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authorMichael Ellerman <mpe@ellerman.id.au>2017-01-24 16:36:57 +1100
committerMichael Ellerman <mpe@ellerman.id.au>2017-01-25 13:36:10 +1100
commitb5fa0f7f88edcde37df1807fdf9ff10ec787a60e (patch)
tree3f0c8e6904907d51ccaf858963bb597970266d05 /arch
parentf2574030b0e33263b8a1c28fa3c4fa9292283799 (diff)
downloadlinux-b5fa0f7f88edcde37df1807fdf9ff10ec787a60e.tar.bz2
powerpc: Fix build failure with clang due to BUILD_BUG_ON()
Anton says: In commit 4db7327194db ("powerpc: Add option to use jump label for cpu_has_feature()") and commit c12e6f24d413 ("powerpc: Add option to use jump label for mmu_has_feature()") we added: BUILD_BUG_ON(!__builtin_constant_p(feature)) to cpu_has_feature() and mmu_has_feature() in order to catch usage issues (such as cpu_has_feature(cpu_has_feature(X), which has happened once in the past). Unfortunately LLVM isn't smart enough to resolve this, and it errors out. I work around it in my clang/LLVM builds of the kernel, but I have just discovered that it causes a lot of issues for the bcc (eBPF) trace tool (which uses LLVM). For now just #ifdef it away for clang builds. Fixes: 4db7327194db ("powerpc: Add option to use jump label for cpu_has_feature()") Fixes: c12e6f24d413 ("powerpc: Add option to use jump label for mmu_has_feature()") Cc: stable@vger.kernel.org # v4.8+ Reported-by: Anton Blanchard <anton@samba.org> Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/include/asm/cpu_has_feature.h2
-rw-r--r--arch/powerpc/include/asm/mmu.h2
2 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/cpu_has_feature.h b/arch/powerpc/include/asm/cpu_has_feature.h
index b312b152461b..6e834caa3720 100644
--- a/arch/powerpc/include/asm/cpu_has_feature.h
+++ b/arch/powerpc/include/asm/cpu_has_feature.h
@@ -23,7 +23,9 @@ static __always_inline bool cpu_has_feature(unsigned long feature)
{
int i;
+#ifndef __clang__ /* clang can't cope with this */
BUILD_BUG_ON(!__builtin_constant_p(feature));
+#endif
#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
if (!static_key_initialized) {
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index a34c764ca8dd..233a7e8cc8e3 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -160,7 +160,9 @@ static __always_inline bool mmu_has_feature(unsigned long feature)
{
int i;
+#ifndef __clang__ /* clang can't cope with this */
BUILD_BUG_ON(!__builtin_constant_p(feature));
+#endif
#ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
if (!static_key_initialized) {