linux-kernel - Re: [bpf-next 0/6] bpf,powerpc: Add support for bpf arena and arena atomics

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Message-ID: <aJR/W7w/csyL7Ov4@linux.ibm.com>
Date: Thu, 7 Aug 2025 15:56:35 +0530
From: Saket Kumar Bhaskar <skb99@...ux.ibm.com>
To: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: bpf@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        hbathini@...ux.ibm.com, sachinpb@...ux.ibm.com, venkat88@...ux.ibm.com,
        andrii@...nel.org, eddyz87@...il.com, mykolal@...com, ast@...nel.org,
        daniel@...earbox.net, martin.lau@...ux.dev, song@...nel.org,
        yonghong.song@...ux.dev, john.fastabend@...il.com, kpsingh@...nel.org,
        sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org,
        naveen@...nel.org, maddy@...ux.ibm.com, mpe@...erman.id.au,
        npiggin@...il.com, memxor@...il.com, iii@...ux.ibm.com,
        shuah@...nel.org
Subject: Re: [bpf-next 0/6] bpf,powerpc: Add support for bpf arena and arena
 atomics

On Tue, Aug 05, 2025 at 09:45:39AM +0200, Christophe Leroy wrote:
> 
> 
> Le 05/08/2025 à 08:27, Saket Kumar Bhaskar a écrit :
> > This patch series introduces support for the PROBE_MEM32,
> > bpf_addr_space_cast and PROBE_ATOMIC instructions in the powerpc BPF JIT,
> > facilitating the implementation of BPF arena and arena atomics.
> 
> This series seems to be limited to powerpc64. Please make it explicit in all
> patches subject, see exemple below:
> 
> $ git log --oneline arch/powerpc/net/bpf_jit_comp64.c
> cf2a6de32cabb (tag: powerpc-6.17-2, origin/next-test, origin/next)
> powerpc64/bpf: Add jit support for load_acquire and store_release
> 59ba025948be2 powerpc/bpf: fix JIT code size calculation of bpf trampoline
> d243b62b7bd3d powerpc64/bpf: Add support for bpf trampolines
> 9670f6d2097c4 powerpc64/bpf: Fold bpf_jit_emit_func_call_hlp() into
> bpf_jit_emit_func_call_rel()
> fde318326daa4 powerpc64/bpf: jit support for signed division and modulo
> 597b1710982d1 powerpc64/bpf: jit support for sign extended mov
> 717756c9c8dda powerpc64/bpf: jit support for sign extended load
> a71c0b09a14db powerpc64/bpf: jit support for unconditional byte swap
> 3c086ce222cef powerpc64/bpf: jit support for 32bit offset jmp instruction
> b1e7cee961274 powerpc/bpf: enforce full ordering for ATOMIC operations with
> BPF_FETCH
> 61688a82e047a powerpc/bpf: enable kfunc call
> 
Chris, will keep this in mind while sending v2.
> 
> > 
> > The last patch in the series has fix for arena spinlock selftest
> > failure.
> > 
> > This series is rebased on top of:
> > https://lore.kernel.org/bpf/20250717202935.29018-2-puranjay@kernel.org/
> > 
> > All selftests related to bpf_arena, bpf_arena_atomic(except
> > load_acquire/store_release) enablement are passing:
> > 
> > # ./test_progs -t arena_list
> > #5/1     arena_list/arena_list_1:OK
> > #5/2     arena_list/arena_list_1000:OK
> > #5       arena_list:OK
> > Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED
> > 
> > # ./test_progs -t arena_htab
> > #4/1     arena_htab/arena_htab_llvm:OK
> > #4/2     arena_htab/arena_htab_asm:OK
> > #4       arena_htab:OK
> > Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED
> > 
> > # ./test_progs -t verifier_arena
> > #464/1   verifier_arena/basic_alloc1:OK
> > #464/2   verifier_arena/basic_alloc2:OK
> > #464/3   verifier_arena/basic_alloc3:OK
> > #464/4   verifier_arena/iter_maps1:OK
> > #464/5   verifier_arena/iter_maps2:OK
> > #464/6   verifier_arena/iter_maps3:OK
> > #464     verifier_arena:OK
> > #465/1   verifier_arena_large/big_alloc1:OK
> > #465/2   verifier_arena_large/big_alloc2:OK
> > #465     verifier_arena_large:OK
> > Summary: 2/8 PASSED, 0 SKIPPED, 0 FAILED
> > 
> > # ./test_progs -t arena_atomics
> > #3/1     arena_atomics/add:OK
> > #3/2     arena_atomics/sub:OK
> > #3/3     arena_atomics/and:OK
> > #3/4     arena_atomics/or:OK
> > #3/5     arena_atomics/xor:OK
> > #3/6     arena_atomics/cmpxchg:OK
> > #3/7     arena_atomics/xchg:OK
> > #3/8     arena_atomics/uaf:OK
> > #3/9     arena_atomics/load_acquire:SKIP
> > #3/10    arena_atomics/store_release:SKIP
> > #3       arena_atomics:OK (SKIP: 2/10)
> > Summary: 1/8 PASSED, 2 SKIPPED, 0 FAILED
> > 
> > All selftests related to arena_spin_lock are passing:
> > 
> > # ./test_progs -t arena_spin_lock
> > #6/1     arena_spin_lock/arena_spin_lock_1:OK
> > #6/2     arena_spin_lock/arena_spin_lock_1000:OK
> > #6/3     arena_spin_lock/arena_spin_lock_50000:OK
> > #6       arena_spin_lock:OK
> > Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED
> > 
> > Saket Kumar Bhaskar (6):
> >    bpf,powerpc: Introduce bpf_jit_emit_probe_mem_store() to emit store
> >      instructions
> >    bpf,powerpc: Implement PROBE_MEM32 pseudo instructions
> >    bpf,powerpc: Implement bpf_addr_space_cast instruction
> >    bpf,powerpc: Introduce bpf_jit_emit_atomic_ops() to emit atomic
> >      instructions
> >    bpf,powerpc: Implement PROBE_ATOMIC instructions
> >    selftests/bpf: Fix arena_spin_lock selftest failure
> > 
> >   arch/powerpc/net/bpf_jit.h                    |   6 +-
> >   arch/powerpc/net/bpf_jit_comp.c               |  32 +-
> >   arch/powerpc/net/bpf_jit_comp32.c             |   2 +-
> >   arch/powerpc/net/bpf_jit_comp64.c             | 378 +++++++++++++-----
> >   .../bpf/prog_tests/arena_spin_lock.c          |  23 +-
> >   .../selftests/bpf/progs/arena_spin_lock.c     |   8 +-
> >   .../selftests/bpf/progs/bpf_arena_spin_lock.h |   4 +-
> >   7 files changed, 348 insertions(+), 105 deletions(-)
> > 
> > base-commit: ea2aecdf7a954a8c0015e185cc870c4191d1d93f
>