/* * 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>#include <linux/delay.h>#include <linux/stop_machine.h>#include <asm/sections.h>#include <asm/uaccess.h>#include <asm/unaligned.h> extern char __start_unwind[], __end_unwind[]; #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;	struct unwind_table *link;	const char *name;} root_table, *last_table; 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;} 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,                              unsigned long table_size){	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;	table->link = NULL;	table->name = name;} void __init unwind_init(void){	init_unwind_table(&root_table, "kernel",	                  _text, _end - _text,	                  NULL, 0,	                  __start_unwind, __end_unwind - __start_unwind);} #ifdef CONFIG_MODULES /* 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,	                  table_start, table_size); 	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);} #endif /* CONFIG_MODULES */ 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;} 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:

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