This is the mail archive of the binutils@sources.redhat.com mailing list for the binutils project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Test for overflow in the R_MIPS_26 reloc


Ian Lance Taylor <ian@wasabisystems.com> writes:
> Index: elfxx-mips.c
> ===================================================================
> RCS file: /cvs/src/src/bfd/elfxx-mips.c,v
> retrieving revision 1.113
> diff -p -u -r1.113 elfxx-mips.c
> --- elfxx-mips.c	16 Nov 2004 09:54:10 -0000	1.113
> +++ elfxx-mips.c	8 Dec 2004 20:24:55 -0000
> @@ -3350,7 +3350,10 @@ mips_elf_calculate_relocation (bfd *abfd
>        if (local_p)
>  	value = ((addend | ((p + 4) & 0xf0000000)) + symbol) >> 2;
>        else
> -	value = (_bfd_mips_elf_sign_extend (addend, 28) + symbol) >> 2;
> +	{
> +	  value = (_bfd_mips_elf_sign_extend (addend, 28) + symbol) >> 2;
> +	  overflowed_p = (value >> 26) != ((p + 4) >> 28);
> +	}
>        value &= howto->dst_mask;
>        break;

On non-PIC targets, the overflow triggers for code like:

    void foo (void)
    {
      if (weak_symbol)
        weak_symbol ();
    }

when weak_symbol is undefined and foo() is outside the low 256MB
(in KSEG0, for example).  This is causing lots of link failures
in the mips64-elf gcc testsuite.

Is the patch below OK?  Tested against the gcc testsuite on mips64-elf.
Also tested against the gas, ld & binutils testsuite on mips64-elf,
mips-elf, mipsisa64el-elf and mips64-linux-gnu.

Richard


bfd/
	* elfxx-mips.c (mips_elf_calculate_relocation): Don't report an
	overflow for calls to undefined weak symbols.

ld/testsuite/
	* ld-mips-elf/jal-overflow-2.[sd]: New test.
	* ld-mips-elf/mips-elf.exp: Run it.

Index: bfd/elfxx-mips.c
===================================================================
RCS file: /cvs/src/src/bfd/elfxx-mips.c,v
retrieving revision 1.116
diff -c -p -F^\([(a-zA-Z0-9_]\|#define\) -r1.116 elfxx-mips.c
*** bfd/elfxx-mips.c	9 Dec 2004 07:12:28 -0000	1.116
--- bfd/elfxx-mips.c	13 Dec 2004 13:10:31 -0000
*************** mips_elf_calculate_relocation (bfd *abfd
*** 3352,3358 ****
        else
  	{
  	  value = (_bfd_mips_elf_sign_extend (addend, 28) + symbol) >> 2;
! 	  overflowed_p = (value >> 26) != ((p + 4) >> 28);
  	}
        value &= howto->dst_mask;
        break;
--- 3352,3359 ----
        else
  	{
  	  value = (_bfd_mips_elf_sign_extend (addend, 28) + symbol) >> 2;
! 	  if (h->root.root.type != bfd_link_hash_undefweak)
! 	    overflowed_p = (value >> 26) != ((p + 4) >> 28);
  	}
        value &= howto->dst_mask;
        break;
Index: ld/testsuite/ld-mips-elf/mips-elf.exp
===================================================================
RCS file: /cvs/src/src/ld/testsuite/ld-mips-elf/mips-elf.exp,v
retrieving revision 1.22
diff -c -p -F^\([(a-zA-Z0-9_]\|#define\) -r1.22 mips-elf.exp
*** ld/testsuite/ld-mips-elf/mips-elf.exp	13 Dec 2004 13:09:55 -0000	1.22
--- ld/testsuite/ld-mips-elf/mips-elf.exp	13 Dec 2004 13:10:31 -0000
*************** if {$has_newabi && $linux_gnu} {
*** 81,86 ****
--- 81,87 ----
  }
  
  run_dump_test "jaloverflow"
+ run_dump_test "jaloverflow-2"
  if {$has_newabi} {
      run_dump_test "jalbal"
  }
diff -c /dev/null ld/testsuite/ld-mips-elf/jaloverflow-2.d
*** /dev/null	Fri Apr 23 00:21:55 2004
--- ld/testsuite/ld-mips-elf/jaloverflow-2.d	Mon Dec 13 11:39:44 2004
***************
*** 0 ****
--- 1,8 ----
+ #name: JAL overflow 2
+ #source: jaloverflow-2.s
+ #as:
+ #ld: -Ttext=0x10000000 -e start
+ #objdump: -dr
+ #...
+ 0*10000000:	0c000000.*
+ #pass
diff -c /dev/null ld/testsuite/ld-mips-elf/jaloverflow-2.s
*** /dev/null	Fri Apr 23 00:21:55 2004
--- ld/testsuite/ld-mips-elf/jaloverflow-2.s	Mon Dec 13 11:39:29 2004
***************
*** 0 ****
--- 1,7 ----
+ # jal relocs against undefined weak symbols should not be treated as
+ # overflowing
+ 
+ 	.globl	start
+ 	.weak	foo
+ start:
+ 	jal	foo


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]