On Tue, Nov 26, 2019 at 12:41:19PM +0100, Marco Elver wrote: > Prefer __always_inline for atomic wrappers. When building for size > (CC_OPTIMIZE_FOR_SIZE), some compilers appear to be less inclined to > inline even relatively small static inline functions that are assumed to > be inlinable such as atomic ops. This can cause problems, for example in > UACCESS regions. > > By using __always_inline, we let the real implementation and not the > wrapper determine the final inlining preference. > > For x86 tinyconfig we observe: > - vmlinux baseline: 1316204 > - vmlinux with patch: 1315988 (-216 bytes) > > This came up when addressing UACCESS warnings with CC_OPTIMIZE_FOR_SIZE > in the KCSAN runtime: > http://lkml.kernel.org/r/58708908-84a0-0a81-a836-ad97e33dbb62@xxxxxxxxxxxxx > > Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> > Signed-off-by: Marco Elver <elver@xxxxxxxxxx> > --- > v2: > * Add missing '#include <linux/compiler.h>' > * Add size diff to commit message. > > v1: http://lkml.kernel.org/r/20191122154221.247680-1-elver@xxxxxxxxxx > --- > include/asm-generic/atomic-instrumented.h | 335 +++++++++++----------- > include/asm-generic/atomic-long.h | 331 ++++++++++----------- > scripts/atomic/gen-atomic-instrumented.sh | 7 +- > scripts/atomic/gen-atomic-long.sh | 3 +- > 4 files changed, 340 insertions(+), 336 deletions(-) > diff --git a/scripts/atomic/gen-atomic-instrumented.sh b/scripts/atomic/gen-atomic-instrumented.sh > index 8b8b2a6f8d68..86d27252b988 100755 > --- a/scripts/atomic/gen-atomic-instrumented.sh > +++ b/scripts/atomic/gen-atomic-instrumented.sh > @@ -84,7 +84,7 @@ gen_proto_order_variant() > [ ! -z "${guard}" ] && printf "#if ${guard}\n" > > cat <<EOF > -static inline ${ret} > +static __always_inline ${ret} > ${atomicname}(${params}) > { > ${checks} > @@ -146,17 +146,18 @@ cat << EOF > #ifndef _ASM_GENERIC_ATOMIC_INSTRUMENTED_H > #define _ASM_GENERIC_ATOMIC_INSTRUMENTED_H > > +#include <linux/compiler.h> > #include <linux/build_bug.h> Sorry for the (super) trivial nit, but could you please re-order these two alphabetically, i.e. #include <linux/build_bug.h> #include <linux/compiler.h> With that: Acked-by: Mark Rutland <mark.rutland@xxxxxxx> [...] > @@ -64,6 +64,7 @@ cat << EOF > #ifndef _ASM_GENERIC_ATOMIC_LONG_H > #define _ASM_GENERIC_ATOMIC_LONG_H > > +#include <linux/compiler.h> > #include <asm/types.h> Unlike the above, this doesn't need to be re-ordered; for whatever reason, linux/* includes typically come before asm/* includes. Thanks, Mark.
