release/src-rt-6.x.4708/linux/linux-2.6.36/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 _TILE_BACKTRACE_H
  16 #define _TILE_BACKTRACE_H
  17
  18
  19
  20 #include <linux/types.h>
  21
  22 #include <arch/chip.h>
  23
  24 #if defined(__tile__)
  25 typedef unsigned long VirtualAddress;
  26 #elif CHIP_VA_WIDTH() > 32
  27 typedef unsigned long long VirtualAddress;
  28 #else
  29 typedef unsigned int VirtualAddress;
  30 #endif
  31
  32
  33 /** Reads 'size' bytes from 'address' and writes the data to 'result'.
  34  * Returns true if successful, else false (e.g. memory not readable).
  35  */
  36 typedef bool (*BacktraceMemoryReader)(void *result,
  37                                       VirtualAddress address,
  38                                       unsigned int size,
  39                                       void *extra);
  40
  41 typedef struct {
  42         /** Current PC. */
  43         VirtualAddress pc;
  44
  45         /** Current stack pointer value. */
  46         VirtualAddress sp;
  47
  48         /** Current frame pointer value (i.e. caller's stack pointer) */
  49         VirtualAddress fp;
  50
  51         /** Internal use only: caller's PC for first frame. */
  52         VirtualAddress initial_frame_caller_pc;
  53
  54         /** Internal use only: callback to read memory. */
  55         BacktraceMemoryReader read_memory_func;
  56
  57         /** Internal use only: arbitrary argument to read_memory_func. */
  58         void *read_memory_func_extra;
  59
  60 } BacktraceIterator;
  61
  62
  63 /** Initializes a backtracer to start from the given location.
  64  *
  65  * If the frame pointer cannot be determined it is set to -1.
  66  *
  67  * @param state The state to be filled in.
  68  * @param read_memory_func A callback that reads memory. If NULL, a default
  69  *        value is provided.
  70  * @param read_memory_func_extra An arbitrary argument to read_memory_func.
  71  * @param pc The current PC.
  72  * @param lr The current value of the 'lr' register.
  73  * @param sp The current value of the 'sp' register.
  74  * @param r52 The current value of the 'r52' register.
  75  */
  76 extern void backtrace_init(BacktraceIterator *state,
  77                            BacktraceMemoryReader read_memory_func,
  78                            void *read_memory_func_extra,
  79                            VirtualAddress pc, VirtualAddress lr,
  80                            VirtualAddress sp, VirtualAddress r52);
  81
  82
  83 /** Advances the backtracing state to the calling frame, returning
  84  * true iff successful.
  85  */
  86 extern bool backtrace_next(BacktraceIterator *state);
  87
  88
  89 typedef enum {
  90
  91         /* We have no idea what the caller's pc is. */
  92         PC_LOC_UNKNOWN,
  93
  94         /* The caller's pc is currently in lr. */
  95         PC_LOC_IN_LR,
  96
  97         /* The caller's pc can be found by dereferencing the caller's sp. */
  98         PC_LOC_ON_STACK
  99
 100 } CallerPCLocation;
 101
 102
 103 typedef enum {
 104
 105         /* We have no idea what the caller's sp is. */
 106         SP_LOC_UNKNOWN,
 107
 108         /* The caller's sp is currently in r52. */
 109         SP_LOC_IN_R52,
 110
 111         /* The caller's sp can be found by adding a certain constant
 112          * to the current value of sp.
 113          */
 114         SP_LOC_OFFSET
 115
 116 } CallerSPLocation;
 117
 118
 119 /* Bit values ORed into CALLER_* values for info ops. */
 120 enum {
 121         /* Setting the low bit on any of these values means the info op
 122          * applies only to one bundle ago.
 123          */
 124         ONE_BUNDLE_AGO_FLAG = 1,
 125
 126         /* Setting this bit on a CALLER_SP_* value means the PC is in LR.
 127          * If not set, PC is on the stack.
 128          */
 129         PC_IN_LR_FLAG = 2,
 130
 131         /* This many of the low bits of a CALLER_SP_* value are for the
 132          * flag bits above.
 133          */
 134         NUM_INFO_OP_FLAGS = 2,
 135
 136         /* We cannot have one in the memory pipe so this is the maximum. */
 137         MAX_INFO_OPS_PER_BUNDLE = 2
 138 };
 139
 140
 141 /** Internal constants used to define 'info' operands. */
 142 enum {
 143         /* 0 and 1 are reserved, as are all negative numbers. */
 144
 145         CALLER_UNKNOWN_BASE = 2,
 146
 147         CALLER_SP_IN_R52_BASE = 4,
 148
 149         CALLER_SP_OFFSET_BASE = 8
 150 };
 151
 152
 153 /** Current backtracer state describing where it thinks the caller is. */
 154 typedef struct {
 155         /*
 156          * Public fields
 157          */
 158
 159         /* How do we find the caller's PC? */
 160         CallerPCLocation pc_location : 8;
 161
 162         /* How do we find the caller's SP? */
 163         CallerSPLocation sp_location : 8;
 164
 165         /* If sp_location == SP_LOC_OFFSET, then caller_sp == sp +
 166          * loc->sp_offset. Else this field is undefined.
 167          */
 168         uint16_t sp_offset;
 169
 170         /* In the most recently visited bundle a terminating bundle? */
 171         bool at_terminating_bundle;
 172
 173         /*
 174          * Private fields
 175          */
 176
 177         /* Will the forward scanner see someone clobbering sp
 178          * (i.e. changing it with something other than addi sp, sp, N?)
 179          */
 180         bool sp_clobber_follows;
 181
 182         /* Operand to next "visible" info op (no more than one bundle past
 183          * the next terminating bundle), or -32768 if none.
 184          */
 185         int16_t next_info_operand;
 186
 187         /* Is the info of in next_info_op in the very next bundle? */
 188         bool is_next_info_operand_adjacent;
 189
 190 } CallerLocation;
 191
 192
 193
 194
 195 #endif /* _TILE_BACKTRACE_H */