clang/ld.lld build fails with `can't create dynamic relocation R_PPC64_ADDR64 against local symbol in readonly segment`

clang/ld.lld build fails with `can't create dynamic relocation R_PPC64_ADDR64 against local symbol in readonly segment`

[Paul Menzel]

Dear Linux folks,


I just wanted to make you aware that building Linux for ppc64le with 
clang/lld.ld fails with [1]:

     ld.lld: error: can't create dynamic relocation R_PPC64_ADDR64 
against symbol: empty_zero_page in readonly segment; recompile object 
files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in 
the output
     >>> defined in arch/powerpc/kernel/head_64.o
     >>> referenced by 
arch/powerpc/kernel/head_64.o:(___ksymtab+empty_zero_page+0x0)

The patch below from one of the comments [2] fixes it.

--- i/arch/powerpc/Makefile
+++ w/arch/powerpc/Makefile
@@ -122,7 +122,7 @@ cflags-$(CONFIG_STACKPROTECTOR)     += 
-mstack-protector-guard-reg=r2
  endif

  LDFLAGS_vmlinux-y := -Bstatic
-LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
+LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie -z notext
  LDFLAGS_vmlinux        := $(LDFLAGS_vmlinux-y)
  LDFLAGS_vmlinux += $(call ld-option,--orphan-handling=warn)


Kind regards,

Paul


[1]: https://github.com/ClangBuiltLinux/linux/issues/811
[2]: 
https://github.com/ClangBuiltLinux/linux/issues/811#issuecomment-568316320

Re: clang/ld.lld build fails with `can't create dynamic relocation R_PPC64_ADDR64 against local symbol in readonly segment`

[Paul Menzel]

Dear Linux folks,


Am 29.07.21 um 10:23 schrieb Paul Menzel:

> I just wanted to make you aware that building Linux for ppc64le with 
> clang/lld.ld fails with [1]:
> 
>      ld.lld: error: can't create dynamic relocation R_PPC64_ADDR64 
> against symbol: empty_zero_page in readonly segment; recompile object 
> files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in 
> the output
>      >>> defined in arch/powerpc/kernel/head_64.o
>      >>> referenced by 
> arch/powerpc/kernel/head_64.o:(___ksymtab+empty_zero_page+0x0)
> 
> The patch below from one of the comments [2] fixes it.
> 
> --- i/arch/powerpc/Makefile
> +++ w/arch/powerpc/Makefile
> @@ -122,7 +122,7 @@ cflags-$(CONFIG_STACKPROTECTOR)     += 
> -mstack-protector-guard-reg=r2
>   endif
> 
>   LDFLAGS_vmlinux-y := -Bstatic
> -LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
> +LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie -z notext
>   LDFLAGS_vmlinux        := $(LDFLAGS_vmlinux-y)
>   LDFLAGS_vmlinux += $(call ld-option,--orphan-handling=warn)

Any comments, if this is the right fix? Current Linux master branch 
still fails to build with `LLVM=1` on Ubuntu 21.04 without this change.


Kind regards,

Paul


> [1]: https://github.com/ClangBuiltLinux/linux/issues/811
> [2]: https://github.com/ClangBuiltLinux/linux/issues/811#issuecomment-568316320

Re: clang/ld.lld build fails with `can't create dynamic relocation R_PPC64_ADDR64 against local symbol in readonly segment`

[Christophe Leroy]

Le 10/08/2021 à 20:38, Paul Menzel a écrit :
> Dear Linux folks,
> 
> 
> Am 29.07.21 um 10:23 schrieb Paul Menzel:
> 
>> I just wanted to make you aware that building Linux for ppc64le with clang/lld.ld fails with [1]:
>>
>>      ld.lld: error: can't create dynamic relocation R_PPC64_ADDR64 against symbol: empty_zero_page 
>> in readonly segment; recompile object files with -fPIC or pass '-Wl,-z,notext' to allow text 
>> relocations in the output
>>      >>> defined in arch/powerpc/kernel/head_64.o
>>      >>> referenced by arch/powerpc/kernel/head_64.o:(___ksymtab+empty_zero_page+0x0)
>>
>> The patch below from one of the comments [2] fixes it.
>>
>> --- i/arch/powerpc/Makefile
>> +++ w/arch/powerpc/Makefile
>> @@ -122,7 +122,7 @@ cflags-$(CONFIG_STACKPROTECTOR)     += -mstack-protector-guard-reg=r2
>>   endif
>>
>>   LDFLAGS_vmlinux-y := -Bstatic
>> -LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
>> +LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie -z notext
>>   LDFLAGS_vmlinux        := $(LDFLAGS_vmlinux-y)
>>   LDFLAGS_vmlinux += $(call ld-option,--orphan-handling=warn)
> 
> Any comments, if this is the right fix? Current Linux master branch still fails to build with 
> `LLVM=1` on Ubuntu 21.04 without this change.

Which kernel version are you building ?

Since https://github.com/linuxppc/linux/commit/45b30fafe528601f1a4449c9d68d8ebe7bbc39ad , 
empty_zero_page[] is in arch/powerpc/mm/mem.c not in arch/powerpc/kernel/head_64.o

Do you still have the issue with kernel 5.14 ?

Christophe

Re: clang/ld.lld build fails with `can't create dynamic relocation R_PPC64_ADDR64 against local symbol in readonly segment`

[Paul Menzel]

Dear Christophe,


Am 11.08.21 um 16:10 schrieb Christophe Leroy:

> Le 10/08/2021 à 20:38, Paul Menzel a écrit :

>> Am 29.07.21 um 10:23 schrieb Paul Menzel:
>>
>>> I just wanted to make you aware that building Linux for ppc64le with 
>>> clang/lld.ld fails with [1]:
>>>
>>>      ld.lld: error: can't create dynamic relocation R_PPC64_ADDR64 
>>> against symbol: empty_zero_page in readonly segment; recompile object 
>>> files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in 
>>> the output
>>>      >>> defined in arch/powerpc/kernel/head_64.o
>>>      >>> referenced by 
>>> arch/powerpc/kernel/head_64.o:(___ksymtab+empty_zero_page+0x0)
>>>
>>> The patch below from one of the comments [2] fixes it.
>>>
>>> --- i/arch/powerpc/Makefile
>>> +++ w/arch/powerpc/Makefile
>>> @@ -122,7 +122,7 @@ cflags-$(CONFIG_STACKPROTECTOR)     += 
>>> -mstack-protector-guard-reg=r2
>>>   endif
>>>
>>>   LDFLAGS_vmlinux-y := -Bstatic
>>> -LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
>>> +LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie -z notext
>>>   LDFLAGS_vmlinux        := $(LDFLAGS_vmlinux-y)
>>>   LDFLAGS_vmlinux += $(call ld-option,--orphan-handling=warn)
>>
>> Any comments, if this is the right fix? Current Linux master branch 
>> still fails to build with `LLVM=1` on Ubuntu 21.04 without this change.
> 
> Which kernel version are you building ?
> 
> Since 
> https://github.com/linuxppc/linux/commit/45b30fafe528601f1a4449c9d68d8ebe7bbc39ad 
> , empty_zero_page[] is in arch/powerpc/mm/mem.c not in 
> arch/powerpc/kernel/head_64.o
> 
> Do you still have the issue with kernel 5.14 ?

Yes, before sending the message, I reproduced it with

     $ git describe
     v5.14-rc5-2-g9a73fa375d58

containing the commit you mentioned.


Kind regards,

Paul

Re: clang/ld.lld build fails with `can't create dynamic relocation R_PPC64_ADDR64 against local symbol in readonly segment`

[Michael Ellerman]

Paul Menzel <pmenzel@molgen.mpg.de> writes:
> Am 29.07.21 um 10:23 schrieb Paul Menzel:
>
>> I just wanted to make you aware that building Linux for ppc64le with 
>> clang/lld.ld fails with [1]:
>> 
>>      ld.lld: error: can't create dynamic relocation R_PPC64_ADDR64 
>> against symbol: empty_zero_page in readonly segment; recompile object 
>> files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in 
>> the output
>>      >>> defined in arch/powerpc/kernel/head_64.o
>>      >>> referenced by 
>> arch/powerpc/kernel/head_64.o:(___ksymtab+empty_zero_page+0x0)
>> 
>> The patch below from one of the comments [2] fixes it.
>> 
>> --- i/arch/powerpc/Makefile
>> +++ w/arch/powerpc/Makefile
>> @@ -122,7 +122,7 @@ cflags-$(CONFIG_STACKPROTECTOR)     += 
>> -mstack-protector-guard-reg=r2
>>   endif
>> 
>>   LDFLAGS_vmlinux-y := -Bstatic
>> -LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
>> +LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie -z notext
>>   LDFLAGS_vmlinux        := $(LDFLAGS_vmlinux-y)
>>   LDFLAGS_vmlinux += $(call ld-option,--orphan-handling=warn)
>
> Any comments, if this is the right fix? Current Linux master branch 
> still fails to build with `LLVM=1` on Ubuntu 21.04 without this change.

Sorry but I have no idea if it's the right fix. What I need is the
author (or someone else) to send a patch with a change log explaining
the change, what it does, why it's right for llvm, and why it's right
for binutils.

cheers