linux-kernel - Re: [bpf-next v2 0/5] powerpc64/bpf: Add support for bpf arena and arena atomics

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Message-Id: <7DC6CA27-C35F-4220-856A-48AC8BF45896@linux.ibm.com>
Date: Tue, 2 Sep 2025 21:03:36 +0530
From: Venkat <venkat88@...ux.ibm.com>
To: Saket Kumar Bhaskar <skb99@...ux.ibm.com>
Cc: bpf@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kselftest@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Hari Bathini <hbathini@...ux.ibm.com>, sachinpb@...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, Jiri Olsa <jolsa@...nel.org>,
        christophe.leroy@...roup.eu, naveen@...nel.org, maddy@...ux.ibm.com,
        Michael Ellerman <mpe@...erman.id.au>, npiggin@...il.com,
        memxor@...il.com, iii@...ux.ibm.com, shuah@...nel.org
Subject: Re: [bpf-next v2 0/5] powerpc64/bpf: Add support for bpf arena and
 arena atomics



> On 29 Aug 2025, at 10:21 PM, Saket Kumar Bhaskar <skb99@...ux.ibm.com> wrote:
> 
> 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.
> 
> The last patch in the series has fix for arena spinlock selftest
> failure.
> 
> 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
> 
> Changes since v1:
> 
> Addressed comments from Chris:
> * Squashed introduction of bpf_jit_emit_probe_mem_store() and its usage in
>  one patch.
> * Defined and used PPC_RAW_RLDICL_DOT to avoid the CMPDI.
> * Removed conditional statement for fixup[0] = PPC_RAW_LI(dst_reg, 0);
> * Indicated this change is limited to powerpc64 in subject.
> 
> Addressed comments from Alexei:
> * Removed skel->rodata->nr_cpus = get_nprocs() and its usage to get
>  currently online cpus(as it needs to be updated from userspace).
> 
> Saket Kumar Bhaskar (5):
>  powerpc64/bpf: Implement PROBE_MEM32 pseudo instructions
>  powerpc64/bpf: Implement bpf_addr_space_cast instruction
>  powerpc64/bpf: Introduce bpf_jit_emit_atomic_ops() to emit atomic
>    instructions
>  powerpc64/bpf: Implement PROBE_ATOMIC instructions
>  selftests/bpf: Fix arena_spin_lock selftest failure
> 
> arch/powerpc/include/asm/ppc-opcode.h         |   1 +
> 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             | 401 +++++++++++++-----
> .../bpf/prog_tests/arena_spin_lock.c          |  13 +
> .../selftests/bpf/progs/arena_spin_lock.c     |   5 +-
> 7 files changed, 347 insertions(+), 113 deletions(-)
> 
> -- 
> 2.43.5
> 

Tested this patch set by applying on top of bpd-next repo and it works as expected. Hence, please add below tag for the series.

Tested-by: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>

Regards,
Venkat.