arm/patch: Fix !MMU compile

Now that patch.o is unconditionally selected for ftrace, it can also
get compiled for !MMU kernels. These (obviously) lack
{set,clear}_fixmap() support.

Also remove the superfluous __acquire/__release nonsense.

Fixes: 42e51f187f86 ("arm/ftrace: Use __patch_text()")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/arm/kernel/patch.c

@@ -16,10 +16,10 @@ struct patch {
 	unsigned int insn;
 };
 
+#ifdef CONFIG_MMU
 static DEFINE_RAW_SPINLOCK(patch_lock);
 
 static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
-	__acquires(&patch_lock)
 {
 	unsigned int uintaddr = (uintptr_t) addr;
 	bool module = !core_kernel_text(uintaddr);
@@ -34,8 +34,6 @@ static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
 
 	if (flags)
 		raw_spin_lock_irqsave(&patch_lock, *flags);
-	else
-		__acquire(&patch_lock);
 
 	set_fixmap(fixmap, page_to_phys(page));
 
@@ -43,15 +41,19 @@ static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
 }
 
 static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
-	__releases(&patch_lock)
 {
 	clear_fixmap(fixmap);
 
 	if (flags)
 		raw_spin_unlock_irqrestore(&patch_lock, *flags);
-	else
-		__release(&patch_lock);
 }
+#else
+static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
+{
+	return addr;
+}
+static void __kprobes patch_unmap(int fixmap, unsigned long *flags) { }
+#endif
 
 void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 {
@@ -64,8 +66,6 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 
 	if (remap)
 		waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
-	else
-		__acquire(&patch_lock);
 
 	if (thumb2 && __opcode_is_thumb16(insn)) {
 		*(u16 *)waddr = __opcode_to_mem_thumb16(insn);
@@ -102,8 +102,7 @@ void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
 	if (waddr != addr) {
 		flush_kernel_vmap_range(waddr, twopage ? size / 2 : size);
 		patch_unmap(FIX_TEXT_POKE0, &flags);
-	} else
-		__release(&patch_lock);
+	}
 
 	flush_icache_range((uintptr_t)(addr),
 			   (uintptr_t)(addr) + size);