Also find CFI in sections of type SHT_X86_64_UNWIND

On my system with g++ (GCC) 8.2.1 20180831 with GNU gold (GNU Binutils
2.31.1) 1.16, the .eh_frame section does not have type PROGBITS
but rather is using X86_64_UNWIND nowadays:

```
$ echo "int main(){ return 0; }" > test.c
$ gcc test.c
$ readelf --sections a.out | grep .eh_frame
  [14] .eh_frame         X86_64_UNWIND    0000000000000670  00000670
  [15] .eh_frame_hdr     X86_64_UNWIND    0000000000000724  00000724
```

Without this patch, libdw refuses to use the available unwind
information, leading to broken backtraces while unwinding. With the
patch applied, unwinding works once more in such situations.

Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
Signed-off-by: Mark Wielaard <mark@klomp.org>
Tested-by: Milian Wolff <milian.wolff@kdab.com>

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index ebe002c..627fdde 100644 (file)
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,7 @@
+2018-10-29  Milian Wolff  <milian.wolff@kdab.com>
+
+       * dwarf_getcfi_elf.c (getcfi_shdr): Check sh_type != SHT_NOBITS.
+
 2018-09-13  Mark Wielaard  <mark@klomp.org>
 
        * dwarf_begin_elf.c (check_section): Drop ehdr argument, add and

diff --git a/libdw/dwarf_getcfi_elf.c b/libdw/dwarf_getcfi_elf.c
index 315cc02..adcaea0 100644 (file)
--- a/libdw/dwarf_getcfi_elf.c
+++ b/libdw/dwarf_getcfi_elf.c
@@ -298,7 +298,7 @@ getcfi_shdr (Elf *elf, const GElf_Ehdr *ehdr)
            }
          else if (!strcmp (name, ".eh_frame"))
            {
-             if (shdr->sh_type == SHT_PROGBITS)
+             if (shdr->sh_type != SHT_NOBITS)
                return getcfi_scn_eh_frame (elf, ehdr, scn, shdr,
                                            hdr_scn, hdr_vaddr);
              else