linux-kernel - Re: Urgent: x86-32 and GNU ld 2.22.52.0.1

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Message-ID: <CAMe9rOpUoj_1TM0NOqVX31aHEez3_i9v6f7_zkGeM8SZ+XDxyQ@mail.gmail.com>
Date:	Fri, 18 May 2012 09:50:29 -0700
From:	"H.J. Lu" <hjl.tools@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jarkko Sakkinen <jarkko.sakkinen@...el.com>
Subject: Re: Urgent: x86-32 and GNU ld 2.22.52.0.1

On Fri, May 18, 2012 at 9:46 AM, H. Peter Anvin <hpa@...or.com> wrote:
> On 05/18/2012 09:35 AM, H.J. Lu wrote:
>>
>> In that case, both 2.22.52.0.1 and 2.22.52.0.2 are bad.
>>
>
> I suspect that really means we should have a patch which verifies by
> construction, and not rely on version numbers.
>

A small testcase:

[hjl@...-6 pr14052]$ cat pr14052.s
	.text
	.global start	/* Used by SH targets.  */
start:
	.global _start
_start:
	.global __start
__start:
	.global main	/* Used by HPPA targets.  */
main:
	.dc.a 0
[hjl@...-6 pr14052]$ cat pr14052.t
SECTIONS {
	.text : {
		*(.text)
	}
	. = ALIGN (0x1000);
	.data : {
		_data_start = .;
		*(.data)
	}
	/DISCARD/ : { *(.*) }
}
[hjl@...-6 pr14052]$ make
as   -o pr14052.o pr14052.s
./ld  -o pr14052 -T pr14052.t pr14052.o
readelf -s pr14052

Symbol table '.symtab' contains 7 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000000000     0 SECTION LOCAL  DEFAULT    1
     2: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    1 __start
     3: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    1 _start
     4: 0000000000001000     0 NOTYPE  GLOBAL DEFAULT    1 _data_start
     5: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    1 main
     6: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    1 start
[hjl@...-6 pr14052]$

There should be no symbols in ABS section.

-- 
H.J.
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