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rcu: tiny: Record kvfree_call_rcu() call stack for KASAN

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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>
This commit is contained in:
Johannes Berg 2022-05-27 17:07:45 +02:00 committed by Paul E. McKenney
parent 9c9b26b0df
commit 800d6acf40
2 changed files with 24 additions and 1 deletions
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11
include/linux/rcutiny.h
View File

@ -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)

14
kernel/rcu/tiny.c
View File

@ -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);