A change in clang 13 results in the __lwsync macro being defined as __builtin_ppc_lwsync, which emits 'lwsync' or 'msync' depending on what the target supports. This breaks the build because of -Werror in arch/powerpc, along with thousands of warnings:
In file included from arch/powerpc/kernel/pmc.c:12: In file included from include/linux/bug.h:5: In file included from arch/powerpc/include/asm/bug.h:109: In file included from include/asm-generic/bug.h:20: In file included from include/linux/kernel.h:12: In file included from include/linux/bitops.h:32: In file included from arch/powerpc/include/asm/bitops.h:62: arch/powerpc/include/asm/barrier.h:49:9: error: '__lwsync' macro redefined [-Werror,-Wmacro-redefined] #define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory") ^ <built-in>:308:9: note: previous definition is here #define __lwsync __builtin_ppc_lwsync ^ 1 error generated.
Undefine this macro so that the runtime patching introduced by commit 2d1b2027626d ("powerpc: Fixup lwsync at runtime") continues to work properly with clang and the build no longer breaks.
Cc: stable@vger.kernel.org Link: https://github.com/ClangBuiltLinux/linux/issues/1386 Link: https://github.com/llvm/llvm-project/commit/62b5df7fe2b3fda1772befeda15598fb... Signed-off-by: Nathan Chancellor nathan@kernel.org --- arch/powerpc/include/asm/barrier.h | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h index 7ae29cfb06c0..f0e687236484 100644 --- a/arch/powerpc/include/asm/barrier.h +++ b/arch/powerpc/include/asm/barrier.h @@ -46,6 +46,8 @@ # define SMPWMB eieio #endif
+/* clang defines this macro for a builtin, which will not work with runtime patching */ +#undef __lwsync #define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory") #define dma_rmb() __lwsync() #define dma_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
base-commit: 97e5bf604b7a0d6e1b3e00fe31d5fd4b9bffeaae
On Fri, May 28, 2021 at 11:29 AM Nathan Chancellor nathan@kernel.org wrote:
A change in clang 13 results in the __lwsync macro being defined as __builtin_ppc_lwsync, which emits 'lwsync' or 'msync' depending on what the target supports.
Indeed, $ clang --target=powerpc64le-linux-gnu -mcpu=e500 -m32 for example.
Thanks for the patch! Reviewed-by: Nick Desaulniers ndesaulniers@google.com
This breaks the build because of -Werror in arch/powerpc, along with thousands of warnings:
In file included from arch/powerpc/kernel/pmc.c:12: In file included from include/linux/bug.h:5: In file included from arch/powerpc/include/asm/bug.h:109: In file included from include/asm-generic/bug.h:20: In file included from include/linux/kernel.h:12: In file included from include/linux/bitops.h:32: In file included from arch/powerpc/include/asm/bitops.h:62: arch/powerpc/include/asm/barrier.h:49:9: error: '__lwsync' macro redefined [-Werror,-Wmacro-redefined] #define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory") ^ <built-in>:308:9: note: previous definition is here #define __lwsync __builtin_ppc_lwsync ^ 1 error generated.
Undefine this macro so that the runtime patching introduced by commit 2d1b2027626d ("powerpc: Fixup lwsync at runtime") continues to work properly with clang and the build no longer breaks.
Cc: stable@vger.kernel.org Link: https://github.com/ClangBuiltLinux/linux/issues/1386 Link: https://github.com/llvm/llvm-project/commit/62b5df7fe2b3fda1772befeda15598fb... Signed-off-by: Nathan Chancellor nathan@kernel.org
arch/powerpc/include/asm/barrier.h | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h index 7ae29cfb06c0..f0e687236484 100644 --- a/arch/powerpc/include/asm/barrier.h +++ b/arch/powerpc/include/asm/barrier.h @@ -46,6 +46,8 @@ # define SMPWMB eieio #endif
+/* clang defines this macro for a builtin, which will not work with runtime patching */ +#undef __lwsync #define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory") #define dma_rmb() __lwsync() #define dma_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
base-commit: 97e5bf604b7a0d6e1b3e00fe31d5fd4b9bffeaae
2.32.0.rc0
On Fri, 28 May 2021 11:27:52 -0700, Nathan Chancellor wrote:
A change in clang 13 results in the __lwsync macro being defined as __builtin_ppc_lwsync, which emits 'lwsync' or 'msync' depending on what the target supports. This breaks the build because of -Werror in arch/powerpc, along with thousands of warnings:
In file included from arch/powerpc/kernel/pmc.c:12: In file included from include/linux/bug.h:5: In file included from arch/powerpc/include/asm/bug.h:109: In file included from include/asm-generic/bug.h:20: In file included from include/linux/kernel.h:12: In file included from include/linux/bitops.h:32: In file included from arch/powerpc/include/asm/bitops.h:62: arch/powerpc/include/asm/barrier.h:49:9: error: '__lwsync' macro redefined [-Werror,-Wmacro-redefined] #define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory") ^ <built-in>:308:9: note: previous definition is here #define __lwsync __builtin_ppc_lwsync ^ 1 error generated.
[...]
Applied to powerpc/next.
[1/1] powerpc/barrier: Avoid collision with clang's __lwsync macro https://git.kernel.org/powerpc/c/015d98149b326e0f1f02e44413112ca8b4330543
cheers
linux-stable-mirror@lists.linaro.org
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Nick Desaulniers