From 107521e8039688f7a9548f17919dfde670b911c1 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Fri, 18 Dec 2020 22:16:18 +1100 Subject: [PATCH] powerpc/vdso: Don't pass 64-bit ABI cflags to 32-bit VDSO When building the 32-bit VDSO, we are building 32-bit code as part of a 64-bit kernel build. That requires us to tweak the cflags to trick the compiler into building 32-bit code for us. The main way we do that is by passing -m32, but there are other options that affect code generation and ABI selection. In particular when building vgettimeofday.c, we end up passing -mcall-aixdesc because it's in KBUILD_CFLAGS, which causes the compiler to generate function descriptors, and dot symbols, eg: $ nm arch/powerpc/kernel/vdso32/vgettimeofday.o 000005d0 T .__c_kernel_clock_getres 00000024 D __c_kernel_clock_getres ... We get away with that at the moment because we also use the DOTSYM macro, and that is also incorrectly prepending a '.' in 32-bit VDSO code due to a separate bug. But we shouldn't be generating function descriptors for this file, there's no 32-bit ABI that includes function descriptors, so the resulting object file is some frankenstein and it's surprising that it even links. So filter out all the ABI-related options we add to CFLAGS for 64-bit builds, so that they're not used when building 32-bit code. With that we only see regular text symbols: $ nm arch/powerpc/kernel/vdso32/vgettimeofday.o michael@alpine1-p1 000005d0 T __c_kernel_clock_getres 00000000 T __c_kernel_clock_gettime 00000200 T __c_kernel_clock_gettime64 00000410 T __c_kernel_gettimeofday 00000650 T __c_kernel_time Fixes: ab037dd87a2f ("powerpc/vdso: Switch VDSO to generic C implementation.") Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201218111619.1206391-2-mpe@ellerman.id.au --- arch/powerpc/kernel/vdso32/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/vdso32/Makefile b/arch/powerpc/kernel/vdso32/Makefile index 6616f4e794d0..9cb6f524854b 100644 --- a/arch/powerpc/kernel/vdso32/Makefile +++ b/arch/powerpc/kernel/vdso32/Makefile @@ -27,7 +27,7 @@ endif CC32FLAGS := ifdef CONFIG_PPC64 CC32FLAGS += -m32 -KBUILD_CFLAGS := $(filter-out -mcmodel=medium,$(KBUILD_CFLAGS)) +KBUILD_CFLAGS := $(filter-out -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc,$(KBUILD_CFLAGS)) endif targets := $(obj-vdso32) vdso32.so.dbg