[Bug 239007] lang/gcc8 enable secure-plt by default for powerpc*

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=239007

Mark Millard <[email protected]> changed:

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--- Comment #5 from Mark Millard <[email protected]> ---
(In reply to Justin Hibbits from comment #3)

For system-clang-b-ased cross build contexts,
possibly including powerpc64 building its lib32,
what I've observed follows (in hopes that it
will help track things down).

For lld based ld . . .

From what I've seen via trying cc/c++ commands
that target linking for 32-bit powerpc, with with
-### added, the linker command has the likes of:

"-m" "elf32ppc_fbsd"

and I do not see anything else that it is given
on the command line that directly indicates a
32-bit powerpc context.

So my guess is that the linker needs to enable
allowing the --secure-plt option based on the
likes of that -m elf32ppc_fbsd .

lld does not do this yet and rejects the
option.



As for modern gnu ld . . .

Modern gnu ld does allow the --secure-plt (as
does the historical FreeBSD system binutils).

But, unlike the old FreeBSD binutils, modern
gnu ld returns an error code when --secure-plt
was specified but the linker reports the likes
of:

/usr/local/powerpc64-unknown-freebsd13.0/bin/ld: bss-plt forced due to ...

(and it does report such during builds when
system-clang is used).

The non-zero return status from ld stops the
build when such a modern gnu ld is used.

The easiest way to see many of using bss-plt
messages is to search building with system clang
and the historical freebsd binutils:

Using bss-plt due to
/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/powerpc.powerpc/tmp/usr/lib/crt1.o
Using bss-plt due to
/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/powerpc.powerpc/tmp/usr/lib/crtbeginS.o
Using bss-plt due to
/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/powerpc.powerpc/tmp/usr/lib/libgcc.a(fixdfdi.o)
Using bss-plt due to
/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/powerpc.powerpc/tmp/usr/lib/libgcc.a(fixsfdi.o)
Using bss-plt due to
/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/powerpc.powerpc/tmp/usr/lib/libgcc.a(floatdidf.o)
Using bss-plt due to
/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/powerpc.powerpc/tmp/usr/lib/libgcc.a(floatdisf.o)
Using bss-plt due to
/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/powerpc.powerpc/tmp/usr/lib/libgcc.a(floatundidf.o)
Using bss-plt due to
/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/powerpc.powerpc/tmp/usr/lib/libgcc.a(floatundisf.o)
Using bss-plt due to
/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/powerpc.powerpc/tmp/usr/lib/libgcc.a(moddi3.o)
Using bss-plt due to
/usr/obj/powerpcvtsc_clang/powerpc.powerpc/usr/src/powerpc.powerpc/tmp/usr/lib/libgcc.a(umoddi3.o)
Using bss-plt due to accf_http.kld
Using bss-plt due to acl_nfs4.kld
Using bss-plt due to acl_posix1e.kld
Using bss-plt due to if_ae.kld
Using bss-plt due to if_age.kld
Using bss-plt due to reloc.o

Note: This stopped where it did because of:

--- agp.ko.full ---
ld: agp.kld(.text+0x37a4): R_PPC_PLTREL24 reloc against local symbol
agp.kld: could not read symbols: Bad value
*** [agp.ko.full] Error code 1

so there might be more places.

(I'll not here get into why gnu ld decides that
bss-plt is to be used for the clang output.)


Between the two types of modern ld's, I've not managed
a system-clang based 32-bit powerpc cross build since
the secure-plt switch was made.

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