| Message ID | 20220512074546.231616-5-hbathini@linux.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Atomics support for eBPF on powerpc | expand |
Le 12/05/2022 à 09:45, Hari Bathini a écrit : > Adding instructions for ppc32 for > > atomic_and > atomic_or > atomic_xor > atomic_fetch_add > atomic_fetch_and > atomic_fetch_or > atomic_fetch_xor > > Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> > --- > arch/powerpc/net/bpf_jit_comp32.c | 45 +++++++++++++++++++++---------- > 1 file changed, 31 insertions(+), 14 deletions(-) > > diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c > index e46ed1e8c6ca..5604ae1b60ab 100644 > --- a/arch/powerpc/net/bpf_jit_comp32.c > +++ b/arch/powerpc/net/bpf_jit_comp32.c > @@ -798,25 +798,42 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * > * BPF_STX ATOMIC (atomic ops) > */ > case BPF_STX | BPF_ATOMIC | BPF_W: > - if (imm != BPF_ADD) { > - pr_err_ratelimited("eBPF filter atomic op code %02x (@%d) unsupported\n", > - code, i); > - return -ENOTSUPP; > - } > - > - /* *(u32 *)(dst + off) += src */ > - > bpf_set_seen_register(ctx, tmp_reg); > /* Get offset into TMP_REG */ > EMIT(PPC_RAW_LI(tmp_reg, off)); > + tmp_idx = ctx->idx * 4; > /* load value from memory into r0 */ > EMIT(PPC_RAW_LWARX(_R0, tmp_reg, dst_reg, 0)); > - /* add value from src_reg into this */ > - EMIT(PPC_RAW_ADD(_R0, _R0, src_reg)); > - /* store result back */ > - EMIT(PPC_RAW_STWCX(_R0, tmp_reg, dst_reg)); > - /* we're done if this succeeded */ > - PPC_BCC_SHORT(COND_NE, (ctx->idx - 3) * 4); > + switch (imm) { > + case BPF_ADD: > + case BPF_ADD | BPF_FETCH: > + EMIT(PPC_RAW_ADD(_R0, _R0, src_reg)); > + goto atomic_ops; > + case BPF_AND: > + case BPF_AND | BPF_FETCH: > + EMIT(PPC_RAW_AND(_R0, _R0, src_reg)); > + goto atomic_ops; > + case BPF_OR: > + case BPF_OR | BPF_FETCH: > + EMIT(PPC_RAW_OR(_R0, _R0, src_reg)); > + goto atomic_ops; > + case BPF_XOR: > + case BPF_XOR | BPF_FETCH: > + EMIT(PPC_RAW_XOR(_R0, _R0, src_reg)); > +atomic_ops: This looks like an odd construct. The default case doesn't fall through, so the below part could go after the switch and all cases could just break instead of goto atomic_ops. > + /* For the BPF_FETCH variant, get old data into src_reg */ > + if (imm & BPF_FETCH) > + EMIT(PPC_RAW_LWARX(src_reg, tmp_reg, dst_reg, 0)); I think this is wrong. By doing a new LWARX you kill the reservation done by the previous one. If the data has changed between the first LWARX and now, it will go undetected. It should be a LWZX I believe. But there is another problem: you clobber src_reg, then what happens if STWCX fails and it loops back to tmp_idx ? > + /* store result back */ > + EMIT(PPC_RAW_STWCX(_R0, tmp_reg, dst_reg)); > + /* we're done if this succeeded */ > + PPC_BCC_SHORT(COND_NE, tmp_idx); > + break; > + default: > + pr_err_ratelimited("eBPF filter atomic op code %02x (@%d) unsupported\n", > + code, i); > + return -EOPNOTSUPP; > + } > break; > > case BPF_STX | BPF_ATOMIC | BPF_DW: /* *(u64 *)(dst + off) += src */
diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index e46ed1e8c6ca..5604ae1b60ab 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -798,25 +798,42 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * * BPF_STX ATOMIC (atomic ops) */ case BPF_STX | BPF_ATOMIC | BPF_W: - if (imm != BPF_ADD) { - pr_err_ratelimited("eBPF filter atomic op code %02x (@%d) unsupported\n", - code, i); - return -ENOTSUPP; - } - - /* *(u32 *)(dst + off) += src */ - bpf_set_seen_register(ctx, tmp_reg); /* Get offset into TMP_REG */ EMIT(PPC_RAW_LI(tmp_reg, off)); + tmp_idx = ctx->idx * 4; /* load value from memory into r0 */ EMIT(PPC_RAW_LWARX(_R0, tmp_reg, dst_reg, 0)); - /* add value from src_reg into this */ - EMIT(PPC_RAW_ADD(_R0, _R0, src_reg)); - /* store result back */ - EMIT(PPC_RAW_STWCX(_R0, tmp_reg, dst_reg)); - /* we're done if this succeeded */ - PPC_BCC_SHORT(COND_NE, (ctx->idx - 3) * 4); + switch (imm) { + case BPF_ADD: + case BPF_ADD | BPF_FETCH: + EMIT(PPC_RAW_ADD(_R0, _R0, src_reg)); + goto atomic_ops; + case BPF_AND: + case BPF_AND | BPF_FETCH: + EMIT(PPC_RAW_AND(_R0, _R0, src_reg)); + goto atomic_ops; + case BPF_OR: + case BPF_OR | BPF_FETCH: + EMIT(PPC_RAW_OR(_R0, _R0, src_reg)); + goto atomic_ops; + case BPF_XOR: + case BPF_XOR | BPF_FETCH: + EMIT(PPC_RAW_XOR(_R0, _R0, src_reg)); +atomic_ops: + /* For the BPF_FETCH variant, get old data into src_reg */ + if (imm & BPF_FETCH) + EMIT(PPC_RAW_LWARX(src_reg, tmp_reg, dst_reg, 0)); + /* store result back */ + EMIT(PPC_RAW_STWCX(_R0, tmp_reg, dst_reg)); + /* we're done if this succeeded */ + PPC_BCC_SHORT(COND_NE, tmp_idx); + break; + default: + pr_err_ratelimited("eBPF filter atomic op code %02x (@%d) unsupported\n", + code, i); + return -EOPNOTSUPP; + } break; case BPF_STX | BPF_ATOMIC | BPF_DW: /* *(u64 *)(dst + off) += src */
Adding instructions for ppc32 for atomic_and atomic_or atomic_xor atomic_fetch_add atomic_fetch_and atomic_fetch_or atomic_fetch_xor Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> --- arch/powerpc/net/bpf_jit_comp32.c | 45 +++++++++++++++++++++---------- 1 file changed, 31 insertions(+), 14 deletions(-)