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Date: Mon, 09 Dec 2019 11:17:35 +0000
From: Russell King <rmk+kernel@...linux.org.uk>
To: Daniel Borkmann <daniel@...earbox.net>
Cc: Shubham Bansal <illusionist.neo@...il.com>,
Alexei Starovoitov <ast@...nel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
Andrii Nakryiko <andriin@...com>, netdev@...r.kernel.org,
bpf@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: [PATCH] ARM: net: bpf: improve endian conversion
Make the endian conversion function easier to read by moving it out
of the big switch, and avoid doing anything if we're requested to
convert from a 64-bit LE value (we're LE anyway here.)
Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
---
arch/arm/net/bpf_jit_32.c | 91 +++++++++++++++++++++------------------
1 file changed, 50 insertions(+), 41 deletions(-)
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index cc29869d12a3..646ab5785ca4 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -1245,6 +1245,55 @@ static inline void emit_rev32(const u8 rd, const u8 rn, struct jit_ctx *ctx)
#endif
}
+static void emit_a32_endian(const s8 dst[], u8 code, s32 bits,
+ struct jit_ctx *ctx)
+{
+ const s8 *tmp = bpf2a32[TMP_REG_1];
+ const s8 *tmp2 = bpf2a32[TMP_REG_2];
+ const s8 *rd;
+
+ /* Converting from LE and 64-bit value is a no-op. */
+ if (code == BPF_FROM_LE && bits == 64)
+ return;
+
+ rd = arm_bpf_get_reg64(dst, tmp, ctx);
+
+ if (code != BPF_FROM_LE) {
+ /* endian swap */
+ switch (imm) {
+ case 16:
+ emit_rev16(rd[1], rd[1], ctx);
+ break;
+ case 32:
+ emit_rev32(rd[1], rd[1], ctx);
+ break;
+ case 64:
+ emit_rev32(ARM_LR, rd[1], ctx);
+ emit_rev32(rd[1], rd[0], ctx);
+ emit(ARM_MOV_R(rd[0], ARM_LR), ctx);
+ break;
+ }
+ }
+
+ /* zero-extend size to 64-bit */
+ switch (imm) {
+ case 16:
+#if __LINUX_ARM_ARCH__ < 6
+ emit_a32_mov_i(tmp2[1], 0xffff, ctx);
+ emit(ARM_AND_R(rd[1], rd[1], tmp2[1]), ctx);
+#else /* ARMv6+ */
+ emit(ARM_UXTH(rd[1], rd[1]), ctx);
+#endif
+ /* FALLTHROUGH */
+ case 32:
+ if (!ctx->prog->aux->verifier_zext)
+ emit(ARM_MOV_I(rd[0], 0), ctx);
+ break;
+ }
+
+ arm_bpf_put_reg64(dst, rd, ctx);
+}
+
// push the scratch stack register on top of the stack
static inline void emit_push_r64(const s8 src[], struct jit_ctx *ctx)
{
@@ -1523,47 +1572,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
/* dst = htobe(dst) */
case BPF_ALU | BPF_END | BPF_FROM_LE:
case BPF_ALU | BPF_END | BPF_FROM_BE:
- rd = arm_bpf_get_reg64(dst, tmp, ctx);
- if (BPF_SRC(code) == BPF_FROM_LE)
- goto emit_bswap_uxt;
- switch (imm) {
- case 16:
- emit_rev16(rd[1], rd[1], ctx);
- goto emit_bswap_uxt;
- case 32:
- emit_rev32(rd[1], rd[1], ctx);
- goto emit_bswap_uxt;
- case 64:
- emit_rev32(ARM_LR, rd[1], ctx);
- emit_rev32(rd[1], rd[0], ctx);
- emit(ARM_MOV_R(rd[0], ARM_LR), ctx);
- break;
- }
- goto exit;
-emit_bswap_uxt:
- switch (imm) {
- case 16:
- /* zero-extend 16 bits into 64 bits */
-#if __LINUX_ARM_ARCH__ < 6
- emit_a32_mov_i(tmp2[1], 0xffff, ctx);
- emit(ARM_AND_R(rd[1], rd[1], tmp2[1]), ctx);
-#else /* ARMv6+ */
- emit(ARM_UXTH(rd[1], rd[1]), ctx);
-#endif
- if (!ctx->prog->aux->verifier_zext)
- emit(ARM_EOR_R(rd[0], rd[0], rd[0]), ctx);
- break;
- case 32:
- /* zero-extend 32 bits into 64 bits */
- if (!ctx->prog->aux->verifier_zext)
- emit(ARM_EOR_R(rd[0], rd[0], rd[0]), ctx);
- break;
- case 64:
- /* nop */
- break;
- }
-exit:
- arm_bpf_put_reg64(dst, rd, ctx);
+ emit_a32_endian(dst, BPF_SRC(code), imm, ctx);
break;
/* dst = imm64 */
case BPF_LD | BPF_IMM | BPF_DW:
--
2.20.1
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