bpf, kconfig: Add consolidated menu entry for bpf with core options

Right now, all core BPF related options are scattered in different Kconfig
locations mainly due to historic reasons. Moving forward, lets add a proper
subsystem entry under ...

  General setup  --->
    BPF subsystem  --->

... in order to have all knobs in a single location and thus ease BPF related
configuration. Networking related bits such as sockmap are out of scope for
the general setup and therefore better suited to remain in net/Kconfig.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/f23f58765a4d59244ebd8037da7b6a6b2fb58446.1620765074.git.daniel@iogearbox.net

init/Kconfig

@@ -439,6 +439,7 @@ config AUDITSYSCALL
 
 source "kernel/irq/Kconfig"
 source "kernel/time/Kconfig"
+source "kernel/bpf/Kconfig"
 source "kernel/Kconfig.preempt"
 
 menu "CPU/Task time and stats accounting"
@@ -1705,46 +1706,6 @@ config KALLSYMS_BASE_RELATIVE
 
 # syscall, maps, verifier
 
-config BPF_LSM
-	bool "LSM Instrumentation with BPF"
-	depends on BPF_EVENTS
-	depends on BPF_SYSCALL
-	depends on SECURITY
-	depends on BPF_JIT
-	help
-	  Enables instrumentation of the security hooks with eBPF programs for
-	  implementing dynamic MAC and Audit Policies.
-
-	  If you are unsure how to answer this question, answer N.
-
-config BPF_SYSCALL
-	bool "Enable bpf() system call"
-	select BPF
-	select IRQ_WORK
-	select TASKS_TRACE_RCU
-	select BINARY_PRINTF
-	select NET_SOCK_MSG if INET
-	default n
-	help
-	  Enable the bpf() system call that allows to manipulate eBPF
-	  programs and maps via file descriptors.
-
-config ARCH_WANT_DEFAULT_BPF_JIT
-	bool
-
-config BPF_JIT_ALWAYS_ON
-	bool "Permanently enable BPF JIT and remove BPF interpreter"
-	depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
-	help
-	  Enables BPF JIT and removes BPF interpreter to avoid
-	  speculative execution of BPF instructions by the interpreter
-
-config BPF_JIT_DEFAULT_ON
-	def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
-	depends on HAVE_EBPF_JIT && BPF_JIT
-
-source "kernel/bpf/preload/Kconfig"
-
 config USERFAULTFD
 	bool "Enable userfaultfd() system call"
 	depends on MMU

kernel/bpf/Kconfig

+# SPDX-License-Identifier: GPL-2.0-only
+
+# BPF interpreter that, for example, classic socket filters depend on.
+config BPF
+	bool
+
+# Used by archs to tell that they support BPF JIT compiler plus which
+# flavour. Only one of the two can be selected for a specific arch since
+# eBPF JIT supersedes the cBPF JIT.
+
+# Classic BPF JIT (cBPF)
+config HAVE_CBPF_JIT
+	bool
+
+# Extended BPF JIT (eBPF)
+config HAVE_EBPF_JIT
+	bool
+
+# Used by archs to tell that they want the BPF JIT compiler enabled by
+# default for kernels that were compiled with BPF JIT support.
+config ARCH_WANT_DEFAULT_BPF_JIT
+	bool
+
+menu "BPF subsystem"
+
+config BPF_SYSCALL
+	bool "Enable bpf() system call"
+	select BPF
+	select IRQ_WORK
+	select TASKS_TRACE_RCU
+	select BINARY_PRINTF
+	select NET_SOCK_MSG if INET
+	default n
+	help
+	  Enable the bpf() system call that allows to manipulate BPF programs
+	  and maps via file descriptors.
+
+config BPF_JIT
+	bool "Enable BPF Just In Time compiler"
+	depends on HAVE_CBPF_JIT || HAVE_EBPF_JIT
+	depends on MODULES
+	help
+	  BPF programs are normally handled by a BPF interpreter. This option
+	  allows the kernel to generate native code when a program is loaded
+	  into the kernel. This will significantly speed-up processing of BPF
+	  programs.
+
+	  Note, an admin should enable this feature changing:
+	  /proc/sys/net/core/bpf_jit_enable
+	  /proc/sys/net/core/bpf_jit_harden   (optional)
+	  /proc/sys/net/core/bpf_jit_kallsyms (optional)
+
+config BPF_JIT_ALWAYS_ON
+	bool "Permanently enable BPF JIT and remove BPF interpreter"
+	depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
+	help
+	  Enables BPF JIT and removes BPF interpreter to avoid speculative
+	  execution of BPF instructions by the interpreter.
+
+config BPF_JIT_DEFAULT_ON
+	def_bool ARCH_WANT_DEFAULT_BPF_JIT || BPF_JIT_ALWAYS_ON
+	depends on HAVE_EBPF_JIT && BPF_JIT
+
+source "kernel/bpf/preload/Kconfig"
+
+config BPF_LSM
+	bool "Enable BPF LSM Instrumentation"
+	depends on BPF_EVENTS
+	depends on BPF_SYSCALL
+	depends on SECURITY
+	depends on BPF_JIT
+	help
+	  Enables instrumentation of the security hooks with BPF programs for
+	  implementing dynamic MAC and Audit Policies.
+
+	  If you are unsure how to answer this question, answer N.
+
+endmenu # "BPF subsystem"

net/Kconfig

@@ -302,21 +302,6 @@ config BQL
 	select DQL
 	default y
 
-config BPF_JIT
-	bool "enable BPF Just In Time compiler"
-	depends on HAVE_CBPF_JIT || HAVE_EBPF_JIT
-	depends on MODULES
-	help
-	  Berkeley Packet Filter filtering capabilities are normally handled
-	  by an interpreter. This option allows kernel to generate a native
-	  code when filter is loaded in memory. This should speedup
-	  packet sniffing (libpcap/tcpdump).
-
-	  Note, admin should enable this feature changing:
-	  /proc/sys/net/core/bpf_jit_enable
-	  /proc/sys/net/core/bpf_jit_harden   (optional)
-	  /proc/sys/net/core/bpf_jit_kallsyms (optional)
-
 config BPF_STREAM_PARSER
 	bool "enable BPF STREAM_PARSER"
 	depends on INET
@@ -470,15 +455,3 @@ config ETHTOOL_NETLINK
 	  e.g. notification messages.
 
 endif   # if NET
-
-# Used by archs to tell that they support BPF JIT compiler plus which flavour.
-# Only one of the two can be selected for a specific arch since eBPF JIT supersedes
-# the cBPF JIT.
-
-# Classic BPF JIT (cBPF)
-config HAVE_CBPF_JIT
-	bool
-
-# Extended BPF JIT (eBPF)
-config HAVE_EBPF_JIT
-	bool