With CONFIG_CFI_CLANG, the compiler replaces function addresses in
instrumented C code with jump table addresses. This change implements
the function_nocfi() macro, which returns the actual function address
instead.
Signed-off-by: Sami Tolvanen <samitolva...@google.com>
---
arch/x86/include/asm/page.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index 7555b48803a8..5499a05c44fc 100644
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -71,6 +71,20 @@ static inline void copy_user_page(void *to, void *from,
unsigned long vaddr,
extern bool __virt_addr_valid(unsigned long kaddr);
#define virt_addr_valid(kaddr) __virt_addr_valid((unsigned long) (kaddr))
+#ifdef CONFIG_CFI_CLANG
+/*
+ * With CONFIG_CFI_CLANG, the compiler replaces function address
+ * references with the address of the function's CFI jump table
+ * entry. The function_nocfi macro always returns the address of the
+ * actual function instead.
+ */
+#define function_nocfi(x) ({ \
+ void *addr; \
+ asm("leaq " __stringify(x) "(%%rip), %0\n\t" : "=r" (addr)); \
+ addr; \
+})
+#endif
+
#endif /* __ASSEMBLY__ */
#include <asm-generic/memory_model.h>
--
2.31.1.368.gbe11c130af-goog
