x86/retpoline: Move the retpoline thunk declarations to nospec-branch.h

Because it makes no sense to split the retpoline gunk over multiple
headers.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120310.106290934@infradead.org

arch/x86/include/asm/asm-prototypes.h

@@ -17,11 +17,3 @@
 extern void cmpxchg8b_emu(void);
 #endif
 
-#ifdef CONFIG_RETPOLINE
-
-#define GEN(reg) \
-	extern asmlinkage void __x86_indirect_thunk_ ## reg (void);
-#include <asm/GEN-for-each-reg.h>
-#undef GEN
-
-#endif /* CONFIG_RETPOLINE */

arch/x86/include/asm/nospec-branch.h

@@ -5,6 +5,7 @@
 
 #include <linux/static_key.h>
 #include <linux/objtool.h>
+#include <linux/linkage.h>
 
 #include <asm/alternative.h>
 #include <asm/cpufeatures.h>
@@ -118,6 +119,12 @@
 	".popsection\n\t"
 
 #ifdef CONFIG_RETPOLINE
+
+#define GEN(reg) \
+	extern asmlinkage void __x86_indirect_thunk_ ## reg (void);
+#include <asm/GEN-for-each-reg.h>
+#undef GEN
+
 #ifdef CONFIG_X86_64
 
 /*

arch/x86/net/bpf_jit_comp.c

@@ -15,7 +15,6 @@
 #include <asm/set_memory.h>
 #include <asm/nospec-branch.h>
 #include <asm/text-patching.h>
-#include <asm/asm-prototypes.h>
 
 static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
 {