linux-kernel - [PATCH v2 bpf-next 0/2] arm64/bpf: remove 128MB limit for BPF JIT programs

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Date:   Fri,  5 Nov 2021 16:50:44 +0000
From:   Alan Maguire <alan.maguire@...cle.com>
To:     ardb@...nel.org, catalin.marinas@....com, will@...nel.org,
        daniel@...earbox.net, ast@...nel.org
Cc:     zlim.lnx@...il.com, andrii@...nel.org, kafai@...com,
        songliubraving@...com, yhs@...com, john.fastabend@...il.com,
        kpsingh@...nel.org, andreyknvl@...il.com,
        vincenzo.frascino@....com, mark.rutland@....com,
        samitolvanen@...gle.com, joey.gouly@....com, maz@...nel.org,
        daizhiyuan@...tium.com.cn, jthierry@...hat.com,
        tiantao6@...ilicon.com, pcc@...gle.com, akpm@...ux-foundation.org,
        rppt@...nel.org, Jisheng.Zhang@...aptics.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        Alan Maguire <alan.maguire@...cle.com>
Subject: [PATCH v2 bpf-next 0/2] arm64/bpf: remove 128MB limit for BPF JIT programs

There is a 128MB limit on BPF JIT program allocations; this is
to ensure BPF programs are in branching range of each other.
Patch 1 in this series removes this restriction.  To verify
exception handling still works, a test case to validate
exception handling in BPF programs is added in patch 2.

There was previous discussion around this topic [1], in particular
would be good to get feedback from Daniel if this approach makes
sense.

[1] https://lore.kernel.org/all/20181121131733.14910-1-ard.biesheuvel@linaro.org/

Changes since v1:

 - respin picked up changes in arm64 exception handling changes
   which removed need for special BPF exception handling in patch 1
 - made selftest use task creation/task_struct field instead to
   minimize BPF selftests parallel runs, moved from CHECK()s
   to ASSERT_*()s (Andrii, patch 2)

Alan Maguire (1):
  selftests/bpf: add exception handling selftests for tp_bpf program

Russell King (1):
  arm64/bpf: remove 128MB limit for BPF JIT programs

 arch/arm64/include/asm/extable.h                   |  9 -----
 arch/arm64/include/asm/memory.h                    |  5 +--
 arch/arm64/kernel/traps.c                          |  2 +-
 arch/arm64/mm/ptdump.c                             |  2 -
 arch/arm64/net/bpf_jit_comp.c                      |  7 +---
 tools/testing/selftests/bpf/prog_tests/exhandler.c | 43 ++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/exhandler_kern.c | 43 ++++++++++++++++++++++
 7 files changed, 90 insertions(+), 21 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/exhandler.c
 create mode 100644 tools/testing/selftests/bpf/progs/exhandler_kern.c

-- 
1.8.3.1