value = get_uleb128(&ptr.p8, end);
				set_rule(value,
				         Memory,
				         (uleb128_t)0 - get_uleb128(&ptr.p8, end), state);
				break;
			case DW_CFA_GNU_window_save:
			default:
				result = 0;
				break;
			}
			break;
		case 1:
			result = advance_loc(*ptr.p8++ & 0x3f, state);
			break;
		case 2:
			value = *ptr.p8++ & 0x3f;
			set_rule(value, Memory, get_uleb128(&ptr.p8, end), state);
			break;
		case 3:
			set_rule(*ptr.p8++ & 0x3f, Nowhere, 0, state);
			break;
		}
		if (ptr.p8 > end)
			result = 0;
		if (result && targetLoc != 0 && targetLoc < state->loc)
			return 1;
	}

	return result
	   && ptr.p8 == end
	   && (targetLoc == 0
	    || (/*todo While in theory this should apply, gcc in practice omits
	          everything past the function prolog, and hence the location
	          never reaches the end of the function.
	        targetLoc < state->loc &&*/ state->label == NULL));
}

/* Unwind to previous to frame.  Returns 0 if successful, negative
 * number in case of an error. */
int unwind(struct unwind_frame_info *frame)
{
#define FRAME_REG(r, t) (((t *)frame)[reg_info[r].offs])
	const u32 *fde = NULL, *cie = NULL;
	const u8 *ptr = NULL, *end = NULL;
789
	unsigned long pc = UNW_PC(frame) - frame->call_frame;
790 791 792 793
	unsigned long startLoc = 0, endLoc = 0, cfa;
	unsigned i;
	signed ptrType = -1;
	uleb128_t retAddrReg = 0;
794
	const struct unwind_table *table;
795 796 797 798
	struct unwind_state state;

	if (UNW_PC(frame) == 0)
		return -EINVAL;
799
	if ((table = find_table(pc)) != NULL
800
	    && !(table->size & (sizeof(*fde) - 1))) {
801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841
		const u8 *hdr = table->header;
		unsigned long tableSize;

		smp_rmb();
		if (hdr && hdr[0] == 1) {
			switch(hdr[3] & DW_EH_PE_FORM) {
			case DW_EH_PE_native: tableSize = sizeof(unsigned long); break;
			case DW_EH_PE_data2: tableSize = 2; break;
			case DW_EH_PE_data4: tableSize = 4; break;
			case DW_EH_PE_data8: tableSize = 8; break;
			default: tableSize = 0; break;
			}
			ptr = hdr + 4;
			end = hdr + table->hdrsz;
			if (tableSize
			    && read_pointer(&ptr, end, hdr[1])
			       == (unsigned long)table->address
			    && (i = read_pointer(&ptr, end, hdr[2])) > 0
			    && i == (end - ptr) / (2 * tableSize)
			    && !((end - ptr) % (2 * tableSize))) {
				do {
					const u8 *cur = ptr + (i / 2) * (2 * tableSize);

					startLoc = read_pointer(&cur,
					                        cur + tableSize,
					                        hdr[3]);
					if (pc < startLoc)
						i /= 2;
					else {
						ptr = cur - tableSize;
						i = (i + 1) / 2;
					}
				} while (startLoc && i > 1);
				if (i == 1
				    && (startLoc = read_pointer(&ptr,
				                                ptr + tableSize,
				                                hdr[3])) != 0
				    && pc >= startLoc)
					fde = (void *)read_pointer(&ptr,
					                           ptr + tableSize,
					                           hdr[3]);
842
			}
843 844 845 846
		}

		if (fde != NULL) {
			cie = cie_for_fde(fde, table);
847
			ptr = (const u8 *)(fde + 2);
848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895
			if(cie != NULL
			   && cie != &bad_cie
			   && cie != &not_fde
			   && (ptrType = fde_pointer_type(cie)) >= 0
			   && read_pointer(&ptr,
			                   (const u8 *)(fde + 1) + *fde,
			                   ptrType) == startLoc) {
				if (!(ptrType & DW_EH_PE_indirect))
					ptrType &= DW_EH_PE_FORM|DW_EH_PE_signed;
				endLoc = startLoc
				         + read_pointer(&ptr,
				                        (const u8 *)(fde + 1) + *fde,
				                        ptrType);
				if(pc >= endLoc)
					fde = NULL;
			} else
				fde = NULL;
		}
		if (fde == NULL) {
			for (fde = table->address, tableSize = table->size;
			     cie = NULL, tableSize > sizeof(*fde)
			     && tableSize - sizeof(*fde) >= *fde;
			     tableSize -= sizeof(*fde) + *fde,
			     fde += 1 + *fde / sizeof(*fde)) {
				cie = cie_for_fde(fde, table);
				if (cie == &bad_cie) {
					cie = NULL;
					break;
				}
				if (cie == NULL
				    || cie == &not_fde
				    || (ptrType = fde_pointer_type(cie)) < 0)
					continue;
				ptr = (const u8 *)(fde + 2);
				startLoc = read_pointer(&ptr,
				                        (const u8 *)(fde + 1) + *fde,
				                        ptrType);
				if (!startLoc)
					continue;
				if (!(ptrType & DW_EH_PE_indirect))
					ptrType &= DW_EH_PE_FORM|DW_EH_PE_signed;
				endLoc = startLoc
				         + read_pointer(&ptr,
				                        (const u8 *)(fde + 1) + *fde,
				                        ptrType);
				if (pc >= startLoc && pc < endLoc)
					break;
			}
896 897 898 899 900 901 902
		}
	}
	if (cie != NULL) {
		memset(&state, 0, sizeof(state));
		state.cieEnd = ptr; /* keep here temporarily */
		ptr = (const u8 *)(cie + 2);
		end = (const u8 *)(cie + 1) + *cie;
903
		frame->call_frame = 1;
904 905 906 907 908
		if ((state.version = *ptr) != 1)
			cie = NULL; /* unsupported version */
		else if (*++ptr) {
			/* check if augmentation size is first (and thus present) */
			if (*ptr == 'z') {
909 910 911 912 913 914 915 916 917 918 919 920
				while (++ptr < end && *ptr) {
					switch(*ptr) {
					/* check for ignorable (or already handled)
					 * nul-terminated augmentation string */
					case 'L':
					case 'P':
					case 'R':
						continue;
					case 'S':
						frame->call_frame = 0;
						continue;
					default:
921
						break;
922 923 924
					}
					break;
				}
925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940
			}
			if (ptr >= end || *ptr)
				cie = NULL;
		}
		++ptr;
	}
	if (cie != NULL) {
		/* get code aligment factor */
		state.codeAlign = get_uleb128(&ptr, end);
		/* get data aligment factor */
		state.dataAlign = get_sleb128(&ptr, end);
		if (state.codeAlign == 0 || state.dataAlign == 0 || ptr >= end)
			cie = NULL;
		else {
			retAddrReg = state.version <= 1 ? *ptr++ : get_uleb128(&ptr, end);
			/* skip augmentation */
941 942 943 944 945
			if (((const char *)(cie + 2))[1] == 'z') {
				uleb128_t augSize = get_uleb128(&ptr, end);

				ptr += augSize;
			}
946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013
			if (ptr > end
			   || retAddrReg >= ARRAY_SIZE(reg_info)
			   || REG_INVALID(retAddrReg)
			   || reg_info[retAddrReg].width != sizeof(unsigned long))
				cie = NULL;
		}
	}
	if (cie != NULL) {
		state.cieStart = ptr;
		ptr = state.cieEnd;
		state.cieEnd = end;
		end = (const u8 *)(fde + 1) + *fde;
		/* skip augmentation */
		if (((const char *)(cie + 2))[1] == 'z') {
			uleb128_t augSize = get_uleb128(&ptr, end);

			if ((ptr += augSize) > end)
				fde = NULL;
		}
	}
	if (cie == NULL || fde == NULL) {
#ifdef CONFIG_FRAME_POINTER
		unsigned long top, bottom;

		top = STACK_TOP(frame->task);
		bottom = STACK_BOTTOM(frame->task);
# if FRAME_RETADDR_OFFSET < 0
		if (UNW_SP(frame) < top
		    && UNW_FP(frame) <= UNW_SP(frame)
		    && bottom < UNW_FP(frame)
# else
		if (UNW_SP(frame) > top
		    && UNW_FP(frame) >= UNW_SP(frame)
		    && bottom > UNW_FP(frame)
# endif
		   && !((UNW_SP(frame) | UNW_FP(frame))
		        & (sizeof(unsigned long) - 1))) {
			unsigned long link;

			if (!__get_user(link,
			                (unsigned long *)(UNW_FP(frame)
			                                  + FRAME_LINK_OFFSET))
# if FRAME_RETADDR_OFFSET < 0
			   && link > bottom && link < UNW_FP(frame)
# else
			   && link > UNW_FP(frame) && link < bottom
# endif
			   && !(link & (sizeof(link) - 1))
			   && !__get_user(UNW_PC(frame),
			                  (unsigned long *)(UNW_FP(frame)
			                                    + FRAME_RETADDR_OFFSET))) {
				UNW_SP(frame) = UNW_FP(frame) + FRAME_RETADDR_OFFSET
# if FRAME_RETADDR_OFFSET < 0
					-
# else
					+
# endif
					  sizeof(UNW_PC(frame));
				UNW_FP(frame) = link;
				return 0;
			}
		}
#endif
		return -ENXIO;
	}
	state.org = startLoc;
	memcpy(&state.cfa, &badCFA, sizeof(state.cfa));
	/* process instructions */
1014
	if (!processCFI(ptr, end, pc, ptrType, &state)
1015 1016 1017 1018 1019 1020 1021
	   || state.loc > endLoc
	   || state.regs[retAddrReg].where == Nowhere
	   || state.cfa.reg >= ARRAY_SIZE(reg_info)
	   || reg_info[state.cfa.reg].width != sizeof(unsigned long)
	   || state.cfa.offs % sizeof(unsigned long))
		return -EIO;
	/* update frame */
1022 1023 1024 1025 1026
#ifndef CONFIG_AS_CFI_SIGNAL_FRAME
	if(frame->call_frame
	   && !UNW_DEFAULT_RA(state.regs[retAddrReg], state.dataAlign))
		frame->call_frame = 0;
#endif
1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129
	cfa = FRAME_REG(state.cfa.reg, unsigned long) + state.cfa.offs;
	startLoc = min((unsigned long)UNW_SP(frame), cfa);
	endLoc = max((unsigned long)UNW_SP(frame), cfa);
	if (STACK_LIMIT(startLoc) != STACK_LIMIT(endLoc)) {
		startLoc = min(STACK_LIMIT(cfa), cfa);
		endLoc = max(STACK_LIMIT(cfa), cfa);
	}
#ifndef CONFIG_64BIT
# define CASES CASE(8); CASE(16); CASE(32)
#else
# define CASES CASE(8); CASE(16); CASE(32); CASE(64)
#endif
	for (i = 0; i < ARRAY_SIZE(state.regs); ++i) {
		if (REG_INVALID(i)) {
			if (state.regs[i].where == Nowhere)
				continue;
			return -EIO;
		}
		switch(state.regs[i].where) {
		default:
			break;
		case Register:
			if (state.regs[i].value >= ARRAY_SIZE(reg_info)
			   || REG_INVALID(state.regs[i].value)
			   || reg_info[i].width > reg_info[state.regs[i].value].width)
				return -EIO;
			switch(reg_info[state.regs[i].value].width) {
#define CASE(n) \
			case sizeof(u##n): \
				state.regs[i].value = FRAME_REG(state.regs[i].value, \
				                                const u##n); \
				break
			CASES;
#undef CASE
			default:
				return -EIO;
			}
			break;
		}
	}
	for (i = 0; i < ARRAY_SIZE(state.regs); ++i) {
		if (REG_INVALID(i))
			continue;
		switch(state.regs[i].where) {
		case Nowhere:
			if (reg_info[i].width != sizeof(UNW_SP(frame))
			   || &FRAME_REG(i, __typeof__(UNW_SP(frame)))
			      != &UNW_SP(frame))
				continue;
			UNW_SP(frame) = cfa;
			break;
		case Register:
			switch(reg_info[i].width) {
#define CASE(n) case sizeof(u##n): \
				FRAME_REG(i, u##n) = state.regs[i].value; \
				break
			CASES;
#undef CASE
			default:
				return -EIO;
			}
			break;
		case Value:
			if (reg_info[i].width != sizeof(unsigned long))
				return -EIO;
			FRAME_REG(i, unsigned long) = cfa + state.regs[i].value
			                                    * state.dataAlign;
			break;
		case Memory: {
				unsigned long addr = cfa + state.regs[i].value
				                           * state.dataAlign;

				if ((state.regs[i].value * state.dataAlign)
				    % sizeof(unsigned long)
				    || addr < startLoc
				    || addr + sizeof(unsigned long) < addr
				    || addr + sizeof(unsigned long) > endLoc)
					return -EIO;
				switch(reg_info[i].width) {
#define CASE(n)     case sizeof(u##n): \
					__get_user(FRAME_REG(i, u##n), (u##n *)addr); \
					break
				CASES;
#undef CASE
				default:
					return -EIO;
				}
			}
			break;
		}
	}

	return 0;
#undef CASES
#undef FRAME_REG
}
EXPORT_SYMBOL(unwind);

int unwind_init_frame_info(struct unwind_frame_info *info,
                           struct task_struct *tsk,
                           /*const*/ struct pt_regs *regs)
{
	info->task = tsk;
1130
	info->call_frame = 0;
1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143
	arch_unw_init_frame_info(info, regs);

	return 0;
}
EXPORT_SYMBOL(unwind_init_frame_info);

/*
 * Prepare to unwind a blocked task.
 */
int unwind_init_blocked(struct unwind_frame_info *info,
                        struct task_struct *tsk)
{
	info->task = tsk;
1144
	info->call_frame = 0;
1145 1146 1147 1148 1149 1150 1151 1152 1153 1154
	arch_unw_init_blocked(info);

	return 0;
}
EXPORT_SYMBOL(unwind_init_blocked);

/*
 * Prepare to unwind the currently running thread.
 */
int unwind_init_running(struct unwind_frame_info *info,
1155 1156
                        asmlinkage int (*callback)(struct unwind_frame_info *,
                                                   void *arg),
1157 1158 1159
                        void *arg)
{
	info->task = current;
1160
	info->call_frame = 0;
1161

1162
	return arch_unwind_init_running(info, callback, arg);
1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182
}
EXPORT_SYMBOL(unwind_init_running);

/*
 * Unwind until the return pointer is in user-land (or until an error
 * occurs).  Returns 0 if successful, negative number in case of
 * error.
 */
int unwind_to_user(struct unwind_frame_info *info)
{
	while (!arch_unw_user_mode(info)) {
		int err = unwind(info);

		if (err < 0)
			return err;
	}

	return 0;
}
EXPORT_SYMBOL(unwind_to_user);