mono/mini/mini-unwind.h

   1 /*
   2  * mini-unwind.h: Stack Unwinding Interface
   3  *
   4  * Authors:
   5  *   Zoltan Varga (vargaz@gmail.com)
   6  *
   7  * (C) 2007 Novell, Inc.
   8  */
   9
  10 #ifndef __MONO_UNWIND_H__
  11 #define __MONO_UNWIND_H__
  12
  13 #include "mini.h"
  14
  15 /* This is the same as mgreg_t, except on 32 bit bit platforms with callee saved fp regs */
  16 #ifndef mono_unwind_reg_t
  17 #define mono_unwind_reg_t mgreg_t
  18 #endif
  19
  20 /*
  21  * This is a platform-independent interface for unwinding through stack frames
  22  * based on the Dwarf unwinding interface.
  23  * See http://dwarfstd.org/Dwarf3.pdf, section "Call Frame Information".
  24  */
  25
  26 /*
  27  * CFA = Canonical Frame Address. By convention, this is the value of the stack pointer
  28  * prior to the execution of the call instruction in the caller. I.e. on x86, it is
  29  * esp + 4 on entry to a function. The value of the CFA does not change during execution
  30  * of a function. There are two kinds of unwind directives:
  31  * - those that describe how to compute the CFA at a given pc offset inside a function
  32  * - those that describe where a given register is saved relative to the CFA.
  33  */
  34
  35 /* Unwind ops */
  36
  37 /* The low 6 bits contain additional information */
  38 #define DW_CFA_advance_loc        0x40
  39 #define DW_CFA_offset             0x80
  40 #define DW_CFA_restore            0xc0
  41
  42 #define DW_CFA_nop              0x00
  43 #define DW_CFA_set_loc          0x01
  44 #define DW_CFA_advance_loc1     0x02
  45 #define DW_CFA_advance_loc2     0x03
  46 #define DW_CFA_advance_loc4     0x04
  47 #define DW_CFA_offset_extended  0x05
  48 #define DW_CFA_restore_extended 0x06
  49 #define DW_CFA_undefined        0x07
  50 #define DW_CFA_same_value       0x08
  51 #define DW_CFA_register         0x09
  52 #define DW_CFA_remember_state   0x0a
  53 #define DW_CFA_restore_state    0x0b
  54 #define DW_CFA_def_cfa          0x0c
  55 #define DW_CFA_def_cfa_register 0x0d
  56 #define DW_CFA_def_cfa_offset   0x0e
  57 #define DW_CFA_def_cfa_expression 0x0f
  58 #define DW_CFA_expression       0x10
  59 #define DW_CFA_offset_extended_sf 0x11
  60 #define DW_CFA_def_cfa_sf       0x12
  61 #define DW_CFA_def_cfa_offset_sf 0x13
  62 #define DW_CFA_val_offset        0x14
  63 #define DW_CFA_val_offset_sf     0x15
  64 #define DW_CFA_val_expression    0x16
  65 #define DW_CFA_lo_user           0x1c
  66 #define DW_CFA_hi_user           0x3f
  67
  68 /*
  69  * Mono extension, advance loc to a location stored outside the unwind info.
  70  * This is required to make the unwind descriptors sharable, since otherwise each one would contain
  71  * an advance_loc with a different offset just before the unwind ops for the epilog.
  72  */
  73 #define DW_CFA_mono_advance_loc DW_CFA_lo_user
  74
  75 /* Represents one unwind instruction */
  76 typedef struct {
  77         guint8 op; /* One of DW_CFA_... */
  78         guint16 reg; /* register number in the hardware encoding */
  79         gint32 val; /* arbitrary value */
  80         guint32 when; /* The offset _after_ the cpu instruction this unwind op belongs to */
  81 } MonoUnwindOp;
  82
  83 /*
  84  * Macros for emitting MonoUnwindOp structures.
  85  * These should be called _after_ emitting the cpu instruction the unwind op
  86  * belongs to.
  87  */
  88
  89 /* Set cfa to reg+offset */
  90 #define mono_emit_unwind_op_def_cfa(cfg,ip,reg,offset) do { mono_emit_unwind_op (cfg, (ip) - (cfg)->native_code, DW_CFA_def_cfa, (reg), (offset)); (cfg)->cur_cfa_reg = (reg); (cfg)->cur_cfa_offset = (offset); } while (0)
  91 /* Set cfa to reg+existing offset */
  92 #define mono_emit_unwind_op_def_cfa_reg(cfg,ip,reg) do { mono_emit_unwind_op (cfg, (ip) - (cfg)->native_code, DW_CFA_def_cfa_register, (reg), (0)); (cfg)->cur_cfa_reg = (reg); } while (0)
  93 /* Set cfa to existing reg+offset */
  94 #define mono_emit_unwind_op_def_cfa_offset(cfg,ip,offset) do { mono_emit_unwind_op (cfg, (ip) - (cfg)->native_code, DW_CFA_def_cfa_offset, (0), (offset)); (cfg)->cur_cfa_offset = (offset); } while (0)
  95 /* Reg is the same as it was on enter to the function */
  96 #define mono_emit_unwind_op_same_value(cfg,ip,reg) mono_emit_unwind_op (cfg, (ip) - (cfg)->native_code, DW_CFA_same_value, (reg), 0)
  97 /* Reg is saved at cfa+offset */
  98 #define mono_emit_unwind_op_offset(cfg,ip,reg,offset) mono_emit_unwind_op (cfg, (ip) - (cfg)->native_code, DW_CFA_offset, (reg), (offset))
  99 /* Save the unwind state into an implicit stack */
 100 #define mono_emit_unwind_op_remember_state(cfg,ip) mono_emit_unwind_op (cfg, (ip) - (cfg)->native_code, DW_CFA_remember_state, 0, 0)
 101 /* Restore the unwind state from the state stack */
 102 #define mono_emit_unwind_op_restore_state(cfg,ip) mono_emit_unwind_op (cfg, (ip) - (cfg)->native_code, DW_CFA_restore_state, 0, 0)
 103 /*
 104  * Mark the current location as a location stored outside the unwind info, which will be passed
 105  * explicitly to mono_unwind_frame () in the MARK_LOCATIONS argument. This allows the unwind info
 106  * to be shared among multiple methods.
 107  */
 108 #define mono_emit_unwind_op_mark_loc(cfg,ip,n) mono_emit_unwind_op (cfg, (ip) - (cfg)->native_code, DW_CFA_mono_advance_loc, 0, (n))
 109
 110 /* Similar macros usable when a cfg is not available, like for trampolines */
 111 #define mono_add_unwind_op_def_cfa(op_list,code,buf,reg,offset) do { (op_list) = g_slist_append ((op_list), mono_create_unwind_op ((code) - (buf), DW_CFA_def_cfa, (reg), (offset))); } while (0)
 112 #define mono_add_unwind_op_def_cfa_reg(op_list,code,buf,reg) do { (op_list) = g_slist_append ((op_list), mono_create_unwind_op ((code) - (buf), DW_CFA_def_cfa_register, (reg), (0))); } while (0)
 113 #define mono_add_unwind_op_def_cfa_offset(op_list,code,buf,offset) do { (op_list) = g_slist_append ((op_list), mono_create_unwind_op ((code) - (buf), DW_CFA_def_cfa_offset, 0, (offset))); } while (0)
 114 #define mono_add_unwind_op_same_value(op_list,code,buf,reg) do { (op_list) = g_slist_append ((op_list), mono_create_unwind_op ((code) - (buf), DW_CFA_same_value, (reg), 0)); } while (0)
 115 #define mono_add_unwind_op_offset(op_list,code,buf,reg,offset) do { (op_list) = g_slist_append ((op_list), mono_create_unwind_op ((code) - (buf), DW_CFA_offset, (reg), (offset))); } while (0)
 116
 117 /* Pointer Encoding in the .eh_frame */
 118 enum {
 119         DW_EH_PE_absptr = 0x00,
 120         DW_EH_PE_omit = 0xff,
 121
 122         DW_EH_PE_udata4 = 0x03,
 123         DW_EH_PE_sdata4 = 0x0b,
 124         DW_EH_PE_sdata8 = 0x0c,
 125
 126         DW_EH_PE_pcrel = 0x10,
 127         DW_EH_PE_textrel = 0x20,
 128         DW_EH_PE_datarel = 0x30,
 129         DW_EH_PE_funcrel = 0x40,
 130         DW_EH_PE_aligned = 0x50,
 131
 132         DW_EH_PE_indirect = 0x80
 133 };
 134
 135 int
 136 mono_hw_reg_to_dwarf_reg (int reg);
 137
 138 int
 139 mono_dwarf_reg_to_hw_reg (int reg);
 140
 141 int
 142 mono_unwind_get_dwarf_data_align (void);
 143
 144 int
 145 mono_unwind_get_dwarf_pc_reg (void);
 146
 147 guint8*
 148 mono_unwind_ops_encode (GSList *unwind_ops, guint32 *out_len);
 149
 150 void
 151 mono_unwind_frame (guint8 *unwind_info, guint32 unwind_info_len,
 152                                    guint8 *start_ip, guint8 *end_ip, guint8 *ip, guint8 **mark_locations,
 153                                    mono_unwind_reg_t *regs, int nregs,
 154                                    mgreg_t **save_locations, int save_locations_len,
 155                                    guint8 **out_cfa);
 156
 157 void mono_unwind_init (void);
 158
 159 void mono_unwind_cleanup (void);
 160
 161 guint32 mono_cache_unwind_info (guint8 *unwind_info, guint32 unwind_info_len);
 162
 163 guint8* mono_get_cached_unwind_info (guint32 index, guint32 *unwind_info_len);
 164
 165 guint8* mono_unwind_decode_fde (guint8 *fde, guint32 *out_len, guint32 *code_len, MonoJitExceptionInfo **ex_info, guint32 *ex_info_len, gpointer **type_info, int *this_reg, int *this_offset) MONO_LLVM_INTERNAL;
 166
 167 /* Data retrieved from an LLVM Mono FDE entry */
 168 typedef struct {
 169         /* Malloc'ed */
 170         guint8 *unw_info;
 171         guint32 unw_info_len;
 172         MonoJitExceptionInfo *ex_info;
 173         guint32 ex_info_len;
 174         gpointer *type_info;
 175         int this_reg;
 176         int this_offset;
 177 } MonoLLVMFDEInfo;
 178
 179 void
 180 mono_unwind_decode_llvm_mono_fde (guint8 *fde, int fde_len, guint8 *cie, guint8 *code, MonoLLVMFDEInfo *res);
 181
 182 GSList* mono_unwind_get_cie_program (void);
 183
 184 void mono_print_unwind_info (guint8 *unwind_info, int unwind_info_len) MONO_LLVM_INTERNAL;
 185
 186 #endif