Commit f89b7755 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller
Browse files

bpf: split eBPF out of NET 



introduce two configs:
- hidden CONFIG_BPF to select eBPF interpreter that classic socket filters
  depend on
- visible CONFIG_BPF_SYSCALL (default off) that tracing and sockets can use

that solves several problems:
- tracing and others that wish to use eBPF don't need to depend on NET.
  They can use BPF_SYSCALL to allow loading from userspace or select BPF
  to use it directly from kernel in NET-less configs.
- in 3.18 programs cannot be attached to events yet, so don't force it on
- when the rest of eBPF infra is there in 3.19+, it's still useful to
  switch it off to minimize kernel size

bloat-o-meter on x64 shows:
add/remove: 0/60 grow/shrink: 0/2 up/down: 0/-15601 (-15601)

tested with many different config combinations. Hopefully didn't miss anything.

Signed-off-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Acked-by: default avatarDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8ae3c911

init/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -1341,6 +1341,10 @@ config SYSCTL_ARCH_UNALIGN_ALLOW 
config HAVE_PCSPKR_PLATFORM

	bool



# interpreter that classic socket filters depend on

config BPF

	bool



menuconfig EXPERT

	bool "Configure standard kernel features (expert users)"

	# Unhide debug options, to make the on-by-default options visible
@@ -1521,6 +1525,16 @@ config EVENTFD 


	  If unsure, say Y.



# syscall, maps, verifier

config BPF_SYSCALL

	bool "Enable bpf() system call" if EXPERT

	select ANON_INODES

	select BPF

	default n

	help

	  Enable the bpf() system call that allows to manipulate eBPF

	  programs and maps via file descriptors.



config SHMEM

	bool "Use full shmem filesystem" if EXPERT

	default y

kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -86,7 +86,7 @@ obj-$(CONFIG_RING_BUFFER) += trace/ 
obj-$(CONFIG_TRACEPOINTS) += trace/

obj-$(CONFIG_IRQ_WORK) += irq_work.o

obj-$(CONFIG_CPU_PM) += cpu_pm.o

obj-$(CONFIG_NET) += bpf/

obj-$(CONFIG_BPF) += bpf/



obj-$(CONFIG_PERF_EVENTS) += events/

kernel/bpf/Makefile

+3 −3
Original line number Diff line number Diff line 
obj-y := core.o syscall.o verifier.o



obj-y := core.o

obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o

ifdef CONFIG_TEST_BPF

obj-y += test_stub.o

obj-$(CONFIG_BPF_SYSCALL) += test_stub.o

endif

kernel/bpf/core.c

+9 −0
Original line number Diff line number Diff line
@@ -655,3 +655,12 @@ void bpf_prog_free(struct bpf_prog *fp) 
	schedule_work(&aux->work);

}

EXPORT_SYMBOL_GPL(bpf_prog_free);



/* To execute LD_ABS/LD_IND instructions __bpf_prog_run() may call

 * skb_copy_bits(), so provide a weak definition of it for NET-less config.

 */

int __weak skb_copy_bits(const struct sk_buff *skb, int offset, void *to,

			 int len)

{

	return -EFAULT;

}

net/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -6,7 +6,7 @@ menuconfig NET 
	bool "Networking support"

	select NLATTR

	select GENERIC_NET_UTILS

	select ANON_INODES

	select BPF

	---help---

	  Unless you really know what you are doing, you should say Y here.

	  The reason is that some programs need kernel networking support even

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