[PATCH v3 30/39] x86/ibt: Ensure module init/exit points have references

Peter Zijlstra
2022-03-03T11:31:06Z

Since the references to the module init/exit points only have external
references, a module LTO run will consider them 'unused' and seal
them, leading to an immediate fail on module load.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
include/linux/cfi.h | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

--- a/include/linux/cfi.h
+++ b/include/linux/cfi.h
@@ -34,8 +34,17 @@ static inline void cfi_module_remove(str

#else /* !CONFIG_CFI_CLANG */

-#define __CFI_ADDRESSABLE(fn, __attr)
+#ifdef CONFIG_X86_KERNEL_IBT
+
+#define __CFI_ADDRESSABLE(fn, __attr) \
+ const void *__cfi_jt_ ## fn __visible __attr = (void *)&fn
+
+#endif /* CONFIG_X86_KERNEL_IBT */

#endif /* CONFIG_CFI_CLANG */

+#ifndef __CFI_ADDRESSABLE
+#define __CFI_ADDRESSABLE(fn, __attr)
+#endif
+
#endif /* _LINUX_CFI_H */