NOLOAD section attribute results in incorrect debug information

[Ina Pandit]

Hi,

We have built toolchains for H8/SH targets using 
binutils-2.17.90 (20070806), gcc-4.2.1 and newlib-1.15.0 sources.

During our internal testing we found a problem in the GNU Linker.
When a user defined section with NOLOAD attribute is used in the 
application, the debugging information generated is not correct. 
The ".debug_info" section is incomplete and incorrect. 
Hence it is not possible to debug the application properly.

The test case below, demonstrates the problem:

//////////// C Program - t.c ////////////
int j __attribute__((section ("dont_load")));

int main(void)
{
  return 0;
}
////////////////////////////////////////////

////////////// Linker script ///////////////
SECTIONS
{
	.text 0x00000800 :
	{
		*(.text)
		*(.text.*)
	}

	.dont_load 0x00FFF000 (NOLOAD) :
	{
		*(dont_load)
	}	
}
////////////////////////////////////////////

Commands used:
sh-elf-gcc t.c -Tscript -g -g2 -nostartfiles 
sh-elf-readelf -w a.out > dmp

The "dmp" file shows that ".debug_info" section is incomplete 
and incorrect.

//////////// .debug_info section //////////
  Compilation Unit @ offset 0x0:
   Length:        168
   Version:       2
   Abbrev Offset: 0
   Pointer Size:  4
 <0><b>: Abbrev Number: 1 (DW_TAG_compile_unit)
  < c>     DW_AT_producer   : GNU C 4.2-GNUSH_v0703	
  <22>     DW_AT_language  : 1	(ANSI C)
  <23>     DW_AT_name       : t.c	
  <27>     DW_AT_comp_dir  : 	               <- Missing
  <28>     DW_AT_low_pc     : 0x72	   <- Incorrect-should be 0x800
  <2c>     DW_AT_high_pc    : 0x6f677261  <- Incorrect-should be 0x810
  <30>     DW_AT_stmt_list   : 0x6d204669 <- Incorrect-should be 0	
 <1><34>: Abbrev Number: 108
////////////////////////////////////////////

The following debugging information entries are also missing:
	1. DW_TAG_subprogram
	2. DW_TAG_base_type
	3. DW_TAG_variable

Please note that correct debug information is present in the 
object file. After linking, the information generated
is incorrect.

Please note that this problem was not present in 
binutils-2.17.50(20070417).

After investigating further, we found that reverting the 
following patch from binutils, solves the problem.
http://sourceware.org/ml/binutils-cvs/2007-05/msg00158.html 

However, to revert the above mentioned patch, we had to revert 
the patches mentioned below as well,
1. http://sourceware.org/ml/binutils-cvs/2007-06/msg00115.html
2. http://sourceware.org/ml/binutils-cvs/2007-06/msg00114.html

The problem exists in binutils 2.18 as well.

Any help on this will be appreciated.

Regards,
Ina Pandit

KPIT Cummins InfoSystems Ltd.
Pune, India
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