[deliverable/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
 */

#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

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.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 */
	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 struct unwind_idx __start_unwind_idx[];
extern 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 entries are
 * guaranteed to be sorted in ascending order by the linker.
 */
static struct unwind_idx *search_index(unsigned long addr,
				       struct unwind_idx *first,
				       struct unwind_idx *last)
{
	pr_debug("%s(%08lx, %p, %p)\n", __func__, addr, first, last);

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

	while (first < last - 1) {
		struct unwind_idx *mid = first + ((last - first + 1) >> 1);

		if (addr < mid->addr)
			last = mid;
		else
			first = mid;
	}

	return first;
}

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

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

	if (core_kernel_text(addr))
		/* main unwind table */
		idx = search_index(addr, __start_unwind_idx,
				   __stop_unwind_idx - 1);
	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->stop - 1);
				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;
	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) + 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_idx *idx;
	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 = (struct unwind_idx *)start;
	tab->stop = (struct unwind_idx *)(start + size);
	tab->begin_addr = text_addr;
	tab->end_addr = text_addr + text_size;

	/* Convert the symbol addresses to absolute values */
	for (idx = tab->start; idx < tab->stop; idx++)
		idx->addr = prel31_to_addr(&idx->addr);

	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);
}

int __init unwind_init(void)
{
	struct unwind_idx *idx;

	/* Convert the symbol addresses to absolute values */
	for (idx = __start_unwind_idx; idx < __stop_unwind_idx; idx++)
		idx->addr = prel31_to_addr(&idx->addr);

	pr_debug("unwind: ARM stack unwinding initialised\n");

	return 0;
}
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
6603a4fd CS	29	#if !defined (__ARM_EABI__)
	30	#warning Your compiler does not have EABI support.
	31	#warning ARM unwind is known to compile only with EABI compilers.
	32	#warning Change compiler or disable ARM_UNWIND option.
	33	#elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2)
	34	#warning Your compiler is too buggy; it is known to not compile ARM unwind support.
	35	#warning Change compiler or disable ARM_UNWIND option.
	36	#endif
	37
bff595c1 CM	38	#include <linux/kernel.h>
	39	#include <linux/init.h>
	40	#include <linux/module.h>
	41	#include <linux/sched.h>
	42	#include <linux/slab.h>
	43	#include <linux/spinlock.h>
	44	#include <linux/list.h>
	45
	46	#include <asm/stacktrace.h>
	47	#include <asm/traps.h>
	48	#include <asm/unwind.h>
	49
	50	/* Dummy functions to avoid linker complaints */
	51	void __aeabi_unwind_cpp_pr0(void)
	52	{
	53	};
	54	EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0);
	55
	56	void __aeabi_unwind_cpp_pr1(void)
	57	{
	58	};
	59	EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1);
	60
	61	void __aeabi_unwind_cpp_pr2(void)
	62	{
	63	};
	64	EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
	65
	66	struct unwind_ctrl_block {
	67	unsigned long vrs[16]; /* virtual register set */
	68	unsigned long insn; / pointer to the current instructions word */
	69	int entries; /* number of entries left to interpret */
	70	int byte; /* current byte number in the instructions word */
	71	};
	72
	73	enum regs {
b86040a5 CM	74	#ifdef CONFIG_THUMB2_KERNEL
	75	FP = 7,
	76	#else
bff595c1	77	FP = 11,
b86040a5	78	#endif
bff595c1 CM	79	SP = 13,
	80	LR = 14,
	81	PC = 15
	82	};
	83
	84	extern struct unwind_idx __start_unwind_idx[];
	85	extern struct unwind_idx __stop_unwind_idx[];
	86
	87	static DEFINE_SPINLOCK(unwind_lock);
	88	static LIST_HEAD(unwind_tables);
	89
	90	/* Convert a prel31 symbol to an absolute address */
	91	#define prel31_to_addr(ptr) \
	92	({ \
	93	/* sign-extend to 32 bits */ \
	94	long offset = (((long)*(ptr)) << 1) >> 1; \
	95	(unsigned long)(ptr) + offset; \
	96	})
	97
	98	/*
	99	* Binary search in the unwind index. The entries entries are
	100	* guaranteed to be sorted in ascending order by the linker.
	101	*/
	102	static struct unwind_idx *search_index(unsigned long addr,
	103	struct unwind_idx *first,
	104	struct unwind_idx *last)
	105	{
	106	pr_debug("%s(%08lx, %p, %p)\n", __func__, addr, first, last);
	107
	108	if (addr < first->addr) {
	109	pr_warning("unwind: Unknown symbol address %08lx\n", addr);
	110	return NULL;
	111	} else if (addr >= last->addr)
	112	return last;
	113
	114	while (first < last - 1) {
	115	struct unwind_idx *mid = first + ((last - first + 1) >> 1);
	116
	117	if (addr < mid->addr)
	118	last = mid;
	119	else
	120	first = mid;
	121	}
	122
	123	return first;
	124	}
	125
	126	static struct unwind_idx *unwind_find_idx(unsigned long addr)
	127	{
	128	struct unwind_idx *idx = NULL;
	129	unsigned long flags;
	130
	131	pr_debug("%s(%08lx)\n", __func__, addr);
	132
	133	if (core_kernel_text(addr))
	134	/* main unwind table */
	135	idx = search_index(addr, __start_unwind_idx,
	136	__stop_unwind_idx - 1);
	137	else {
	138	/* module unwind tables */
	139	struct unwind_table *table;
	140
	141	spin_lock_irqsave(&unwind_lock, flags);
	142	list_for_each_entry(table, &unwind_tables, list) {
143	if (addr >= table->begin_addr &&
144	addr < table->end_addr) {
145	idx = search_index(addr, table->start,
146	table->stop - 1);
147	break;
148	}
149	}
150	spin_unlock_irqrestore(&unwind_lock, flags);
151	}
152
153	pr_debug("%s: idx = %p\n", __func__, idx);
154	return idx;
155	}
156
157	static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl)
158	{
159	unsigned long ret;
160
161	if (ctrl->entries <= 0) {
162	pr_warning("unwind: Corrupt unwind table\n");
163	return 0;
164	}
165
166	ret = (ctrl->insn >> (ctrl->byte 8)) & 0xff;
167
168	if (ctrl->byte == 0) {
169	ctrl->insn++;
170	ctrl->entries--;
171	ctrl->byte = 3;
172	} else
173	ctrl->byte--;
174
175	return ret;
176	}
177
178	/*
179	* Execute the current unwind instruction.
180	*/
181	static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
182	{
183	unsigned long insn = unwind_get_byte(ctrl);
184
185	pr_debug("%s: insn = %08lx\n", __func__, insn);
186
187	if ((insn & 0xc0) == 0x00)
188	ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4;
189	else if ((insn & 0xc0) == 0x40)
190	ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
191	else if ((insn & 0xf0) == 0x80) {
192	unsigned long mask;
193	unsigned long vsp = (unsigned long )ctrl->vrs[SP];
194	int load_sp, reg = 4;
195
196	insn = (insn << 8) \| unwind_get_byte(ctrl);
197	mask = insn & 0x0fff;
198	if (mask == 0) {
199	pr_warning("unwind: 'Refuse to unwind' instruction %04lx\n",
200	insn);
201	return -URC_FAILURE;
202	}
203
204	/* pop R4-R15 according to mask */
205	load_sp = mask & (1 << (13 - 4));
206	while (mask) {
207	if (mask & 1)
208	ctrl->vrs[reg] = *vsp++;
209	mask >>= 1;
210	reg++;
211	}
212	if (!load_sp)
213	ctrl->vrs[SP] = (unsigned long)vsp;
214	} else if ((insn & 0xf0) == 0x90 &&
215	(insn & 0x0d) != 0x0d)
216	ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
217	else if ((insn & 0xf0) == 0xa0) {
218	unsigned long vsp = (unsigned long )ctrl->vrs[SP];
219	int reg;
220
221	/* pop R4-R[4+bbb] */
222	for (reg = 4; reg <= 4 + (insn & 7); reg++)
223	ctrl->vrs[reg] = *vsp++;
224	if (insn & 0x80)
225	ctrl->vrs[14] = *vsp++;
226	ctrl->vrs[SP] = (unsigned long)vsp;
227	} else if (insn == 0xb0) {
c894ed69 CM	228	if (ctrl->vrs[PC] == 0)
c894ed69 CM	229	ctrl->vrs[PC] = ctrl->vrs[LR];
bff595c1 CM	230	/* no further processing */
	231	ctrl->entries = 0;
	232	} else if (insn == 0xb1) {
	233	unsigned long mask = unwind_get_byte(ctrl);
	234	unsigned long vsp = (unsigned long )ctrl->vrs[SP];
	235	int reg = 0;
	236
	237	if (mask == 0 \|\| mask & 0xf0) {
	238	pr_warning("unwind: Spare encoding %04lx\n",
	239	(insn << 8) \| mask);
	240	return -URC_FAILURE;
	241	}
	242
	243	/* pop R0-R3 according to mask */
	244	while (mask) {
	245	if (mask & 1)
	246	ctrl->vrs[reg] = *vsp++;
	247	mask >>= 1;
	248	reg++;
	249	}
	250	ctrl->vrs[SP] = (unsigned long)vsp;
	251	} else if (insn == 0xb2) {
	252	unsigned long uleb128 = unwind_get_byte(ctrl);
	253
	254	ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
	255	} else {
	256	pr_warning("unwind: Unhandled instruction %02lx\n", insn);
	257	return -URC_FAILURE;
	258	}
	259
	260	pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
	261	ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);
	262
	263	return URC_OK;
	264	}
	265
	266	/*
	267	* Unwind a single frame starting with sp for the symbol at pc. It
	268	* updates the pc and sp with the new values.
	269	*/
	270	int unwind_frame(struct stackframe *frame)
	271	{
	272	unsigned long high, low;
	273	struct unwind_idx *idx;
	274	struct unwind_ctrl_block ctrl;
	275
	276	/* only go to a higher address on the stack */
	277	low = frame->sp;
	278	high = ALIGN(low, THREAD_SIZE) + THREAD_SIZE;
	279
	280	pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
	281	frame->pc, frame->lr, frame->sp);
	282
	283	if (!kernel_text_address(frame->pc))
	284	return -URC_FAILURE;
	285
	286	idx = unwind_find_idx(frame->pc);
	287	if (!idx) {
	288	pr_warning("unwind: Index not found %08lx\n", frame->pc);
	289	return -URC_FAILURE;
	290	}
	291
	292	ctrl.vrs[FP] = frame->fp;
	293	ctrl.vrs[SP] = frame->sp;
294	ctrl.vrs[LR] = frame->lr;
295	ctrl.vrs[PC] = 0;
296
297	if (idx->insn == 1)
298	/* can't unwind */
299	return -URC_FAILURE;
300	else if ((idx->insn & 0x80000000) == 0)
301	/* prel31 to the unwind table */
302	ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn);
303	else if ((idx->insn & 0xff000000) == 0x80000000)
304	/* only personality routine 0 supported in the index */
305	ctrl.insn = &idx->insn;
306	else {
307	pr_warning("unwind: Unsupported personality routine %08lx in the index at %p\n",
308	idx->insn, idx);
309	return -URC_FAILURE;
310	}
311
312	/* check the personality routine */
313	if ((*ctrl.insn & 0xff000000) == 0x80000000) {
314	ctrl.byte = 2;
315	ctrl.entries = 1;
316	} else if ((*ctrl.insn & 0xff000000) == 0x81000000) {
317	ctrl.byte = 1;
318	ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16);
319	} else {
320	pr_warning("unwind: Unsupported personality routine %08lx at %p\n",
321	*ctrl.insn, ctrl.insn);
322	return -URC_FAILURE;
323	}
324
325	while (ctrl.entries > 0) {
c894ed69	326	int urc = unwind_exec_insn(&ctrl);
bff595c1 CM	327	if (urc < 0)
bff595c1 CM	328	return urc;
c894ed69 CM	329	if (ctrl.vrs[SP] < low \|\| ctrl.vrs[SP] >= high)
c894ed69 CM	330	return -URC_FAILURE;
bff595c1 CM	331	}
	332
	333	if (ctrl.vrs[PC] == 0)
	334	ctrl.vrs[PC] = ctrl.vrs[LR];
	335
c894ed69 CM	336	/* check for infinite loop */
	337	if (frame->pc == ctrl.vrs[PC])
	338	return -URC_FAILURE;
	339
bff595c1 CM	340	frame->fp = ctrl.vrs[FP];
	341	frame->sp = ctrl.vrs[SP];
	342	frame->lr = ctrl.vrs[LR];
	343	frame->pc = ctrl.vrs[PC];
	344
	345	return URC_OK;
	346	}
	347
	348	void unwind_backtrace(struct pt_regs regs, struct task_struct tsk)
	349	{
	350	struct stackframe frame;
bff595c1 CM	351	register unsigned long current_sp asm ("sp");
	352
	353	pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
	354
	355	if (!tsk)
	356	tsk = current;
	357
	358	if (regs) {
	359	frame.fp = regs->ARM_fp;
	360	frame.sp = regs->ARM_sp;
	361	frame.lr = regs->ARM_lr;
51d47999 LP	362	/* PC might be corrupted, use LR in that case. */
	363	frame.pc = kernel_text_address(regs->ARM_pc)
	364	? regs->ARM_pc : regs->ARM_lr;
bff595c1 CM	365	} else if (tsk == current) {
	366	frame.fp = (unsigned long)__builtin_frame_address(0);
	367	frame.sp = current_sp;
	368	frame.lr = (unsigned long)__builtin_return_address(0);
	369	frame.pc = (unsigned long)unwind_backtrace;
	370	} else {
	371	/* task blocked in __switch_to */
	372	frame.fp = thread_saved_fp(tsk);
	373	frame.sp = thread_saved_sp(tsk);
	374	/*
	375	* The function calling __switch_to cannot be a leaf function
	376	* so LR is recovered from the stack.
	377	*/
	378	frame.lr = 0;
	379	frame.pc = thread_saved_pc(tsk);
	380	}
	381
bff595c1 CM	382	while (1) {
	383	int urc;
	384	unsigned long where = frame.pc;
	385
	386	urc = unwind_frame(&frame);
	387	if (urc < 0)
	388	break;
	389	dump_backtrace_entry(where, frame.pc, frame.sp - 4);
	390	}
	391	}
	392
	393	struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
	394	unsigned long text_addr,
	395	unsigned long text_size)
	396	{
	397	unsigned long flags;
	398	struct unwind_idx *idx;
	399	struct unwind_table tab = kmalloc(sizeof(tab), GFP_KERNEL);
	400
	401	pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size,
	402	text_addr, text_size);
	403
	404	if (!tab)
	405	return tab;
	406
	407	tab->start = (struct unwind_idx *)start;
	408	tab->stop = (struct unwind_idx *)(start + size);
	409	tab->begin_addr = text_addr;
	410	tab->end_addr = text_addr + text_size;
	411
	412	/* Convert the symbol addresses to absolute values */
	413	for (idx = tab->start; idx < tab->stop; idx++)
	414	idx->addr = prel31_to_addr(&idx->addr);
	415
	416	spin_lock_irqsave(&unwind_lock, flags);
	417	list_add_tail(&tab->list, &unwind_tables);
	418	spin_unlock_irqrestore(&unwind_lock, flags);
	419
	420	return tab;
	421	}
	422
	423	void unwind_table_del(struct unwind_table *tab)
	424	{
	425	unsigned long flags;
	426
	427	if (!tab)
	428	return;
	429
	430	spin_lock_irqsave(&unwind_lock, flags);
	431	list_del(&tab->list);
	432	spin_unlock_irqrestore(&unwind_lock, flags);
	433
	434	kfree(tab);
	435	}
	436
	437	int __init unwind_init(void)
	438	{
	439	struct unwind_idx *idx;
	440
	441	/* Convert the symbol addresses to absolute values */
	442	for (idx = __start_unwind_idx; idx < __stop_unwind_idx; idx++)
	443	idx->addr = prel31_to_addr(&idx->addr);
	444
	445	pr_debug("unwind: ARM stack unwinding initialised\n");
446
447	return 0;
448	}