[PATCH 0/4] bpf: permit JIT allocations to be served outside the module region

[Ard Biesheuvel]

On arm64, modules are allocated from a 128 MB window which is close to
the core kernel, so that relative direct branches are guaranteed to be
in range (except in some KASLR configurations). Also, module_alloc()
is in charge of allocating KASAN shadow memory when running with KASAN
enabled.

This means that the way BPF reuses module_alloc()/module_memfree() is
undesirable on arm64 (and potentially other architectures as well),
and so this series refactors BPF's use of those functions to permit
architectures to change this behavior.

Patch #1 fixes a bug introduced during the merge window, where the new
alloc/free tracking does not account for memory that is freed by some
arch code.

Patch #2 refactors the freeing path so that architectures can switch to
something other than module_memfree().

Patch #3 does the same for module_alloc().

Patch #4 implements the new alloc/free overrides for arm64

Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>

Cc: Jessica Yu <jeyu@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Paul Burton <paul.burton@xxxxxxxx>
Cc: James Hogan <jhogan@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Cc: sparclinux@xxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx

Ard Biesheuvel (4):
  bpf: account for freed JIT allocations in arch code
  net/bpf: refactor freeing of executable allocations
  bpf: add __weak hook for allocating executable memory
  arm64/bpf: don't allocate BPF JIT programs in module memory

 arch/arm64/net/bpf_jit_comp.c     | 11 ++++++++++
 arch/mips/net/bpf_jit.c           |  7 ++-----
 arch/powerpc/net/bpf_jit_comp.c   |  7 ++-----
 arch/powerpc/net/bpf_jit_comp64.c | 12 +++--------
 arch/sparc/net/bpf_jit_comp_32.c  |  7 ++-----
 kernel/bpf/core.c                 | 22 ++++++++++----------
 6 files changed, 31 insertions(+), 35 deletions(-)

-- 
2.17.1