Re: Re: size of executable

[Rich Felker <dalias@libc.org>]

On Mon, Aug 12, 2019 at 11:16:39AM -0700, Khem Raj wrote:
> On Mon, Aug 12, 2019 at 10:19 AM Rich Felker <dalias@libc.org> wrote:
> >
> > On Mon, Aug 12, 2019 at 05:55:28PM +0100, Jorge Almeida wrote:
> > > On Mon, Aug 12, 2019 at 5:48 PM Jorge Almeida <jjalmeida@gmail.com> wrote:
> > > >
> > >
> > > > with gcc-8.3.0 on x86_64. Could someone check the following hello.c
> > > > and see what size you get?
> > > > I get 16768 bytes (not stripped) and 12324 (stripped).
> > > > Note that I'm not even using printf.
> > > >
> > > > Thanks
> > > >
> > > > #include <unistd.h>
> > > > int main(int argc, char* argv[]){
> > > >  write(1, "Hello, bloated world...\n", 24);
> > > > }
> > >
> > > Sorry, I forgot to add the compile options. In attachement, due to
> > > Gmail interface being what it is.
> >
> > > gcc -static -Os -march=native -fomit-frame-pointer -pipe -Wall  -Werror=pedantic  -Werror=implicit-function-declaration -pedantic -pedantic-errors -mpreferred-stack-boundary=4 -falign-functions=1 -falign-jumps=1 -falign-loops=1 -fno-unwind-tables -fdata-sections -ffunction-sections -Wl,--gc-sections -fno-asynchronous-unwind-tables -fstrict-aliasing -Wstrict-aliasing=2 -Wno-unused-function -std=c11 hello.c
> > >
> > > Stripping:
> > >
> > > strip -s a.out
> > > strip -S --strip-unneeded --remove-section=.note.gnu.gold-version --remove-section=.comment --remove-section=.note --remove-section=.note.gnu.build-id --remove-section=.note.ABI-tag --remove-section=.eh_frame --remove-section=.eh_frame_ptr -R .note -R .comment -R .note.GNU-stack a.out
> > > sstrip a.out
> >
> > This is a binutils regression from a dubious anti-ROP feature, -z
> > separate-code. Add -Wl,-z,noseparate-code and it will go away.
> >
> 
> is this still so with latest release as well.

The breakage that caused separate-code to crash at runtime was fixed
between 2.31 and 2.32, but the size and performance regression
remains. With separate-code, a couple extra pages of memory and disk
are needed, with corresponding runtime cost to mmap them properly.

All to avoid ROP gadgets, when every single dynamic-linked program has
a nice ROP gadget named "system" (among many others) in it...

Rich