LCOV - code coverage report
Current view: top level - libdw - dwarf_next_cfi.c (source / functions) Hit Total Coverage
Test: elfutils-0.191 Lines: 87 117 74.4 %
Date: 2024-03-27 15:13:09 Functions: 1 1 100.0 %
Legend: Lines: hit not hit | Branches: + taken - not taken # not executed Branches: 52 93 55.9 %

           Branch data     Line data    Source code
       1                 :            : /* Advance to next CFI entry.
       2                 :            :    Copyright (C) 2009-2010, 2014 Red Hat, Inc.
       3                 :            :    This file is part of elfutils.
       4                 :            : 
       5                 :            :    This file is free software; you can redistribute it and/or modify
       6                 :            :    it under the terms of either
       7                 :            : 
       8                 :            :      * the GNU Lesser General Public License as published by the Free
       9                 :            :        Software Foundation; either version 3 of the License, or (at
      10                 :            :        your option) any later version
      11                 :            : 
      12                 :            :    or
      13                 :            : 
      14                 :            :      * the GNU General Public License as published by the Free
      15                 :            :        Software Foundation; either version 2 of the License, or (at
      16                 :            :        your option) any later version
      17                 :            : 
      18                 :            :    or both in parallel, as here.
      19                 :            : 
      20                 :            :    elfutils is distributed in the hope that it will be useful, but
      21                 :            :    WITHOUT ANY WARRANTY; without even the implied warranty of
      22                 :            :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      23                 :            :    General Public License for more details.
      24                 :            : 
      25                 :            :    You should have received copies of the GNU General Public License and
      26                 :            :    the GNU Lesser General Public License along with this program.  If
      27                 :            :    not, see <http://www.gnu.org/licenses/>.  */
      28                 :            : 
      29                 :            : #ifdef HAVE_CONFIG_H
      30                 :            : # include <config.h>
      31                 :            : #endif
      32                 :            : 
      33                 :            : #include "cfi.h"
      34                 :            : #include "encoded-value.h"
      35                 :            : 
      36                 :            : #include <string.h>
      37                 :            : 
      38                 :            : 
      39                 :            : int
      40                 :      61156 : dwarf_next_cfi (const unsigned char e_ident[],
      41                 :            :                 Elf_Data *data,
      42                 :            :                 bool eh_frame_p,
      43                 :            :                 Dwarf_Off off,
      44                 :            :                 Dwarf_Off *next_off,
      45                 :            :                 Dwarf_CFI_Entry *entry)
      46                 :            : {
      47                 :            :   /* Dummy struct for memory-access.h macros.  */
      48                 :      61156 :   BYTE_ORDER_DUMMY (dw, e_ident);
      49                 :            : 
      50                 :            :   /* If we reached the end before don't do anything.  */
      51         [ +  + ]:      61156 :   if (off == (Dwarf_Off) -1l
      52                 :            :       /* Make sure there is enough space in the .debug_frame section
      53                 :            :          for at least the initial word.  We cannot test the rest since
      54                 :            :          we don't know yet whether this is a 64-bit object or not.  */
      55         [ +  + ]:      60950 :       || unlikely (off + 4 >= data->d_size))
      56                 :            :     {
      57                 :        284 :     done:
      58                 :        286 :       *next_off = (Dwarf_Off) -1l;
      59                 :        286 :       return 1;
      60                 :            :     }
      61                 :            : 
      62                 :            :   /* This points into the .debug_frame section at the start of the entry.  */
      63                 :      60872 :   const uint8_t *bytes = data->d_buf + off;
      64                 :      60872 :   const uint8_t *limit = data->d_buf + data->d_size;
      65                 :            : 
      66                 :            :   /* The format of a CFI entry is described in DWARF3 6.4.1:
      67                 :            :    */
      68                 :            : 
      69         [ +  + ]:      60872 :   uint64_t length = read_4ubyte_unaligned_inc (&dw, bytes);
      70                 :      60872 :   size_t offset_size = 4;
      71         [ -  + ]:      60872 :   if (length == DWARF3_LENGTH_64_BIT)
      72                 :            :     {
      73                 :            :       /* This is the 64-bit DWARF format.  */
      74                 :          0 :       offset_size = 8;
      75         [ #  # ]:          0 :       if (unlikely (limit - bytes < 8))
      76                 :            :         {
      77                 :          0 :         invalid:
      78                 :          0 :           __libdw_seterrno (DWARF_E_INVALID_DWARF);
      79                 :          0 :           return -1;
      80                 :            :         }
      81         [ #  # ]:          0 :       length = read_8ubyte_unaligned_inc (&dw, bytes);
      82                 :            :     }
      83                 :            : 
      84                 :            :   /* Not explicitly in the DWARF spec, but mentioned in the LSB exception
      85                 :            :      frames (.eh_frame) spec. If Length contains the value 0, then this
      86                 :            :      CIE shall be considered a terminator and processing shall end.  */
      87         [ +  + ]:      60872 :   if (length == 0)
      88                 :          2 :     goto done;
      89                 :            : 
      90         [ +  - ]:      60870 :   if (unlikely ((uint64_t) (limit - bytes) < length)
      91         [ -  + ]:      60870 :       || unlikely (length < offset_size + 1))
      92                 :          0 :     goto invalid;
      93                 :            : 
      94                 :            :   /* Now we know how large the entry is.  Note the trick in the
      95                 :            :      computation.  If the offset_size is 4 the '- 4' term undoes the
      96                 :            :      '2 *'.  If offset_size is 8 this term computes the size of the
      97                 :            :      escape value plus the 8 byte offset.  */
      98                 :      60870 :   *next_off = off + (2 * offset_size - 4) + length;
      99                 :            : 
     100                 :      60870 :   limit = bytes + length;
     101                 :            : 
     102                 :      60870 :   const uint8_t *const cie_pointer_start = bytes;
     103         [ -  + ]:      60870 :   if (offset_size == 8)
     104         [ #  # ]:          0 :     entry->cie.CIE_id = read_8ubyte_unaligned_inc (&dw, bytes);
     105                 :            :   else
     106                 :            :     {
     107         [ +  + ]:      60870 :       entry->cie.CIE_id = read_4ubyte_unaligned_inc (&dw, bytes);
     108                 :            :       /* Canonicalize the 32-bit CIE_ID value to 64 bits.  */
     109   [ +  +  +  + ]:      60870 :       if (!eh_frame_p && entry->cie.CIE_id == DW_CIE_ID_32)
     110                 :        140 :         entry->cie.CIE_id = DW_CIE_ID_64;
     111                 :            :     }
     112         [ -  + ]:        366 :   if (eh_frame_p)
     113                 :            :     {
     114                 :            :       /* Canonicalize the .eh_frame CIE pointer to .debug_frame format.  */
     115         [ +  + ]:      60504 :       if (entry->cie.CIE_id == 0)
     116                 :      11110 :         entry->cie.CIE_id = DW_CIE_ID_64;
     117                 :            :       else
     118                 :            :         {
     119                 :            :           /* In .eh_frame format, a CIE pointer is the distance from where
     120                 :            :              it appears back to the beginning of the CIE.  */
     121                 :      49394 :           ptrdiff_t pos = cie_pointer_start - (const uint8_t *) data->d_buf;
     122         [ +  - ]:      49394 :           if (unlikely (entry->cie.CIE_id > (Dwarf_Off) pos)
     123         [ -  + ]:      49394 :               || unlikely (pos <= (ptrdiff_t) offset_size))
     124                 :          0 :             goto invalid;
     125                 :      49394 :           entry->cie.CIE_id = pos - entry->cie.CIE_id;
     126                 :            :         }
     127                 :            :     }
     128                 :            : 
     129         [ +  + ]:      60870 :   if (entry->cie.CIE_id == DW_CIE_ID_64)
     130                 :            :     {
     131                 :            :       /* Read the version stamp.  Always an 8-bit value.  */
     132                 :      11250 :       uint8_t version = *bytes++;
     133                 :            : 
     134   [ -  +  -  -  :      11250 :       if (version != 1 && (unlikely (version < 3) || unlikely (version > 4)))
                   -  - ]
     135                 :          0 :         goto invalid;
     136                 :            : 
     137                 :      11250 :       entry->cie.augmentation = (const char *) bytes;
     138                 :            : 
     139                 :      11250 :       bytes = memchr (bytes, '\0', limit - bytes);
     140         [ -  + ]:      11250 :       if (unlikely (bytes == NULL))
     141                 :          0 :         goto invalid;
     142                 :      11250 :       ++bytes;
     143                 :            : 
     144                 :            :       /* The address size for CFI is implicit in the ELF class.  */
     145         [ +  + ]:      11250 :       uint_fast8_t address_size = e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8;
     146                 :      11250 :       uint_fast8_t segment_size = 0;
     147         [ -  + ]:      11250 :       if (version >= 4)
     148                 :            :         {
     149         [ #  # ]:          0 :           if (unlikely (limit - bytes < 5))
     150                 :          0 :             goto invalid;
     151                 :            :           /* XXX We don't actually support address_size not matching the class.
     152                 :            :              To do so, we'd have to return it here so that intern_new_cie
     153                 :            :              could use it choose a specific fde_encoding.  */
     154         [ #  # ]:          0 :           if (unlikely (*bytes != address_size))
     155                 :            :             {
     156                 :          0 :               __libdw_seterrno (DWARF_E_VERSION);
     157                 :          0 :               return -1;
     158                 :            :             }
     159                 :          0 :           address_size = *bytes++;
     160                 :          0 :           segment_size = *bytes++;
     161                 :            :           /* We don't actually support segment selectors.  We'd have to
     162                 :            :              roll this into the fde_encoding bits or something.  */
     163         [ #  # ]:          0 :           if (unlikely (segment_size != 0))
     164                 :            :             {
     165                 :          0 :               __libdw_seterrno (DWARF_E_VERSION);
     166                 :          0 :               return -1;
     167                 :            :             }
     168                 :            :         }
     169                 :            : 
     170                 :      11250 :       const char *ap = entry->cie.augmentation;
     171                 :            : 
     172                 :            :       /* g++ v2 "eh" has pointer immediately following augmentation string,
     173                 :            :          so it must be handled first.  */
     174   [ -  +  -  - ]:      11250 :       if (unlikely (ap[0] == 'e' && ap[1] == 'h'))
     175                 :            :         {
     176                 :          0 :           ap += 2;
     177                 :          0 :           bytes += address_size;
     178                 :            :         }
     179                 :            : 
     180         [ -  + ]:      11250 :       if (bytes >= limit)
     181                 :          0 :         goto invalid;
     182                 :      11250 :       get_uleb128 (entry->cie.code_alignment_factor, bytes, limit);
     183                 :            : 
     184         [ -  + ]:      11250 :       if (bytes >= limit)
     185                 :          0 :         goto invalid;
     186                 :      11250 :       get_sleb128 (entry->cie.data_alignment_factor, bytes, limit);
     187                 :            : 
     188         [ -  + ]:      11250 :       if (bytes >= limit)
     189                 :          0 :         goto invalid;
     190                 :            : 
     191         [ -  + ]:      11250 :       if (version >= 3)              /* DWARF 3+ */
     192                 :          0 :         get_uleb128 (entry->cie.return_address_register, bytes, limit);
     193                 :            :       else                      /* DWARF 2 */
     194                 :      11250 :         entry->cie.return_address_register = *bytes++;
     195                 :            : 
     196                 :      11250 :       entry->cie.fde_augmentation_data_size = 0;
     197                 :      11250 :       entry->cie.augmentation_data = bytes;
     198                 :      11250 :       bool sized_augmentation = *ap == 'z';
     199         [ +  + ]:      11250 :       if (sized_augmentation)
     200                 :            :         {
     201                 :      11108 :           ++ap;
     202         [ -  + ]:      11108 :           if (bytes >= limit)
     203                 :          0 :             goto invalid;
     204                 :      11108 :           get_uleb128 (entry->cie.augmentation_data_size, bytes, limit);
     205         [ -  + ]:      11108 :           if ((Dwarf_Word) (limit - bytes) < entry->cie.augmentation_data_size)
     206                 :          0 :             goto invalid;
     207                 :      11108 :           entry->cie.augmentation_data = bytes;
     208                 :            :         }
     209                 :            : 
     210         [ +  + ]:      22444 :       for (; *ap != '\0'; ++ap)
     211                 :            :         {
     212                 :      11194 :           uint8_t encoding;
     213   [ +  +  +  +  :      11194 :           switch (*ap)
                      - ]
     214                 :            :             {
     215                 :         44 :             case 'L':
     216         [ +  - ]:         44 :               if (sized_augmentation)
     217                 :            :                 {
     218                 :            :                   /* Skip LSDA pointer encoding byte.  */
     219                 :         44 :                   encoding = *bytes++;
     220                 :         88 :                   entry->cie.fde_augmentation_data_size
     221                 :         44 :                     += encoded_value_size (data, e_ident, encoding, NULL);
     222                 :         44 :                   continue;
     223                 :            :                 }
     224                 :            :               break;
     225                 :      11092 :             case 'R':
     226         [ +  - ]:      11092 :               if (sized_augmentation)
     227                 :            :                 {
     228                 :            :                   /* Skip FDE address encoding byte.  */
     229                 :      11092 :                   bytes++;
     230                 :      11092 :                   continue;
     231                 :            :                 }
     232                 :            :               break;
     233                 :         52 :             case 'P':
     234         [ +  - ]:         52 :               if (sized_augmentation)
     235                 :            :                 {
     236                 :            :                   /* Skip encoded personality routine pointer. */
     237                 :         52 :                   encoding = *bytes++;
     238                 :         52 :                   bytes += encoded_value_size (data, e_ident, encoding, bytes);
     239                 :         52 :                   continue;
     240                 :            :                 }
     241                 :            :               break;
     242                 :          6 :             case 'S':
     243         [ +  - ]:          6 :               if (sized_augmentation)
     244                 :            :                 /* Skip signal-frame flag.  */
     245                 :          6 :                 continue;
     246                 :            :               break;
     247                 :            :             default:
     248                 :            :               /* Unknown augmentation string.  initial_instructions might
     249                 :            :                  actually start with some augmentation data.  */
     250                 :            :               break;
     251                 :            :             }
     252                 :            :           break;
     253                 :            :         }
     254         [ +  + ]:      11250 :       if (! sized_augmentation)
     255                 :        142 :         entry->cie.augmentation_data_size = bytes - entry->cie.augmentation_data;
     256                 :            :       else
     257                 :            :         {
     258         [ -  + ]:      11108 :           if (bytes > entry->cie.augmentation_data + entry->cie.augmentation_data_size)
     259                 :          0 :             goto invalid;
     260                 :      11108 :           bytes = entry->cie.augmentation_data + entry->cie.augmentation_data_size;
     261                 :            :         }
     262                 :            : 
     263                 :      11250 :       entry->cie.initial_instructions = bytes;
     264                 :      11250 :       entry->cie.initial_instructions_end = limit;
     265                 :            :     }
     266                 :            :   else
     267                 :            :     {
     268                 :      49620 :       entry->fde.start = bytes;
     269                 :      49620 :       entry->fde.end = limit;
     270                 :            :     }
     271                 :            : 
     272                 :            :   return 0;
     273                 :            : }
     274                 :            : INTDEF (dwarf_next_cfi)

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