Messages in this thread | | | Date | Mon, 2 May 2022 16:54:53 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2 3/3] jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds |
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On Mon, May 02, 2022 at 03:25:14PM +0200, Marco Elver wrote: > On Mon, May 02, 2022 at 03:09PM +0200, Peter Zijlstra wrote: > > > > Subject: jump_label,noinstr: Avoid instrumentation for JUMP_LABEL=n builds > > From: Peter Zijlstra <peterz@infradead.org> > > Date: Mon May 2 12:30:20 CEST 2022 > > > > 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 arch_atomic_read(&key->enabled.count); > > Curious if this compiles - s/.count// ?
It does if you have JUMP_LABEL=y... (-:
*sigh*... how I about I go back to mowing the lawn and try again later...
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