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-rw-r--r--arch/x86/include/asm/stackprotector.h38
1 files changed, 38 insertions, 0 deletions
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
new file mode 100644
index 0000000..36a700a
--- /dev/null
+++ b/arch/x86/include/asm/stackprotector.h
@@ -0,0 +1,38 @@
+#ifndef _ASM_STACKPROTECTOR_H
+#define _ASM_STACKPROTECTOR_H 1
+
+#include <asm/tsc.h>
+#include <asm/processor.h>
+
+/*
+ * 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)
+{
+ u64 canary;
+ u64 tsc;
+
+ /*
+ * Build time only check to make sure the stack_canary is at
+ * offset 40 in the pda; this is a gcc ABI requirement
+ */
+ BUILD_BUG_ON(offsetof(union irq_stack_union, stack_canary) != 40);
+
+ /*
+ * We both use the random pool and the current TSC as a source
+ * of randomness. The TSC only matters for very early init,
+ * there it already has some randomness on most systems. Later
+ * on during the bootup the random pool has true entropy too.
+ */
+ get_random_bytes(&canary, sizeof(canary));
+ tsc = __native_read_tsc();
+ canary += tsc + (tsc << 32UL);
+
+ current->stack_canary = canary;
+ percpu_write(irq_stack_union.stack_canary, canary);
+}
+
+#endif
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