[net-next-2.6.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/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
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>
	41	#include <linux/init.h>
	42	#include <linux/module.h>
	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 */
	70	unsigned long insn; / pointer to the current instructions word */
	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
	86	extern struct unwind_idx __start_unwind_idx[];
	87	extern struct unwind_idx __stop_unwind_idx[];
	88
	89	static DEFINE_SPINLOCK(unwind_lock);
	90	static LIST_HEAD(unwind_tables);
	91
	92	/* Convert a prel31 symbol to an absolute address */
	93	#define prel31_to_addr(ptr) \
	94	({ \
	95	/* sign-extend to 32 bits */ \
	96	long offset = (((long)*(ptr)) << 1) >> 1; \
	97	(unsigned long)(ptr) + offset; \
	98	})
	99
	100	/*
	101	* Binary search in the unwind index. The entries entries are
	102	* guaranteed to be sorted in ascending order by the linker.
	103	*/
	104	static struct unwind_idx *search_index(unsigned long addr,
	105	struct unwind_idx *first,
	106	struct unwind_idx *last)
	107	{
	108	pr_debug("%s(%08lx, %p, %p)\n", __func__, addr, first, last);
	109
	110	if (addr < first->addr) {
	111	pr_warning("unwind: Unknown symbol address %08lx\n", addr);
	112	return NULL;
	113	} else if (addr >= last->addr)
	114	return last;
	115
	116	while (first < last - 1) {
	117	struct unwind_idx *mid = first + ((last - first + 1) >> 1);
	118
	119	if (addr < mid->addr)
	120	last = mid;
	121	else
	122	first = mid;
	123	}
	124
	125	return first;
	126	}
	127
	128	static struct unwind_idx *unwind_find_idx(unsigned long addr)
	129	{
	130	struct unwind_idx *idx = NULL;
	131	unsigned long flags;
	132
	133	pr_debug("%s(%08lx)\n", __func__, addr);
	134
	135	if (core_kernel_text(addr))
	136	/* main unwind table */
	137	idx = search_index(addr, __start_unwind_idx,
	138	__stop_unwind_idx - 1);
	139	else {
	140	/* module unwind tables */
	141	struct unwind_table *table;
	142
	143	spin_lock_irqsave(&unwind_lock, flags);
	144	list_for_each_entry(table, &unwind_tables, list) {
145	if (addr >= table->begin_addr &&
146	addr < table->end_addr) {
147	idx = search_index(addr, table->start,
148	table->stop - 1);
149	break;
150	}
151	}
152	spin_unlock_irqrestore(&unwind_lock, flags);
153	}
154
155	pr_debug("%s: idx = %p\n", __func__, idx);
156	return idx;
157	}
158
159	static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl)
160	{
161	unsigned long ret;
162
163	if (ctrl->entries <= 0) {
164	pr_warning("unwind: Corrupt unwind table\n");
165	return 0;
166	}
167
168	ret = (ctrl->insn >> (ctrl->byte 8)) & 0xff;
169
170	if (ctrl->byte == 0) {
171	ctrl->insn++;
172	ctrl->entries--;
173	ctrl->byte = 3;
174	} else
175	ctrl->byte--;
176
177	return ret;
178	}
179
180	/*
181	* Execute the current unwind instruction.
182	*/
183	static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
184	{
185	unsigned long insn = unwind_get_byte(ctrl);
186
187	pr_debug("%s: insn = %08lx\n", __func__, insn);
188
189	if ((insn & 0xc0) == 0x00)
190	ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4;
191	else if ((insn & 0xc0) == 0x40)
192	ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
193	else if ((insn & 0xf0) == 0x80) {
194	unsigned long mask;
195	unsigned long vsp = (unsigned long )ctrl->vrs[SP];
196	int load_sp, reg = 4;
197
198	insn = (insn << 8) \| unwind_get_byte(ctrl);
199	mask = insn & 0x0fff;
200	if (mask == 0) {
201	pr_warning("unwind: 'Refuse to unwind' instruction %04lx\n",
202	insn);
203	return -URC_FAILURE;
204	}
205
206	/* pop R4-R15 according to mask */
207	load_sp = mask & (1 << (13 - 4));
208	while (mask) {
209	if (mask & 1)
210	ctrl->vrs[reg] = *vsp++;
211	mask >>= 1;
212	reg++;
213	}
214	if (!load_sp)
215	ctrl->vrs[SP] = (unsigned long)vsp;
216	} else if ((insn & 0xf0) == 0x90 &&
217	(insn & 0x0d) != 0x0d)
218	ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
219	else if ((insn & 0xf0) == 0xa0) {
220	unsigned long vsp = (unsigned long )ctrl->vrs[SP];
221	int reg;
222
223	/* pop R4-R[4+bbb] */
224	for (reg = 4; reg <= 4 + (insn & 7); reg++)
225	ctrl->vrs[reg] = *vsp++;
226	if (insn & 0x80)
227	ctrl->vrs[14] = *vsp++;
228	ctrl->vrs[SP] = (unsigned long)vsp;
229	} else if (insn == 0xb0) {
c894ed69 CM	230	if (ctrl->vrs[PC] == 0)
c894ed69 CM	231	ctrl->vrs[PC] = ctrl->vrs[LR];
bff595c1 CM	232	/* no further processing */
	233	ctrl->entries = 0;
	234	} else if (insn == 0xb1) {
	235	unsigned long mask = unwind_get_byte(ctrl);
	236	unsigned long vsp = (unsigned long )ctrl->vrs[SP];
	237	int reg = 0;
	238
	239	if (mask == 0 \|\| mask & 0xf0) {
	240	pr_warning("unwind: Spare encoding %04lx\n",
	241	(insn << 8) \| mask);
	242	return -URC_FAILURE;
	243	}
	244
	245	/* pop R0-R3 according to mask */
	246	while (mask) {
	247	if (mask & 1)
	248	ctrl->vrs[reg] = *vsp++;
	249	mask >>= 1;
	250	reg++;
	251	}
	252	ctrl->vrs[SP] = (unsigned long)vsp;
	253	} else if (insn == 0xb2) {
	254	unsigned long uleb128 = unwind_get_byte(ctrl);
	255
	256	ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
	257	} else {
	258	pr_warning("unwind: Unhandled instruction %02lx\n", insn);
	259	return -URC_FAILURE;
	260	}
	261
	262	pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
	263	ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);
	264
	265	return URC_OK;
	266	}
	267
	268	/*
	269	* Unwind a single frame starting with sp for the symbol at pc. It
	270	* updates the pc and sp with the new values.
	271	*/
	272	int unwind_frame(struct stackframe *frame)
	273	{
	274	unsigned long high, low;
	275	struct unwind_idx *idx;
	276	struct unwind_ctrl_block ctrl;
	277
	278	/* only go to a higher address on the stack */
	279	low = frame->sp;
	280	high = ALIGN(low, THREAD_SIZE) + THREAD_SIZE;
	281
	282	pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
	283	frame->pc, frame->lr, frame->sp);
	284
	285	if (!kernel_text_address(frame->pc))
	286	return -URC_FAILURE;
	287
	288	idx = unwind_find_idx(frame->pc);
	289	if (!idx) {
	290	pr_warning("unwind: Index not found %08lx\n", frame->pc);
	291	return -URC_FAILURE;
	292	}
	293
	294	ctrl.vrs[FP] = frame->fp;
	295	ctrl.vrs[SP] = frame->sp;
296	ctrl.vrs[LR] = frame->lr;
297	ctrl.vrs[PC] = 0;
298
299	if (idx->insn == 1)
300	/* can't unwind */
301	return -URC_FAILURE;
302	else if ((idx->insn & 0x80000000) == 0)
303	/* prel31 to the unwind table */
304	ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn);
305	else if ((idx->insn & 0xff000000) == 0x80000000)
306	/* only personality routine 0 supported in the index */
307	ctrl.insn = &idx->insn;
308	else {
309	pr_warning("unwind: Unsupported personality routine %08lx in the index at %p\n",
310	idx->insn, idx);
311	return -URC_FAILURE;
312	}
313
314	/* check the personality routine */
315	if ((*ctrl.insn & 0xff000000) == 0x80000000) {
316	ctrl.byte = 2;
317	ctrl.entries = 1;
318	} else if ((*ctrl.insn & 0xff000000) == 0x81000000) {
319	ctrl.byte = 1;
320	ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16);
321	} else {
322	pr_warning("unwind: Unsupported personality routine %08lx at %p\n",
323	*ctrl.insn, ctrl.insn);
324	return -URC_FAILURE;
325	}
326
327	while (ctrl.entries > 0) {
c894ed69	328	int urc = unwind_exec_insn(&ctrl);
bff595c1 CM	329	if (urc < 0)
bff595c1 CM	330	return urc;
c894ed69 CM	331	if (ctrl.vrs[SP] < low \|\| ctrl.vrs[SP] >= high)
c894ed69 CM	332	return -URC_FAILURE;
bff595c1 CM	333	}
	334
	335	if (ctrl.vrs[PC] == 0)
	336	ctrl.vrs[PC] = ctrl.vrs[LR];
	337
c894ed69 CM	338	/* check for infinite loop */
	339	if (frame->pc == ctrl.vrs[PC])
	340	return -URC_FAILURE;
	341
bff595c1 CM	342	frame->fp = ctrl.vrs[FP];
	343	frame->sp = ctrl.vrs[SP];
	344	frame->lr = ctrl.vrs[LR];
	345	frame->pc = ctrl.vrs[PC];
	346
	347	return URC_OK;
	348	}
	349
	350	void unwind_backtrace(struct pt_regs regs, struct task_struct tsk)
	351	{
	352	struct stackframe frame;
bff595c1 CM	353	register unsigned long current_sp asm ("sp");
	354
	355	pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
	356
	357	if (!tsk)
	358	tsk = current;
	359
	360	if (regs) {
	361	frame.fp = regs->ARM_fp;
	362	frame.sp = regs->ARM_sp;
	363	frame.lr = regs->ARM_lr;
51d47999 LP	364	/* PC might be corrupted, use LR in that case. */
	365	frame.pc = kernel_text_address(regs->ARM_pc)
	366	? regs->ARM_pc : regs->ARM_lr;
bff595c1 CM	367	} else if (tsk == current) {
	368	frame.fp = (unsigned long)__builtin_frame_address(0);
	369	frame.sp = current_sp;
	370	frame.lr = (unsigned long)__builtin_return_address(0);
	371	frame.pc = (unsigned long)unwind_backtrace;
	372	} else {
	373	/* task blocked in __switch_to */
	374	frame.fp = thread_saved_fp(tsk);
	375	frame.sp = thread_saved_sp(tsk);
	376	/*
	377	* The function calling __switch_to cannot be a leaf function
	378	* so LR is recovered from the stack.
	379	*/
	380	frame.lr = 0;
	381	frame.pc = thread_saved_pc(tsk);
	382	}
	383
bff595c1 CM	384	while (1) {
	385	int urc;
	386	unsigned long where = frame.pc;
	387
	388	urc = unwind_frame(&frame);
	389	if (urc < 0)
	390	break;
	391	dump_backtrace_entry(where, frame.pc, frame.sp - 4);
	392	}
	393	}
	394
	395	struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
	396	unsigned long text_addr,
	397	unsigned long text_size)
	398	{
	399	unsigned long flags;
	400	struct unwind_idx *idx;
	401	struct unwind_table tab = kmalloc(sizeof(tab), GFP_KERNEL);
	402
	403	pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size,
	404	text_addr, text_size);
	405
	406	if (!tab)
	407	return tab;
	408
	409	tab->start = (struct unwind_idx *)start;
	410	tab->stop = (struct unwind_idx *)(start + size);
	411	tab->begin_addr = text_addr;
	412	tab->end_addr = text_addr + text_size;
	413
	414	/* Convert the symbol addresses to absolute values */
	415	for (idx = tab->start; idx < tab->stop; idx++)
	416	idx->addr = prel31_to_addr(&idx->addr);
	417
	418	spin_lock_irqsave(&unwind_lock, flags);
	419	list_add_tail(&tab->list, &unwind_tables);
	420	spin_unlock_irqrestore(&unwind_lock, flags);
	421
	422	return tab;
	423	}
	424
	425	void unwind_table_del(struct unwind_table *tab)
	426	{
	427	unsigned long flags;
	428
	429	if (!tab)
	430	return;
	431
	432	spin_lock_irqsave(&unwind_lock, flags);
	433	list_del(&tab->list);
	434	spin_unlock_irqrestore(&unwind_lock, flags);
	435
	436	kfree(tab);
	437	}
	438
	439	int __init unwind_init(void)
	440	{
	441	struct unwind_idx *idx;
	442
	443	/* Convert the symbol addresses to absolute values */
	444	for (idx = __start_unwind_idx; idx < __stop_unwind_idx; idx++)
	445	idx->addr = prel31_to_addr(&idx->addr);
	446
	447	pr_debug("unwind: ARM stack unwinding initialised\n");
448
449	return 0;
450	}