Re: [PATCH] csu: Fix static when PIE is enabled but static PIE is not supported (BZ #29575)

[Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>]

On 05/10/22 16:04, Siddhesh Poyarekar wrote:
> 
> 
> On 2022-10-05 13:08, Adhemerval Zanella wrote:
>> On architectures where static PIE is not supported, both libc and
>> static binaries are built still with -fPIE and -DPIC.  It leads to
>> wrong code for some architectures (for instance sparc).
>>
>> This patch only enables -DPIC for .o files iff static-pie is also
>> supported.  Since the same rule is used for both libc.a objects and
>> installed binaries, the -fno-pie is added if static-pie is not
>> supported (with a strategy similar to how stack protector is
>> disabled for some architectures).
>>
>> Checked on x86_64-linux-gnu (with and without --disable-static-pie)
>> and I also checked on sparc64-linux-gnu to verify that static binaries
>> are not broken and both binaries and tests continue to be built
>> for PIE.
>> ---
> 
> It should be --disable-default-pie.  Can you please check again and confirm?

My mistake, I did use --disable-default-pie (the config.make files on
sparc64 build differs for build-pie-default).

> 
> Thanks,
> Sid
> 
>>   Makeconfig            | 15 +++++++++++++++
>>   Makerules             |  7 +++++++
>>   csu/Makefile          |  4 ++++
>>   stdio-common/Makefile |  4 ++--
>>   4 files changed, 28 insertions(+), 2 deletions(-)
>>
>> diff --git a/Makeconfig b/Makeconfig
>> index 842f49eb58..4b0d9003cd 100644
>> --- a/Makeconfig
>> +++ b/Makeconfig
>> @@ -404,6 +404,9 @@ else
>>   # for PIE to support exception.
>>   static-pie-ldflag = -Wl,-pie,--no-dynamic-linker,--eh-frame-hdr,-z,text
>>   endif # have-static-pie
>> +else
>> +no-static-pie = $(no-pie-ccflag)
>> +no-pic-flag = -UPIC
>>   endif # enable-static-pie
>>   endif # build-pie-default
>>   @@ -901,6 +904,18 @@ define elide-stack-protector
>>   $(if $(filter $(@F),$(patsubst %,%$(1),$(2))), $(no-stack-protector))
>>   endef
>>   +# If static-pie is not supported, add the compiler option to avoid building it
>> +# for pie and to remove the PIC define.  The first argument is the extension
>> +# (.o, .os, .oS) and the second is a list of routines that this path should be
>> +# applied to.
>> +define elide-pie
>> +$(if $(filter $(@F),$(patsubst %,%$(1),$(2))), $(no-static-pie))
>> +endef
>> +# Smae as elide-pie, but remove the PIC flag.
> 
> s/Smae/Same/
> 

Ack.

>> +define elide-pic-flag
>> +$(if $(filter $(@F),$(patsubst %,%$(1),$(2))), $(no-pic-flag))
>> +endef
>> +
>>   # The program that makes Emacs-style TAGS files.
>>   ETAGS    := etags
>>   diff --git a/Makerules b/Makerules
>> index 09c0cf8357..0fcaf565eb 100644
>> --- a/Makerules
>> +++ b/Makerules
>> @@ -1239,6 +1239,13 @@ tests += $(foreach t,$(tests-time64),$(t))
>>   xtests += $(foreach t,$(xtests-time64),$(t))
>>   endif
>>   +# Disable static-pie for libc.a if target does not support it.
>> +CFLAGS-.o += $(call elide-pie,.o,$(routines))
>> +CFLAGS-.op += $(call elide-pie,.op,$(routines))
>> +# And also remove the PIC flag.
>> +CPPFLAGS-.o += $(call elide-pic-flag,.o,$(routines))
>> +CPPFLAGS-.op += $(call elide-pic-flag,.op,$(routines))
> 
> All static routines.  OK.
> 
>> +
>>   # The only difference between MODULE_NAME=testsuite and MODULE_NAME=nonlib is
>>   # that almost all internal declarations from config.h, libc-symbols.h, and
>>   # include/*.h are not available to 'testsuite' code, but are to 'nonlib' code.
>> diff --git a/csu/Makefile b/csu/Makefile
>> index f71a5eb6c6..62a819608f 100644
>> --- a/csu/Makefile
>> +++ b/csu/Makefile
>> @@ -66,6 +66,10 @@ CFLAGS-.os += $(call elide-stack-protector,.os,$(filter-out \
>>                            $(ssp-safe.os), \
>>                            $(routines) $(extra-no-ssp)))
>>   +# Remove PIC flag for init objects.
>> +CPPFLAGS-.o += $(call elide-pic-flag,.o,$(basename $(extra-objs)))
>> +CPPFLAGS-.op += $(call elide-pic-flag,.op,$(basename $(extra-objs)))
>> +
> 
> crt* too.  OK.
> 
>>   ifeq (yes,$(build-shared))
>>   extra-objs += S$(start-installed-name) gmon-start.os
>>   ifneq ($(start-installed-name),$(static-start-installed-name))
>> diff --git a/stdio-common/Makefile b/stdio-common/Makefile
>> index 9c98c02884..6eee9ba73c 100644
>> --- a/stdio-common/Makefile
>> +++ b/stdio-common/Makefile
>> @@ -265,7 +265,7 @@ $(objpfx)errlist-data-aux-shared.S: errlist-data-gen.c
>>     $(objpfx)errlist-data-aux.S: errlist-data-gen.c
>>       $(make-target-directory)
>> -    $(compile-command.c) $(pie-default) $(no-stack-protector) -S
>> +    $(compile-command.c) $(pic-cppflags) $(pic-ccflag) $(no-stack-protector) -S
>>     ifndef no_deps
>>   -include $(objpfx)errlist-data-aux.S.d $(objpfx)errlist-data-aux-shared.S.d
>> @@ -280,7 +280,7 @@ $(objpfx)siglist-aux-shared.S: siglist-gen.c
>>     $(objpfx)siglist-aux.S: siglist-gen.c
>>       $(make-target-directory)
>> -    $(compile-command.c) $(pie-default) $(no-stack-protector) -S
>> +    $(compile-command.c) $(pic-cppflags) $(pic-ccflag) $(no-stack-protector) -S
>>     ifndef no_deps
>>   -include $(objpfx)siglist-aux.S.d $(objpfx)siglist-aux-shared.S.d