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Re: RFC: Automatically test IFUNC implementations
On Fri, Sep 28, 2012 at 7:25 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Thu, Sep 27, 2012 at 5:16 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Thu, Sep 27, 2012 at 3:31 PM, Roland McGrath <roland@hack.frob.com> wrote:
>>>> I thought we'd discussed returning a count from __libc_func,
>>>> and the (static) array provided by the test program.
>>>>
>>>> Certainly that's going to be less dead bss space in libc.so.
>>>
>>> IMHO this feature must be done in a way that adds zero data space
>>> (including zero relro const data), zero bss space, and zero relocs
>>> to the library.
>>
>> I updated hjl/ifunc/test branch. __libc_func is now specified as:
>>
>> /* Fill ARRAY of MAX elements with IFUNC implementations for function
>> NAME supported on target machine and return the number of valid
>> entries. */
>> extern int __libc_func (const char *name, struct libc_func_test *array,
>> int max);
>>
>> arch-specific __libc_func can issue a run-time error if array is too
>> small. There are no .bss nor .data spaces:
>>
Here are comparisons of master branch vs. hjl/ifunc/test branch:
x86-64 master branch:
[hjl@gnu-tools-1 build-x86_64-linux]$ readelf -r libc.so|wc -l
1291
[hjl@gnu-tools-1 build-x86_64-linux]$ readelf -SW libc.so | egrep "data|bss"
[15] .rodata PROGBITS 000000000014da60 14da60
021ad0 00 A 0 0 32
[21] .tdata PROGBITS 000000000039f748 19f748
000010 00 WAT 0 0 8
[22] .tbss NOBITS 000000000039f758 19f758
000058 00 WAT 0 0 8
[27] .data.rel.ro PROGBITS 000000000039f880 19f880
003320 00 WA 0 0 32
[31] .data PROGBITS 00000000003a3080 1a3080
0016d8 00 WA 0 0 32
[32] .bss NOBITS 00000000003a4760 1a4758
004520 00 WA 0 0 32
[hjl@gnu-tools-1 build-x86_64-linux]$
x86-64 hjl/ifunc/test branch:
[hjl@gnu-tools-1 build-x86_64-linux]$ readelf -r libc.so|wc -l1291
[hjl@gnu-tools-1 build-x86_64-linux]$ readelf -SW libc.so | egrep "data|bss"
[15] .rodata PROGBITS 000000000014eb20 14eb20
022270 00 A 0 0 32
[21] .tdata PROGBITS 00000000003a1758 1a1758
000010 00 WAT 0 0 8
[22] .tbss NOBITS 00000000003a1768 1a1768
000058 00 WAT 0 0 8
[27] .data.rel.ro PROGBITS 00000000003a1880 1a1880
003320 00 WA 0 0 32
[31] .data PROGBITS 00000000003a5080 1a5080
0016d8 00 WA 0 0 32
[32] .bss NOBITS 00000000003a6760 1a6758
004520 00 WA 0 0 32
[hjl@gnu-tools-1 build-x86_64-linux]$
i686 master branch:
[hjl@gnu-tools-1 build-i686-linux]$ readelf -r libc.so|wc -l
1360
[hjl@gnu-tools-1 build-i686-linux]$ readelf -SW libc.so | egrep "data|bss"
[15] .rodata PROGBITS 0014d140 14d140 01eed8 00 A 0 0 32
[21] .tdata PROGBITS 001a51fc 1a51fc 000008 00 WAT 0 0 4
[22] .tbss NOBITS 001a5204 1a5204 000038 00 WAT 0 0 4
[27] .data.rel.ro PROGBITS 001a52a0 1a52a0 001b1c 00 WA 0 0 32
[31] .data PROGBITS 001a7040 1a7040 000e9c 00 WA 0 0 32
[32] .bss NOBITS 001a7ee0 1a7edc 002c1c 00 WA 0 0 32
[hjl@gnu-tools-1 build-i686-linux]$
i686 hjl/ifunc/test branch:
[hjl@gnu-tools-1 build-i686-linux]$ readelf -r libc.so|wc -l
1360
[hjl@gnu-tools-1 build-i686-linux]$ readelf -SW libc.so | egrep "data|bss"
[15] .rodata PROGBITS 0014e2a0 14e2a0 01f708 00 A 0 0 32
[21] .tdata PROGBITS 001a6204 1a6204 000008 00 WAT 0 0 4
[22] .tbss NOBITS 001a620c 1a620c 000038 00 WAT 0 0 4
[27] .data.rel.ro PROGBITS 001a62a0 1a62a0 001b1c 00 WA 0 0 32
[31] .data PROGBITS 001a8040 1a8040 000e9c 00 WA 0 0 32
[32] .bss NOBITS 001a8ee0 1a8edc 002c1c 00 WA 0 0 32
[hjl@gnu-tools-1 build-i686-linux]$
There are no changes in run-time relocations and .data/.bss section sizes.
There are about 2K increases in .rodata section for IFUNC function name
strings. OK to install?
Thanks.
--
H.J.