1 files changed, 26 insertions, 0 deletions
diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c
index 79d7e73e2cfd..35f6b6e6a908 100644
--- a/mm/kmsan/hooks.c
+++ b/mm/kmsan/hooks.c
@@ -348,6 +348,32 @@ void kmsan_unpoison_memory(const void *address, size_t size)
 }
 EXPORT_SYMBOL(kmsan_unpoison_memory);
 
+/*
+ * Version of kmsan_unpoison_memory() that can be called from within the KMSAN
+ * runtime.
+ *
+ * Non-instrumented IRQ entry functions receive struct pt_regs from assembly
+ * code. Those regs need to be unpoisoned, otherwise using them will result in
+ * false positives.
+ * Using kmsan_unpoison_memory() is not an option in entry code, because the
+ * return value of in_task() is inconsistent - as a result, certain calls to
+ * kmsan_unpoison_memory() are ignored. kmsan_unpoison_entry_regs() ensures that
+ * the registers are unpoisoned even if kmsan_in_runtime() is true in the early
+ * entry code.
+ */
+void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
+{
+	unsigned long ua_flags;
+
+	if (!kmsan_enabled)
+		return;
+
+	ua_flags = user_access_save();
+	kmsan_internal_unpoison_memory((void *)regs, sizeof(*regs),
+				       KMSAN_POISON_NOCHECK);
+	user_access_restore(ua_flags);
+}
+
 void kmsan_check_memory(const void *addr, size_t size)
 {
 	if (!kmsan_enabled)