Re: GCC 7 libbacktrace patch committed: Ignore compressed debug sections

[Ian Lance Taylor]

On Tue, Oct 10, 2017 at 12:47 PM, Paolo Carlini
 wrote:
>
> On 10/10/2017 18:55, Ian Lance Taylor wrote:
>>
>> Index: elf.c
>> ===
>> --- elf.c   (revision 253593)
>> +++ elf.c   (working copy)
>> @@ -103,6 +103,7 @@
>>   #undef SHT_SYMTAB
>>   #undef SHT_STRTAB
>>   #undef SHT_DYNSYM
>> +#undef SFH_COMPRESSED
>>   #undef STT_OBJECT
>>   #undef STT_FUNC
>
> You appear to have a typo here: SFH_COMPRESSED instead of SHF_COMPRESSED.
> That breaks the bootstrap for me:
>
> ../../../../gcc-7-branch/libsanitizer/libbacktrace/../../libbacktrace/elf.c:199:0:
> error: "SHF_COMPRESSED" redefined [-Werror]
>  #define SHF_COMPRESSED 0x800
>
> I'm going to test and commit the obvious fix, if nobody beats me to it.

Argh.  Sorry about that.  Please do commit the obvious fix.  Thanks.

Ian

Re: GCC 7 libbacktrace patch committed: Ignore compressed debug sections

[Paolo Carlini]

Hi,

On 10/10/2017 18:55, Ian Lance Taylor wrote:

Index: elf.c
===
--- elf.c   (revision 253593)
+++ elf.c   (working copy)
@@ -103,6 +103,7 @@
  #undef SHT_SYMTAB
  #undef SHT_STRTAB
  #undef SHT_DYNSYM
+#undef SFH_COMPRESSED
  #undef STT_OBJECT
  #undef STT_FUNC
You appear to have a typo here: SFH_COMPRESSED instead of 
SHF_COMPRESSED. That breaks the bootstrap for me:


../../../../gcc-7-branch/libsanitizer/libbacktrace/../../libbacktrace/elf.c:199:0: 
error: "SHF_COMPRESSED" redefined [-Werror]

 #define SHF_COMPRESSED 0x800

I'm going to test and commit the obvious fix, if nobody beats me to it.

Paolo.

GCC 7 libbacktrace patch committed: Ignore compressed debug sections

[Ian Lance Taylor]

This patch to the GCC 7 libbacktrace ignores compressed debug
sections.  If we don't, the DWARF reader reports an error.  Since the
GCC 7 libbacktrace does not support uncompressing the debug sections,
ignoring them is the best approach (on trunk, we uncompress).  This is
for PR 80914.  Bootstrapped and ran libbacktrace tests on
x86_64-pc-linux-gnu.  Committed to GCC 7 branch.

Ian

2017-10-10  Ian Lance Taylor  

PR go/80914
* elf.c (SHF_COMPRESSED): Define.
(elf_add): Ignore debug sections with SHF_COMPRESSED set.
Index: elf.c
===
--- elf.c   (revision 253593)
+++ elf.c   (working copy)
@@ -103,6 +103,7 @@
 #undef SHT_SYMTAB
 #undef SHT_STRTAB
 #undef SHT_DYNSYM
+#undef SFH_COMPRESSED
 #undef STT_OBJECT
 #undef STT_FUNC
 
@@ -195,6 +196,8 @@
 #define SHT_STRTAB 3
 #define SHT_DYNSYM 11
 
+#define SHF_COMPRESSED 0x800
+
 #if BACKTRACE_ELF_SIZE == 32
 
 typedef struct
@@ -700,7 +703,8 @@
 
   for (j = 0; j < (int) DEBUG_MAX; ++j)
{
- if (strcmp (name, debug_section_names[j]) == 0)
+ if (strcmp (name, debug_section_names[j]) == 0
+  && (shdr->sh_flags & SHF_COMPRESSED) == 0)
{
  sections[j].offset = shdr->sh_offset;
  sections[j].size = shdr->sh_size;