ARM: 8840/1: use a raw_spinlock_t in unwind

[ Upstream commit 74ffe79ae538283bbf7c155e62339f1e5c87b55a ]

Mostly unwind is done with irqs enabled however SLUB may call it with
irqs disabled while creating a new SLUB cache.

I had system freeze while loading a module which called
kmem_cache_create() on init. That means SLUB's __slab_alloc() disabled
interrupts and then

->new_slab_objects()
 ->new_slab()
  ->setup_object()
   ->setup_object_debug()
    ->init_tracking()
     ->set_track()
      ->save_stack_trace()
       ->save_stack_trace_tsk()
        ->walk_stackframe()
         ->unwind_frame()
          ->unwind_find_idx()
           =>spin_lock_irqsave(&unwind_lock);

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index 0bee233fef9a30bc92df73da7beee4e3f2966f2f..314cfb232a6353165dc899f35e5747a27a7ef617 100644 (file)
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -93,7 +93,7 @@ extern const struct unwind_idx __start_unwind_idx[];
 static const struct unwind_idx *__origin_unwind_idx;
 extern const struct unwind_idx __stop_unwind_idx[];
 
-static DEFINE_SPINLOCK(unwind_lock);
+static DEFINE_RAW_SPINLOCK(unwind_lock);
 static LIST_HEAD(unwind_tables);
 
 /* Convert a prel31 symbol to an absolute address */
@@ -201,7 +201,7 @@ static const struct unwind_idx *unwind_find_idx(unsigned long addr)
                /* module unwind tables */
                struct unwind_table *table;
 
-               spin_lock_irqsave(&unwind_lock, flags);
+               raw_spin_lock_irqsave(&unwind_lock, flags);
                list_for_each_entry(table, &unwind_tables, list) {
                        if (addr >= table->begin_addr &&
                            addr < table->end_addr) {
@@ -213,7 +213,7 @@ static const struct unwind_idx *unwind_find_idx(unsigned long addr)
                                break;
                        }
                }
-               spin_unlock_irqrestore(&unwind_lock, flags);
+               raw_spin_unlock_irqrestore(&unwind_lock, flags);
        }
 
        pr_debug("%s: idx = %p\n", __func__, idx);
@@ -529,9 +529,9 @@ struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
        tab->begin_addr = text_addr;
        tab->end_addr = text_addr + text_size;
 
-       spin_lock_irqsave(&unwind_lock, flags);
+       raw_spin_lock_irqsave(&unwind_lock, flags);
        list_add_tail(&tab->list, &unwind_tables);
-       spin_unlock_irqrestore(&unwind_lock, flags);
+       raw_spin_unlock_irqrestore(&unwind_lock, flags);
 
        return tab;
 }
@@ -543,9 +543,9 @@ void unwind_table_del(struct unwind_table *tab)
        if (!tab)
                return;
 
-       spin_lock_irqsave(&unwind_lock, flags);
+       raw_spin_lock_irqsave(&unwind_lock, flags);
        list_del(&tab->list);
-       spin_unlock_irqrestore(&unwind_lock, flags);
+       raw_spin_unlock_irqrestore(&unwind_lock, flags);
 
        kfree(tab);
 }