On 27 December 2017 at 20:07, Linus Torvalds
[off-list ref] wrote:

On Wed, Dec 27, 2017 at 12:50 AM, Ard Biesheuvel
[off-list ref] wrote:

quoted

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 52e611ab9a6c..fe752d365334 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h

@@ -327,4 +327,15 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
        compiletime_assert(__native_word(t),                            \
                "Need native word sized stores/loads for atomicity.")

+/*
+ * Force the compiler to emit 'sym' as a symbol, so that we can reference
+ * it from inline assembler. Necessary in case 'sym' could be inlined
+ * otherwise, or eliminated entirely due to lack of references that are
+ * visibile to the compiler.
+ */
+#define __ADDRESSABLE(sym) \
+       static void *__attribute__((section(".discard.text"), used))    \
+               __PASTE(__discard_##sym, __LINE__)(void)                \
+                       { return (void *)&sym; }                        \
+
 #endif /* __LINUX_COMPILER_H */

Isn't this logically the point where you should add the arm64
vmlinux.lds.S change, and explain how ".discard.text" turns into
".init.discard.text" for some odd arm64 reason?

I tried to keep the generic patches generic, so perhaps I should just
put the arm64 vmlinux.lds.S change in a patch on its own?