The existing code for emitting bpf atomic instruction sequences for atomic operations such as XCHG, CMPXCHG, ADD, AND, OR, and XOR has been refactored into a reusable function, bpf_jit_emit_ppc_atomic_op(). It also computes the jump offset and tracks the instruction index for jited LDARX/LWARX to be used in case it causes a fault.
Signed-off-by: Saket Kumar Bhaskar skb99@linux.ibm.com --- arch/powerpc/net/bpf_jit_comp64.c | 203 +++++++++++++++++------------- 1 file changed, 115 insertions(+), 88 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 76efb47f02a6..cb4d1e954961 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -423,6 +423,111 @@ asm ( " blr ;" );
+static int bpf_jit_emit_atomic_ops(u32 *image, struct codegen_context *ctx, + const struct bpf_insn *insn, u32 *jmp_off, + u32 *tmp_idx, u32 *addrp) +{ + u32 tmp1_reg = bpf_to_ppc(TMP_REG_1); + u32 tmp2_reg = bpf_to_ppc(TMP_REG_2); + u32 size = BPF_SIZE(insn->code); + u32 src_reg = bpf_to_ppc(insn->src_reg); + u32 dst_reg = bpf_to_ppc(insn->dst_reg); + s32 imm = insn->imm; + + u32 save_reg = tmp2_reg; + u32 ret_reg = src_reg; + u32 fixup_idx; + + /* Get offset into TMP_REG_1 */ + EMIT(PPC_RAW_LI(tmp1_reg, insn->off)); + /* + * Enforce full ordering for operations with BPF_FETCH by emitting a 'sync' + * before and after the operation. + * + * This is a requirement in the Linux Kernel Memory Model. + * See __cmpxchg_u64() in asm/cmpxchg.h as an example. + */ + if ((imm & BPF_FETCH) && IS_ENABLED(CONFIG_SMP)) + EMIT(PPC_RAW_SYNC()); + + *tmp_idx = ctx->idx; + + /* load value from memory into TMP_REG_2 */ + if (size == BPF_DW) + EMIT(PPC_RAW_LDARX(tmp2_reg, tmp1_reg, dst_reg, 0)); + else + EMIT(PPC_RAW_LWARX(tmp2_reg, tmp1_reg, dst_reg, 0)); + /* Save old value in _R0 */ + if (imm & BPF_FETCH) + EMIT(PPC_RAW_MR(_R0, tmp2_reg)); + + switch (imm) { + case BPF_ADD: + case BPF_ADD | BPF_FETCH: + EMIT(PPC_RAW_ADD(tmp2_reg, tmp2_reg, src_reg)); + break; + case BPF_AND: + case BPF_AND | BPF_FETCH: + EMIT(PPC_RAW_AND(tmp2_reg, tmp2_reg, src_reg)); + break; + case BPF_OR: + case BPF_OR | BPF_FETCH: + EMIT(PPC_RAW_OR(tmp2_reg, tmp2_reg, src_reg)); + break; + case BPF_XOR: + case BPF_XOR | BPF_FETCH: + EMIT(PPC_RAW_XOR(tmp2_reg, tmp2_reg, src_reg)); + break; + case BPF_CMPXCHG: + /* + * Return old value in BPF_REG_0 for BPF_CMPXCHG & + * in src_reg for other cases. + */ + ret_reg = bpf_to_ppc(BPF_REG_0); + + /* Compare with old value in BPF_R0 */ + if (size == BPF_DW) + EMIT(PPC_RAW_CMPD(bpf_to_ppc(BPF_REG_0), tmp2_reg)); + else + EMIT(PPC_RAW_CMPW(bpf_to_ppc(BPF_REG_0), tmp2_reg)); + /* Don't set if different from old value */ + PPC_BCC_SHORT(COND_NE, (ctx->idx + 3) * 4); + fallthrough; + case BPF_XCHG: + save_reg = src_reg; + break; + default: + return -EOPNOTSUPP; + } + + /* store new value */ + if (size == BPF_DW) + EMIT(PPC_RAW_STDCX(save_reg, tmp1_reg, dst_reg)); + else + EMIT(PPC_RAW_STWCX(save_reg, tmp1_reg, dst_reg)); + /* we're done if this succeeded */ + PPC_BCC_SHORT(COND_NE, *tmp_idx * 4); + fixup_idx = ctx->idx; + + if (imm & BPF_FETCH) { + /* Emit 'sync' to enforce full ordering */ + if (IS_ENABLED(CONFIG_SMP)) + EMIT(PPC_RAW_SYNC()); + EMIT(PPC_RAW_MR(ret_reg, _R0)); + /* + * Skip unnecessary zero-extension for 32-bit cmpxchg. + * For context, see commit 39491867ace5. + */ + if (size != BPF_DW && imm == BPF_CMPXCHG && + insn_is_zext(insn + 1)) + *addrp = ctx->idx * 4; + } + + *jmp_off = (fixup_idx - *tmp_idx) * 4; + + return 0; +} + static int bpf_jit_emit_probe_mem_store(struct codegen_context *ctx, u32 src_reg, s16 off, u32 code, u32 *image) { @@ -538,7 +643,6 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code u32 size = BPF_SIZE(code); u32 tmp1_reg = bpf_to_ppc(TMP_REG_1); u32 tmp2_reg = bpf_to_ppc(TMP_REG_2); - u32 save_reg, ret_reg; s16 off = insn[i].off; s32 imm = insn[i].imm; bool func_addr_fixed; @@ -546,6 +650,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code u64 imm64; u32 true_cond; u32 tmp_idx; + u32 jmp_off;
/* * addrs[] maps a BPF bytecode address into a real offset from @@ -1080,93 +1185,15 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code return -EOPNOTSUPP; }
- save_reg = tmp2_reg; - ret_reg = src_reg; - - /* Get offset into TMP_REG_1 */ - EMIT(PPC_RAW_LI(tmp1_reg, off)); - /* - * Enforce full ordering for operations with BPF_FETCH by emitting a 'sync' - * before and after the operation. - * - * This is a requirement in the Linux Kernel Memory Model. - * See __cmpxchg_u64() in asm/cmpxchg.h as an example. - */ - if ((imm & BPF_FETCH) && IS_ENABLED(CONFIG_SMP)) - EMIT(PPC_RAW_SYNC()); - tmp_idx = ctx->idx * 4; - /* load value from memory into TMP_REG_2 */ - if (size == BPF_DW) - EMIT(PPC_RAW_LDARX(tmp2_reg, tmp1_reg, dst_reg, 0)); - else - EMIT(PPC_RAW_LWARX(tmp2_reg, tmp1_reg, dst_reg, 0)); - - /* Save old value in _R0 */ - if (imm & BPF_FETCH) - EMIT(PPC_RAW_MR(_R0, tmp2_reg)); - - switch (imm) { - case BPF_ADD: - case BPF_ADD | BPF_FETCH: - EMIT(PPC_RAW_ADD(tmp2_reg, tmp2_reg, src_reg)); - break; - case BPF_AND: - case BPF_AND | BPF_FETCH: - EMIT(PPC_RAW_AND(tmp2_reg, tmp2_reg, src_reg)); - break; - case BPF_OR: - case BPF_OR | BPF_FETCH: - EMIT(PPC_RAW_OR(tmp2_reg, tmp2_reg, src_reg)); - break; - case BPF_XOR: - case BPF_XOR | BPF_FETCH: - EMIT(PPC_RAW_XOR(tmp2_reg, tmp2_reg, src_reg)); - break; - case BPF_CMPXCHG: - /* - * Return old value in BPF_REG_0 for BPF_CMPXCHG & - * in src_reg for other cases. - */ - ret_reg = bpf_to_ppc(BPF_REG_0); - - /* Compare with old value in BPF_R0 */ - if (size == BPF_DW) - EMIT(PPC_RAW_CMPD(bpf_to_ppc(BPF_REG_0), tmp2_reg)); - else - EMIT(PPC_RAW_CMPW(bpf_to_ppc(BPF_REG_0), tmp2_reg)); - /* Don't set if different from old value */ - PPC_BCC_SHORT(COND_NE, (ctx->idx + 3) * 4); - fallthrough; - case BPF_XCHG: - save_reg = src_reg; - break; - default: - pr_err_ratelimited( - "eBPF filter atomic op code %02x (@%d) unsupported\n", - code, i); - return -EOPNOTSUPP; - } - - /* store new value */ - if (size == BPF_DW) - EMIT(PPC_RAW_STDCX(save_reg, tmp1_reg, dst_reg)); - else - EMIT(PPC_RAW_STWCX(save_reg, tmp1_reg, dst_reg)); - /* we're done if this succeeded */ - PPC_BCC_SHORT(COND_NE, tmp_idx); - - if (imm & BPF_FETCH) { - /* Emit 'sync' to enforce full ordering */ - if (IS_ENABLED(CONFIG_SMP)) - EMIT(PPC_RAW_SYNC()); - EMIT(PPC_RAW_MR(ret_reg, _R0)); - /* - * Skip unnecessary zero-extension for 32-bit cmpxchg. - * For context, see commit 39491867ace5. - */ - if (size != BPF_DW && imm == BPF_CMPXCHG && - insn_is_zext(&insn[i + 1])) - addrs[++i] = ctx->idx * 4; + ret = bpf_jit_emit_atomic_ops(image, ctx, &insn[i], + &jmp_off, &tmp_idx, &addrs[i + 1]); + if (ret) { + if (ret == -EOPNOTSUPP) { + pr_err_ratelimited( + "eBPF filter atomic op code %02x (@%d) unsupported\n", + code, i); + } + return ret; } break;