Merge branch 'tracing/ftrace' into auto-ftrace-next

3 files changed, 68 insertions, 2 deletions

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 8bcb6f40ccb6..42394b353c6a 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -49,6 +49,60 @@
 #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);
+
+void register_page_fault_handler(struct pf_handler *new_pfh)
+{
+        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);
+}
+EXPORT_SYMBOL_GPL(register_page_fault_handler);
+
+/**
+ * unregister_page_fault_handler:
+ * 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().
+ */
+void unregister_page_fault_handler(struct pf_handler *old_pfh)
+{
+        unsigned long flags;
+        spin_lock_irqsave(&pf_handlers_writer, flags);
+        hlist_del_rcu(&old_pfh->hlist);
+        spin_unlock_irqrestore(&pf_handlers_writer, flags);
+}
+EXPORT_SYMBOL_GPL(unregister_page_fault_handler);
+#endif
+
+/* 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)
+{
+#ifdef CONFIG_PAGE_FAULT_HANDLERS
+        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;
+        }
+        rcu_read_unlock();
+        return ret;
+#else
+        return 0;
+#endif
+}
+
 static inline int notify_page_fault(struct pt_regs *regs)
 {
 #ifdef CONFIG_KPROBES
@@ -606,6 +660,8 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
 
         if (notify_page_fault(regs))
                 return;
+        if (handle_custom_pf(regs, error_code, address))
+                return;
 
         /*
          * We fault-in kernel-space virtual memory on-demand. The
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index ec30d10154b6..f96eca21ad8f 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -710,6 +710,8 @@ void mark_rodata_ro(void)
         unsigned long start = PFN_ALIGN(_text);
         unsigned long size = PFN_ALIGN(_etext) - start;
 
+#ifndef CONFIG_DYNAMIC_FTRACE
+        /* Dynamic tracing modifies the kernel text section */
         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
         printk(KERN_INFO "Write protecting the kernel text: %luk\n",
                 size >> 10);
@@ -722,6 +724,8 @@ void mark_rodata_ro(void)
         printk(KERN_INFO "Testing CPA: write protecting again\n");
         set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
 #endif
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
         start += size;
         size = (unsigned long)__end_rodata - start;
         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 819dad973b13..17c0a6138a53 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -767,6 +767,13 @@ EXPORT_SYMBOL_GPL(rodata_test_data);
 void mark_rodata_ro(void)
 {
         unsigned long start = PFN_ALIGN(_stext), end = PFN_ALIGN(__end_rodata);
+        unsigned long rodata_start =
+                ((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+        /* Dynamic tracing modifies the kernel text section */
+        start = rodata_start;
+#endif
 
         printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
                (end - start) >> 10);
@@ -776,8 +783,7 @@ void mark_rodata_ro(void)
          * The rodata section (but not the kernel text!) should also be
          * not-executable.
          */
-        start = ((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
-        set_memory_nx(start, (end - start) >> PAGE_SHIFT);
+        set_memory_nx(rodata_start, (end - rodata_start) >> PAGE_SHIFT);
 
         rodata_test();