Re: [perfmon2] [PATCH] Limit functions visibility in the libpfm library to ones listed in header files

[Stephane E. <er...@go...>]

Hi Will,

Indeed seeing a size reduction on the .so on X86 and ARM.
Patch applied.
Thanks.


On Mon, Mar 14, 2016 at 3:06 PM, William Cohen <wc...@re...> wrote:

> On 03/12/2016 05:50 PM, Andreas Beckmann wrote:
> > On 2016-03-12 17:10, Stephane Eranian wrote:
> >> Hi Will,
> >>
> >> I tried your patch on my Ubuntu system.
> >> It is using gcc version 4.8.4 (Ubuntu 4.8.4-2ubuntu1~14.04.1).
> >>
> >> It compiles fine but I see no difference in size using size -t
> lib/libpfm.a.
> >
> >> So do you need a specific compiler version or the patch is missing
> >> something?
> >
> > That patch primarily affects the (exported) content of the shared
> > library, not the static library.
> >
> > I gave it a short test on Debian and papi (the only user of the libpfm4
> > package) continued to work after I installed the new libpfm4 package
> > which exports fewer symbols. (In Debian, papi is built against the
> > separately packaged libpfm4, not the bundled copy. It uses the shared
> > library.)
> >
> > Andreas
>
> Hi Stephane and Andreas,
>
> Yes, the change is only going to affect the libpfm.so file.  The libpfm.a
> is going to be the same.  the abidiff from libabigail (
> https://www.sourceware.org/libabigail/) shows that a lot of the internal
> symbols are no longer exported.  Attached is the output of:
>
>
>  abidiff libpfm-4.7.0.orig/lib/libpfm.so.4.7.0
> libpfm-4.7.0.hidden/lib/libpfm.so.4.7.0 > abidiff.log
>
>
> eu-size shows the reduction in size:
>
> $ eu-size libpfm-4.7.0.orig/lib/libpfm.so.4.7.0
> libpfm-4.7.0.hidden/lib/libpfm.so.4.7.0
>               text               data                bss
> dec            hex filename
>            1120871             673600               6208
> 1800679         1b79e7 libpfm-4.7.0.orig/lib/libpfm.so.4.7.0
>            1106646             673368               6208
> 1786222         1b416e libpfm-4.7.0.hidden/lib/libpfm.so.4.7.0
>
> "eu-readelf -l" also shows the reductions:
>
> $ eu-readelf -l libpfm-4.7.0.orig/lib/libpfm.so.4.7.0
> libpfm-4.7.0.hidden/lib/libpfm.so.4.7.0
>
> libpfm-4.7.0.orig/lib/libpfm.so.4.7.0:
>
> Program Headers:
>   Type           Offset   VirtAddr           PhysAddr           FileSiz
> MemSiz   Flg Align
>   LOAD           0x000000 0x0000000000000000 0x0000000000000000 0x111c4c
> 0x111c4c R E 0x200000
>   LOAD           0x112570 0x0000000000312570 0x0000000000312570 0x0a4768
> 0x0a5fb0 RW  0x200000
>   DYNAMIC        0x1a5da0 0x00000000003a5da0 0x00000000003a5da0 0x0001d0
> 0x0001d0 RW  0x8
>   NOTE           0x0001c8 0x00000000000001c8 0x00000000000001c8 0x000024
> 0x000024 R   0x4
>   GNU_EH_FRAME   0x10f614 0x000000000010f614 0x000000000010f614 0x00078c
> 0x00078c R   0x4
>   GNU_STACK      0x000000 0x0000000000000000 0x0000000000000000 0x000000
> 0x000000 RW  0x10
>   GNU_RELRO      0x112570 0x0000000000312570 0x0000000000312570 0x093a90
> 0x093a90 R   0x1
>
>  Section to Segment mapping:
>   Segment Sections...
>    00      [RO: .note.gnu.build-id .gnu.hash .dynsym .dynstr .gnu.version
> .gnu.version_r .rela.dyn .rela.plt .init .plt .text .fini .rodata
> .eh_frame_hdr .eh_frame]
>    01      [RELRO: .init_array .fini_array .jcr .data.rel.ro .dynamic
> .got] .got.plt .data .bss
>    02      [RELRO: .dynamic]
>    03      [RO: .note.gnu.build-id]
>    04      [RO: .eh_frame_hdr]
>    05
>    06      [RELRO: .init_array .fini_array .jcr .data.rel.ro .dynamic
> .got]
>
> libpfm-4.7.0.hidden/lib/libpfm.so.4.7.0:
>
> Program Headers:
>   Type           Offset   VirtAddr           PhysAddr           FileSiz
> MemSiz   Flg Align
>   LOAD           0x000000 0x0000000000000000 0x0000000000000000 0x10e4cc
> 0x10e4cc R E 0x200000
>   LOAD           0x10e5c8 0x000000000030e5c8 0x000000000030e5c8 0x0a4670
> 0x0a5eb8 RW  0x200000
>   DYNAMIC        0x1a1de0 0x00000000003a1de0 0x00000000003a1de0 0x0001d0
> 0x0001d0 RW  0x8
>   NOTE           0x0001c8 0x00000000000001c8 0x00000000000001c8 0x000024
> 0x000024 R   0x4
>   GNU_EH_FRAME   0x10be94 0x000000000010be94 0x000000000010be94 0x00078c
> 0x00078c R   0x4
>   GNU_STACK      0x000000 0x0000000000000000 0x0000000000000000 0x000000
> 0x000000 RW  0x10
>   GNU_RELRO      0x10e5c8 0x000000000030e5c8 0x000000000030e5c8 0x093a38
> 0x093a38 R   0x1
>
>  Section to Segment mapping:
>   Segment Sections...
>    00      [RO: .note.gnu.build-id .gnu.hash .dynsym .dynstr .gnu.version
> .gnu.version_r .rela.dyn .rela.plt .init .plt .text .fini .rodata
> .eh_frame_hdr .eh_frame]
>    01      [RELRO: .init_array .fini_array .jcr .data.rel.ro .dynamic
> .got] .got.plt .data .bss
>    02      [RELRO: .dynamic]
>    03      [RO: .note.gnu.build-id]
>    04      [RO: .eh_frame_hdr]
>    05
>    06      [RELRO: .init_array .fini_array .jcr .data.rel.ro .dynamic
> .got]
>
>
> -Will
>
>
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