linux-kernel - Re: [PATCH v5 1/5] Shared library support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAK7LNAQ+t3z8R+VB7UvGQQqHZcDq+B_F3W0=zTLzmFs_fSybOw@mail.gmail.com>
Date:	Fri, 11 Mar 2016 15:19:33 +0900
From:	Masahiro Yamada <yamada.masahiro@...ionext.com>
To:	Emese Revfy <re.emese@...il.com>
Cc:	Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
	pageexec@...email.hu, spender@...ecurity.net,
	kernel-hardening@...ts.openwall.com,
	Michal Marek <mmarek@...e.com>,
	Kees Cook <keescook@...omium.org>, linux@...musvillemoes.dk,
	fengguang.wu@...el.com, dvyukov@...gle.com,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 1/5] Shared library support

Hi Emese,

2016-03-07 8:03 GMT+09:00 Emese Revfy <re.emese@...il.com>:
> Infrastructure for building independent shared library targets.
> This effectively also reverts commit 62e2210798ed38928ab24841e8b4878a
> (Masahiro Yamada, kbuild: drop shared library support from Makefile.host).
>
> Signed-off-by: Emese Revfy <re.emese@...il.com>
> ---
>  scripts/Makefile.build |  2 +-
>  scripts/Makefile.clean |  3 ++-
>  scripts/Makefile.host  | 69 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  3 files changed, 71 insertions(+), 3 deletions(-)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 130a452..bd2a31e 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -60,7 +60,7 @@ endif
>  endif
>
>  # Do not include host rules unless needed
> -ifneq ($(hostprogs-y)$(hostprogs-m),)
> +ifneq ($(hostprogs-y)$(hostprogs-m)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),)
>  include scripts/Makefile.host
>  endif
>
> diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean
> index 55c96cb..e4e88ab 100644
> --- a/scripts/Makefile.clean
> +++ b/scripts/Makefile.clean
> @@ -38,7 +38,8 @@ subdir-ymn    := $(addprefix $(obj)/,$(subdir-ymn))
>  __clean-files  := $(extra-y) $(extra-m) $(extra-)       \
>                    $(always) $(targets) $(clean-files)   \
>                    $(host-progs)                         \
> -                  $(hostprogs-y) $(hostprogs-m) $(hostprogs-)
> +                  $(hostprogs-y) $(hostprogs-m) $(hostprogs-) \
> +                  $(hostlibs-y) $(hostlibs-m) $(hostlibs-)
>
>  __clean-files   := $(filter-out $(no-clean-files), $(__clean-files))
>
> diff --git a/scripts/Makefile.host b/scripts/Makefile.host
> index 133edfa..4d180d9 100644
> --- a/scripts/Makefile.host
> +++ b/scripts/Makefile.host
> @@ -20,7 +20,25 @@
>  # Will compile qconf as a C++ program, and menu as a C program.
>  # They are linked as C++ code to the executable qconf
>
> +# hostprogs-y := conf
> +# conf-objs  := conf.o libkconfig.so
> +# libkconfig-objs := expr.o type.o
> +# Will create a shared library named libkconfig.so that consists of
> +# expr.o and type.o (they are both compiled as C code and the object files
> +# are made as position independent code).
> +# conf.c is compiled as a C program, and conf.o is linked together with
> +# libkconfig.so as the executable conf.
> +# Note: Shared libraries consisting of C++ files are not supported

I do not see any use-case for the above.

This series adds cases for "foo.so" as a final target.


As an alternative, you can add needed build rules
into tools/gcc/Makefile, not scripts/Makefile.host

I guess these rule won't be used in other places.



> +# hostcc-option
> +# Usage: cflags-y += $(call hostcc-option,-march=winchip-c6,-march=i586)
> +
> +hostcc-option = $(call try-run,\
> +       $(HOSTCC) $(HOSTCFLAGS) $(HOST_EXTRACFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2))
> +
>  __hostprogs := $(sort $(hostprogs-y) $(hostprogs-m))
> +__hostlibs := $(sort $(hostlibs-y) $(hostlibs-m))
> +__hostcxxlibs := $(sort $(hostcxxlibs-y) $(hostcxxlibs-m))
>
>  # C code
>  # Executables compiled from a single .c file
> @@ -42,6 +60,19 @@ host-cxxmulti        := $(foreach m,$(__hostprogs),$(if $($(m)-cxxobjs),$(m)))
>  # C++ Object (.o) files compiled from .cc files
>  host-cxxobjs   := $(sort $(foreach m,$(host-cxxmulti),$($(m)-cxxobjs)))
>
> +# Shared libaries (only .c supported)
> +# Shared libraries (.so) - all .so files referenced in "xxx-objs"
> +host-cshlib    := $(sort $(filter %.so, $(host-cobjs)))

useless.

> +host-cshlib    += $(sort $(filter %.so, $(__hostlibs)))
> +host-cxxshlib  := $(sort $(filter %.so, $(__hostcxxlibs)))
> +# Remove .so files from "xxx-objs"
> +host-cobjs     := $(filter-out %.so,$(host-cobjs))
> +host-cxxobjs   := $(filter-out %.so,$(host-cxxobjs))
> +
> +# Object (.o) files used by the shared libaries
> +host-cshobjs   := $(sort $(foreach m,$(host-cshlib),$($(m:.so=-objs))))
> +host-cxxshobjs := $(sort $(foreach m,$(host-cxxshlib),$($(m:.so=-objs))))
> +
>  # output directory for programs/.o files
>  # hostprogs-y := tools/build may have been specified.
>  # Retrieve also directory of .o files from prog-objs or prog-cxxobjs notation
> @@ -56,6 +87,10 @@ host-cmulti  := $(addprefix $(obj)/,$(host-cmulti))
>  host-cobjs     := $(addprefix $(obj)/,$(host-cobjs))
>  host-cxxmulti  := $(addprefix $(obj)/,$(host-cxxmulti))
>  host-cxxobjs   := $(addprefix $(obj)/,$(host-cxxobjs))
> +host-cshlib    := $(addprefix $(obj)/,$(host-cshlib))
> +host-cxxshlib  := $(addprefix $(obj)/,$(host-cxxshlib))
> +host-cshobjs   := $(addprefix $(obj)/,$(host-cshobjs))
> +host-cxxshobjs := $(addprefix $(obj)/,$(host-cxxshobjs))
>  host-objdirs    := $(addprefix $(obj)/,$(host-objdirs))
>
>  obj-dirs += $(host-objdirs)
> @@ -124,5 +159,37 @@ quiet_cmd_host-cxxobjs     = HOSTCXX $@
>  $(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE
>         $(call if_changed_dep,host-cxxobjs)
>
> +# Compile .c file, create position independent .o file
> +# host-cshobjs -> .o
> +quiet_cmd_host-cshobjs = HOSTCC  -fPIC $@
> +      cmd_host-cshobjs = $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $<
> +$(host-cshobjs): $(obj)/%.o: $(src)/%.c FORCE
> +       $(call if_changed_dep,host-cshobjs)
> +
> +# Compile .c file, create position independent .o file
> +# host-cxxshobjs -> .o
> +quiet_cmd_host-cxxshobjs       = HOSTCXX -fPIC $@
> +      cmd_host-cxxshobjs       = $(HOSTCXX) $(hostcxx_flags) -fPIC -c -o $@ $<
> +$(host-cxxshobjs): $(obj)/%.o: $(src)/%.c FORCE
> +       $(call if_changed_dep,host-cxxshobjs)
> +
> +# Link a shared library, based on position independent .o files
> +# *.o -> .so shared library (host-cshlib)
> +quiet_cmd_host-cshlib  = HOSTLLD -shared $@
> +      cmd_host-cshlib  = $(HOSTCC) $(HOSTLDFLAGS) -shared -o $@ \
> +                         $(addprefix $(obj)/,$($(@F:.so=-objs))) \
> +                         $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
> +$(host-cshlib): $(obj)/%: $(host-cshobjs) FORCE
> +       $(call if_changed,host-cshlib)


Could you use $(call multi-depend, ...)
if you need to handle multi-object please?

Please refer to commit c8589d1e9e01 and commit 97e3226e6e984c8.

But, I still do not see any gcc-plugin that is large enough
to be linked from multiple objects.





-- 
Best Regards
Masahiro Yamada