On Wed, Aug 14, 2024 at 12:56 PM Xi Ruoyao <xry111@xxxxxxxxxxx> wrote:
>
> On Thu, 2024-07-18 at 10:34 -0700, Fangrui Song wrote:
> > glibc added support for .gnu.hash in 2006 and .hash has been obsoleted
> > for more than one decade in many Linux distributions. Using
> > --hash-style=sysv might imply unaddressed issues and confuse readers.
> >
> > Just drop the option and rely on the linker default, which is likely
> > "both", or "gnu" when the distribution really wants to eliminate sysv
> > hash overhead.
> >
> > Similar to commit 6b7e26547fad ("x86/vdso: Emit a GNU hash").
> >
> > Signed-off-by: Fangrui Song <maskray@xxxxxxxxxx>
>
> Hi Fangrui,
>
> If I read tools/testing/selftests/vDSO/parse_vdso.c correctly, it does
> know DT_GNU_HASH as at now. Thus after this change the vDSO selftests
> are skipped with "Couldn't find __vdso_gettimeofday" etc if the distro
> enables --hash-style=gnu by default.
>
> So it seems we need to add DT_GNU_HASH support for parse_vdso.c to keep
> test coverage.
Hi Xi,
Perhaps the selftests file needs DT_GNU_HASH support like
https://github.com/abseil/abseil-cpp/commit/1278ee9bd9bd4916181521fac96d6fa1100e38e6
> > ---
> > arch/arm64/kernel/vdso/Makefile | 2 +-
> > arch/arm64/kernel/vdso32/Makefile | 2 +-
> > 2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
> > index d63930c82839..d11da6461278 100644
> > --- a/arch/arm64/kernel/vdso/Makefile
> > +++ b/arch/arm64/kernel/vdso/Makefile
> > @@ -21,7 +21,7 @@ btildflags-$(CONFIG_ARM64_BTI_KERNEL) += -z force-bti
> > # potential future proofing if we end up with internal calls to the exported
> > # routines, as x86 does (see 6f121e548f83 ("x86, vdso: Reimplement vdso.so
> > # preparation in build-time C")).
> > -ldflags-y := -shared -soname=linux-vdso.so.1 --hash-style=sysv \
> > +ldflags-y := -shared -soname=linux-vdso.so.1 \
> > -Bsymbolic --build-id=sha1 -n $(btildflags-y)
> >
> > ifdef CONFIG_LD_ORPHAN_WARN
> > diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
> > index cc4508c604b2..25a2cb6317f3 100644
> > --- a/arch/arm64/kernel/vdso32/Makefile
> > +++ b/arch/arm64/kernel/vdso32/Makefile
> > @@ -98,7 +98,7 @@ VDSO_AFLAGS += -D__ASSEMBLY__
> > # From arm vDSO Makefile
> > VDSO_LDFLAGS += -Bsymbolic --no-undefined -soname=linux-vdso.so.1
> > VDSO_LDFLAGS += -z max-page-size=4096 -z common-page-size=4096
> > -VDSO_LDFLAGS += -shared --hash-style=sysv --build-id=sha1
> > +VDSO_LDFLAGS += -shared --build-id=sha1
> > VDSO_LDFLAGS += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
> >
> >
>
> --
> Xi Ruoyao <xry111@xxxxxxxxxxx>
> School of Aerospace Science and Technology, Xidian University
--
宋方睿
