From 800d6acf40e5ce676b53a1259fb4e93e56279367 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 27 May 2022 17:07:45 +0200 Subject: rcu: tiny: Record kvfree_call_rcu() call stack for KASAN 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 Signed-off-by: Johannes Berg Signed-off-by: Paul E. McKenney --- kernel/rcu/tiny.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'kernel/rcu/tiny.c') diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c index 340b3f8b090d..58ff3721d975 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); + } + + __kvfree_call_rcu(head, func); +} +EXPORT_SYMBOL_GPL(kvfree_call_rcu); +#endif + void __init rcu_init(void) { open_softirq(RCU_SOFTIRQ, rcu_process_callbacks); -- cgit v1.2.3-70-g09d2