1/*
  2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
  3 *
  4 *   This program is free software; you can redistribute it and/or
  5 *   modify it under the terms of the GNU General Public License
  6 *   as published by the Free Software Foundation, version 2.
  7 *
  8 *   This program is distributed in the hope that it will be useful, but
  9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 11 *   NON INFRINGEMENT.  See the GNU General Public License for
 12 *   more details.
 13 */
 14
 15#ifndef _ASM_TILE_BACKTRACE_H
 16#define _ASM_TILE_BACKTRACE_H
 17
 18#include <linux/types.h>
 19
 20/* Reads 'size' bytes from 'address' and writes the data to 'result'.
 21 * Returns true if successful, else false (e.g. memory not readable).
 22 */
 23typedef bool (*BacktraceMemoryReader)(void *result,
 24				      unsigned long address,
 25				      unsigned int size,
 26				      void *extra);
 27
 28typedef struct {
 29	/* Current PC. */
 30	unsigned long pc;
 31
 32	/* Current stack pointer value. */
 33	unsigned long sp;
 34
 35	/* Current frame pointer value (i.e. caller's stack pointer) */
 36	unsigned long fp;
 37
 38	/* Internal use only: caller's PC for first frame. */
 39	unsigned long initial_frame_caller_pc;
 40
 41	/* Internal use only: callback to read memory. */
 42	BacktraceMemoryReader read_memory_func;
 43
 44	/* Internal use only: arbitrary argument to read_memory_func. */
 45	void *read_memory_func_extra;
 46
 47} BacktraceIterator;
 48
 49
 50typedef enum {
 51
 52	/* We have no idea what the caller's pc is. */
 53	PC_LOC_UNKNOWN,
 54
 55	/* The caller's pc is currently in lr. */
 56	PC_LOC_IN_LR,
 57
 58	/* The caller's pc can be found by dereferencing the caller's sp. */
 59	PC_LOC_ON_STACK
 60
 61} CallerPCLocation;
 62
 63
 64typedef enum {
 65
 66	/* We have no idea what the caller's sp is. */
 67	SP_LOC_UNKNOWN,
 68
 69	/* The caller's sp is currently in r52. */
 70	SP_LOC_IN_R52,
 71
 72	/* The caller's sp can be found by adding a certain constant
 73	 * to the current value of sp.
 74	 */
 75	SP_LOC_OFFSET
 76
 77} CallerSPLocation;
 78
 79
 80/* Bit values ORed into CALLER_* values for info ops. */
 81enum {
 82	/* Setting the low bit on any of these values means the info op
 83	 * applies only to one bundle ago.
 84	 */
 85	ONE_BUNDLE_AGO_FLAG = 1,
 86
 87	/* Setting this bit on a CALLER_SP_* value means the PC is in LR.
 88	 * If not set, PC is on the stack.
 89	 */
 90	PC_IN_LR_FLAG = 2,
 91
 92	/* This many of the low bits of a CALLER_SP_* value are for the
 93	 * flag bits above.
 94	 */
 95	NUM_INFO_OP_FLAGS = 2,
 96
 97	/* We cannot have one in the memory pipe so this is the maximum. */
 98	MAX_INFO_OPS_PER_BUNDLE = 2
 99};
100
101
102/* Internal constants used to define 'info' operands. */
103enum {
104	/* 0 and 1 are reserved, as are all negative numbers. */
105
106	CALLER_UNKNOWN_BASE = 2,
107
108	CALLER_SP_IN_R52_BASE = 4,
109
110	CALLER_SP_OFFSET_BASE = 8,
111};
112
113
114/* Current backtracer state describing where it thinks the caller is. */
115typedef struct {
116	/*
117	 * Public fields
118	 */
119
120	/* How do we find the caller's PC? */
121	CallerPCLocation pc_location : 8;
122
123	/* How do we find the caller's SP? */
124	CallerSPLocation sp_location : 8;
125
126	/* If sp_location == SP_LOC_OFFSET, then caller_sp == sp +
127	 * loc->sp_offset. Else this field is undefined.
128	 */
129	uint16_t sp_offset;
130
131	/* In the most recently visited bundle a terminating bundle? */
132	bool at_terminating_bundle;
133
134	/*
135	 * Private fields
136	 */
137
138	/* Will the forward scanner see someone clobbering sp
139	 * (i.e. changing it with something other than addi sp, sp, N?)
140	 */
141	bool sp_clobber_follows;
142
143	/* Operand to next "visible" info op (no more than one bundle past
144	 * the next terminating bundle), or -32768 if none.
145	 */
146	int16_t next_info_operand;
147
148	/* Is the info of in next_info_op in the very next bundle? */
149	bool is_next_info_operand_adjacent;
150
151} CallerLocation;
152
153extern void backtrace_init(BacktraceIterator *state,
154                          BacktraceMemoryReader read_memory_func,
155                          void *read_memory_func_extra,
156                          unsigned long pc, unsigned long lr,
157                          unsigned long sp, unsigned long r52);
158
159
160extern bool backtrace_next(BacktraceIterator *state);
161
162#endif /* _ASM_TILE_BACKTRACE_H */