[Buildroot] [PATCH] package/dmalloc: Fix for ARC with enabled BR2_SSP_ALL

[Yann E. MORIN <yann.morin.1998@free.fr>]

Veronika, All,

+Fabrice, see below...

On 2021-02-09 13:47 +0300, Veronika Kremneva spake thusly:
> When building dmalloc for ARC while having "-fstack-protector-all" option on,
> we are getting the following error:
> ------------------------------->8---------------------------
> >>> dmalloc 5.5.2 Installing to target
> cp -dpf $HOME/buildroot/output/host/arc-buildroot-linux-gnu/sysroot/usr/lib/libdmalloc*.so
> $HOME/buildroot/output/target/usr/lib
> cp -dpf $HOME/buildroot/output/host/arc-buildroot-linux-gnu/sysroot/usr/bin/dmalloc
> $HOME/buildroot/output/target/usr/bin/dmalloc
> ERROR: architecture for "/usr/lib/libdmallocthcxx.so" is "ARCompact", should be "ARCv2"
> ERROR: architecture for "/usr/lib/libdmallocth.so" is "ARCompact", should be "ARCv2"
> ERROR: architecture for "/usr/lib/libdmalloc.so" is "ARCompact", should be "ARCv2"
> ERROR: architecture for "/usr/lib/libdmallocxx.so" is "ARCompact", should be "ARCv2"
> make: *** [$HOME/buildroot/output/build/dmalloc-5.5.2/.stamp_installed] Error 1
> ------------------------------->8---------------------------
> 
> You can observe this error in following builds:
> http://autobuild.buildroot.net/results/57f/57fc51cee4ec9339ea3be23f8c8c9f7ecca1a857/
> http://autobuild.buildroot.net/results/b4d/b4d457369f35e1942c294b0ea3b3cab4cae0d7a3/
> http://autobuild.buildroot.net/results/cfc/cfc111076c955dd5c1125c6e34a161121ea11200/
> http://autobuild.buildroot.net/results/1d0/1d0ffcefbf545d1748e928603fd07c0a8de98eb5/
> 
> In all of those builds architecture "ARCv2" was explicitly chosen during configuration
> yet we are getting this error. As we go deeper we find that the object file that linker
> is trying to process contains no target code thus the default "ARCompact" is being used.
> But why the object file is empty? Went to check link args:
> ------------------------------->8---------------------------
> $HOME/buildroot/output/host/bin/arc-buildroot-linux-gnu-ld: conftest.a(conftest.o):
> relocation R_ARC_32_ME against `__stack_chk_guard' can not be used when making a shared
> object; recompile with -fPIC
> $HOME/buildrootc/output/host/bin/arc-buildroot-linux-gnu-ld: BFD (GNU Binutils) 2.34.50.20200611
> assertion fail elf32-arc.c:1802
> $HOME/buildroot/output/host/bin/arc-buildroot-linux-gnu-ld: unrecognized option '-all'
> $HOME/buildroot/output/host/bin/arc-buildroot-linux-gnu-ld: use the --help option for usage information
> configure:4475: result: $HOME/buildroot/output/host/bin/arc-buildroot-linux-gnu-ld -G -o $@.t
> ------------------------------->8---------------------------
> 
> Looks like we are missing the -fPIC flag in DMALLOC_CFLAGS. As shared libraries should always
> be compiled with "-fPIC" following patch adds this flag to the dmalloc.mk.

While reviewing that patch, I see that Fabrice already sent a similar
patch quite some time ago now:

    https://patchwork.ozlabs.org/project/buildroot/patch/20200601092104.830051-1-fontaine.fabrice at gmail.com/

> Signed-off-by: Veronika Kremneva <kremneva@synopsys.com>
> ---
>  package/dmalloc/dmalloc.mk | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/package/dmalloc/dmalloc.mk b/package/dmalloc/dmalloc.mk
> index 38b2c02027..638fe0fcda 100644
> --- a/package/dmalloc/dmalloc.mk
> +++ b/package/dmalloc/dmalloc.mk
> @@ -16,6 +16,10 @@ DMALLOC_INSTALL_STAGING = YES
>  DMALLOC_CONF_OPTS = --enable-shlib
>  DMALLOC_CFLAGS = $(TARGET_CFLAGS)
>  
> +ifeq ($(BR2_STATIC_LIBS),)
> +DMALLOC_CFLAGS += -fPIC

So, it seems that both of you arrived to a similar conclusion, with a
similar analysis.

I think the change from Fabrice would in the end be better, if it at
least because it drops a bundled patch.

Except for that, I wonder if we care about not adding -fPIC for static
libs. Indeed, the current patch unconditionally adds -fPIC to all
builds, shared and static alike...

Besides, -fPIC is almost innocuous for static builds (maybe a very
slight overhead to resolve or jump to some symbols)...

What's your thoughts, both Veronika and Fabrice?

Regards,
Yann E. MORIN.

> +endif
> +
>  ifeq ($(BR2_INSTALL_LIBSTDCPP),y)
>  DMALLOC_CONF_OPTS += --enable-cxx
>  else
> -- 
> 2.16.2
> 
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