Re: [PATCH v2] arm64: vdso: Fix ABI regression in compat vdso

[Thomas Gleixner]

On Thu, 11 Jul 2019, Will Deacon wrote:

> On Wed, Jul 10, 2019 at 03:01:19PM +0100, Vincenzo Frascino wrote:
> > Prior to the introduction of Unified vDSO support and compat layer for
> > vDSO on arm64, AT_SYSINFO_EHDR was not defined for compat tasks.
> > In the current implementation, AT_SYSINFO_EHDR is defined even if the
> > compat vdso layer is not built and this causes a regression in the
> > expected behavior of the ABI.
> > 
> > Restore the ABI behavior making sure that AT_SYSINFO_EHDR for compat
> > tasks is defined only when CONFIG_COMPAT_VDSO is enabled.
> > 
> > Reported-by: John Stultz <john.stultz@xxxxxxxxxx>
> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> > ---
> >  arch/arm64/include/asm/elf.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
> > index 3c7037c6ba9b..b618017205a3 100644
> > --- a/arch/arm64/include/asm/elf.h
> > +++ b/arch/arm64/include/asm/elf.h
> > @@ -202,7 +202,7 @@ typedef compat_elf_greg_t		compat_elf_gregset_t[COMPAT_ELF_NGREG];
> >  ({									\
> >  	set_thread_flag(TIF_32BIT);					\
> >   })
> > -#ifdef CONFIG_GENERIC_COMPAT_VDSO
> > +#ifdef CONFIG_COMPAT_VDSO
> >  #define COMPAT_ARCH_DLINFO						\
> >  do {									\
> >  	/*								\
> 
> Acked-by: Will Deacon <will@xxxxxxxxxx>
> 
> I can take this at -rc1 via arm64 unless tglx plans to send it during the
> rest of the merge window. Please let me know.

I had no plan to pick it up, but if you want I can route it through timer
urgents so it hits Linus tree before rc1.

Thanks,

	tglx