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 80deacfe0cf6feb52bf416c5aae19c47233bd91d..4000fc9cca0fc17be1e155b263eba3cdccdbc8ab 100644 (file)
--- a/wrapper/vmalloc.h
+++ b/wrapper/vmalloc.h
@@ -21,8 +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_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_all(void)
+void wrapper_vmalloc_sync_mappings(void)
 {
        void (*vmalloc_sync_all_sym)(void);
 
@@ -40,13 +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_mappings(void)
+{
+       return vmalloc_sync_mappings();
+}
+
+#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_all();
 }
+
+#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0)) */
+
 #endif
 
 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
@@ -61,7 +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;
 }