[linux.git] / arch / arm / kernel / unwind.c

/*
 * arch/arm/kernel/unwind.c
 *
 * Copyright (C) 2008 ARM Limited
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 *
 * Stack unwinding support for ARM
 *
 * An ARM EABI version of gcc is required to generate the unwind
 * tables. For information about the structure of the unwind tables,
 * see "Exception Handling ABI for the ARM Architecture" at:
 *
 * http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html
 */

#ifndef __CHECKER__
#if !defined (__ARM_EABI__)
#warning Your compiler does not have EABI support.
#warning    ARM unwind is known to compile only with EABI compilers.
#warning    Change compiler or disable ARM_UNWIND option.
#elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2)
#warning Your compiler is too buggy; it is known to not compile ARM unwind support.
#warning    Change compiler or disable ARM_UNWIND option.
#endif
#endif /* __CHECKER__ */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/list.h>

#include <asm/stacktrace.h>
#include <asm/traps.h>
#include <asm/unwind.h>

/* Dummy functions to avoid linker complaints */
void __aeabi_unwind_cpp_pr0(void)
{
};
EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0);

void __aeabi_unwind_cpp_pr1(void)
{
};
EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1);

void __aeabi_unwind_cpp_pr2(void)
{
};
EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);

struct unwind_ctrl_block {
	unsigned long vrs[16];		/* virtual register set */
	const unsigned long *insn;	/* pointer to the current instructions word */
	int entries;			/* number of entries left to interpret */
	int byte;			/* current byte number in the instructions word */
};

enum regs {
#ifdef CONFIG_THUMB2_KERNEL
	FP = 7,
#else
	FP = 11,
#endif
	SP = 13,
	LR = 14,
	PC = 15
};

extern const struct unwind_idx __start_unwind_idx[];
static const struct unwind_idx *__origin_unwind_idx;
extern const struct unwind_idx __stop_unwind_idx[];

static DEFINE_SPINLOCK(unwind_lock);
static LIST_HEAD(unwind_tables);

/* Convert a prel31 symbol to an absolute address */
#define prel31_to_addr(ptr)				\
({							\
	/* sign-extend to 32 bits */			\
	long offset = (((long)*(ptr)) << 1) >> 1;	\
	(unsigned long)(ptr) + offset;			\
})

/*
 * Binary search in the unwind index. The entries are
 * guaranteed to be sorted in ascending order by the linker.
 *
 * start = first entry
 * origin = first entry with positive offset (or stop if there is no such entry)
 * stop - 1 = last entry
 */
static const struct unwind_idx *search_index(unsigned long addr,
				       const struct unwind_idx *start,
				       const struct unwind_idx *origin,
				       const struct unwind_idx *stop)
{
	unsigned long addr_prel31;

	pr_debug("%s(%08lx, %p, %p, %p)\n",
			__func__, addr, start, origin, stop);

	/*
	 * only search in the section with the matching sign. This way the
	 * prel31 numbers can be compared as unsigned longs.
	 */
	if (addr < (unsigned long)start)
		/* negative offsets: [start; origin) */
		stop = origin;
	else
		/* positive offsets: [origin; stop) */
		start = origin;

	/* prel31 for address relavive to start */
	addr_prel31 = (addr - (unsigned long)start) & 0x7fffffff;

	while (start < stop - 1) {
		const struct unwind_idx *mid = start + ((stop - start) >> 1);

		/*
		 * As addr_prel31 is relative to start an offset is needed to
		 * make it relative to mid.
		 */
		if (addr_prel31 - ((unsigned long)mid - (unsigned long)start) <
				mid->addr_offset)
			stop = mid;
		else {
			/* keep addr_prel31 relative to start */
			addr_prel31 -= ((unsigned long)mid -
					(unsigned long)start);
			start = mid;
		}
	}

	if (likely(start->addr_offset <= addr_prel31))
		return start;
	else {
		pr_warning("unwind: Unknown symbol address %08lx\n", addr);
		return NULL;
	}
}

static const struct unwind_idx *unwind_find_origin(
		const struct unwind_idx *start, const struct unwind_idx *stop)
{
	pr_debug("%s(%p, %p)\n", __func__, start, stop);
	while (start < stop) {
		const struct unwind_idx *mid = start + ((stop - start) >> 1);

		if (mid->addr_offset >= 0x40000000)
			/* negative offset */
			start = mid + 1;
		else
			/* positive offset */
			stop = mid;
	}
	pr_debug("%s -> %p\n", __func__, stop);
	return stop;
}

static const struct unwind_idx *unwind_find_idx(unsigned long addr)
{
	const struct unwind_idx *idx = NULL;
	unsigned long flags;

	pr_debug("%s(%08lx)\n", __func__, addr);

	if (core_kernel_text(addr)) {
		if (unlikely(!__origin_unwind_idx))
			__origin_unwind_idx =
				unwind_find_origin(__start_unwind_idx,
						__stop_unwind_idx);

		/* main unwind table */
		idx = search_index(addr, __start_unwind_idx,
				   __origin_unwind_idx,
				   __stop_unwind_idx);
	} else {
		/* module unwind tables */
		struct unwind_table *table;

		spin_lock_irqsave(&unwind_lock, flags);
		list_for_each_entry(table, &unwind_tables, list) {
			if (addr >= table->begin_addr &&
			    addr < table->end_addr) {
				idx = search_index(addr, table->start,
						   table->origin,
						   table->stop);
				/* Move-to-front to exploit common traces */
				list_move(&table->list, &unwind_tables);
				break;
			}
		}
		spin_unlock_irqrestore(&unwind_lock, flags);
	}

	pr_debug("%s: idx = %p\n", __func__, idx);
	return idx;
}

static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl)
{
	unsigned long ret;

	if (ctrl->entries <= 0) {
		pr_warning("unwind: Corrupt unwind table\n");
		return 0;
	}

	ret = (*ctrl->insn >> (ctrl->byte * 8)) & 0xff;

	if (ctrl->byte == 0) {
		ctrl->insn++;
		ctrl->entries--;
		ctrl->byte = 3;
	} else
		ctrl->byte--;

	return ret;
}

/*
 * Execute the current unwind instruction.
 */
static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
{
	unsigned long insn = unwind_get_byte(ctrl);

	pr_debug("%s: insn = %08lx\n", __func__, insn);

	if ((insn & 0xc0) == 0x00)
		ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4;
	else if ((insn & 0xc0) == 0x40)
		ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
	else if ((insn & 0xf0) == 0x80) {
		unsigned long mask;
		unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
		int load_sp, reg = 4;

		insn = (insn << 8) | unwind_get_byte(ctrl);
		mask = insn & 0x0fff;
		if (mask == 0) {
			pr_warning("unwind: 'Refuse to unwind' instruction %04lx\n",
				   insn);
			return -URC_FAILURE;
		}

		/* pop R4-R15 according to mask */
		load_sp = mask & (1 << (13 - 4));
		while (mask) {
			if (mask & 1)
				ctrl->vrs[reg] = *vsp++;
			mask >>= 1;
			reg++;
		}
		if (!load_sp)
			ctrl->vrs[SP] = (unsigned long)vsp;
	} else if ((insn & 0xf0) == 0x90 &&
		   (insn & 0x0d) != 0x0d)
		ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
	else if ((insn & 0xf0) == 0xa0) {
		unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
		int reg;

		/* pop R4-R[4+bbb] */
		for (reg = 4; reg <= 4 + (insn & 7); reg++)
			ctrl->vrs[reg] = *vsp++;
		if (insn & 0x80)
			ctrl->vrs[14] = *vsp++;
		ctrl->vrs[SP] = (unsigned long)vsp;
	} else if (insn == 0xb0) {
		if (ctrl->vrs[PC] == 0)
			ctrl->vrs[PC] = ctrl->vrs[LR];
		/* no further processing */
		ctrl->entries = 0;
	} else if (insn == 0xb1) {
		unsigned long mask = unwind_get_byte(ctrl);
		unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
		int reg = 0;

		if (mask == 0 || mask & 0xf0) {
			pr_warning("unwind: Spare encoding %04lx\n",
			       (insn << 8) | mask);
			return -URC_FAILURE;
		}

		/* pop R0-R3 according to mask */
		while (mask) {
			if (mask & 1)
				ctrl->vrs[reg] = *vsp++;
			mask >>= 1;
			reg++;
		}
		ctrl->vrs[SP] = (unsigned long)vsp;
	} else if (insn == 0xb2) {
		unsigned long uleb128 = unwind_get_byte(ctrl);

		ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
	} else {
		pr_warning("unwind: Unhandled instruction %02lx\n", insn);
		return -URC_FAILURE;
	}

	pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
		 ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);

	return URC_OK;
}

/*
 * Unwind a single frame starting with *sp for the symbol at *pc. It
 * updates the *pc and *sp with the new values.
 */
int unwind_frame(struct stackframe *frame)
{
	unsigned long high, low;
	const struct unwind_idx *idx;
	struct unwind_ctrl_block ctrl;

	/* only go to a higher address on the stack */
	low = frame->sp;
	high = ALIGN(low, THREAD_SIZE);

	pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
		 frame->pc, frame->lr, frame->sp);

	if (!kernel_text_address(frame->pc))
		return -URC_FAILURE;

	idx = unwind_find_idx(frame->pc);
	if (!idx) {
		pr_warning("unwind: Index not found %08lx\n", frame->pc);
		return -URC_FAILURE;
	}

	ctrl.vrs[FP] = frame->fp;
	ctrl.vrs[SP] = frame->sp;
	ctrl.vrs[LR] = frame->lr;
	ctrl.vrs[PC] = 0;

	if (idx->insn == 1)
		/* can't unwind */
		return -URC_FAILURE;
	else if ((idx->insn & 0x80000000) == 0)
		/* prel31 to the unwind table */
		ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn);
	else if ((idx->insn & 0xff000000) == 0x80000000)
		/* only personality routine 0 supported in the index */
		ctrl.insn = &idx->insn;
	else {
		pr_warning("unwind: Unsupported personality routine %08lx in the index at %p\n",
			   idx->insn, idx);
		return -URC_FAILURE;
	}

	/* check the personality routine */
	if ((*ctrl.insn & 0xff000000) == 0x80000000) {
		ctrl.byte = 2;
		ctrl.entries = 1;
	} else if ((*ctrl.insn & 0xff000000) == 0x81000000) {
		ctrl.byte = 1;
		ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16);
	} else {
		pr_warning("unwind: Unsupported personality routine %08lx at %p\n",
			   *ctrl.insn, ctrl.insn);
		return -URC_FAILURE;
	}

	while (ctrl.entries > 0) {
		int urc = unwind_exec_insn(&ctrl);
		if (urc < 0)
			return urc;
		if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= high)
			return -URC_FAILURE;
	}

	if (ctrl.vrs[PC] == 0)
		ctrl.vrs[PC] = ctrl.vrs[LR];

	/* check for infinite loop */
	if (frame->pc == ctrl.vrs[PC])
		return -URC_FAILURE;

	frame->fp = ctrl.vrs[FP];
	frame->sp = ctrl.vrs[SP];
	frame->lr = ctrl.vrs[LR];
	frame->pc = ctrl.vrs[PC];

	return URC_OK;
}

void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
	struct stackframe frame;
	register unsigned long current_sp asm ("sp");

	pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);

	if (!tsk)
		tsk = current;

	if (regs) {
		frame.fp = regs->ARM_fp;
		frame.sp = regs->ARM_sp;
		frame.lr = regs->ARM_lr;
		/* PC might be corrupted, use LR in that case. */
		frame.pc = kernel_text_address(regs->ARM_pc)
			 ? regs->ARM_pc : regs->ARM_lr;
	} else if (tsk == current) {
		frame.fp = (unsigned long)__builtin_frame_address(0);
		frame.sp = current_sp;
		frame.lr = (unsigned long)__builtin_return_address(0);
		frame.pc = (unsigned long)unwind_backtrace;
	} else {
		/* task blocked in __switch_to */
		frame.fp = thread_saved_fp(tsk);
		frame.sp = thread_saved_sp(tsk);
		/*
		 * The function calling __switch_to cannot be a leaf function
		 * so LR is recovered from the stack.
		 */
		frame.lr = 0;
		frame.pc = thread_saved_pc(tsk);
	}

	while (1) {
		int urc;
		unsigned long where = frame.pc;

		urc = unwind_frame(&frame);
		if (urc < 0)
			break;
		dump_backtrace_entry(where, frame.pc, frame.sp - 4);
	}
}

struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
				      unsigned long text_addr,
				      unsigned long text_size)
{
	unsigned long flags;
	struct unwind_table *tab = kmalloc(sizeof(*tab), GFP_KERNEL);

	pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size,
		 text_addr, text_size);

	if (!tab)
		return tab;

	tab->start = (const struct unwind_idx *)start;
	tab->stop = (const struct unwind_idx *)(start + size);
	tab->origin = unwind_find_origin(tab->start, tab->stop);
	tab->begin_addr = text_addr;
	tab->end_addr = text_addr + text_size;

	spin_lock_irqsave(&unwind_lock, flags);
	list_add_tail(&tab->list, &unwind_tables);
	spin_unlock_irqrestore(&unwind_lock, flags);

	return tab;
}

void unwind_table_del(struct unwind_table *tab)
{
	unsigned long flags;

	if (!tab)
		return;

	spin_lock_irqsave(&unwind_lock, flags);
	list_del(&tab->list);
	spin_unlock_irqrestore(&unwind_lock, flags);

	kfree(tab);
}
Commit	Line	Data
bff595c1 CM	1	/*
	2	* arch/arm/kernel/unwind.c
	3	*
	4	* Copyright (C) 2008 ARM Limited
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*
	15	* You should have received a copy of the GNU General Public License
	16	* along with this program; if not, write to the Free Software
	17	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	18	*
	19	*
	20	* Stack unwinding support for ARM
	21	*
	22	* An ARM EABI version of gcc is required to generate the unwind
	23	* tables. For information about the structure of the unwind tables,
	24	* see "Exception Handling ABI for the ARM Architecture" at:
	25	*
	26	* http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html
	27	*/
	28
830703c7	29	#ifndef __CHECKER__
6603a4fd CS	30	#if !defined (__ARM_EABI__)
	31	#warning Your compiler does not have EABI support.
	32	#warning ARM unwind is known to compile only with EABI compilers.
	33	#warning Change compiler or disable ARM_UNWIND option.
	34	#elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2)
	35	#warning Your compiler is too buggy; it is known to not compile ARM unwind support.
	36	#warning Change compiler or disable ARM_UNWIND option.
	37	#endif
830703c7	38	#endif /* __CHECKER__ */
6603a4fd	39
bff595c1 CM	40	#include <linux/kernel.h>
bff595c1 CM	41	#include <linux/init.h>
ecea4ab6	42	#include <linux/export.h>
bff595c1 CM	43	#include <linux/sched.h>
	44	#include <linux/slab.h>
	45	#include <linux/spinlock.h>
	46	#include <linux/list.h>
	47
	48	#include <asm/stacktrace.h>
	49	#include <asm/traps.h>
	50	#include <asm/unwind.h>
	51
	52	/* Dummy functions to avoid linker complaints */
	53	void __aeabi_unwind_cpp_pr0(void)
	54	{
	55	};
	56	EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0);
	57
	58	void __aeabi_unwind_cpp_pr1(void)
	59	{
	60	};
	61	EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1);
	62
	63	void __aeabi_unwind_cpp_pr2(void)
	64	{
	65	};
	66	EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
	67
	68	struct unwind_ctrl_block {
	69	unsigned long vrs[16]; /* virtual register set */
de66a979	70	const unsigned long insn; / pointer to the current instructions word */
bff595c1 CM	71	int entries; /* number of entries left to interpret */
	72	int byte; /* current byte number in the instructions word */
	73	};
	74
	75	enum regs {
b86040a5 CM	76	#ifdef CONFIG_THUMB2_KERNEL
	77	FP = 7,
	78	#else
bff595c1	79	FP = 11,
b86040a5	80	#endif
bff595c1 CM	81	SP = 13,
	82	LR = 14,
	83	PC = 15
	84	};
	85
de66a979 UKK	86	extern const struct unwind_idx __start_unwind_idx[];
	87	static const struct unwind_idx *__origin_unwind_idx;
	88	extern const struct unwind_idx __stop_unwind_idx[];
bff595c1 CM	89
	90	static DEFINE_SPINLOCK(unwind_lock);
	91	static LIST_HEAD(unwind_tables);
	92
	93	/* Convert a prel31 symbol to an absolute address */
	94	#define prel31_to_addr(ptr) \
	95	({ \
	96	/* sign-extend to 32 bits */ \
	97	long offset = (((long)*(ptr)) << 1) >> 1; \
	98	(unsigned long)(ptr) + offset; \
	99	})
	100
	101	/*
de66a979	102	* Binary search in the unwind index. The entries are
bff595c1	103	* guaranteed to be sorted in ascending order by the linker.
de66a979 UKK	104	*
	105	* start = first entry
	106	* origin = first entry with positive offset (or stop if there is no such entry)
	107	* stop - 1 = last entry
bff595c1	108	*/
de66a979 UKK	109	static const struct unwind_idx *search_index(unsigned long addr,
	110	const struct unwind_idx *start,
	111	const struct unwind_idx *origin,
	112	const struct unwind_idx *stop)
bff595c1	113	{
de66a979 UKK	114	unsigned long addr_prel31;
	115
	116	pr_debug("%s(%08lx, %p, %p, %p)\n",
	117	__func__, addr, start, origin, stop);
	118
	119	/*
	120	* only search in the section with the matching sign. This way the
	121	* prel31 numbers can be compared as unsigned longs.
	122	*/
	123	if (addr < (unsigned long)start)
	124	/* negative offsets: [start; origin) */
	125	stop = origin;
	126	else
	127	/* positive offsets: [origin; stop) */
	128	start = origin;
	129
	130	/* prel31 for address relavive to start */
	131	addr_prel31 = (addr - (unsigned long)start) & 0x7fffffff;
bff595c1	132
de66a979 UKK	133	while (start < stop - 1) {
	134	const struct unwind_idx *mid = start + ((stop - start) >> 1);
	135
	136	/*
	137	* As addr_prel31 is relative to start an offset is needed to
	138	* make it relative to mid.
	139	*/
	140	if (addr_prel31 - ((unsigned long)mid - (unsigned long)start) <
	141	mid->addr_offset)
	142	stop = mid;
	143	else {
	144	/* keep addr_prel31 relative to start */
	145	addr_prel31 -= ((unsigned long)mid -
	146	(unsigned long)start);
	147	start = mid;
	148	}
	149	}
	150
	151	if (likely(start->addr_offset <= addr_prel31))
	152	return start;
	153	else {
bff595c1 CM	154	pr_warning("unwind: Unknown symbol address %08lx\n", addr);
bff595c1 CM	155	return NULL;
de66a979 UKK	156	}
de66a979 UKK	157	}
bff595c1	158
de66a979 UKK	159	static const struct unwind_idx *unwind_find_origin(
	160	const struct unwind_idx start, const struct unwind_idx stop)
	161	{
	162	pr_debug("%s(%p, %p)\n", __func__, start, stop);
ddf5a25c	163	while (start < stop) {
de66a979	164	const struct unwind_idx *mid = start + ((stop - start) >> 1);
bff595c1	165
de66a979 UKK	166	if (mid->addr_offset >= 0x40000000)
de66a979 UKK	167	/* negative offset */
ddf5a25c	168	start = mid + 1;
bff595c1	169	else
de66a979 UKK	170	/* positive offset */
de66a979 UKK	171	stop = mid;
bff595c1	172	}
de66a979 UKK	173	pr_debug("%s -> %p\n", __func__, stop);
de66a979 UKK	174	return stop;
bff595c1 CM	175	}
bff595c1 CM	176
de66a979	177	static const struct unwind_idx *unwind_find_idx(unsigned long addr)
bff595c1	178	{
de66a979	179	const struct unwind_idx *idx = NULL;
bff595c1 CM	180	unsigned long flags;
	181
	182	pr_debug("%s(%08lx)\n", __func__, addr);
	183
de66a979 UKK	184	if (core_kernel_text(addr)) {
	185	if (unlikely(!__origin_unwind_idx))
	186	__origin_unwind_idx =
	187	unwind_find_origin(__start_unwind_idx,
	188	__stop_unwind_idx);
	189
bff595c1 CM	190	/* main unwind table */
bff595c1 CM	191	idx = search_index(addr, __start_unwind_idx,
de66a979 UKK	192	__origin_unwind_idx,
	193	__stop_unwind_idx);
	194	} else {
bff595c1 CM	195	/* module unwind tables */
	196	struct unwind_table *table;
	197
	198	spin_lock_irqsave(&unwind_lock, flags);
	199	list_for_each_entry(table, &unwind_tables, list) {
	200	if (addr >= table->begin_addr &&
	201	addr < table->end_addr) {
	202	idx = search_index(addr, table->start,
de66a979 UKK	203	table->origin,
de66a979 UKK	204	table->stop);
5333a3de PC	205	/* Move-to-front to exploit common traces */
5333a3de PC	206	list_move(&table->list, &unwind_tables);
bff595c1 CM	207	break;
	208	}
	209	}
	210	spin_unlock_irqrestore(&unwind_lock, flags);
	211	}
	212
	213	pr_debug("%s: idx = %p\n", __func__, idx);
	214	return idx;
	215	}
	216
	217	static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl)
	218	{
	219	unsigned long ret;
	220
	221	if (ctrl->entries <= 0) {
	222	pr_warning("unwind: Corrupt unwind table\n");
	223	return 0;
	224	}
	225
	226	ret = (ctrl->insn >> (ctrl->byte 8)) & 0xff;
	227
	228	if (ctrl->byte == 0) {
	229	ctrl->insn++;
	230	ctrl->entries--;
	231	ctrl->byte = 3;
	232	} else
	233	ctrl->byte--;
	234
	235	return ret;
	236	}
	237
	238	/*
	239	* Execute the current unwind instruction.
	240	*/
	241	static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
	242	{
	243	unsigned long insn = unwind_get_byte(ctrl);
	244
	245	pr_debug("%s: insn = %08lx\n", __func__, insn);
	246
	247	if ((insn & 0xc0) == 0x00)
	248	ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4;
	249	else if ((insn & 0xc0) == 0x40)
	250	ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
	251	else if ((insn & 0xf0) == 0x80) {
	252	unsigned long mask;
	253	unsigned long vsp = (unsigned long )ctrl->vrs[SP];
	254	int load_sp, reg = 4;
	255
	256	insn = (insn << 8) \| unwind_get_byte(ctrl);
	257	mask = insn & 0x0fff;
	258	if (mask == 0) {
	259	pr_warning("unwind: 'Refuse to unwind' instruction %04lx\n",
	260	insn);
	261	return -URC_FAILURE;
	262	}
	263
	264	/* pop R4-R15 according to mask */
	265	load_sp = mask & (1 << (13 - 4));
	266	while (mask) {
	267	if (mask & 1)
	268	ctrl->vrs[reg] = *vsp++;
	269	mask >>= 1;
	270	reg++;
271	}
272	if (!load_sp)
273	ctrl->vrs[SP] = (unsigned long)vsp;
274	} else if ((insn & 0xf0) == 0x90 &&
275	(insn & 0x0d) != 0x0d)
276	ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
277	else if ((insn & 0xf0) == 0xa0) {
278	unsigned long vsp = (unsigned long )ctrl->vrs[SP];
279	int reg;
280
281	/* pop R4-R[4+bbb] */
282	for (reg = 4; reg <= 4 + (insn & 7); reg++)
283	ctrl->vrs[reg] = *vsp++;
284	if (insn & 0x80)
285	ctrl->vrs[14] = *vsp++;
286	ctrl->vrs[SP] = (unsigned long)vsp;
287	} else if (insn == 0xb0) {
c894ed69 CM	288	if (ctrl->vrs[PC] == 0)
c894ed69 CM	289	ctrl->vrs[PC] = ctrl->vrs[LR];
bff595c1 CM	290	/* no further processing */
	291	ctrl->entries = 0;
	292	} else if (insn == 0xb1) {
	293	unsigned long mask = unwind_get_byte(ctrl);
	294	unsigned long vsp = (unsigned long )ctrl->vrs[SP];
	295	int reg = 0;
	296
	297	if (mask == 0 \|\| mask & 0xf0) {
	298	pr_warning("unwind: Spare encoding %04lx\n",
	299	(insn << 8) \| mask);
	300	return -URC_FAILURE;
	301	}
	302
	303	/* pop R0-R3 according to mask */
	304	while (mask) {
	305	if (mask & 1)
	306	ctrl->vrs[reg] = *vsp++;
	307	mask >>= 1;
	308	reg++;
	309	}
	310	ctrl->vrs[SP] = (unsigned long)vsp;
	311	} else if (insn == 0xb2) {
	312	unsigned long uleb128 = unwind_get_byte(ctrl);
	313
	314	ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
	315	} else {
	316	pr_warning("unwind: Unhandled instruction %02lx\n", insn);
	317	return -URC_FAILURE;
	318	}
	319
	320	pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
	321	ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);
	322
	323	return URC_OK;
	324	}
	325
	326	/*
	327	* Unwind a single frame starting with sp for the symbol at pc. It
	328	* updates the pc and sp with the new values.
	329	*/
	330	int unwind_frame(struct stackframe *frame)
	331	{
	332	unsigned long high, low;
de66a979	333	const struct unwind_idx *idx;
bff595c1 CM	334	struct unwind_ctrl_block ctrl;
	335
	336	/* only go to a higher address on the stack */
	337	low = frame->sp;
d33aadbf	338	high = ALIGN(low, THREAD_SIZE);
bff595c1 CM	339
	340	pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
	341	frame->pc, frame->lr, frame->sp);
	342
	343	if (!kernel_text_address(frame->pc))
	344	return -URC_FAILURE;
	345
	346	idx = unwind_find_idx(frame->pc);
	347	if (!idx) {
	348	pr_warning("unwind: Index not found %08lx\n", frame->pc);
	349	return -URC_FAILURE;
	350	}
	351
	352	ctrl.vrs[FP] = frame->fp;
	353	ctrl.vrs[SP] = frame->sp;
	354	ctrl.vrs[LR] = frame->lr;
	355	ctrl.vrs[PC] = 0;
	356
	357	if (idx->insn == 1)
	358	/* can't unwind */
	359	return -URC_FAILURE;
	360	else if ((idx->insn & 0x80000000) == 0)
	361	/* prel31 to the unwind table */
	362	ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn);
	363	else if ((idx->insn & 0xff000000) == 0x80000000)
	364	/* only personality routine 0 supported in the index */
	365	ctrl.insn = &idx->insn;
	366	else {
	367	pr_warning("unwind: Unsupported personality routine %08lx in the index at %p\n",
	368	idx->insn, idx);
	369	return -URC_FAILURE;
	370	}
	371
	372	/* check the personality routine */
	373	if ((*ctrl.insn & 0xff000000) == 0x80000000) {
	374	ctrl.byte = 2;
	375	ctrl.entries = 1;
	376	} else if ((*ctrl.insn & 0xff000000) == 0x81000000) {
	377	ctrl.byte = 1;
	378	ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16);
	379	} else {
	380	pr_warning("unwind: Unsupported personality routine %08lx at %p\n",
	381	*ctrl.insn, ctrl.insn);
	382	return -URC_FAILURE;
	383	}
	384
	385	while (ctrl.entries > 0) {
c894ed69	386	int urc = unwind_exec_insn(&ctrl);
bff595c1 CM	387	if (urc < 0)
bff595c1 CM	388	return urc;
c894ed69 CM	389	if (ctrl.vrs[SP] < low \|\| ctrl.vrs[SP] >= high)
c894ed69 CM	390	return -URC_FAILURE;
bff595c1 CM	391	}
	392
	393	if (ctrl.vrs[PC] == 0)
	394	ctrl.vrs[PC] = ctrl.vrs[LR];
	395
c894ed69 CM	396	/* check for infinite loop */
	397	if (frame->pc == ctrl.vrs[PC])
	398	return -URC_FAILURE;
	399
bff595c1 CM	400	frame->fp = ctrl.vrs[FP];
	401	frame->sp = ctrl.vrs[SP];
	402	frame->lr = ctrl.vrs[LR];
	403	frame->pc = ctrl.vrs[PC];
	404
	405	return URC_OK;
	406	}
	407
	408	void unwind_backtrace(struct pt_regs regs, struct task_struct tsk)
	409	{
	410	struct stackframe frame;
bff595c1 CM	411	register unsigned long current_sp asm ("sp");
	412
	413	pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
	414
	415	if (!tsk)
	416	tsk = current;
	417
	418	if (regs) {
	419	frame.fp = regs->ARM_fp;
	420	frame.sp = regs->ARM_sp;
	421	frame.lr = regs->ARM_lr;
51d47999 LP	422	/* PC might be corrupted, use LR in that case. */
	423	frame.pc = kernel_text_address(regs->ARM_pc)
	424	? regs->ARM_pc : regs->ARM_lr;
bff595c1 CM	425	} else if (tsk == current) {
	426	frame.fp = (unsigned long)__builtin_frame_address(0);
	427	frame.sp = current_sp;
	428	frame.lr = (unsigned long)__builtin_return_address(0);
	429	frame.pc = (unsigned long)unwind_backtrace;
	430	} else {
	431	/* task blocked in __switch_to */
	432	frame.fp = thread_saved_fp(tsk);
	433	frame.sp = thread_saved_sp(tsk);
	434	/*
	435	* The function calling __switch_to cannot be a leaf function
	436	* so LR is recovered from the stack.
	437	*/
	438	frame.lr = 0;
	439	frame.pc = thread_saved_pc(tsk);
	440	}
	441
bff595c1 CM	442	while (1) {
	443	int urc;
	444	unsigned long where = frame.pc;
	445
	446	urc = unwind_frame(&frame);
	447	if (urc < 0)
	448	break;
	449	dump_backtrace_entry(where, frame.pc, frame.sp - 4);
	450	}
	451	}
	452
	453	struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
	454	unsigned long text_addr,
	455	unsigned long text_size)
	456	{
	457	unsigned long flags;
bff595c1 CM	458	struct unwind_table tab = kmalloc(sizeof(tab), GFP_KERNEL);
	459
	460	pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size,
	461	text_addr, text_size);
	462
	463	if (!tab)
	464	return tab;
	465
de66a979 UKK	466	tab->start = (const struct unwind_idx *)start;
	467	tab->stop = (const struct unwind_idx *)(start + size);
	468	tab->origin = unwind_find_origin(tab->start, tab->stop);
bff595c1 CM	469	tab->begin_addr = text_addr;
	470	tab->end_addr = text_addr + text_size;
	471
bff595c1 CM	472	spin_lock_irqsave(&unwind_lock, flags);
	473	list_add_tail(&tab->list, &unwind_tables);
	474	spin_unlock_irqrestore(&unwind_lock, flags);
	475
	476	return tab;
	477	}
	478
	479	void unwind_table_del(struct unwind_table *tab)
	480	{
	481	unsigned long flags;
	482
	483	if (!tab)
	484	return;
	485
	486	spin_lock_irqsave(&unwind_lock, flags);
	487	list_del(&tab->list);
	488	spin_unlock_irqrestore(&unwind_lock, flags);
	489
	490	kfree(tab);
	491	}