Update for kernel 5.7: use vmalloc_sync_mappings on kernels >= 5.7

[lttng-modules.git] / wrapper / vmalloc.h

diff --git a/wrapper/vmalloc.h b/wrapper/vmalloc.h
index b4d795404a2dfa454f9b1dae11a0f0d8963db6c9..4000fc9cca0fc17be1e155b263eba3cdccdbc8ab 100644 (file)
--- a/wrapper/vmalloc.h
+++ b/wrapper/vmalloc.h
@@ -1,7 +1,5 @@
-#ifndef _LTTNG_WRAPPER_VMALLOC_H
-#define _LTTNG_WRAPPER_VMALLOC_H
-
-/*
+/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
+ *
  * wrapper/vmalloc.h
  *
  * wrapper around vmalloc_sync_all. Using KALLSYMS to get its address when
@@ -9,22 +7,11 @@
  * modules.
  *
  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#ifndef _LTTNG_WRAPPER_VMALLOC_H
+#define _LTTNG_WRAPPER_VMALLOC_H
+
 #include <linux/version.h>
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
@@ -34,8 +21,35 @@
 #include <linux/kallsyms.h>
 #include <wrapper/kallsyms.h>
 
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0))
+
 static inline
-void wrapper_vmalloc_sync_all(void)
+void wrapper_vmalloc_sync_mappings(void)
+{
+       void (*vmalloc_sync_mappings_sym)(void);
+
+       vmalloc_sync_mappings_sym = (void *) kallsyms_lookup_funcptr("vmalloc_sync_mappings");
+       if (vmalloc_sync_mappings_sym) {
+               vmalloc_sync_mappings_sym();
+       } else {
+#ifdef CONFIG_X86
+               /*
+                * Only x86 needs vmalloc_sync_mappings to make sure LTTng does not
+                * trigger recursive page faults.
+                */
+               printk_once(KERN_WARNING "LTTng: vmalloc_sync_mappings symbol lookup failed.\n");
+               printk_once(KERN_WARNING "Page fault handler and NMI tracing might trigger faults.\n");
+#endif
+       }
+}
+
+#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0)) */
+
+/*
+ * Map vmalloc_sync_mappings to vmalloc_sync_all() on kernels before 5.7.
+ */
+static inline
+void wrapper_vmalloc_sync_mappings(void)
 {
        void (*vmalloc_sync_all_sym)(void);
 
@@ -53,13 +67,29 @@ void wrapper_vmalloc_sync_all(void)
 #endif
        }
 }
+
+#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0)) */
+
 #else
 
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0))
+
 static inline
-void wrapper_vmalloc_sync_all(void)
+void wrapper_vmalloc_sync_mappings(void)
+{
+       return vmalloc_sync_mappings();
+}
+
+#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0)) */
+
+static inline
+void wrapper_vmalloc_sync_mappings(void)
 {
        return vmalloc_sync_all();
 }
+
+#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0)) */
+
 #endif
 
 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
@@ -74,7 +104,7 @@ void *lttng_kvmalloc_node(unsigned long size, gfp_t flags, int node)
                 * Make sure we don't trigger recursive page faults in the
                 * tracing fast path.
                 */
-               wrapper_vmalloc_sync_all();
+               wrapper_vmalloc_sync_mappings();
        }
        return ret;
 }