Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751817AbbFZBkd (ORCPT ); Thu, 25 Jun 2015 21:40:33 -0400 Received: from mail-pa0-f45.google.com ([209.85.220.45]:35518 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750994AbbFZBkZ (ORCPT ); Thu, 25 Jun 2015 21:40:25 -0400 From: Xi Wang To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Xi Wang , Zi Shen Lim , Alexei Starovoitov Subject: [RFC PATCH] arm64: bpf: fix endianness conversion bugs Date: Thu, 25 Jun 2015 18:39:15 -0700 Message-Id: <1435282755-12011-1-git-send-email-xi.wang@gmail.com> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2801 Lines: 93 Upper bits should be zeroed in endianness conversion: - even when there's no need to change endianness (i.e., BPF_FROM_BE on big endian or BPF_FROM_LE on little endian); - after rev16. This patch fixes such bugs by emitting extra instructions to clear upper bits. Cc: Zi Shen Lim Cc: Alexei Starovoitov Fixes: e54bcde3d69d ("arm64: eBPF JIT compiler") Signed-off-by: Xi Wang --- The current testsuite catches the 16-bit bugs. I'll send a separate patch that extends test_bpf to catch the 32-bit ones. --- arch/arm64/net/bpf_jit.h | 4 ++++ arch/arm64/net/bpf_jit_comp.c | 22 ++++++++++++++++++++-- 2 files changed, 24 insertions(+), 2 deletions(-) diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h index de0a81a..98a26ce 100644 --- a/arch/arm64/net/bpf_jit.h +++ b/arch/arm64/net/bpf_jit.h @@ -110,6 +110,10 @@ /* Rd = Rn >> shift; signed */ #define A64_ASR(sf, Rd, Rn, shift) A64_SBFM(sf, Rd, Rn, shift, (sf) ? 63 : 31) +/* Zero extend */ +#define A64_UXTH(sf, Rd, Rn) A64_UBFM(sf, Rd, Rn, 0, 15) +#define A64_UXTW(sf, Rd, Rn) A64_UBFM(sf, Rd, Rn, 0, 31) + /* Move wide (immediate) */ #define A64_MOVEW(sf, Rd, imm16, shift, type) \ aarch64_insn_gen_movewide(Rd, imm16, shift, \ diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index c81ddd4..c047598 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -289,23 +289,41 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) case BPF_ALU | BPF_END | BPF_FROM_BE: #ifdef CONFIG_CPU_BIG_ENDIAN if (BPF_SRC(code) == BPF_FROM_BE) - break; + goto emit_bswap_uxt; #else /* !CONFIG_CPU_BIG_ENDIAN */ if (BPF_SRC(code) == BPF_FROM_LE) - break; + goto emit_bswap_uxt; #endif switch (imm) { case 16: emit(A64_REV16(is64, dst, dst), ctx); + /* zero-extend 16 bits into 64 bits */ + emit(A64_UXTH(is64, dst, dst), ctx); break; case 32: emit(A64_REV32(is64, dst, dst), ctx); + /* upper 32 bits already cleared */ break; case 64: emit(A64_REV64(dst, dst), ctx); break; } break; +emit_bswap_uxt: + switch (imm) { + case 16: + /* zero-extend 16 bits into 64 bits */ + emit(A64_UXTH(is64, dst, dst), ctx); + break; + case 32: + /* zero-extend 32 bits into 64 bits */ + emit(A64_UXTW(is64, dst, dst), ctx); + break; + case 64: + /* nop */ + break; + } + break; /* dst = imm */ case BPF_ALU | BPF_MOV | BPF_K: case BPF_ALU64 | BPF_MOV | BPF_K: -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/