Re: static pie: confusion between _DYNAMIC, crt1.o, Scrt1.o

[Xi Ruoyao <xry111@xry111.site>]

On Sat, 2022-10-22 at 16:45 +0200, Samuel Thibault wrote:

/* snip */

> > > So this is static pie (-pie -static)
> > 
> > No it's not.  The GCC option for static PIE is -static-pie (no
> > whitespace between -static and -pie), not -pie -static.
> 
> Oh.
> 
> Is it not possible to make -static -pie get the same behavior? That'd be
> way more orthogonal for people to understand.
> 
> As the gnupg example shows, people seem to be expecting it to be
> static-pie, and I don't think documentation will manage to fix that.

I'm not sure.

> > 
> > A static PIE should use rcrt1.o.  If you pass the correct -static-pie
> > option to GCC, GCC will use it.
> 
> Ok.
> 
> $ gcc test.o -o test -static-pie -v
> [...]
>  /usr/lib/gcc/i686-gnu/12/collect2 -plugin /usr/lib/gcc/i686-gnu/12/liblto_plugin.so -plugin-opt=/usr/lib/gcc/i686-gnu/12/lto-wrapper -plugin-opt=-fresolution=/tmp/cclPHnby.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_eh -plugin-opt=-pass-through=-lc --build-id --eh-frame-hdr -m elf_i386 --hash-style=gnu --as-needed -static -pie --no-dynamic-linker -z text -pie -o test /usr/lib/gcc/i686-gnu/12/../../../i386-gnu/crt1.o /usr/lib/gcc/i686-gnu/12/../../../i386-gnu/crti.o /usr/lib/gcc/i686-gnu/12/crtbegin.o -L/usr/lib/gcc/i686-gnu/12 -L/usr/lib/gcc/i686-gnu/12/../../../i386-gnu -L/usr/lib/gcc/i686-gnu/12/../../.. -L/lib/i386-gnu -L/usr/lib/i386-gnu test.o --start-group -lgcc -lgcc_eh -lc --end-group /usr/lib/gcc/i686-gnu/12/crtendS.o /usr/lib/gcc/i686-gnu/12/../../../i386-gnu/crtn.o
> 
> That doesn't seem to have been fixed for the hurd case, I will have
> a look (and that will most probably point me to the piece that makes
> -static -pie use crt1.o on Linux).

Hmm, I don't have a Hurd.  On a Linux though:

$ cc hw.c -v -static-pie 2>&1 | grep collect2
 /usr/libexec/gcc/x86_64-pc-linux-gnu/12.2.0/collect2 -plugin
/usr/libexec/gcc/x86_64-pc-linux-gnu/12.2.0/liblto_plugin.so -plugin-
opt=/usr/libexec/gcc/x86_64-pc-linux-gnu/12.2.0/lto-wrapper -plugin-
opt=-fresolution=/tmp/ccZqWxf9.res -plugin-opt=-pass-through=-lgcc -
plugin-opt=-pass-through=-lgcc_eh -plugin-opt=-pass-through=-lc --eh-
frame-hdr -m elf_x86_64 -static -pie --no-dynamic-linker -z text -pie
/usr/lib/gcc/x86_64-pc-linux-gnu/12.2.0/../../../../lib/rcrt1.o 
                                                        ^^^^^^^
/usr/lib/gcc/x86_64-pc-linux-gnu/12.2.0/../../../../lib/crti.o
/usr/lib/gcc/x86_64-pc-linux-gnu/12.2.0/crtbeginS.o -
L/usr/lib/gcc/x86_64-pc-linux-gnu/12.2.0 -L/usr/lib/gcc/x86_64-pc-linux-
gnu/12.2.0/../../../../lib -L/lib/../lib -L/usr/lib/../lib -
L/usr/lib/gcc/x86_64-pc-linux-gnu/12.2.0/../../.. /tmp/ccMPRUc3.o --
start-group -lgcc -lgcc_eh -lc --end-group /usr/lib/gcc/x86_64-pc-linux-
gnu/12.2.0/crtendS.o /usr/lib/gcc/x86_64-pc-linux-
gnu/12.2.0/../../../../lib/crtn.o

What does

  gcc -dumpspecs | grep 'startfile:' -A1

say on Hurd?

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University