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 <dan...@iogearbox.net> Cc: Alexei Starovoitov <a...@kernel.org> Cc: Rick Edgecombe <rick.p.edgeco...@intel.com> Cc: Eric Dumazet <eric.duma...@gmail.com> Cc: Jann Horn <ja...@google.com> Cc: Kees Cook <keesc...@chromium.org> Cc: Jessica Yu <j...@kernel.org> Cc: Arnd Bergmann <a...@arndb.de> Cc: Catalin Marinas <catalin.mari...@arm.com> Cc: Will Deacon <will.dea...@arm.com> Cc: Mark Rutland <mark.rutl...@arm.com> Cc: Ralf Baechle <r...@linux-mips.org> Cc: Paul Burton <paul.bur...@mips.com> Cc: James Hogan <jho...@kernel.org> Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org> Cc: Paul Mackerras <pau...@samba.org> Cc: Michael Ellerman <m...@ellerman.id.au> Cc: "David S. Miller" <da...@davemloft.net> Cc: linux-arm-ker...@lists.infradead.org Cc: linux-ker...@vger.kernel.org Cc: linux-m...@linux-mips.org Cc: linuxppc-dev@lists.ozlabs.org Cc: sparcli...@vger.kernel.org Cc: net...@vger.kernel.org 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
