[ARM] 5383/2: unwind: Add core support for ARM stack unwinding

ENTRY(_start)

SECTIONS

{

  /DISCARD/ : {

    *(.ARM.exidx*)

    *(.ARM.extab*)

  }

  . = TEXT_START;

  _text = .;

/*

 * arch/arm/include/asm/unwind.h

 *

 * 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

 */

#ifndef __ASM_UNWIND_H

#define __ASM_UNWIND_H

#ifndef __ASSEMBLY__

/* Unwind reason code according the the ARM EABI documents */

enum unwind_reason_code {

	URC_OK = 0,			/* operation completed successfully */

	URC_CONTINUE_UNWIND = 8,

	URC_FAILURE = 9			/* unspecified failure of some kind */

};

struct unwind_idx {

	unsigned long addr;

	unsigned long insn;

};

struct unwind_table {

	struct list_head list;

	struct unwind_idx *start;

	struct unwind_idx *stop;

	unsigned long begin_addr;

	unsigned long end_addr;

};

extern struct unwind_table *unwind_table_add(unsigned long start,

					     unsigned long size,

					     unsigned long text_addr,

					     unsigned long text_size);

extern void unwind_table_del(struct unwind_table *tab);

extern void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk);

#ifdef CONFIG_ARM_UNWIND

extern int __init unwind_init(void);

#else

static inline int __init unwind_init(void)

{

	return 0;

}

#endif

#endif	/* !__ASSEMBLY__ */

#ifdef CONFIG_ARM_UNWIND

#define UNWIND(code...)		code

#else

#define UNWIND(code...)

#endif

#endif	/* __ASM_UNWIND_H */

#include <asm/mach/irq.h>

#include <asm/mach/time.h>

#include <asm/traps.h>

#include <asm/unwind.h>

#include "compat.h"

#include "atags.h"

	struct machine_desc *mdesc;

	char *from = default_command_line;

	unwind_init();

	setup_processor();

	mdesc = setup_machine(machine_arch_type);

	machine_name = mdesc->name;

#include <asm/system.h>

#include <asm/unistd.h>

#include <asm/traps.h>

#include <asm/unwind.h>

#include "ptrace.h"

#include "signal.h"

		dump_mem("Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));

}

#ifndef CONFIG_ARM_UNWIND

/*

 * Stack pointers should always be within the kernels view of

 * physical memory.  If it is not there, then we can't dump

	return 0;

}

#endif

/*

 * Dump out the contents of some memory nicely...

	set_fs(fs);

}

#ifdef CONFIG_ARM_UNWIND

static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)

{

	unwind_backtrace(regs, tsk);

}

#else

static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)

{

	unsigned int fp, mode;

	if (ok)

		c_backtrace(fp, mode);

}

#endif

void dump_stack(void)

{

/*

 * 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

 */

#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 {

	FP = 11,

	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) {

		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;

		if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= high)

			return -URC_FAILURE;

		urc = unwind_exec_insn(&ctrl);

		if (urc < 0)

			return urc;

	}

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

		ctrl.vrs[PC] = ctrl.vrs[LR];

	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;

	unsigned long high, low;

	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;

		frame.pc = regs->ARM_pc;

	} 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);

	}

	low = frame.sp & ~(THREAD_SIZE - 1);

	high = low + THREAD_SIZE;

	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;

}