Messages in this thread | | | Date | Tue, 21 Jun 2022 12:01:29 +0530 | Subject | Re: [PATCH rcu 07/12] rcu: tiny: Record kvfree_call_rcu() call stack for KASAN | From | Neeraj Upadhyay <> |
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On 6/21/2022 3:50 AM, Paul E. McKenney wrote: > From: Johannes Berg <johannes.berg@intel.com> > > When running KASAN with Tiny RCU (e.g. under ARCH=um, where > a working KASAN patch is now available), we don't get any > information on the original kfree_rcu() (or similar) caller > when a problem is reported, as Tiny RCU doesn't record this. > > Add the recording, which required pulling kvfree_call_rcu() > out of line for the KASAN case since the recording function > (kasan_record_aux_stack_noalloc) is neither exported, nor > can we include kasan.h into rcutiny.h. > > without KASAN, the patch has no size impact (ARCH=um kernel): > text data bss dec hex filename > 6151515 4423154 33148520 43723189 29b29b5 linux > 6151515 4423154 33148520 43723189 29b29b5 linux + patch > > with KASAN, the impact on my build was minimal: > text data bss dec hex filename > 13915539 7388050 33282304 54585893 340ea25 linux > 13911266 7392114 33282304 54585684 340e954 linux + patch > -4273 +4064 +-0 -209 > > Acked-by: Dmitry Vyukov <dvyukov@google.com> > Signed-off-by: Johannes Berg <johannes.berg@intel.com> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > --- > include/linux/rcutiny.h | 11 ++++++++++- > kernel/rcu/tiny.c | 14 ++++++++++++++ > 2 files changed, 24 insertions(+), 1 deletion(-) > > diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h > index 5fed476f977f6..d84e13f2c3848 100644 > --- a/include/linux/rcutiny.h > +++ b/include/linux/rcutiny.h > @@ -38,7 +38,7 @@ static inline void synchronize_rcu_expedited(void) > */ > extern void kvfree(const void *addr); > > -static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > +static inline void __kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > { > if (head) { > call_rcu(head, func); > @@ -51,6 +51,15 @@ static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > kvfree((void *) func); > } > > +#ifdef CONFIG_KASAN_GENERIC > +void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func); > +#else > +static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > +{ > + __kvfree_call_rcu(head, func); > +} > +#endif > + > void rcu_qs(void); > > static inline void rcu_softirq_qs(void) > diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c > index 340b3f8b090d4..58ff3721d975c 100644 > --- a/kernel/rcu/tiny.c > +++ b/kernel/rcu/tiny.c > @@ -217,6 +217,20 @@ bool poll_state_synchronize_rcu(unsigned long oldstate) > } > EXPORT_SYMBOL_GPL(poll_state_synchronize_rcu); > > +#ifdef CONFIG_KASAN_GENERIC > +void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > +{ > + if (head) { > + void *ptr = (void *) head - (unsigned long) func; > + > + kasan_record_aux_stack_noalloc(ptr); > + }
For the !head case; similar to Tree RCU's kvfree_call_rcu() implementation, we do not need to record 'ptr' (which will be 'func')?
Thanks Neeraj
> + > + __kvfree_call_rcu(head, func); > +} > +EXPORT_SYMBOL_GPL(kvfree_call_rcu); > +#endif > + > void __init rcu_init(void) > { > open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
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