Re: [PATCH] Implement x86 SIZE32/SIZE64 relocations

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Wed, Jan 16, 2013 at 12:58 PM, David Miller <davem@davemloft.net> wrote:
> From: "H.J. Lu" <hjl.tools@gmail.com>
> Date: Wed, 16 Jan 2013 12:56:07 -0800
>
>> On Wed, Jan 16, 2013 at 12:39 PM, David Miller <davem@davemloft.net> wrote:
>>> From: "H.J. Lu" <hjl.tools@gmail.com>
>>> Date: Wed, 16 Jan 2013 12:24:19 -0800
>>>
>>>> On Wed, Jan 16, 2013 at 12:14 PM, David Miller <davem@davemloft.net> wrote:
>>>>> GLIBC dynamic linker support is the one that needs the largest amount
>>>>> of lead time, and the one for which it is the most difficult for a
>>>>> developer or use to integrate into their environment on their own.
>>>>>
>>>>> This even applies to the person who writes the binutils support for
>>>>> emitting the relocations themselves.
>>>>
>>>> David, do you plan to add Sparc size relocation support to gas and
>>>> ld? I choose "@SIZE" to indicate size relocation.  I will add both
>>>> gas and ld tests for them.
>>>
>>> Yes I do.
>>>
>>> I intend to use whatever syntax Sun's assembler uses.
>>>
>>> Sun's assembler supports the x86 size relocations as well.
>>
>> What does Sum assembler use for size relocations?
>> I couldn't find an example.
>
> Neither could I, as usual Oracle/Sun's documentation in this area is
> very poor.
>
> I'm asking one of my Oracle/Sun contacts.

If Solaris doesn't define it, I propose @SIZE:

	.text
	movl	$xxx@SIZE, %eax
	movl	$xxx@SIZE - 8, %eax
	movl	$xxx@SIZE + 8, %eax
	movl	$yyy@SIZE, %eax
	movl	$yyy@SIZE - 16, %eax
	movl	$yyy@SIZE + 16, %eax
	movl	$zzz@SIZE, %eax
	movl	$zzz@SIZE - 32, %eax
	movl	$zzz@SIZE + 32, %eax
	.comm	zzz,429496729,32
	.bss
	.global	yyy
	.type	yyy,%object
	.size	yyy,30
yyy:
	.zero	30
	.data
	.global	xxx
	.type	xxx,%object
	.size	xxx,80
xxx:
	.zero	80
	.long	xxx@SIZE - 1
	.long	yyy@SIZE + 2
	.long	zzz@SIZE

which leads to

Relocation section '.rela.text' at offset 0x2e0 contains 9 entries:
 Offset     Info    Type            Sym.Value  Sym. Name + Addend
00000001  00000420 R_X86_64_SIZE32   00000000   xxx + 0
00000006  00000420 R_X86_64_SIZE32   00000000   xxx - 8
0000000b  00000420 R_X86_64_SIZE32   00000000   xxx + 8
00000010  00000520 R_X86_64_SIZE32   00000000   yyy + 0
00000015  00000520 R_X86_64_SIZE32   00000000   yyy - 10
0000001a  00000520 R_X86_64_SIZE32   00000000   yyy + 10
0000001f  00000620 R_X86_64_SIZE32   00000020   zzz + 0
00000024  00000620 R_X86_64_SIZE32   00000020   zzz - 20
00000029  00000620 R_X86_64_SIZE32   00000020   zzz + 20

Relocation section '.rela.data' at offset 0x34c contains 3 entries:
 Offset     Info    Type            Sym.Value  Sym. Name + Addend
00000050  00000420 R_X86_64_SIZE32   00000000   xxx - 1
00000054  00000520 R_X86_64_SIZE32   00000000   yyy + 2
00000058  00000620 R_X86_64_SIZE32   00000020   zzz + 0

How does it look?

-- 
H.J.