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

Christophe Leroy
2021-04-23T17:18:44Z

Le 23/04/2021 à 00:44, Nick Desaulniers a écrit :
> On Wed, Sep 2, 2020 at 11:02 AM Christophe Leroy
> <christophe.leroy@csgroup.eu> wrote:
>>
>>
>>
>> Le 02/09/2020 à 19:41, Nick Desaulniers a écrit :
>>> On Wed, Sep 2, 2020 at 5:14 AM Michael Ellerman <mpe@ellerman.id.au> wrote:
>>>>
>>>> Nick Desaulniers <ndesaulniers@google.com> 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