LXR linux/arch/tile/include/asm/backtrace.h

   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 */
 163