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Commit b1ae32db authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Thomas Gleixner
Browse files

x86/cpufeature: Guard asm_volatile_goto usage for BPF compilation 



Workaround for the sake of BPF compilation which utilizes kernel
headers, but clang does not support ASM GOTO and fails the build.

Fixes: d0266046 ("x86: Remove FAST_FEATURE_TESTS")
Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: daniel@iogearbox.net
Cc: peterz@infradead.org
Cc: netdev@vger.kernel.org
Cc: bp@alien8.de
Cc: yhs@fb.com
Cc: kernel-team@fb.com
Cc: torvalds@linux-foundation.org
Cc: davem@davemloft.net
Link: https://lkml.kernel.org/r/20180513193222.1997938-1-ast@kernel.org
parent 13ebe18c

arch/x86/include/asm/cpufeature.h

+15 −0
Original line number Diff line number Diff line
@@ -140,6 +140,20 @@ extern void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int bit); 


#define setup_force_cpu_bug(bit) setup_force_cpu_cap(bit)



#if defined(__clang__) && !defined(CC_HAVE_ASM_GOTO)



/*

 * Workaround for the sake of BPF compilation which utilizes kernel

 * headers, but clang does not support ASM GOTO and fails the build.

 */

#ifndef __BPF_TRACING__

#warning "Compiler lacks ASM_GOTO support. Add -D __BPF_TRACING__ to your compiler arguments"

#endif



#define static_cpu_has(bit)            boot_cpu_has(bit)



#else



/*

 * Static testing of CPU features.  Used the same as boot_cpu_has().

 * These will statically patch the target code for additional
@@ -195,6 +209,7 @@ static __always_inline __pure bool _static_cpu_has(u16 bit) 
		boot_cpu_has(bit) :				\

		_static_cpu_has(bit)				\

)

#endif



#define cpu_has_bug(c, bit)		cpu_has(c, (bit))

#define set_cpu_bug(c, bit)		set_cpu_cap(c, (bit))

samples/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -255,7 +255,7 @@ $(obj)/tracex5_kern.o: $(obj)/syscall_nrs.h 
$(obj)/%.o: $(src)/%.c

	$(CLANG) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) -I$(obj) \

		-I$(srctree)/tools/testing/selftests/bpf/ \

		-D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \

		-D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign \

		-D__TARGET_ARCH_$(ARCH) -Wno-compare-distinct-pointer-types \

		-Wno-gnu-variable-sized-type-not-at-end \

		-Wno-address-of-packed-member -Wno-tautological-compare \