2015-11-12 22:26:24

by Shi, Yang

Subject: [PATCH] bpf: samples: exclude asm/sysreg.h for arm64

commit 338d4f49d6f7114a017d294ccf7374df4f998edc
("arm64: kernel: Add support for Privileged Access Never") includes sysreg.h
into futex.h and uaccess.h. But, the inline assembly used by asm/sysreg.h is
incompatible with llvm so it will cause BPF samples build failure for ARM64.
Since sysreg.h is useless for BPF samples, just exclude it from Makefile via
defining __ASM_SYSREG_H.

Signed-off-by: Yang Shi <[email protected]>
---
samples/bpf/Makefile | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 79b4596..edd638b 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -67,10 +67,13 @@ HOSTLOADLIBES_lathist += -lelf
# point this to your LLVM backend with bpf support
LLC=$(srctree)/tools/bpf/llvm/bld/Debug+Asserts/bin/llc

+# asm/sysreg.h inline assmbly used by it is incompatible with llvm.
+# But, ehere is not easy way to fix it, so just exclude it since it is
+# useless for BPF samples.
$(obj)/%.o: $(src)/%.c
clang $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \
- -D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \
+ -D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
-O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf -filetype=obj -o $@
clang $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \
- -D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \
+ -D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
-O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf -filetype=asm -o [email protected]
--
2.0.2

2015-11-12 22:42:15

by Alexei Starovoitov

Subject: Re: [PATCH] bpf: samples: exclude asm/sysreg.h for arm64

On Thu, Nov 12, 2015 at 02:07:46PM -0800, Yang Shi wrote:
> commit 338d4f49d6f7114a017d294ccf7374df4f998edc
> ("arm64: kernel: Add support for Privileged Access Never") includes sysreg.h
> into futex.h and uaccess.h. But, the inline assembly used by asm/sysreg.h is
> incompatible with llvm so it will cause BPF samples build failure for ARM64.
> Since sysreg.h is useless for BPF samples, just exclude it from Makefile via
> defining __ASM_SYSREG_H.
>
> Signed-off-by: Yang Shi <[email protected]>

not the prettiest fix, but good enough for sample code.
Acked-by: Alexei Starovoitov <[email protected]>

2015-11-16 19:41:21

by David Miller

Subject: Re: [PATCH] bpf: samples: exclude asm/sysreg.h for arm64

From: Yang Shi <[email protected]>
Date: Thu, 12 Nov 2015 14:07:46 -0800

> commit 338d4f49d6f7114a017d294ccf7374df4f998edc
> ("arm64: kernel: Add support for Privileged Access Never") includes sysreg.h
> into futex.h and uaccess.h. But, the inline assembly used by asm/sysreg.h is
> incompatible with llvm so it will cause BPF samples build failure for ARM64.
> Since sysreg.h is useless for BPF samples, just exclude it from Makefile via
> defining __ASM_SYSREG_H.
>
> Signed-off-by: Yang Shi <[email protected]>

Applied.