tools/objtool/orc_types.h

   1 /*
   2  * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
   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; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #ifndef _ORC_TYPES_H
  19 #define _ORC_TYPES_H
  20
  21 #include <linux/types.h>
  22 #include <linux/compiler.h>
  23
  24 /*
  25  * The ORC_REG_* registers are base registers which are used to find other
  26  * registers on the stack.
  27  *
  28  * ORC_REG_PREV_SP, also known as DWARF Call Frame Address (CFA), is the
  29  * address of the previous frame: the caller's SP before it called the current
  30  * function.
  31  *
  32  * ORC_REG_UNDEFINED means the corresponding register's value didn't change in
  33  * the current frame.
  34  *
  35  * The most commonly used base registers are SP and BP -- which the previous SP
  36  * is usually based on -- and PREV_SP and UNDEFINED -- which the previous BP is
  37  * usually based on.
  38  *
  39  * The rest of the base registers are needed for special cases like entry code
  40  * and GCC realigned stacks.
  41  */
  42 #define ORC_REG_UNDEFINED               0
  43 #define ORC_REG_PREV_SP                 1
  44 #define ORC_REG_DX                      2
  45 #define ORC_REG_DI                      3
  46 #define ORC_REG_BP                      4
  47 #define ORC_REG_SP                      5
  48 #define ORC_REG_R10                     6
  49 #define ORC_REG_R13                     7
  50 #define ORC_REG_BP_INDIRECT             8
  51 #define ORC_REG_SP_INDIRECT             9
  52 #define ORC_REG_MAX                     15
  53
  54 /*
  55  * ORC_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP (the
  56  * caller's SP right before it made the call).  Used for all callable
  57  * functions, i.e. all C code and all callable asm functions.
  58  *
  59  * ORC_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset points
  60  * to a fully populated pt_regs from a syscall, interrupt, or exception.
  61  *
  62  * ORC_TYPE_REGS_IRET: Used in entry code to indicate that sp_reg+sp_offset
  63  * points to the iret return frame.
  64  *
  65  * The UNWIND_HINT macros are used only for the unwind_hint struct.  They
  66  * aren't used in struct orc_entry due to size and complexity constraints.
  67  * Objtool converts them to real types when it converts the hints to orc
  68  * entries.
  69  */
  70 #define ORC_TYPE_CALL                   0
  71 #define ORC_TYPE_REGS                   1
  72 #define ORC_TYPE_REGS_IRET              2
  73 #define UNWIND_HINT_TYPE_SAVE           3
  74 #define UNWIND_HINT_TYPE_RESTORE        4
  75
  76 #ifndef __ASSEMBLY__
  77 /*
  78  * This struct is more or less a vastly simplified version of the DWARF Call
  79  * Frame Information standard.  It contains only the necessary parts of DWARF
  80  * CFI, simplified for ease of access by the in-kernel unwinder.  It tells the
  81  * unwinder how to find the previous SP and BP (and sometimes entry regs) on
  82  * the stack for a given code address.  Each instance of the struct corresponds
  83  * to one or more code locations.
  84  */
  85 struct orc_entry {
  86         s16             sp_offset;
  87         s16             bp_offset;
  88         unsigned        sp_reg:4;
  89         unsigned        bp_reg:4;
  90         unsigned        type:2;
  91 } __packed;
  92
  93 /*
  94  * This struct is used by asm and inline asm code to manually annotate the
  95  * location of registers on the stack for the ORC unwinder.
  96  *
  97  * Type can be either ORC_TYPE_* or UNWIND_HINT_TYPE_*.
  98  */
  99 struct unwind_hint {
 100         u32             ip;
 101         s16             sp_offset;
 102         u8              sp_reg;
 103         u8              type;
 104 };
 105 #endif /* __ASSEMBLY__ */
 106
 107 #endif /* _ORC_TYPES_H */