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

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Message-ID: <20250829165135.1273071-1-skb99@linux.ibm.com>
Date: Fri, 29 Aug 2025 22:21:30 +0530
From: Saket Kumar Bhaskar <skb99@...ux.ibm.com>
To: bpf@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: 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,
        christophe.leroy@...roup.eu, 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: [bpf-next v2 0/5] powerpc64/bpf: Add support for bpf arena and arena atomics

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