x86: explicit call to mmiotrace in do_page_fault()
The custom page fault handler list is replaced with a single function
pointer. All related functions and variables are renamed for
mmiotrace.
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: pq@iki.fi
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 343f5c1..e9a086a 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -49,53 +49,55 @@
#define PF_RSVD (1<<3)
#define PF_INSTR (1<<4)
-#ifdef CONFIG_PAGE_FAULT_HANDLERS
-static HLIST_HEAD(pf_handlers); /* protected by RCU */
-static DEFINE_SPINLOCK(pf_handlers_writer);
+#ifdef CONFIG_MMIOTRACE_HOOKS
+static pf_handler_func mmiotrace_pf_handler; /* protected by RCU */
+static DEFINE_SPINLOCK(mmiotrace_handler_lock);
-void register_page_fault_handler(struct pf_handler *new_pfh)
+int mmiotrace_register_pf(pf_handler_func new_pfh)
{
+ int ret = 0;
unsigned long flags;
- spin_lock_irqsave(&pf_handlers_writer, flags);
- hlist_add_head_rcu(&new_pfh->hlist, &pf_handlers);
- spin_unlock_irqrestore(&pf_handlers_writer, flags);
+ spin_lock_irqsave(&mmiotrace_handler_lock, flags);
+ if (mmiotrace_pf_handler)
+ ret = -EBUSY;
+ else
+ mmiotrace_pf_handler = new_pfh;
+ spin_unlock_irqrestore(&mmiotrace_handler_lock, flags);
+ return ret;
}
-EXPORT_SYMBOL_GPL(register_page_fault_handler);
+EXPORT_SYMBOL_GPL(mmiotrace_register_pf);
/**
- * unregister_page_fault_handler:
+ * mmiotrace_unregister_pf:
* The caller must ensure @old_pfh is not in use anymore before freeing it.
- * This function does not guarantee it. The list of handlers is protected by
- * RCU, so you can do this by e.g. calling synchronize_rcu().
+ * This function does not guarantee it. The handler function pointer is
+ * protected by RCU, so you can do this by e.g. calling synchronize_rcu().
*/
-void unregister_page_fault_handler(struct pf_handler *old_pfh)
+int mmiotrace_unregister_pf(pf_handler_func old_pfh)
{
+ int ret = 0;
unsigned long flags;
- spin_lock_irqsave(&pf_handlers_writer, flags);
- hlist_del_rcu(&old_pfh->hlist);
- spin_unlock_irqrestore(&pf_handlers_writer, flags);
+ spin_lock_irqsave(&mmiotrace_handler_lock, flags);
+ if (mmiotrace_pf_handler != old_pfh)
+ ret = -EPERM;
+ else
+ mmiotrace_pf_handler = NULL;
+ spin_unlock_irqrestore(&mmiotrace_handler_lock, flags);
+ return ret;
}
-EXPORT_SYMBOL_GPL(unregister_page_fault_handler);
-#endif
+EXPORT_SYMBOL_GPL(mmiotrace_unregister_pf);
+#endif /* CONFIG_MMIOTRACE_HOOKS */
/* returns non-zero if do_page_fault() should return */
-static int handle_custom_pf(struct pt_regs *regs, unsigned long error_code,
- unsigned long address)
+static inline int call_mmiotrace(struct pt_regs *regs,
+ unsigned long error_code,
+ unsigned long address)
{
-#ifdef CONFIG_PAGE_FAULT_HANDLERS
+#ifdef CONFIG_MMIOTRACE_HOOKS
int ret = 0;
- struct pf_handler *cur;
- struct hlist_node *ncur;
-
- if (hlist_empty(&pf_handlers))
- return 0;
-
rcu_read_lock();
- hlist_for_each_entry_rcu(cur, ncur, &pf_handlers, hlist) {
- ret = cur->handler(regs, error_code, address);
- if (ret)
- break;
- }
+ if (mmiotrace_pf_handler)
+ ret = mmiotrace_pf_handler(regs, error_code, address);
rcu_read_unlock();
return ret;
#else
@@ -655,7 +657,7 @@
if (notify_page_fault(regs))
return;
- if (handle_custom_pf(regs, error_code, address))
+ if (call_mmiotrace(regs, error_code, address))
return;
/*