[mirror_ubuntu-bionic-kernel.git] / arch / x86 / kernel / unwind_orc.c

#include <linux/module.h>
#include <linux/sort.h>
#include <asm/ptrace.h>
#include <asm/stacktrace.h>
#include <asm/unwind.h>
#include <asm/orc_types.h>
#include <asm/orc_lookup.h>
#include <asm/sections.h>

#define orc_warn(fmt, ...) \
	printk_deferred_once(KERN_WARNING pr_fmt("WARNING: " fmt), ##__VA_ARGS__)

extern int __start_orc_unwind_ip[];
extern int __stop_orc_unwind_ip[];
extern struct orc_entry __start_orc_unwind[];
extern struct orc_entry __stop_orc_unwind[];

static DEFINE_MUTEX(sort_mutex);
int *cur_orc_ip_table = __start_orc_unwind_ip;
struct orc_entry *cur_orc_table = __start_orc_unwind;

unsigned int lookup_num_blocks;
bool orc_init;

static inline unsigned long orc_ip(const int *ip)
{
	return (unsigned long)ip + *ip;
}

static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
				    unsigned int num_entries, unsigned long ip)
{
	int *first = ip_table;
	int *last = ip_table + num_entries - 1;
	int *mid = first, *found = first;

	if (!num_entries)
		return NULL;

	/*
	 * Do a binary range search to find the rightmost duplicate of a given
	 * starting address.  Some entries are section terminators which are
	 * "weak" entries for ensuring there are no gaps.  They should be
	 * ignored when they conflict with a real entry.
	 */
	while (first <= last) {
		mid = first + ((last - first) / 2);

		if (orc_ip(mid) <= ip) {
			found = mid;
			first = mid + 1;
		} else
			last = mid - 1;
	}

	return u_table + (found - ip_table);
}

#ifdef CONFIG_MODULES
static struct orc_entry *orc_module_find(unsigned long ip)
{
	struct module *mod;

	mod = __module_address(ip);
	if (!mod || !mod->arch.orc_unwind || !mod->arch.orc_unwind_ip)
		return NULL;
	return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind,
			  mod->arch.num_orcs, ip);
}
#else
static struct orc_entry *orc_module_find(unsigned long ip)
{
	return NULL;
}
#endif

static struct orc_entry *orc_find(unsigned long ip)
{
	if (!orc_init)
		return NULL;

	/* For non-init vmlinux addresses, use the fast lookup table: */
	if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) {
		unsigned int idx, start, stop;

		idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE;

		if (unlikely((idx >= lookup_num_blocks-1))) {
			orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%pB\n",
				 idx, lookup_num_blocks, (void *)ip);
			return NULL;
		}

		start = orc_lookup[idx];
		stop = orc_lookup[idx + 1] + 1;

		if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) ||
			     (__start_orc_unwind + stop > __stop_orc_unwind))) {
			orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%pB\n",
				 idx, lookup_num_blocks, start, stop, (void *)ip);
			return NULL;
		}

		return __orc_find(__start_orc_unwind_ip + start,
				  __start_orc_unwind + start, stop - start, ip);
	}

	/* vmlinux .init slow lookup: */
	if (ip >= (unsigned long)_sinittext && ip < (unsigned long)_einittext)
		return __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
				  __stop_orc_unwind_ip - __start_orc_unwind_ip, ip);

	/* Module lookup: */
	return orc_module_find(ip);
}

static void orc_sort_swap(void *_a, void *_b, int size)
{
	struct orc_entry *orc_a, *orc_b;
	struct orc_entry orc_tmp;
	int *a = _a, *b = _b, tmp;
	int delta = _b - _a;

	/* Swap the .orc_unwind_ip entries: */
	tmp = *a;
	*a = *b + delta;
	*b = tmp - delta;

	/* Swap the corresponding .orc_unwind entries: */
	orc_a = cur_orc_table + (a - cur_orc_ip_table);
	orc_b = cur_orc_table + (b - cur_orc_ip_table);
	orc_tmp = *orc_a;
	*orc_a = *orc_b;
	*orc_b = orc_tmp;
}

static int orc_sort_cmp(const void *_a, const void *_b)
{
	struct orc_entry *orc_a;
	const int *a = _a, *b = _b;
	unsigned long a_val = orc_ip(a);
	unsigned long b_val = orc_ip(b);

	if (a_val > b_val)
		return 1;
	if (a_val < b_val)
		return -1;

	/*
	 * The "weak" section terminator entries need to always be on the left
	 * to ensure the lookup code skips them in favor of real entries.
	 * These terminator entries exist to handle any gaps created by
	 * whitelisted .o files which didn't get objtool generation.
	 */
	orc_a = cur_orc_table + (a - cur_orc_ip_table);
	return orc_a->sp_reg == ORC_REG_UNDEFINED ? -1 : 1;
}

#ifdef CONFIG_MODULES
void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
			void *_orc, size_t orc_size)
{
	int *orc_ip = _orc_ip;
	struct orc_entry *orc = _orc;
	unsigned int num_entries = orc_ip_size / sizeof(int);

	WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 ||
		     orc_size % sizeof(*orc) != 0 ||
		     num_entries != orc_size / sizeof(*orc));

	/*
	 * The 'cur_orc_*' globals allow the orc_sort_swap() callback to
	 * associate an .orc_unwind_ip table entry with its corresponding
	 * .orc_unwind entry so they can both be swapped.
	 */
	mutex_lock(&sort_mutex);
	cur_orc_ip_table = orc_ip;
	cur_orc_table = orc;
	sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap);
	mutex_unlock(&sort_mutex);

	mod->arch.orc_unwind_ip = orc_ip;
	mod->arch.orc_unwind = orc;
	mod->arch.num_orcs = num_entries;
}
#endif

void __init unwind_init(void)
{
	size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip;
	size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind;
	size_t num_entries = orc_ip_size / sizeof(int);
	struct orc_entry *orc;
	int i;

	if (!num_entries || orc_ip_size % sizeof(int) != 0 ||
	    orc_size % sizeof(struct orc_entry) != 0 ||
	    num_entries != orc_size / sizeof(struct orc_entry)) {
		orc_warn("WARNING: Bad or missing .orc_unwind table.  Disabling unwinder.\n");
		return;
	}

	/* Sort the .orc_unwind and .orc_unwind_ip tables: */
	sort(__start_orc_unwind_ip, num_entries, sizeof(int), orc_sort_cmp,
	     orc_sort_swap);

	/* Initialize the fast lookup table: */
	lookup_num_blocks = orc_lookup_end - orc_lookup;
	for (i = 0; i < lookup_num_blocks-1; i++) {
		orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
				 num_entries,
				 LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i));
		if (!orc) {
			orc_warn("WARNING: Corrupt .orc_unwind table.  Disabling unwinder.\n");
			return;
		}

		orc_lookup[i] = orc - __start_orc_unwind;
	}

	/* Initialize the ending block: */
	orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries,
			 LOOKUP_STOP_IP);
	if (!orc) {
		orc_warn("WARNING: Corrupt .orc_unwind table.  Disabling unwinder.\n");
		return;
	}
	orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind;

	orc_init = true;
}

unsigned long unwind_get_return_address(struct unwind_state *state)
{
	if (unwind_done(state))
		return 0;

	return __kernel_text_address(state->ip) ? state->ip : 0;
}
EXPORT_SYMBOL_GPL(unwind_get_return_address);

unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
{
	if (unwind_done(state))
		return NULL;

	if (state->regs)
		return &state->regs->ip;

	if (state->sp)
		return (unsigned long *)state->sp - 1;

	return NULL;
}

static bool stack_access_ok(struct unwind_state *state, unsigned long _addr,
			    size_t len)
{
	struct stack_info *info = &state->stack_info;
	void *addr = (void *)_addr;

	if (!on_stack(info, addr, len) &&
	    (get_stack_info(addr, state->task, info, &state->stack_mask)))
		return false;

	return true;
}

static bool deref_stack_reg(struct unwind_state *state, unsigned long addr,
			    unsigned long *val)
{
	if (!stack_access_ok(state, addr, sizeof(long)))
		return false;

	*val = READ_ONCE_NOCHECK(*(unsigned long *)addr);
	return true;
}

static bool deref_stack_regs(struct unwind_state *state, unsigned long addr,
			     unsigned long *ip, unsigned long *sp)
{
	struct pt_regs *regs = (struct pt_regs *)addr;

	/* x86-32 support will be more complicated due to the &regs->sp hack */
	BUILD_BUG_ON(IS_ENABLED(CONFIG_X86_32));

	if (!stack_access_ok(state, addr, sizeof(struct pt_regs)))
		return false;

	*ip = regs->ip;
	*sp = regs->sp;
	return true;
}

static bool deref_stack_iret_regs(struct unwind_state *state, unsigned long addr,
				  unsigned long *ip, unsigned long *sp)
{
	struct pt_regs *regs = (void *)addr - IRET_FRAME_OFFSET;

	if (!stack_access_ok(state, addr, IRET_FRAME_SIZE))
		return false;

	*ip = regs->ip;
	*sp = regs->sp;
	return true;
}

bool unwind_next_frame(struct unwind_state *state)
{
	unsigned long ip_p, sp, orig_ip, prev_sp = state->sp;
	enum stack_type prev_type = state->stack_info.type;
	struct orc_entry *orc;
	bool indirect = false;

	if (unwind_done(state))
		return false;

	/* Don't let modules unload while we're reading their ORC data. */
	preempt_disable();

	/* Have we reached the end? */
	if (state->regs && user_mode(state->regs))
		goto done;

	/*
	 * Find the orc_entry associated with the text address.
	 *
	 * Decrement call return addresses by one so they work for sibling
	 * calls and calls to noreturn functions.
	 */
	orc = orc_find(state->signal ? state->ip : state->ip - 1);
	if (!orc || orc->sp_reg == ORC_REG_UNDEFINED)
		goto done;
	orig_ip = state->ip;

	/* Find the previous frame's stack: */
	switch (orc->sp_reg) {
	case ORC_REG_SP:
		sp = state->sp + orc->sp_offset;
		break;

	case ORC_REG_BP:
		sp = state->bp + orc->sp_offset;
		break;

	case ORC_REG_SP_INDIRECT:
		sp = state->sp + orc->sp_offset;
		indirect = true;
		break;

	case ORC_REG_BP_INDIRECT:
		sp = state->bp + orc->sp_offset;
		indirect = true;
		break;

	case ORC_REG_R10:
		if (!state->regs || !state->full_regs) {
			orc_warn("missing regs for base reg R10 at ip %pB\n",
				 (void *)state->ip);
			goto done;
		}
		sp = state->regs->r10;
		break;

	case ORC_REG_R13:
		if (!state->regs || !state->full_regs) {
			orc_warn("missing regs for base reg R13 at ip %pB\n",
				 (void *)state->ip);
			goto done;
		}
		sp = state->regs->r13;
		break;

	case ORC_REG_DI:
		if (!state->regs || !state->full_regs) {
			orc_warn("missing regs for base reg DI at ip %pB\n",
				 (void *)state->ip);
			goto done;
		}
		sp = state->regs->di;
		break;

	case ORC_REG_DX:
		if (!state->regs || !state->full_regs) {
			orc_warn("missing regs for base reg DX at ip %pB\n",
				 (void *)state->ip);
			goto done;
		}
		sp = state->regs->dx;
		break;

	default:
		orc_warn("unknown SP base reg %d for ip %pB\n",
			 orc->sp_reg, (void *)state->ip);
		goto done;
	}

	if (indirect) {
		if (!deref_stack_reg(state, sp, &sp))
			goto done;
	}

	/* Find IP, SP and possibly regs: */
	switch (orc->type) {
	case ORC_TYPE_CALL:
		ip_p = sp - sizeof(long);

		if (!deref_stack_reg(state, ip_p, &state->ip))
			goto done;

		state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
						  state->ip, (void *)ip_p);

		state->sp = sp;
		state->regs = NULL;
		state->signal = false;
		break;

	case ORC_TYPE_REGS:
		if (!deref_stack_regs(state, sp, &state->ip, &state->sp)) {
			orc_warn("can't dereference registers at %p for ip %pB\n",
				 (void *)sp, (void *)orig_ip);
			goto done;
		}

		state->regs = (struct pt_regs *)sp;
		state->full_regs = true;
		state->signal = true;
		break;

	case ORC_TYPE_REGS_IRET:
		if (!deref_stack_iret_regs(state, sp, &state->ip, &state->sp)) {
			orc_warn("can't dereference iret registers at %p for ip %pB\n",
				 (void *)sp, (void *)orig_ip);
			goto done;
		}

		state->regs = (void *)sp - IRET_FRAME_OFFSET;
		state->full_regs = false;
		state->signal = true;
		break;

	default:
		orc_warn("unknown .orc_unwind entry type %d for ip %pB\n",
			 orc->type, (void *)orig_ip);
		break;
	}

	/* Find BP: */
	switch (orc->bp_reg) {
	case ORC_REG_UNDEFINED:
		if (state->regs && state->full_regs)
			state->bp = state->regs->bp;
		break;

	case ORC_REG_PREV_SP:
		if (!deref_stack_reg(state, sp + orc->bp_offset, &state->bp))
			goto done;
		break;

	case ORC_REG_BP:
		if (!deref_stack_reg(state, state->bp + orc->bp_offset, &state->bp))
			goto done;
		break;

	default:
		orc_warn("unknown BP base reg %d for ip %pB\n",
			 orc->bp_reg, (void *)orig_ip);
		goto done;
	}

	/* Prevent a recursive loop due to bad ORC data: */
	if (state->stack_info.type == prev_type &&
	    on_stack(&state->stack_info, (void *)state->sp, sizeof(long)) &&
	    state->sp <= prev_sp) {
		orc_warn("stack going in the wrong direction? ip=%pB\n",
			 (void *)orig_ip);
		goto done;
	}

	preempt_enable();
	return true;

done:
	preempt_enable();
	state->stack_info.type = STACK_TYPE_UNKNOWN;
	return false;
}
EXPORT_SYMBOL_GPL(unwind_next_frame);

void __unwind_start(struct unwind_state *state, struct task_struct *task,
		    struct pt_regs *regs, unsigned long *first_frame)
{
	memset(state, 0, sizeof(*state));
	state->task = task;

	/*
	 * Refuse to unwind the stack of a task while it's executing on another
	 * CPU.  This check is racy, but that's ok: the unwinder has other
	 * checks to prevent it from going off the rails.
	 */
	if (task_on_another_cpu(task))
		goto done;

	if (regs) {
		if (user_mode(regs))
			goto done;

		state->ip = regs->ip;
		state->sp = kernel_stack_pointer(regs);
		state->bp = regs->bp;
		state->regs = regs;
		state->full_regs = true;
		state->signal = true;

	} else if (task == current) {
		asm volatile("lea (%%rip), %0\n\t"
			     "mov %%rsp, %1\n\t"
			     "mov %%rbp, %2\n\t"
			     : "=r" (state->ip), "=r" (state->sp),
			       "=r" (state->bp));

	} else {
		struct inactive_task_frame *frame = (void *)task->thread.sp;

		state->sp = task->thread.sp;
		state->bp = READ_ONCE_NOCHECK(frame->bp);
		state->ip = READ_ONCE_NOCHECK(frame->ret_addr);
	}

	if (get_stack_info((unsigned long *)state->sp, state->task,
			   &state->stack_info, &state->stack_mask)) {
		/*
		 * We weren't on a valid stack.  It's possible that
		 * we overflowed a valid stack into a guard page.
		 * See if the next page up is valid so that we can
		 * generate some kind of backtrace if this happens.
		 */
		void *next_page = (void *)PAGE_ALIGN((unsigned long)state->sp);
		if (get_stack_info(next_page, state->task, &state->stack_info,
				   &state->stack_mask))
			return;
	}

	/*
	 * The caller can provide the address of the first frame directly
	 * (first_frame) or indirectly (regs->sp) to indicate which stack frame
	 * to start unwinding at.  Skip ahead until we reach it.
	 */

	/* When starting from regs, skip the regs frame: */
	if (regs) {
		unwind_next_frame(state);
		return;
	}

	/* Otherwise, skip ahead to the user-specified starting frame: */
	while (!unwind_done(state) &&
	       (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
			state->sp <= (unsigned long)first_frame))
		unwind_next_frame(state);

	return;

done:
	state->stack_info.type = STACK_TYPE_UNKNOWN;
	return;
}
EXPORT_SYMBOL_GPL(__unwind_start);
Commit	Line	Data
ee9f8fce JP	1	#include <linux/module.h>
	2	#include <linux/sort.h>
	3	#include <asm/ptrace.h>
	4	#include <asm/stacktrace.h>
	5	#include <asm/unwind.h>
	6	#include <asm/orc_types.h>
	7	#include <asm/orc_lookup.h>
	8	#include <asm/sections.h>
	9
	10	#define orc_warn(fmt, ...) \
	11	printk_deferred_once(KERN_WARNING pr_fmt("WARNING: " fmt), ##__VA_ARGS__)
	12
	13	extern int __start_orc_unwind_ip[];
	14	extern int __stop_orc_unwind_ip[];
	15	extern struct orc_entry __start_orc_unwind[];
	16	extern struct orc_entry __stop_orc_unwind[];
	17
	18	static DEFINE_MUTEX(sort_mutex);
	19	int *cur_orc_ip_table = __start_orc_unwind_ip;
	20	struct orc_entry *cur_orc_table = __start_orc_unwind;
	21
	22	unsigned int lookup_num_blocks;
	23	bool orc_init;
	24
	25	static inline unsigned long orc_ip(const int *ip)
	26	{
	27	return (unsigned long)ip + *ip;
	28	}
	29
	30	static struct orc_entry __orc_find(int ip_table, struct orc_entry *u_table,
	31	unsigned int num_entries, unsigned long ip)
	32	{
	33	int *first = ip_table;
	34	int *last = ip_table + num_entries - 1;
	35	int mid = first, found = first;
	36
	37	if (!num_entries)
	38	return NULL;
	39
	40	/*
	41	* Do a binary range search to find the rightmost duplicate of a given
	42	* starting address. Some entries are section terminators which are
	43	* "weak" entries for ensuring there are no gaps. They should be
	44	* ignored when they conflict with a real entry.
	45	*/
	46	while (first <= last) {
	47	mid = first + ((last - first) / 2);
	48
	49	if (orc_ip(mid) <= ip) {
	50	found = mid;
	51	first = mid + 1;
	52	} else
	53	last = mid - 1;
	54	}
	55
	56	return u_table + (found - ip_table);
	57	}
	58
	59	#ifdef CONFIG_MODULES
	60	static struct orc_entry *orc_module_find(unsigned long ip)
	61	{
	62	struct module *mod;
	63
	64	mod = __module_address(ip);
65	if (!mod \|\| !mod->arch.orc_unwind \|\| !mod->arch.orc_unwind_ip)
66	return NULL;
67	return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind,
68	mod->arch.num_orcs, ip);
69	}
70	#else
71	static struct orc_entry *orc_module_find(unsigned long ip)
72	{
73	return NULL;
74	}
75	#endif
76
77	static struct orc_entry *orc_find(unsigned long ip)
78	{
79	if (!orc_init)
80	return NULL;
81
82	/* For non-init vmlinux addresses, use the fast lookup table: */
83	if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) {
84	unsigned int idx, start, stop;
85
86	idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE;
87
88	if (unlikely((idx >= lookup_num_blocks-1))) {
58c3862b JP	89	orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%pB\n",
58c3862b JP	90	idx, lookup_num_blocks, (void *)ip);
ee9f8fce JP	91	return NULL;
	92	}
	93
	94	start = orc_lookup[idx];
	95	stop = orc_lookup[idx + 1] + 1;
	96
	97	if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) \|\|
	98	(__start_orc_unwind + stop > __stop_orc_unwind))) {
58c3862b JP	99	orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%pB\n",
58c3862b JP	100	idx, lookup_num_blocks, start, stop, (void *)ip);
ee9f8fce JP	101	return NULL;
	102	}
	103
	104	return __orc_find(__start_orc_unwind_ip + start,
	105	__start_orc_unwind + start, stop - start, ip);
	106	}
	107
	108	/* vmlinux .init slow lookup: */
	109	if (ip >= (unsigned long)_sinittext && ip < (unsigned long)_einittext)
	110	return __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
	111	__stop_orc_unwind_ip - __start_orc_unwind_ip, ip);
	112
	113	/* Module lookup: */
	114	return orc_module_find(ip);
	115	}
	116
	117	static void orc_sort_swap(void _a, void _b, int size)
	118	{
	119	struct orc_entry orc_a, orc_b;
	120	struct orc_entry orc_tmp;
	121	int a = _a, b = _b, tmp;
	122	int delta = _b - _a;
	123
	124	/* Swap the .orc_unwind_ip entries: */
	125	tmp = *a;
	126	a = b + delta;
	127	*b = tmp - delta;
	128
	129	/* Swap the corresponding .orc_unwind entries: */
	130	orc_a = cur_orc_table + (a - cur_orc_ip_table);
	131	orc_b = cur_orc_table + (b - cur_orc_ip_table);
	132	orc_tmp = *orc_a;
	133	orc_a = orc_b;
	134	*orc_b = orc_tmp;
	135	}
	136
	137	static int orc_sort_cmp(const void _a, const void _b)
	138	{
	139	struct orc_entry *orc_a;
	140	const int a = _a, b = _b;
	141	unsigned long a_val = orc_ip(a);
	142	unsigned long b_val = orc_ip(b);
	143
	144	if (a_val > b_val)
	145	return 1;
	146	if (a_val < b_val)
	147	return -1;
	148
	149	/*
	150	* The "weak" section terminator entries need to always be on the left
	151	* to ensure the lookup code skips them in favor of real entries.
	152	* These terminator entries exist to handle any gaps created by
	153	* whitelisted .o files which didn't get objtool generation.
	154	*/
	155	orc_a = cur_orc_table + (a - cur_orc_ip_table);
	156	return orc_a->sp_reg == ORC_REG_UNDEFINED ? -1 : 1;
	157	}
	158
	159	#ifdef CONFIG_MODULES
	160	void unwind_module_init(struct module mod, void _orc_ip, size_t orc_ip_size,
	161	void *_orc, size_t orc_size)
	162	{
	163	int *orc_ip = _orc_ip;
	164	struct orc_entry *orc = _orc;
165	unsigned int num_entries = orc_ip_size / sizeof(int);
166
167	WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 \|\|
168	orc_size % sizeof(*orc) != 0 \|\|
169	num_entries != orc_size / sizeof(*orc));
170
171	/*
172	* The 'cur_orc_*' globals allow the orc_sort_swap() callback to
173	* associate an .orc_unwind_ip table entry with its corresponding
174	* .orc_unwind entry so they can both be swapped.
175	*/
176	mutex_lock(&sort_mutex);
177	cur_orc_ip_table = orc_ip;
178	cur_orc_table = orc;
179	sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap);
180	mutex_unlock(&sort_mutex);
181
182	mod->arch.orc_unwind_ip = orc_ip;
183	mod->arch.orc_unwind = orc;
184	mod->arch.num_orcs = num_entries;
185	}
186	#endif
187
188	void __init unwind_init(void)
189	{
190	size_t orc_ip_size = (void )__stop_orc_unwind_ip - (void )__start_orc_unwind_ip;
191	size_t orc_size = (void )__stop_orc_unwind - (void )__start_orc_unwind;
192	size_t num_entries = orc_ip_size / sizeof(int);
193	struct orc_entry *orc;
194	int i;
195
196	if (!num_entries \|\| orc_ip_size % sizeof(int) != 0 \|\|
197	orc_size % sizeof(struct orc_entry) != 0 \|\|
198	num_entries != orc_size / sizeof(struct orc_entry)) {
199	orc_warn("WARNING: Bad or missing .orc_unwind table. Disabling unwinder.\n");
200	return;
201	}
202
203	/* Sort the .orc_unwind and .orc_unwind_ip tables: */
204	sort(__start_orc_unwind_ip, num_entries, sizeof(int), orc_sort_cmp,
205	orc_sort_swap);
206
207	/* Initialize the fast lookup table: */
208	lookup_num_blocks = orc_lookup_end - orc_lookup;
209	for (i = 0; i < lookup_num_blocks-1; i++) {
210	orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
211	num_entries,
212	LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i));
213	if (!orc) {
214	orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n");
215	return;
216	}
217
218	orc_lookup[i] = orc - __start_orc_unwind;
219	}
220
221	/* Initialize the ending block: */
222	orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries,
223	LOOKUP_STOP_IP);
224	if (!orc) {
225	orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n");
226	return;
227	}
228	orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind;
229
230	orc_init = true;
231	}
232
233	unsigned long unwind_get_return_address(struct unwind_state *state)
234	{
235	if (unwind_done(state))
236	return 0;
237
238	return __kernel_text_address(state->ip) ? state->ip : 0;
239	}
240	EXPORT_SYMBOL_GPL(unwind_get_return_address);
241
242	unsigned long unwind_get_return_address_ptr(struct unwind_state state)
243	{
244	if (unwind_done(state))
245	return NULL;
246
247	if (state->regs)
248	return &state->regs->ip;
249
250	if (state->sp)
251	return (unsigned long *)state->sp - 1;
252
253	return NULL;
254	}
255
b02fcf9b	256	static bool stack_access_ok(struct unwind_state *state, unsigned long _addr,
ee9f8fce JP	257	size_t len)
	258	{
	259	struct stack_info *info = &state->stack_info;
b02fcf9b	260	void addr = (void )_addr;
ee9f8fce	261
b02fcf9b JP	262	if (!on_stack(info, addr, len) &&
	263	(get_stack_info(addr, state->task, info, &state->stack_mask)))
	264	return false;
ee9f8fce JP	265
	266	return true;
	267	}
	268
	269	static bool deref_stack_reg(struct unwind_state *state, unsigned long addr,
	270	unsigned long *val)
	271	{
	272	if (!stack_access_ok(state, addr, sizeof(long)))
	273	return false;
	274
881125bf	275	val = READ_ONCE_NOCHECK((unsigned long *)addr);
ee9f8fce JP	276	return true;
	277	}
	278
ee9f8fce	279	static bool deref_stack_regs(struct unwind_state *state, unsigned long addr,
b02fcf9b	280	unsigned long ip, unsigned long sp)
ee9f8fce	281	{
b02fcf9b	282	struct pt_regs regs = (struct pt_regs )addr;
ee9f8fce	283
b02fcf9b JP	284	/* x86-32 support will be more complicated due to the &regs->sp hack */
b02fcf9b JP	285	BUILD_BUG_ON(IS_ENABLED(CONFIG_X86_32));
ee9f8fce	286
b02fcf9b	287	if (!stack_access_ok(state, addr, sizeof(struct pt_regs)))
ee9f8fce JP	288	return false;
	289
	290	*ip = regs->ip;
b02fcf9b JP	291	*sp = regs->sp;
	292	return true;
	293	}
ee9f8fce	294
b02fcf9b JP	295	static bool deref_stack_iret_regs(struct unwind_state *state, unsigned long addr,
	296	unsigned long ip, unsigned long sp)
	297	{
	298	struct pt_regs regs = (void )addr - IRET_FRAME_OFFSET;
ee9f8fce	299
b02fcf9b JP	300	if (!stack_access_ok(state, addr, IRET_FRAME_SIZE))
b02fcf9b JP	301	return false;
ee9f8fce	302
b02fcf9b JP	303	*ip = regs->ip;
b02fcf9b JP	304	*sp = regs->sp;
ee9f8fce JP	305	return true;
	306	}
	307
	308	bool unwind_next_frame(struct unwind_state *state)
	309	{
	310	unsigned long ip_p, sp, orig_ip, prev_sp = state->sp;
	311	enum stack_type prev_type = state->stack_info.type;
	312	struct orc_entry *orc;
ee9f8fce JP	313	bool indirect = false;
	314
	315	if (unwind_done(state))
	316	return false;
	317
	318	/* Don't let modules unload while we're reading their ORC data. */
	319	preempt_disable();
	320
	321	/* Have we reached the end? */
	322	if (state->regs && user_mode(state->regs))
	323	goto done;
	324
	325	/*
	326	* Find the orc_entry associated with the text address.
	327	*
	328	* Decrement call return addresses by one so they work for sibling
	329	* calls and calls to noreturn functions.
	330	*/
	331	orc = orc_find(state->signal ? state->ip : state->ip - 1);
	332	if (!orc \|\| orc->sp_reg == ORC_REG_UNDEFINED)
	333	goto done;
	334	orig_ip = state->ip;
	335
	336	/* Find the previous frame's stack: */
	337	switch (orc->sp_reg) {
	338	case ORC_REG_SP:
	339	sp = state->sp + orc->sp_offset;
	340	break;
	341
	342	case ORC_REG_BP:
	343	sp = state->bp + orc->sp_offset;
	344	break;
	345
	346	case ORC_REG_SP_INDIRECT:
	347	sp = state->sp + orc->sp_offset;
	348	indirect = true;
	349	break;
	350
	351	case ORC_REG_BP_INDIRECT:
	352	sp = state->bp + orc->sp_offset;
	353	indirect = true;
	354	break;
	355
	356	case ORC_REG_R10:
	357	if (!state->regs \|\| !state->full_regs) {
58c3862b	358	orc_warn("missing regs for base reg R10 at ip %pB\n",
ee9f8fce JP	359	(void *)state->ip);
	360	goto done;
	361	}
	362	sp = state->regs->r10;
	363	break;
	364
	365	case ORC_REG_R13:
	366	if (!state->regs \|\| !state->full_regs) {
58c3862b	367	orc_warn("missing regs for base reg R13 at ip %pB\n",
ee9f8fce JP	368	(void *)state->ip);
	369	goto done;
	370	}
	371	sp = state->regs->r13;
	372	break;
	373
	374	case ORC_REG_DI:
	375	if (!state->regs \|\| !state->full_regs) {
58c3862b	376	orc_warn("missing regs for base reg DI at ip %pB\n",
ee9f8fce JP	377	(void *)state->ip);
	378	goto done;
	379	}
	380	sp = state->regs->di;
	381	break;
	382
	383	case ORC_REG_DX:
	384	if (!state->regs \|\| !state->full_regs) {
58c3862b	385	orc_warn("missing regs for base reg DX at ip %pB\n",
ee9f8fce JP	386	(void *)state->ip);
	387	goto done;
	388	}
	389	sp = state->regs->dx;
	390	break;
	391
	392	default:
58c3862b	393	orc_warn("unknown SP base reg %d for ip %pB\n",
ee9f8fce JP	394	orc->sp_reg, (void *)state->ip);
	395	goto done;
	396	}
	397
	398	if (indirect) {
	399	if (!deref_stack_reg(state, sp, &sp))
	400	goto done;
	401	}
	402
	403	/* Find IP, SP and possibly regs: */
	404	switch (orc->type) {
	405	case ORC_TYPE_CALL:
	406	ip_p = sp - sizeof(long);
	407
	408	if (!deref_stack_reg(state, ip_p, &state->ip))
	409	goto done;
	410
	411	state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
	412	state->ip, (void *)ip_p);
	413
	414	state->sp = sp;
	415	state->regs = NULL;
	416	state->signal = false;
	417	break;
	418
	419	case ORC_TYPE_REGS:
b02fcf9b	420	if (!deref_stack_regs(state, sp, &state->ip, &state->sp)) {
58c3862b	421	orc_warn("can't dereference registers at %p for ip %pB\n",
ee9f8fce JP	422	(void )sp, (void )orig_ip);
	423	goto done;
	424	}
	425
	426	state->regs = (struct pt_regs *)sp;
	427	state->full_regs = true;
	428	state->signal = true;
	429	break;
	430
	431	case ORC_TYPE_REGS_IRET:
b02fcf9b	432	if (!deref_stack_iret_regs(state, sp, &state->ip, &state->sp)) {
58c3862b	433	orc_warn("can't dereference iret registers at %p for ip %pB\n",
ee9f8fce JP	434	(void )sp, (void )orig_ip);
	435	goto done;
	436	}
	437
b02fcf9b JP	438	state->regs = (void *)sp - IRET_FRAME_OFFSET;
b02fcf9b JP	439	state->full_regs = false;
ee9f8fce JP	440	state->signal = true;
	441	break;
	442
	443	default:
58c3862b JP	444	orc_warn("unknown .orc_unwind entry type %d for ip %pB\n",
58c3862b JP	445	orc->type, (void *)orig_ip);
ee9f8fce JP	446	break;
	447	}
	448
	449	/* Find BP: */
	450	switch (orc->bp_reg) {
	451	case ORC_REG_UNDEFINED:
	452	if (state->regs && state->full_regs)
	453	state->bp = state->regs->bp;
	454	break;
	455
	456	case ORC_REG_PREV_SP:
	457	if (!deref_stack_reg(state, sp + orc->bp_offset, &state->bp))
	458	goto done;
	459	break;
	460
	461	case ORC_REG_BP:
	462	if (!deref_stack_reg(state, state->bp + orc->bp_offset, &state->bp))
	463	goto done;
	464	break;
	465
	466	default:
58c3862b	467	orc_warn("unknown BP base reg %d for ip %pB\n",
ee9f8fce JP	468	orc->bp_reg, (void *)orig_ip);
	469	goto done;
	470	}
	471
	472	/* Prevent a recursive loop due to bad ORC data: */
	473	if (state->stack_info.type == prev_type &&
	474	on_stack(&state->stack_info, (void *)state->sp, sizeof(long)) &&
	475	state->sp <= prev_sp) {
58c3862b	476	orc_warn("stack going in the wrong direction? ip=%pB\n",
ee9f8fce JP	477	(void *)orig_ip);
	478	goto done;
	479	}
	480
	481	preempt_enable();
	482	return true;
	483
	484	done:
	485	preempt_enable();
	486	state->stack_info.type = STACK_TYPE_UNKNOWN;
	487	return false;
	488	}
	489	EXPORT_SYMBOL_GPL(unwind_next_frame);
	490
	491	void __unwind_start(struct unwind_state state, struct task_struct task,
	492	struct pt_regs regs, unsigned long first_frame)
	493	{
	494	memset(state, 0, sizeof(*state));
	495	state->task = task;
	496
	497	/*
	498	* Refuse to unwind the stack of a task while it's executing on another
	499	* CPU. This check is racy, but that's ok: the unwinder has other
	500	* checks to prevent it from going off the rails.
	501	*/
	502	if (task_on_another_cpu(task))
	503	goto done;
	504
	505	if (regs) {
	506	if (user_mode(regs))
	507	goto done;
	508
	509	state->ip = regs->ip;
	510	state->sp = kernel_stack_pointer(regs);
	511	state->bp = regs->bp;
	512	state->regs = regs;
	513	state->full_regs = true;
	514	state->signal = true;
	515
	516	} else if (task == current) {
	517	asm volatile("lea (%%rip), %0\n\t"
	518	"mov %%rsp, %1\n\t"
	519	"mov %%rbp, %2\n\t"
	520	: "=r" (state->ip), "=r" (state->sp),
	521	"=r" (state->bp));
	522
	523	} else {
	524	struct inactive_task_frame frame = (void )task->thread.sp;
	525
	526	state->sp = task->thread.sp;
	527	state->bp = READ_ONCE_NOCHECK(frame->bp);
	528	state->ip = READ_ONCE_NOCHECK(frame->ret_addr);
	529	}
	530
	531	if (get_stack_info((unsigned long *)state->sp, state->task,
d3a09104 AL	532	&state->stack_info, &state->stack_mask)) {
	533	/*
	534	* We weren't on a valid stack. It's possible that
	535	* we overflowed a valid stack into a guard page.
	536	* See if the next page up is valid so that we can
	537	* generate some kind of backtrace if this happens.
	538	*/
	539	void next_page = (void )PAGE_ALIGN((unsigned long)state->sp);
	540	if (get_stack_info(next_page, state->task, &state->stack_info,
	541	&state->stack_mask))
	542	return;
	543	}
ee9f8fce JP	544
	545	/*
	546	* The caller can provide the address of the first frame directly
	547	* (first_frame) or indirectly (regs->sp) to indicate which stack frame
	548	* to start unwinding at. Skip ahead until we reach it.
	549	*/
	550
	551	/* When starting from regs, skip the regs frame: */
	552	if (regs) {
	553	unwind_next_frame(state);
	554	return;
	555	}
	556
	557	/* Otherwise, skip ahead to the user-specified starting frame: */
	558	while (!unwind_done(state) &&
	559	(!on_stack(&state->stack_info, first_frame, sizeof(long)) \|\|
	560	state->sp <= (unsigned long)first_frame))
	561	unwind_next_frame(state);
	562
	563	return;
	564
	565	done:
	566	state->stack_info.type = STACK_TYPE_UNKNOWN;
	567	return;
	568	}
	569	EXPORT_SYMBOL_GPL(__unwind_start);