On Fri, Feb 22, 2019 at 12:24:20PM +0000, Vincenzo Frascino wrote: > diff --git a/arch/arm64/include/asm/vdso/compat_barrier.h b/arch/arm64/include/asm/vdso/compat_barrier.h > new file mode 100644 > index 000000000000..b149761d9661 > --- /dev/null > +++ b/arch/arm64/include/asm/vdso/compat_barrier.h > @@ -0,0 +1,36 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright (C) 2018 ARM Limited > + */ > +#ifndef __COMPAT_BARRIER_H > +#define __COMPAT_BARRIER_H > + > +#include <asm/barrier.h> I think it would be safer to not include this header, and explicitly define the AArch32 barriers here in isolation. > + > +#if __LINUX_ARM_ARCH__ >= 8 > +#define aarch32_smp_mb() dmb(ish) > +#define aarch32_smp_rmb() dmb(ishld) > +#define aarch32_smp_wmb() dmb(ishst) > +#else > +#define aarch32_smp_mb() dmb(ish) > +#define aarch32_smp_rmb() aarch32_smp_mb() > +#define aarch32_smp_wmb() dmb(ishst) > +#endif Can't we just code an AArch32-specific version of dmb() here? AFAICT that's the only reason we include the native barrier.h. > +/* > + * Warning: This code is meant to be used with > + * ENABLE_COMPAT_VDSO only. > + */ > +#ifndef ENABLE_COMPAT_VDSO > +#error This header is meant to be used with ENABLE_COMPAT_VDSO only > +#endif > + > +#undef smp_mb > +#undef smp_rmb > +#undef smp_wmb > + > +#define smp_mb() aarch32_smp_mb() > +#define smp_rmb() aarch32_smp_rmb() > +#define smp_wmb() aarch32_smp_wmb() This undeffing looks very fragile to me. [...] > diff --git a/arch/arm64/kernel/vdso32/.gitignore b/arch/arm64/kernel/vdso32/.gitignore > new file mode 100644 > index 000000000000..4fea950fa5ed > --- /dev/null > +++ b/arch/arm64/kernel/vdso32/.gitignore > @@ -0,0 +1,2 @@ > +vdso.lds > +vdso.so.raw > diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile > new file mode 100644 > index 000000000000..ba57d2ae620f > --- /dev/null > +++ b/arch/arm64/kernel/vdso32/Makefile > @@ -0,0 +1,184 @@ > +# SPDX-License-Identifier: GPL-2.0 > +# > +# Makefile for vdso32 > +# > + > +# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before > +# the inclusion of generic Makefile. > +ARCH_REL_TYPE_ABS := R_ARM_JUMP_SLOT|R_ARM_GLOB_DAT|R_ARM_ABS32 > +include $(srctree)/lib/vdso/Makefile > + > +CC_ARM32 := $(CROSS_COMPILE_ARM32)gcc To match HOSTCC, it might make sense to call this COMPATCC ... and likewise, CROSS_COMPILE_COMPAT Thanks, Mark.
