// SPDX-License-Identifier: GPL-2.0-only/* * Copyright (C) 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) * Copyright (C) 2002-2006 Novell, Inc. *	Jan Beulich <jbeulich@novell.com> * * 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/sched.h>#include <linux/module.h>#include <linux/memblock.h>#include <linux/sort.h>#include <linux/slab.h>#include <linux/stop_machine.h>#include <linux/uaccess.h>#include <linux/ptrace.h>#include <asm/sections.h>#include <linux/unaligned.h>#include <asm/unwind.h> extern char __start_unwind[], __end_unwind[];/* extern const u8 __start_unwind_hdr[], __end_unwind_hdr[];*/ /* #define UNWIND_DEBUG */ #ifdef UNWIND_DEBUGint dbg_unw;#define unw_debug(fmt, ...)			\do {						\	if (dbg_unw)				\		pr_info(fmt, ##__VA_ARGS__);	\} while (0);#else#define unw_debug(fmt, ...)#endif #define MAX_STACK_DEPTH 8 #define EXTRA_INFO(f) { \		BUILD_BUG_ON_ZERO(offsetof(struct unwind_frame_info, f) \				% sizeof_field(struct unwind_frame_info, f)) \				+ offsetof(struct unwind_frame_info, f) \				/ sizeof_field(struct unwind_frame_info, f), \				sizeof_field(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 #define CIE_ID	0 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;	const unsigned char *header;	unsigned long hdrsz;	struct unwind_table *link;	const char *name;} root_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 unsigned long read_pointer(const u8 **pLoc,				  const void *end, signed ptrType);static void init_unwind_hdr(struct unwind_table *table,			    void *(*alloc) (unsigned long)); /* * wrappers for header alloc (vs. calling one vs. other at call site) * to elide section mismatches warnings */static void *__init unw_hdr_alloc_early(unsigned long sz){	return memblock_alloc_from(sz, sizeof(unsigned int), MAX_DMA_ADDRESS);} 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,			      const u8 *header_start, unsigned long header_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;	/* To avoid the pointer addition with NULL pointer.*/	if (header_start != NULL) {		const u8 *ptr = header_start + 4;		const u8 *end = header_start + header_size;		/* 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;	table->link = NULL;	table->name = name;} void __init arc_unwind_init(void){	init_unwind_table(&root_table, "kernel", _text, _end - _text, NULL, 0,			  __start_unwind, __end_unwind - __start_unwind,			  NULL, 0);	  /*__start_unwind_hdr, __end_unwind_hdr - __start_unwind_hdr);*/ 	init_unwind_hdr(&root_table, unw_hdr_alloc_early);} static const u32 bad_cie, not_fde;static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *);static const u32 *__cie_for_fde(const u32 *fde);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 init_unwind_hdr(struct unwind_table *table,			    void *(*alloc) (unsigned long)){	const u8 *ptr;	unsigned long tableSize = table->size, hdrSize;	unsigned int 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)		pr_warn(".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)			goto ret_err;		ptrType = fde_pointer_type(cie);		if (ptrType < 0)			goto ret_err; 		ptr = (const u8 *)(fde + 2);		if (!read_pointer(&ptr, (const u8 *)(fde + 1) + *fde,								ptrType)) {			/* FIXME_Rajesh We have 4 instances of null addresses			 * instead of the initial loc addr			 * return;			 */			WARN(1, "unwinder: FDE->initial_location NULL %p\n",				(const u8 *)(fde + 1) + *fde);		}		++n;	} 	if (tableSize || !n)		goto ret_err; 	hdrSize = 4 + sizeof(unsigned long) + sizeof(unsigned int)	    + 2 * n * sizeof(unsigned long); 	header = alloc(hdrSize);	if (!header)		goto ret_err; 	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 = __cie_for_fde(fde); 		if (fde[1] == CIE_ID)			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, NULL); 	table->hdrsz = hdrSize;	smp_wmb();	table->header = (const void *)header;	return; ret_err:	panic("Attention !!! Dwarf FDE parsing errors\n");} #ifdef CONFIG_MODULESstatic void *unw_hdr_alloc(unsigned long sz){	return kmalloc(sz, GFP_KERNEL);} static struct unwind_table *last_table; /* 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;	struct module_memory *core_text;	struct module_memory *init_text; 	if (table_size <= 0)		return NULL; 	table = kmalloc_obj(*table);	if (!table)		return NULL; 	core_text = &module->mem[MOD_TEXT];	init_text = &module->mem[MOD_INIT_TEXT]; 	init_unwind_table(table, module->name, core_text->base, core_text->size,			  init_text->base, init_text->size, table_start, table_size, NULL, 0); 	init_unwind_hdr(table, unw_hdr_alloc); #ifdef UNWIND_DEBUG	unw_debug("Table added for [%s] %lx %lx\n",		module->name, table->core.pc, table->core.range);#endif	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; 	unlink_table(&info); /* XXX: SMP */	kfree(table->header);	kfree(table);} #endif /* CONFIG_MODULES */ static uleb128_t get_uleb128(const u8 **pcur, const u8 *end){	const u8 *cur = *pcur;	uleb128_t value;	unsigned int 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 int 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 const u32 *__cie_for_fde(const u32 *fde){	const u32 *cie; 	cie = fde + 1 - fde[1] / sizeof(*fde); 	return cie;}

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