path: root/kernel/unwind.c

/*
 * Copyright (C) 2002-2006 Novell, Inc.
 *	Jan Beulich <jbeulich@novell.com>
 * This code is released under version 2 of the GNU GPL.
 *
 * A simple API for unwinding kernel stacks.  This is used for
 * debugging and error reporting purposes.  The kernel doesn't need
 * full-blown stack unwinding with all the bells and whistles, so there
 * is not much point in implementing the full Dwarf2 unwind API.
 */

#include <linux/unwind.h>
#include <linux/module.h>
#include <linux/bootmem.h>
#include <linux/sort.h>
#include <linux/stop_machine.h>
#include <linux/uaccess.h>
#include <asm/sections.h>
#include <asm/uaccess.h>
#include <asm/unaligned.h>

extern const char __start_unwind[], __end_unwind[];
extern const u8 __start_unwind_hdr[], __end_unwind_hdr[];

#define MAX_STACK_DEPTH 8

#define EXTRA_INFO(f) { \
		BUILD_BUG_ON_ZERO(offsetof(struct unwind_frame_info, f) \
		                  % FIELD_SIZEOF(struct unwind_frame_info, f)) \
		+ offsetof(struct unwind_frame_info, f) \
		  / FIELD_SIZEOF(struct unwind_frame_info, f), \
		FIELD_SIZEOF(struct unwind_frame_info, f) \
	}
#define PTREGS_INFO(f) EXTRA_INFO(regs.f)

static const struct {
	unsigned offs:BITS_PER_LONG / 2;
	unsigned width:BITS_PER_LONG / 2;
} reg_info[] = {
	UNW_REGISTER_INFO
};

#undef PTREGS_INFO
#undef EXTRA_INFO

#ifndef REG_INVALID
#define REG_INVALID(r) (reg_info[r].width == 0)
#endif

#define DW_CFA_nop                          0x00
#define DW_CFA_set_loc                      0x01
#define DW_CFA_advance_loc1                 0x02
#define DW_CFA_advance_loc2                 0x03
#define DW_CFA_advance_loc4                 0x04
#define DW_CFA_offset_extended              0x05
#define DW_CFA_restore_extended             0x06
#define DW_CFA_undefined                    0x07
#define DW_CFA_same_value                   0x08
#define DW_CFA_register                     0x09
#define DW_CFA_remember_state               0x0a
#define DW_CFA_restore_state                0x0b
#define DW_CFA_def_cfa                      0x0c
#define DW_CFA_def_cfa_register             0x0d
#define DW_CFA_def_cfa_offset               0x0e
#define DW_CFA_def_cfa_expression           0x0f
#define DW_CFA_expression                   0x10
#define DW_CFA_offset_extended_sf           0x11
#define DW_CFA_def_cfa_sf                   0x12
#define DW_CFA_def_cfa_offset_sf            0x13
#define DW_CFA_val_offset                   0x14
#define DW_CFA_val_offset_sf                0x15
#define DW_CFA_val_expression               0x16
#define DW_CFA_lo_user                      0x1c
#define DW_CFA_GNU_window_save              0x2d
#define DW_CFA_GNU_args_size                0x2e
#define DW_CFA_GNU_negative_offset_extended 0x2f
#define DW_CFA_hi_user                      0x3f

#define DW_EH_PE_FORM     0x07
#define DW_EH_PE_native   0x00
#define DW_EH_PE_leb128   0x01
#define DW_EH_PE_data2    0x02
#define DW_EH_PE_data4    0x03
#define DW_EH_PE_data8    0x04
#define DW_EH_PE_signed   0x08
#define DW_EH_PE_ADJUST   0x70
#define DW_EH_PE_abs      0x00
#define DW_EH_PE_pcrel    0x10
#define DW_EH_PE_textrel  0x20
#define DW_EH_PE_datarel  0x30
#define DW_EH_PE_funcrel  0x40
#define DW_EH_PE_aligned  0x50
#define DW_EH_PE_indirect 0x80
#define DW_EH_PE_omit     0xff

typedef unsigned long uleb128_t;
typedef   signed long sleb128_t;
#define sleb128abs __builtin_labs

static struct unwind_table {
	struct {
		unsigned long pc;
		unsigned long range;
	} core, init;
	const void *address;
	unsigned long size;
	const unsigned char *header;
	unsigned long hdrsz;
	struct unwind_table *link;
	const char *name;
} root_table;

struct unwind_item {
	enum item_location {
		Nowhere,
		Memory,
		Register,
		Value
	} where;
	uleb128_t value;
};

struct unwind_state {
	uleb128_t loc, org;
	const u8 *cieStart, *cieEnd;
	uleb128_t codeAlign;
	sleb128_t dataAlign;
	struct cfa {
		uleb128_t reg, offs;
	} cfa;
	struct