1 files changed, 47 insertions, 0 deletions
diff --git a/arch/arm/include/asm/stackprotector.h b/arch/arm/include/asm/stackprotector.h
new file mode 100644
index 000000000..72a20c3a0
--- /dev/null
+++ b/arch/arm/include/asm/stackprotector.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * GCC stack protector support.
+ *
+ * Stack protector works by putting predefined pattern at the start of
+ * the stack frame and verifying that it hasn't been overwritten when
+ * returning from the function.  The pattern is called stack canary
+ * and gcc expects it to be defined by a global variable called
+ * "__stack_chk_guard" on ARM.  This prevents SMP systems from using a
+ * different value for each task unless we enable a GCC plugin that
+ * replaces these symbol references with references to each task's own
+ * value.
+ */
+
+#ifndef _ASM_STACKPROTECTOR_H
+#define _ASM_STACKPROTECTOR_H 1
+
+#include <linux/random.h>
+#include <linux/version.h>
+
+#include <asm/thread_info.h>
+
+extern unsigned long __stack_chk_guard;
+
+/*
+ * Initialize the stackprotector canary value.
+ *
+ * NOTE: this must only be called from functions that never return,
+ * and it must always be inlined.
+ */
+static __always_inline void boot_init_stack_canary(void)
+{
+	unsigned long canary;
+
+	/* Try to get a semi random initial value. */
+	get_random_bytes(&canary, sizeof(canary));
+	canary ^= LINUX_VERSION_CODE;
+
+	current->stack_canary = canary;
+#ifndef CONFIG_STACKPROTECTOR_PER_TASK
+	__stack_chk_guard = current->stack_canary;
+#else
+	current_thread_info()->stack_canary = current->stack_canary;
+#endif
+}
+
+#endif	/* _ASM_STACKPROTECTOR_H */