Re: [PATCH 1/2] powerpc/vdso64: link vdso64 with linker

[Christophe Leroy]

Le 23/04/2021 à 00:44, Nick Desaulniers a écrit :
> On Wed, Sep 2, 2020 at 11:02 AM Christophe Leroy
> <christophe.leroy@xxxxxxxxxx> wrote:
> > Le 02/09/2020 à 19:41, Nick Desaulniers a écrit :
> > > On Wed, Sep 2, 2020 at 5:14 AM Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
> > > > Nick Desaulniers <ndesaulniers@xxxxxxxxxx> writes:
> > > > > Fixes: commit f2af201002a8 ("powerpc/build: vdso linker warning for orphan sections")
> > > >
> > > > I think I'll just revert that for v5.9 ?
> > >
> > > SGTM; you'll probably still want these changes with some modifications
> > > at some point; vdso32 did have at least one orphaned section, and will
> > > be important for hermetic builds.  Seeing crashes in supported
> > > versions of the tools ties our hands at the moment.
> >
> > Keeping the tool problem aside with binutils 2.26, do you have a way to
> > really link an elf32ppc object when  building vdso32 for PPC64 ?
>
> Sorry, I'm doing a bug scrub and found
> https://github.com/ClangBuiltLinux/linux/issues/774 still open (and my
> reply to this thread still in Drafts; never sent). With my patches
> rebased:
> $ file arch/powerpc/kernel/vdso32/vdso32.so
> arch/powerpc/kernel/vdso32/vdso32.so: ELF 32-bit MSB shared object,
> PowerPC or cisco 4500, version 1 (SYSV), dynamically linked, stripped
>
> Are you still using 2.26?
>
> I'm not able to repro Nathan's reported issue from
> https://lore.kernel.org/lkml/20200902052123.GA2687902@ubuntu-n2-xlarge-x86/,
> so I'm curious if I should resend the rebased patches as v2?

One comment on your rebased patch:

> diff --git a/arch/powerpc/include/asm/vdso.h b/arch/powerpc/include/asm/vdso.h
> index 8542e9bbeead..0bd06ec06aaa 100644
> --- a/arch/powerpc/include/asm/vdso.h
> +++ b/arch/powerpc/include/asm/vdso.h
> @@ -25,19 +25,7 @@ int vdso_getcpu_init(void);
>
>   #else /* __ASSEMBLY__ */
>
> -#ifdef __VDSO64__
> -#define V_FUNCTION_BEGIN(name)		\
> -	.globl name;			\
> -	name:				\
> -
> -#define V_FUNCTION_END(name)		\
> -	.size name,.-name;
> -
> -#define V_LOCAL_FUNC(name) (name)
> -#endif /* __VDSO64__ */
> -
> -#ifdef __VDSO32__
> -
> +#if defined(__VDSO32__) || defined (__VDSO64__)

You always have either __VDSO32__ or __VDSO64__ so this #if is pointless

>   #define V_FUNCTION_BEGIN(name)		\
>   	.globl name;			\
>   	.type name,@function; 		\
> @@ -47,8 +35,7 @@ int vdso_getcpu_init(void);
>   	.size name,.-name;
>
>   #define V_LOCAL_FUNC(name) (name)
> -
> -#endif /* __VDSO32__ */
> +#endif /* __VDSO{32|64}__ */
>
>   #endif /* __ASSEMBLY__ */
>


Christophe