Commit 51f5fd2e authored Oct 31, 2018 by Will Deacon Committed by Arnaldo Carvalho de Melo Nov 01, 2018

tools headers barrier: Fix arm64 tools build failure wrt smp_load_{acquire,release}

Cheers for reporting this. I managed to reproduce the build failure with
gcc version 6.3.0 20170516 (Debian 6.3.0-18+deb9u1).

The code in question is the arm64 versions of smp_load_acquire() and
smp_store_release(). Unlike other architectures, these are not built
around READ_ONCE() and WRITE_ONCE() since we have instructions we can
use instead of fences. Bringing our macros up-to-date with those (i.e.
tweaking the union initialisation and using the special "uXX_alias_t"
types) appears to fix the issue for me.

Committer notes:

Testing it in the systems previously failing:

# time dm android-ndk:r12b-arm \
android-ndk:r15c-arm \
debian:experimental-x-arm64 \
ubuntu:14.04.4-x-linaro-arm64 \
ubuntu:16.04-x-arm \
ubuntu:16.04-x-arm64 \
ubuntu:18.04-x-arm \
ubuntu:18.04-x-arm64
1 android-ndk:r12b-arm : Ok arm-linux-androideabi-gcc (GCC) 4.9.x 20150123 (prerelease)
2 android-ndk:r15c-arm : Ok arm-linux-androideabi-gcc (GCC) 4.9.x 20150123 (prerelease)
3 debian:experimental-x-arm64 : Ok aarch64-linux-gnu-gcc (Debian 8.2.0-7) 8.2.0
4 ubuntu:14.04.4-x-linaro-arm64 : Ok aarch64-linux-gnu-gcc (Linaro GCC 5.5-2017.10) 5.5.0
5 ubuntu:16.04-x-arm : Ok arm-linux-gnueabihf-gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
6 ubuntu:16.04-x-arm64 : Ok aarch64-linux-gnu-gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
7 ubuntu:18.04-x-arm : Ok arm-linux-gnueabihf-gcc (Ubuntu/Linaro 7.3.0-27ubuntu1~18.04) 7.3.0
8 ubuntu:18.04-x-arm64 : Ok aarch64-linux-gnu-gcc (Ubuntu/Linaro 7.3.0-27ubuntu1~18.04) 7.3.0

Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20181031174408.GA27871@arm.com

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 29995d29

tools/arch/arm64/include/asm/barrier.h

+67 −66

Original line number	Diff line number	Diff line
		@@ -17,31 +17,31 @@
		#define smp_store_release(p, v) \
		do { \
		union { typeof(*p) __val; char __c[1]; } __u = \
		{ .__val = (__force typeof(*p)) (v) }; \
		{ .__val = (v) }; \
		\
		switch (sizeof(*p)) { \
		case 1: \
		asm volatile ("stlrb %w1, %0" \
		: "=Q" (*p) \
		: "r" ((__u8 )__u.__c) \
		: "r" ((__u8_alias_t )__u.__c) \
		: "memory"); \
		break; \
		case 2: \
		asm volatile ("stlrh %w1, %0" \
		: "=Q" (*p) \
		: "r" ((__u16 )__u.__c) \
		: "r" ((__u16_alias_t )__u.__c) \
		: "memory"); \
		break; \
		case 4: \
		asm volatile ("stlr %w1, %0" \
		: "=Q" (*p) \
		: "r" ((__u32 )__u.__c) \
		: "r" ((__u32_alias_t )__u.__c) \
		: "memory"); \
		break; \
		case 8: \
		asm volatile ("stlr %1, %0" \
		: "=Q" (*p) \
		: "r" ((__u64 )__u.__c) \
		: "r" ((__u64_alias_t )__u.__c) \
		: "memory"); \
		break; \
		default: \
		@@ -53,27 +53,28 @@ do { \

		#define smp_load_acquire(p) \
		({ \
		union { typeof(*p) __val; char __c[1]; } __u; \
		union { typeof(*p) __val; char __c[1]; } __u = \
		{ .__c = { 0 } }; \
		\
		switch (sizeof(*p)) { \
		case 1: \
		asm volatile ("ldarb %w0, %1" \
		: "=r" ((__u8 )__u.__c) \
		: "=r" ((__u8_alias_t )__u.__c) \
		: "Q" (*p) : "memory"); \
		break; \
		case 2: \
		asm volatile ("ldarh %w0, %1" \
		: "=r" ((__u16 )__u.__c) \
		: "=r" ((__u16_alias_t )__u.__c) \
		: "Q" (*p) : "memory"); \
		break; \
		case 4: \
		asm volatile ("ldar %w0, %1" \
		: "=r" ((__u32 )__u.__c) \
		: "=r" ((__u32_alias_t )__u.__c) \
		: "Q" (*p) : "memory"); \
		break; \
		case 8: \
		asm volatile ("ldar %0, %1" \
		: "=r" ((__u64 )__u.__c) \
		: "=r" ((__u64_alias_t )__u.__c) \
		: "Q" (*p) : "memory"); \
		break; \
		default: \