bpf: Eliminate CONFIG_MODULES limitation from JIT for arm64

CONFIG_MODULES is only needed for its memory allocator, which is trivial
to add back into arm64 when modules aren't enabled. Do so in order to
take advantage of JIT compilation when CONFIG_MODULES=n.

Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: atndko <z1281552865@gmail.com>
Signed-off-by: Vaisakh Murali <mvaisakh@statixos.com>

arch/arm64/kernel/Makefile

@@ -19,7 +19,7 @@ ccflags-y += -Ikernel/sched/
 arm64-obj-y		:= debug-monitors.o entry.o irq.o fpsimd.o		\
 			   entry-fpsimd.o process.o ptrace.o setup.o signal.o	\
 			   sys.o stacktrace.o time.o traps.o io.o vdso.o	\
-			   hyp-stub.o psci.o cpu_ops.o insn.o	\
+			   hyp-stub.o psci.o cpu_ops.o insn.o module.o		\
 			   return_address.o cpuinfo.o cpu_errata.o		\
 			   cpufeature.o alternative.o cacheinfo.o		\
 			   smp.o smp_spin_table.o topology.o smccc-call.o
@@ -37,7 +37,7 @@ arm64-obj-$(CONFIG_COMPAT)		+= sigreturn32.o
 endif
 arm64-obj-$(CONFIG_KUSER_HELPERS)	+= kuser32.o
 arm64-obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o entry-ftrace.o
-arm64-obj-$(CONFIG_MODULES)		+= arm64ksyms.o module.o
+arm64-obj-$(CONFIG_MODULES)		+= arm64ksyms.o
 arm64-obj-$(CONFIG_ARM64_MODULE_PLTS)	+= module-plts.o
 arm64-obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o perf_callchain.o
 arm64-obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event.o

arch/arm64/kernel/module.c

@@ -30,6 +30,7 @@
 #include <asm/insn.h>
 #include <asm/sections.h>
 
+#if defined(CONFIG_MODULES) || defined(CONFIG_BPF_JIT)
 void *module_alloc(unsigned long size)
 {
 	void *p;
@@ -66,6 +67,13 @@ void *module_alloc(unsigned long size)
 	return p;
 }
 
+void module_memfree(void *module_region)
+{
+	vfree(module_region);
+}
+#endif /* CONFIG_MODULES || CONFIG_BPF_JIT */
+
+#ifdef CONFIG_MODULES
 enum aarch64_reloc_op {
 	RELOC_OP_NONE,
 	RELOC_OP_ABS,
@@ -425,3 +433,4 @@ int module_finalize(const Elf_Ehdr *hdr,
 
 	return 0;
 }
+#endif /* CONFIG_MODULES */