Re: disable-pie build

[Michael Tokarev <mjt@tls.msk.ru>]

12.11.2023 20:03, Paolo Bonzini пишет:
> 
> 
> Il sab 11 nov 2023, 03:40 Michael Tokarev <mjt@tls.msk.ru <mailto:mjt@tls.msk.ru>> ha scritto:
> 
>     Hi!
> 
>     It looks like --disable-pie configure, which uses -fno-pie -no-pie flags
>     for the compiler, is broken: it does not not tell the *linker* about the
>     option, so the link fails (at least on debian bookworm):
> 
>     /usr/bin/ld: libcommon.fa.p/hw_core_cpu-common.c.o: relocation R_X86_64_32 against `.rodata' can not be used when making a PIE object; recompile with
>     -fPIE
>     /usr/bin/ld: failed to set dynamic section sizes: bad value
> 
>     This is failing for *all* executables, including tests, qemu-img, etc.
> 
> 
> Is this new in bookworm? And also can you compare 8.0, 8.1 and 8.2?

First I observed this with 7.2, but the same happens with 8.1 and current master
(8.2-tobe).

cc -m64 -mcx16  -o subprojects/libvhost-user/link-test subprojects/libvhost-user/link-test.p/link-test.c.o -Wl,--as-needed -Wl,--no-undefined 
-Wl,--whole-archive -Wl,--start-group subprojects/libvhost-user/libvhost-user.a -Wl,--end-group -Wl,--no-whole-archive -fstack-protector-strong 
-Wl,-z,relro -Wl,-z,now -Wl,--warn-common -pthread
/usr/bin/ld: subprojects/libvhost-user/link-test.p/link-test.c.o: relocation R_X86_64_32 against `.text.unlikely' can not be used when making a PIE 
object; recompile with -fPIE
/usr/bin/ld: failed to set dynamic section sizes: bad value

Note: there's no -no-pie in there.  With the change to add -no-pie to qemu_ldflags,
it is there and the link succeeds:

cc -m64 -mcx16  -o subprojects/libvhost-user/link-test subprojects/libvhost-user/link-test.p/link-test.c.o -Wl,--as-needed -Wl,--no-undefined 
-Wl,--whole-archive -Wl,--start-group subprojects/libvhost-user/libvhost-user.a -Wl,--end-group -Wl,--no-whole-archive -no-pie 
-fstack-protector-strong -Wl,-z,relro -Wl,-z,now -Wl,--warn-common -pthread


And nope, this is not new in bookworm, -- it fails to build on bullseye
exactly the same way.  And it succeeds with the same change applied,
adding -no-pie to qemu_ldflags.

It looks like debian enabled pie by default in around 2018 or so.

I stumbled across this issue (with qemu can't be built on debian with --disable-pie)
several times just because I tried to run one or another CI test to reproduce some
issue, and it happened the test used --disable-pie (and most of that is executed on
redhat).

/mjt


>     diff --git a/meson.build b/meson.build
>     index a9c4f28247..0b7ca45d48 100644
>     --- a/meson.build
>     +++ b/meson.build
>     @@ -278,7 +278,8 @@ endif
>        # tries to build an executable instead of a shared library and fails.  So
>        # don't add -no-pie anywhere and cross fingers. :(
>        if not get_option('b_pie')
>     -  qemu_common_flags += cc.get_supported_arguments('-fno-pie', '-no-pie')
>     +  qemu_common_flags += cc.get_supported_arguments('-fno-pie')
>     +  qemu_ldflags += cc.get_supported_arguments('-no-pie')
>        endif
> 
>        if not get_option('stack_protector').disabled()