From: Daniel Borkmann <daniel@iogearbox.net>
Date: Wed, 12 May 2021 20:57:14 +0200
Subject: bpf: Fix BPF_JIT kconfig symbol dependency
Patch-mainline: v5.13-rc4
Git-commit: 6bdacdb48e94ff26c03c6eeeef48c03c5e2f7dd4
References: git-fixes jsc#SLE-22574

Randy reported a randconfig build error recently on i386:

  ld: arch/x86/net/bpf_jit_comp32.o: in function `do_jit':
  bpf_jit_comp32.c:(.text+0x28c9): undefined reference to `__bpf_call_base'
  ld: arch/x86/net/bpf_jit_comp32.o: in function `bpf_int_jit_compile':
  bpf_jit_comp32.c:(.text+0x3694): undefined reference to `bpf_jit_blind_constants'
  ld: bpf_jit_comp32.c:(.text+0x3719): undefined reference to `bpf_jit_binary_free'
  ld: bpf_jit_comp32.c:(.text+0x3745): undefined reference to `bpf_jit_binary_alloc'
  ld: bpf_jit_comp32.c:(.text+0x37d3): undefined reference to `bpf_jit_prog_release_other'
  [...]

The cause was that b24abcff918a ("bpf, kconfig: Add consolidated menu entry for
bpf with core options") moved BPF_JIT from net/Kconfig into kernel/bpf/Kconfig
and previously BPF_JIT was guarded by a 'if NET'. However, there is no actual
dependency on NET, it's just that menuconfig NET selects BPF. And the latter in
turn causes kernel/bpf/core.o to be built which contains above symbols. Randy's
randconfig didn't have NET set, and BPF wasn't either, but BPF_JIT otoh was.
Detangle this by making BPF_JIT depend on BPF instead. arm64 was the only arch
that pulled in its JIT in net/ via obj-$(CONFIG_NET), all others unconditionally
pull this dir in via obj-y. Do the same since CONFIG_NET guard there is really
useless as we compiled the JIT via obj-$(CONFIG_BPF_JIT) += bpf_jit_comp.o anyway.

Fixes: b24abcff918a ("bpf, kconfig: Add consolidated menu entry for bpf with core options")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
syu: arch/arm64/Kbuild doesn't exists, patch Makefile instead
---
 arch/arm64/Makefile |    3 +--
 kernel/bpf/Kconfig  |    1 +
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -138,8 +138,7 @@ KBUILD_AFLAGS += -DKASAN_SHADOW_SCALE_SH
 
 export	TEXT_OFFSET GZFLAGS
 
-core-y		+= arch/arm64/kernel/ arch/arm64/mm/
-core-$(CONFIG_NET) += arch/arm64/net/
+core-y		+= arch/arm64/kernel/ arch/arm64/mm/ arch/arm64/net/
 core-$(CONFIG_KVM) += arch/arm64/kvm/
 core-$(CONFIG_XEN) += arch/arm64/xen/
 core-$(CONFIG_CRYPTO) += arch/arm64/crypto/
--- a/kernel/bpf/Kconfig
+++ b/kernel/bpf/Kconfig
@@ -34,6 +34,7 @@ config BPF_SYSCALL
 
 config BPF_JIT
 	bool "Enable BPF Just In Time compiler"
+	depends on BPF
 	depends on HAVE_CBPF_JIT || HAVE_EBPF_JIT
 	depends on MODULES
 	help