ebpf: bpf_map_*: fix linker error on avr32 and openrisc arch
authorDaniel Borkmann <daniel@iogearbox.net>
Thu, 5 Mar 2015 22:27:51 +0000 (23:27 +0100)
committerDavid S. Miller <davem@davemloft.net>
Sat, 7 Mar 2015 02:50:55 +0000 (21:50 -0500)
commit3ba67dabaa58e3223325f0a813a6e830fb5f5cc5
tree96e4798c1ed9bcaf56f8e7db339544facdb8703d
parent58025e46ea2d39f1840d5b1be5edea3297cfd23f
ebpf: bpf_map_*: fix linker error on avr32 and openrisc arch

Fengguang reported, that on openrisc and avr32 architectures, we
get the following linker errors on *_defconfig builds that have
no bpf syscall support:

  net/built-in.o:(.rodata+0x1cd0): undefined reference to `bpf_map_lookup_elem_proto'
  net/built-in.o:(.rodata+0x1cd4): undefined reference to `bpf_map_update_elem_proto'
  net/built-in.o:(.rodata+0x1cd8): undefined reference to `bpf_map_delete_elem_proto'

Fix it up by providing built-in weak definitions of the symbols,
so they can be overridden when the syscall is enabled. I think
the issue might be that gcc is not able to optimize all that away.
This patch fixes the linker errors for me, tested with Fengguang's
make.cross [1] script.

  [1] https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Fixes: d4052c4aea0c ("ebpf: remove CONFIG_BPF_SYSCALL ifdefs in socket filter code")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
kernel/bpf/core.c