[gentoo-dev] Re: [PATCH] To enable ssp default in Gcc the toolchain.eclass need some changes.

[Ryan Hill <dirtyepic@gentoo.org>]

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On Fri, 10 Jan 2014 15:08:02 -0500
"Anthony G. Basile" <basile@opensource.dyc.edu> wrote:

> On 01/10/2014 10:50 AM, Ryan Hill wrote:
> > Having slept on it I'm starting to agree.  My first argument was that on
> > hardened ssp is -fstack-protector-all, which is much more expensive, and it
> > adds -fstack-check and -z,now to the linker by default as well.  The pie
> > half
> 
> I'm pretty sure we're not adding -fstack-check unless something has 
> changed.  Where are you seeing that?
> 
> The reason I'm concerned is because of situations like bug #471756. 
> stack-check incumbers a register which in some situations (like the asm 
> in ffmpeg) can get you into trouble with not enough GENERAL_REGS.

40_all_gcc48_config_esp.patch:

  54 +   #if defined ( EFAULT_SSP ) || defined ( EFAULT_PIE_SSP )
  55 +       #define ESP_OPTIONS_SSP_SPEC \
  56 +           "%{nostdlib|nodefaultlibs|ffreestanding|fno-stack-protector| \
  57 +           fstack-protector|fstack-protector-all:;:-fstack-protector-all} \
  58 +           %{fstack-check|fstack-check=*:;: -fstack-check}"

> > It might be useful to have these flags so we can mask them on archs that
> > don't support ssp/pie.  But that's always been true and it looks like sh is
> > the only place we've bothered for some reason.
> 
> Yes please.  I had this issue on mips where gcc didn't support ssp for 
> early versions of gcc 4.x.

There's a list of arches in every gcc ebuild that support PIE and SSP for
both glibc and uclibc.  AFAICT you would just have to remove mips from that
list.


-- 
Ryan Hill                        psn: dirtyepic_sk
   gcc-porting/toolchain/wxwidgets @ gentoo.org

47C3 6D62 4864 0E49 8E9E  7F92 ED38 BD49 957A 8463

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