arm64: ftrace: minimize ifdeffery

Now that we no longer refer to mod->arch.ftrace_trampolines in the body
of ftrace_make_call(), we can use IS_ENABLED() rather than ifdeffery,
and make the code easier to follow. Likewise in ftrace_make_nop().

Let's do so.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Torsten Duwe <duwe@suse.de>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: Torsten Duwe <duwe@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>

arch/arm64/kernel/ftrace.c

@@ -62,18 +62,18 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 	return ftrace_modify_code(pc, 0, new, false);
 }
 
-#ifdef CONFIG_ARM64_MODULE_PLTS
 static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr)
 {
+#ifdef CONFIG_ARM64_MODULE_PLTS
 	struct plt_entry *plt = mod->arch.ftrace_trampolines;
 
 	if (addr == FTRACE_ADDR)
 		return &plt[FTRACE_PLT_IDX];
 	if (addr == FTRACE_REGS_ADDR && IS_ENABLED(CONFIG_FTRACE_WITH_REGS))
 		return &plt[FTRACE_REGS_PLT_IDX];
+#endif
 	return NULL;
 }
-#endif
 
 /*
  * Turn on the call to ftrace_caller() in instrumented function
@@ -85,10 +85,12 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	long offset = (long)pc - (long)addr;
 
 	if (offset < -SZ_128M || offset >= SZ_128M) {
-#ifdef CONFIG_ARM64_MODULE_PLTS
 		struct module *mod;
 		struct plt_entry *plt;
 
+		if (!IS_ENABLED(CONFIG_ARM64_MODULE_PLTS))
+			return -EINVAL;
+
 		/*
 		 * On kernels that support module PLTs, the offset between the
 		 * branch instruction and its target may legally exceed the
@@ -113,9 +115,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 		}
 
 		addr = (unsigned long)plt;
-#else /* CONFIG_ARM64_MODULE_PLTS */
-		return -EINVAL;
-#endif /* CONFIG_ARM64_MODULE_PLTS */
 	}
 
 	old = aarch64_insn_gen_nop();
@@ -185,9 +184,11 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 	long offset = (long)pc - (long)addr;
 
 	if (offset < -SZ_128M || offset >= SZ_128M) {
-#ifdef CONFIG_ARM64_MODULE_PLTS
 		u32 replaced;
 
+		if (!IS_ENABLED(CONFIG_ARM64_MODULE_PLTS))
+			return -EINVAL;
+
 		/*
 		 * 'mod' is only set at module load time, but if we end up
 		 * dealing with an out-of-range condition, we can assume it
@@ -218,9 +219,6 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 			return -EINVAL;
 
 		validate = false;
-#else /* CONFIG_ARM64_MODULE_PLTS */
-		return -EINVAL;
-#endif /* CONFIG_ARM64_MODULE_PLTS */
 	} else {
 		old = aarch64_insn_gen_branch_imm(pc, addr,
 						  AARCH64_INSN_BRANCH_LINK);