On Tue, 2020-05-19 at 08:48 -0700, Paul E. McKenney wrote: > On Tue, May 19, 2020 at 10:23:59AM +0800, Walter Wu wrote: > > This feature will record the last two call_rcu() call stacks and > > prints up to 2 call_rcu() call stacks in KASAN report. > > > > When call_rcu() is called, we store the call_rcu() call stack into > > slub alloc meta-data, so that the KASAN report can print rcu stack. > > > > [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437 > > [2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ > > > > Signed-off-by: Walter Wu <walter-zh.wu@xxxxxxxxxxxx> > > Suggested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > > Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> > > Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > > Cc: Alexander Potapenko <glider@xxxxxxxxxx> > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > Cc: Paul E. McKenney <paulmck@xxxxxxxxxx> > > Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx> > > Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> > > Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx> > > Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> > > From an RCU perspective: > > Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxx> > Hi Paul, Thank you for your suggestion and review. Walter > > --- > > include/linux/kasan.h | 2 ++ > > kernel/rcu/tree.c | 2 ++ > > lib/Kconfig.kasan | 2 ++ > > mm/kasan/common.c | 4 ++-- > > mm/kasan/generic.c | 19 +++++++++++++++++++ > > mm/kasan/kasan.h | 10 ++++++++++ > > mm/kasan/report.c | 24 ++++++++++++++++++++++++ > > 7 files changed, 61 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/kasan.h b/include/linux/kasan.h > > index 31314ca7c635..23b7ee00572d 100644 > > --- a/include/linux/kasan.h > > +++ b/include/linux/kasan.h > > @@ -174,11 +174,13 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; } > > > > void kasan_cache_shrink(struct kmem_cache *cache); > > void kasan_cache_shutdown(struct kmem_cache *cache); > > +void kasan_record_aux_stack(void *ptr); > > > > #else /* CONFIG_KASAN_GENERIC */ > > > > static inline void kasan_cache_shrink(struct kmem_cache *cache) {} > > static inline void kasan_cache_shutdown(struct kmem_cache *cache) {} > > +static inline void kasan_record_aux_stack(void *ptr) {} > > > > #endif /* CONFIG_KASAN_GENERIC */ > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index 06548e2ebb72..36a4ff7f320b 100644 > > --- a/kernel/rcu/tree.c > > +++ b/kernel/rcu/tree.c > > @@ -57,6 +57,7 @@ > > #include <linux/slab.h> > > #include <linux/sched/isolation.h> > > #include <linux/sched/clock.h> > > +#include <linux/kasan.h> > > #include "../time/tick-internal.h" > > > > #include "tree.h" > > @@ -2668,6 +2669,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func) > > head->func = func; > > head->next = NULL; > > local_irq_save(flags); > > + kasan_record_aux_stack(head); > > rdp = this_cpu_ptr(&rcu_data); > > > > /* Add the callback to our list. */ > > diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan > > index 81f5464ea9e1..4e83cf6e3caa 100644 > > --- a/lib/Kconfig.kasan > > +++ b/lib/Kconfig.kasan > > @@ -58,6 +58,8 @@ config KASAN_GENERIC > > For better error detection enable CONFIG_STACKTRACE. > > Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB > > (the resulting kernel does not boot). > > + In generic mode KASAN prints the last two call_rcu() call stacks in > > + reports. > > > > config KASAN_SW_TAGS > > bool "Software tag-based mode" > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > > index 2906358e42f0..8bc618289bb1 100644 > > --- a/mm/kasan/common.c > > +++ b/mm/kasan/common.c > > @@ -41,7 +41,7 @@ > > #include "kasan.h" > > #include "../slab.h" > > > > -static inline depot_stack_handle_t save_stack(gfp_t flags) > > +depot_stack_handle_t kasan_save_stack(gfp_t flags) > > { > > unsigned long entries[KASAN_STACK_DEPTH]; > > unsigned int nr_entries; > > @@ -54,7 +54,7 @@ static inline depot_stack_handle_t save_stack(gfp_t flags) > > static inline void set_track(struct kasan_track *track, gfp_t flags) > > { > > track->pid = current->pid; > > - track->stack = save_stack(flags); > > + track->stack = kasan_save_stack(flags); > > } > > > > void kasan_enable_current(void) > > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c > > index 56ff8885fe2e..3372bdcaf92a 100644 > > --- a/mm/kasan/generic.c > > +++ b/mm/kasan/generic.c > > @@ -325,3 +325,22 @@ DEFINE_ASAN_SET_SHADOW(f2); > > DEFINE_ASAN_SET_SHADOW(f3); > > DEFINE_ASAN_SET_SHADOW(f5); > > DEFINE_ASAN_SET_SHADOW(f8); > > + > > +void kasan_record_aux_stack(void *addr) > > +{ > > + struct page *page = kasan_addr_to_page(addr); > > + struct kmem_cache *cache; > > + struct kasan_alloc_meta *alloc_info; > > + void *object; > > + > > + if (!(page && PageSlab(page))) > > + return; > > + > > + cache = page->slab_cache; > > + object = nearest_obj(cache, page, addr); > > + alloc_info = get_alloc_info(cache, object); > > + > > + /* record the last two call_rcu() call stacks */ > > + alloc_info->aux_stack[1] = alloc_info->aux_stack[0]; > > + alloc_info->aux_stack[0] = kasan_save_stack(GFP_NOWAIT); > > +} > > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > > index e8f37199d885..a7391bc83070 100644 > > --- a/mm/kasan/kasan.h > > +++ b/mm/kasan/kasan.h > > @@ -104,7 +104,15 @@ struct kasan_track { > > > > struct kasan_alloc_meta { > > struct kasan_track alloc_track; > > +#ifdef CONFIG_KASAN_GENERIC > > + /* > > + * call_rcu() call stack is stored into struct kasan_alloc_meta. > > + * The free stack is stored into struct kasan_free_meta. > > + */ > > + depot_stack_handle_t aux_stack[2]; > > +#else > > struct kasan_track free_track[KASAN_NR_FREE_STACKS]; > > +#endif > > #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY > > u8 free_pointer_tag[KASAN_NR_FREE_STACKS]; > > u8 free_track_idx; > > @@ -159,6 +167,8 @@ void kasan_report_invalid_free(void *object, unsigned long ip); > > > > struct page *kasan_addr_to_page(const void *addr); > > > > +depot_stack_handle_t kasan_save_stack(gfp_t flags); > > + > > #if defined(CONFIG_KASAN_GENERIC) && \ > > (defined(CONFIG_SLAB) || defined(CONFIG_SLUB)) > > void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache); > > diff --git a/mm/kasan/report.c b/mm/kasan/report.c > > index 80f23c9da6b0..6f8f2bf8f53b 100644 > > --- a/mm/kasan/report.c > > +++ b/mm/kasan/report.c > > @@ -179,6 +179,17 @@ static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, > > return &alloc_meta->free_track[i]; > > } > > > > +#ifdef CONFIG_KASAN_GENERIC > > +static void print_stack(depot_stack_handle_t stack) > > +{ > > + unsigned long *entries; > > + unsigned int nr_entries; > > + > > + nr_entries = stack_depot_fetch(stack, &entries); > > + stack_trace_print(entries, nr_entries, 0); > > +} > > +#endif > > + > > static void describe_object(struct kmem_cache *cache, void *object, > > const void *addr, u8 tag) > > { > > @@ -192,6 +203,19 @@ static void describe_object(struct kmem_cache *cache, void *object, > > free_track = kasan_get_free_track(cache, object, tag); > > print_track(free_track, "Freed"); > > pr_err("\n"); > > + > > +#ifdef CONFIG_KASAN_GENERIC > > + if (alloc_info->aux_stack[0]) { > > + pr_err("Last one call_rcu() call stack:\n"); > > + print_stack(alloc_info->aux_stack[0]); > > + pr_err("\n"); > > + } > > + if (alloc_info->aux_stack[1]) { > > + pr_err("Second to last call_rcu() call stack:\n"); > > + print_stack(alloc_info->aux_stack[1]); > > + pr_err("\n"); > > + } > > +#endif > > } > > > > describe_object_addr(cache, object, addr); > > -- > > 2.18.0
