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

[Siddhesh Poyarekar <siddhesh@sourceware.org>]

On 2022-10-06 14:09, Adhemerval Zanella Netto wrote:
> 
> 
> 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).

OK then it looks good with the typo fixed.

Thanks,
Sid

> 
>>
>> 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
>