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  */
  23 typedef bool (*BacktraceMemoryReader)(void *result,
  24                                       unsigned long address,
  25                                       unsigned int size,
  26                                       void *extra);
  27
  28 typedef 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
  50 typedef 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
  64 typedef 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. */
  81 enum {
  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. */
 103 enum {
 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. */
 115 typedef 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
 153 extern 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
 160 extern bool backtrace_next(BacktraceIterator *state);
 161
 162 #endif /* _ASM_TILE_BACKTRACE_H */