Messages in this thread | | | From | Marco Elver <> | Date | Mon, 2 May 2022 13:23:49 +0200 | Subject | Re: [PATCH 3/3] jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds |
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On Mon, 2 May 2022 at 13:12, Peter Zijlstra <peterz@infradead.org> wrote: > > When building x86_64 with JUMP_LABEL=n it's possible for > instrumentation to sneak into noinstr: > > vmlinux.o: warning: objtool: exit_to_user_mode+0x14: call to static_key_count.constprop.0() leaves .noinstr.text section > vmlinux.o: warning: objtool: syscall_exit_to_user_mode+0x2d: call to static_key_count.constprop.0() leaves .noinstr.text section > vmlinux.o: warning: objtool: irqentry_exit_to_user_mode+0x1b: call to static_key_count.constprop.0() leaves .noinstr.text section > > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > include/linux/jump_label.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > --- a/include/linux/jump_label.h > +++ b/include/linux/jump_label.h > @@ -256,9 +256,9 @@ extern void static_key_disable_cpuslocke > #include <linux/atomic.h> > #include <linux/bug.h> > > -static inline int static_key_count(struct static_key *key) > +static __always_inline int static_key_count(struct static_key *key) > { > - return atomic_read(&key->enabled); > + return READ_ONCE_NOCHECK(&key->enabled.count); > }
Did arch_atomic_read() not work? Or should this also be unchecked in instrumented functions?
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