Commit 8f415333 authored by Michael Ellerman's avatar Michael Ellerman Committed by Greg Kroah-Hartman

powerpc: Fix build failure with clang due to BUILD_BUG_ON()

commit b5fa0f7f upstream.

Anton says: In commit 4db73271 ("powerpc: Add option to use jump
label for cpu_has_feature()") and commit c12e6f24 ("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: 4db73271 ("powerpc: Add option to use jump label for cpu_has_feature()")
Fixes: c12e6f24 ("powerpc: Add option to use jump label for mmu_has_feature()")
Reported-by: default avatarAnton Blanchard <anton@samba.org>
Tested-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent bbf69e51
......@@ -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) {
......
......@@ -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) {
......
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