[PATCH v2 1/3] sh: thin archives fix linking

[PATCH v2 1/3] sh: thin archives fix linking

[Nicholas Piggin]

The VDSO symbols can't be linked into built-in.o when building with
thin archives, so change this to linking a new object file that is
included into the built-in.o.

Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: linux-sh@vger.kernel.org
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/sh/kernel/vsyscall/Makefile | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/arch/sh/kernel/vsyscall/Makefile b/arch/sh/kernel/vsyscall/Makefile
index 8f0ea5fc835c..efc7a6837ef6 100644
--- a/arch/sh/kernel/vsyscall/Makefile
+++ b/arch/sh/kernel/vsyscall/Makefile
@@ -1,4 +1,4 @@
-obj-y += vsyscall.o vsyscall-syscall.o
+obj-y += vsyscall.o vsyscall-syscall.o vsyscall-syms.o
 
 $(obj)/vsyscall-syscall.o: \
 	$(foreach F,trapa,$(obj)/vsyscall-$F.so)
@@ -26,11 +26,13 @@ $(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
 # We also create a special relocatable object that should mirror the symbol
 # table and layout of the linked DSO.  With ld -R we can then refer to
 # these symbols in the kernel code rather than hand-coded addresses.
-extra-y += vsyscall-syms.o
-$(obj)/built-in.o: $(obj)/vsyscall-syms.o
-$(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o
-
-SYSCFLAGS_vsyscall-syms.o = -r
-$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds \
+SYSCFLAGS_vsyscall-dummy.o = -r
+$(obj)/vsyscall-dummy.o: $(src)/vsyscall.lds \
 			$(obj)/vsyscall-trapa.o $(obj)/vsyscall-note.o FORCE
 	$(call if_changed,syscall)
+
+quiet_cmd_syscall_syms = SYSCALL $@
+      cmd_syscall_syms = $(LD) -r -R $(obj)/vsyscall-dummy.o -o $@
+
+$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o
+	$(call if_changed,syscall_syms)
-- 
2.11.0

Re: [PATCH v2 1/3] sh: thin archives fix linking

[Masahiro Yamada]

2017-06-22 21:39 GMT+09:00 Nicholas Piggin <npiggin@gmail.com>:
> The VDSO symbols can't be linked into built-in.o when building with
> thin archives, so change this to linking a new object file that is
> included into the built-in.o.
>
> Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> Cc: Rich Felker <dalias@libc.org>
> Cc: linux-sh@vger.kernel.org
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  arch/sh/kernel/vsyscall/Makefile | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/arch/sh/kernel/vsyscall/Makefile b/arch/sh/kernel/vsyscall/Makefile
> index 8f0ea5fc835c..efc7a6837ef6 100644
> --- a/arch/sh/kernel/vsyscall/Makefile
> +++ b/arch/sh/kernel/vsyscall/Makefile
> @@ -1,4 +1,4 @@
> -obj-y += vsyscall.o vsyscall-syscall.o
> +obj-y += vsyscall.o vsyscall-syscall.o vsyscall-syms.o
>
>  $(obj)/vsyscall-syscall.o: \
>         $(foreach F,trapa,$(obj)/vsyscall-$F.so)
> @@ -26,11 +26,13 @@ $(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
>  # We also create a special relocatable object that should mirror the symbol
>  # table and layout of the linked DSO.  With ld -R we can then refer to
>  # these symbols in the kernel code rather than hand-coded addresses.
> -extra-y += vsyscall-syms.o
> -$(obj)/built-in.o: $(obj)/vsyscall-syms.o
> -$(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o
> -
> -SYSCFLAGS_vsyscall-syms.o = -r
> -$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds \
> +SYSCFLAGS_vsyscall-dummy.o = -r
> +$(obj)/vsyscall-dummy.o: $(src)/vsyscall.lds \
>                         $(obj)/vsyscall-trapa.o $(obj)/vsyscall-note.o FORCE
>         $(call if_changed,syscall)
> +
> +quiet_cmd_syscall_syms = SYSCALL $@
> +      cmd_syscall_syms = $(LD) -r -R $(obj)/vsyscall-dummy.o -o $@
> +
> +$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o
> +       $(call if_changed,syscall_syms)
> --
> 2.11.0

I applied this, but
I just noticed vsyscall-dummy is rebuilt every time.


  SYSCALL arch/sh/kernel/vsyscall/vsyscall-dummy.o
  SYSCALL arch/sh/kernel/vsyscall/vsyscall-syms.o
  AR      arch/sh/kernel/vsyscall/built-in.o
  AR      arch/sh/kernel/built-in.o



We can avoid the unneeded rebuild by adding "vsyscall-dummy.o" to "targets".

targets += vsyscall-note.o vsyscall.lds vsyscall-dummy.o



-- 
Best Regards
Masahiro Yamada

Re: [PATCH v2 1/3] sh: thin archives fix linking

[Nicholas Piggin]

On Fri, 23 Jun 2017 12:25:10 +0900
Masahiro Yamada <yamada.masahiro@socionext.com> wrote:

> 2017-06-22 21:39 GMT+09:00 Nicholas Piggin <npiggin@gmail.com>:
> > The VDSO symbols can't be linked into built-in.o when building with
> > thin archives, so change this to linking a new object file that is
> > included into the built-in.o.
> >
> > Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> > Cc: Rich Felker <dalias@libc.org>
> > Cc: linux-sh@vger.kernel.org
> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> > ---
> >  arch/sh/kernel/vsyscall/Makefile | 16 +++++++++-------
> >  1 file changed, 9 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/sh/kernel/vsyscall/Makefile b/arch/sh/kernel/vsyscall/Makefile
> > index 8f0ea5fc835c..efc7a6837ef6 100644
> > --- a/arch/sh/kernel/vsyscall/Makefile
> > +++ b/arch/sh/kernel/vsyscall/Makefile
> > @@ -1,4 +1,4 @@
> > -obj-y += vsyscall.o vsyscall-syscall.o
> > +obj-y += vsyscall.o vsyscall-syscall.o vsyscall-syms.o
> >
> >  $(obj)/vsyscall-syscall.o: \
> >         $(foreach F,trapa,$(obj)/vsyscall-$F.so)
> > @@ -26,11 +26,13 @@ $(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
> >  # We also create a special relocatable object that should mirror the symbol
> >  # table and layout of the linked DSO.  With ld -R we can then refer to
> >  # these symbols in the kernel code rather than hand-coded addresses.
> > -extra-y += vsyscall-syms.o
> > -$(obj)/built-in.o: $(obj)/vsyscall-syms.o
> > -$(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o
> > -
> > -SYSCFLAGS_vsyscall-syms.o = -r
> > -$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds \
> > +SYSCFLAGS_vsyscall-dummy.o = -r
> > +$(obj)/vsyscall-dummy.o: $(src)/vsyscall.lds \
> >                         $(obj)/vsyscall-trapa.o $(obj)/vsyscall-note.o FORCE
> >         $(call if_changed,syscall)
> > +
> > +quiet_cmd_syscall_syms = SYSCALL $@
> > +      cmd_syscall_syms = $(LD) -r -R $(obj)/vsyscall-dummy.o -o $@
> > +
> > +$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o
> > +       $(call if_changed,syscall_syms)
> > --
> > 2.11.0  
> 
> I applied this, but
> I just noticed vsyscall-dummy is rebuilt every time.
> 
> 
>   SYSCALL arch/sh/kernel/vsyscall/vsyscall-dummy.o
>   SYSCALL arch/sh/kernel/vsyscall/vsyscall-syms.o
>   AR      arch/sh/kernel/vsyscall/built-in.o
>   AR      arch/sh/kernel/built-in.o
> 
> 
> 
> We can avoid the unneeded rebuild by adding "vsyscall-dummy.o" to "targets".
> 
> targets += vsyscall-note.o vsyscall.lds vsyscall-dummy.o

Thanks, good catch. The tile patch may have the same issue?

Re: [PATCH v2 1/3] sh: thin archives fix linking

[Masahiro Yamada]

2017-06-23 12:50 GMT+09:00 Nicholas Piggin <npiggin@gmail.com>:
> On Fri, 23 Jun 2017 12:25:10 +0900
> Masahiro Yamada <yamada.masahiro@socionext.com> wrote:
>
>> 2017-06-22 21:39 GMT+09:00 Nicholas Piggin <npiggin@gmail.com>:
>> > The VDSO symbols can't be linked into built-in.o when building with
>> > thin archives, so change this to linking a new object file that is
>> > included into the built-in.o.
>> >
>> > Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
>> > Cc: Rich Felker <dalias@libc.org>
>> > Cc: linux-sh@vger.kernel.org
>> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>> > ---
>> >  arch/sh/kernel/vsyscall/Makefile | 16 +++++++++-------
>> >  1 file changed, 9 insertions(+), 7 deletions(-)
>> >
>> > diff --git a/arch/sh/kernel/vsyscall/Makefile b/arch/sh/kernel/vsyscall/Makefile
>> > index 8f0ea5fc835c..efc7a6837ef6 100644
>> > --- a/arch/sh/kernel/vsyscall/Makefile
>> > +++ b/arch/sh/kernel/vsyscall/Makefile
>> > @@ -1,4 +1,4 @@
>> > -obj-y += vsyscall.o vsyscall-syscall.o
>> > +obj-y += vsyscall.o vsyscall-syscall.o vsyscall-syms.o
>> >
>> >  $(obj)/vsyscall-syscall.o: \
>> >         $(foreach F,trapa,$(obj)/vsyscall-$F.so)
>> > @@ -26,11 +26,13 @@ $(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
>> >  # We also create a special relocatable object that should mirror the symbol
>> >  # table and layout of the linked DSO.  With ld -R we can then refer to
>> >  # these symbols in the kernel code rather than hand-coded addresses.
>> > -extra-y += vsyscall-syms.o
>> > -$(obj)/built-in.o: $(obj)/vsyscall-syms.o
>> > -$(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o
>> > -
>> > -SYSCFLAGS_vsyscall-syms.o = -r
>> > -$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds \
>> > +SYSCFLAGS_vsyscall-dummy.o = -r
>> > +$(obj)/vsyscall-dummy.o: $(src)/vsyscall.lds \
>> >                         $(obj)/vsyscall-trapa.o $(obj)/vsyscall-note.o FORCE
>> >         $(call if_changed,syscall)
>> > +
>> > +quiet_cmd_syscall_syms = SYSCALL $@
>> > +      cmd_syscall_syms = $(LD) -r -R $(obj)/vsyscall-dummy.o -o $@
>> > +
>> > +$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o
>> > +       $(call if_changed,syscall_syms)
>> > --
>> > 2.11.0
>>
>> I applied this, but
>> I just noticed vsyscall-dummy is rebuilt every time.
>>
>>
>>   SYSCALL arch/sh/kernel/vsyscall/vsyscall-dummy.o
>>   SYSCALL arch/sh/kernel/vsyscall/vsyscall-syms.o
>>   AR      arch/sh/kernel/vsyscall/built-in.o
>>   AR      arch/sh/kernel/built-in.o
>>
>>
>>
>> We can avoid the unneeded rebuild by adding "vsyscall-dummy.o" to "targets".
>>
>> targets += vsyscall-note.o vsyscall.lds vsyscall-dummy.o
>
> Thanks, good catch. The tile patch may have the same issue?
> --

I think so.


One more fix.


+$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o
+       $(call if_changed,syscall_syms)


$(call if_changed,...) must have FORCE in the dependency field.
Otherwise, if_changed may not be evaluated.

I can fix up it locally.  :-)


-- 
Best Regards
Masahiro Yamada

Re: [PATCH v2 1/3] sh: thin archives fix linking

[Masahiro Yamada]

2017-06-23 19:02 GMT+09:00 Masahiro Yamada <yamada.masahiro@socionext.com>:
> 2017-06-23 12:50 GMT+09:00 Nicholas Piggin <npiggin@gmail.com>:
>> On Fri, 23 Jun 2017 12:25:10 +0900
>> Masahiro Yamada <yamada.masahiro@socionext.com> wrote:
>>
>>> 2017-06-22 21:39 GMT+09:00 Nicholas Piggin <npiggin@gmail.com>:
>>> > The VDSO symbols can't be linked into built-in.o when building with
>>> > thin archives, so change this to linking a new object file that is
>>> > included into the built-in.o.
>>> >
>>> > Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
>>> > Cc: Rich Felker <dalias@libc.org>
>>> > Cc: linux-sh@vger.kernel.org
>>> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>>> > ---
>>> >  arch/sh/kernel/vsyscall/Makefile | 16 +++++++++-------
>>> >  1 file changed, 9 insertions(+), 7 deletions(-)
>>> >
>>> > diff --git a/arch/sh/kernel/vsyscall/Makefile b/arch/sh/kernel/vsyscall/Makefile
>>> > index 8f0ea5fc835c..efc7a6837ef6 100644
>>> > --- a/arch/sh/kernel/vsyscall/Makefile
>>> > +++ b/arch/sh/kernel/vsyscall/Makefile
>>> > @@ -1,4 +1,4 @@
>>> > -obj-y += vsyscall.o vsyscall-syscall.o
>>> > +obj-y += vsyscall.o vsyscall-syscall.o vsyscall-syms.o
>>> >
>>> >  $(obj)/vsyscall-syscall.o: \
>>> >         $(foreach F,trapa,$(obj)/vsyscall-$F.so)
>>> > @@ -26,11 +26,13 @@ $(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
>>> >  # We also create a special relocatable object that should mirror the symbol
>>> >  # table and layout of the linked DSO.  With ld -R we can then refer to
>>> >  # these symbols in the kernel code rather than hand-coded addresses.
>>> > -extra-y += vsyscall-syms.o
>>> > -$(obj)/built-in.o: $(obj)/vsyscall-syms.o
>>> > -$(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o
>>> > -
>>> > -SYSCFLAGS_vsyscall-syms.o = -r
>>> > -$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds \
>>> > +SYSCFLAGS_vsyscall-dummy.o = -r
>>> > +$(obj)/vsyscall-dummy.o: $(src)/vsyscall.lds \
>>> >                         $(obj)/vsyscall-trapa.o $(obj)/vsyscall-note.o FORCE
>>> >         $(call if_changed,syscall)
>>> > +
>>> > +quiet_cmd_syscall_syms = SYSCALL $@
>>> > +      cmd_syscall_syms = $(LD) -r -R $(obj)/vsyscall-dummy.o -o $@
>>> > +
>>> > +$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o
>>> > +       $(call if_changed,syscall_syms)
>>> > --
>>> > 2.11.0
>>>
>>> I applied this, but
>>> I just noticed vsyscall-dummy is rebuilt every time.
>>>
>>>
>>>   SYSCALL arch/sh/kernel/vsyscall/vsyscall-dummy.o
>>>   SYSCALL arch/sh/kernel/vsyscall/vsyscall-syms.o
>>>   AR      arch/sh/kernel/vsyscall/built-in.o
>>>   AR      arch/sh/kernel/built-in.o
>>>
>>>
>>>
>>> We can avoid the unneeded rebuild by adding "vsyscall-dummy.o" to "targets".
>>>
>>> targets += vsyscall-note.o vsyscall.lds vsyscall-dummy.o
>>
>> Thanks, good catch. The tile patch may have the same issue?
>> --
>
> I think so.
>
>
> One more fix.
>
>
> +$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o
> +       $(call if_changed,syscall_syms)
>
>
> $(call if_changed,...) must have FORCE in the dependency field.
> Otherwise, if_changed may not be evaluated.
>
> I can fix up it locally.  :-)
>


I updated thin-ar branch.

Just in case, the following is my local fix-up:

 - Fix incremental build
 - Do not repeat "$(obj)/vsyscall-dummy.o" in the build command




diff --git a/arch/sh/kernel/vsyscall/Makefile b/arch/sh/kernel/vsyscall/Makefile
index efc7a68..99685e5 100644
--- a/arch/sh/kernel/vsyscall/Makefile
+++ b/arch/sh/kernel/vsyscall/Makefile
@@ -5,7 +5,7 @@ $(obj)/vsyscall-syscall.o: \

 # Teach kbuild about targets
 targets += $(foreach F,trapa,vsyscall-$F.o vsyscall-$F.so)
-targets += vsyscall-note.o vsyscall.lds
+targets += vsyscall-note.o vsyscall.lds vsyscall-dummy.o

 # The DSO images are built using a special linker script
 quiet_cmd_syscall = SYSCALL $@
@@ -32,7 +32,7 @@ $(obj)/vsyscall-dummy.o: $(src)/vsyscall.lds \
        $(call if_changed,syscall)

 quiet_cmd_syscall_syms = SYSCALL $@
-      cmd_syscall_syms = $(LD) -r -R $(obj)/vsyscall-dummy.o -o $@
+      cmd_syscall_syms = $(LD) -r -o $@ -R $<

-$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o
+$(obj)/vsyscall-syms.o: $(obj)/vsyscall-dummy.o FORCE
        $(call if_changed,syscall_syms)








-- 
Best Regards
Masahiro Yamada