netdev - [PATCH bpf-next v3 07/16] bpf: JIT blinds support JMP32

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Date:   Thu, 24 Jan 2019 19:10:19 -0500
From:   Jiong Wang <jiong.wang@...ronome.com>
To:     ast@...nel.org, daniel@...earbox.net
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com,
        Jiong Wang <jiong.wang@...ronome.com>
Subject: [PATCH bpf-next v3 07/16] bpf: JIT blinds support JMP32

This patch adds JIT blinds support for JMP32.

Like BPF_JMP_REG/IMM, JMP32 version are needed for building raw bpf insn.
They are added to both include/linux/filter.h and
tools/include/linux/filter.h.

Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
---
 include/linux/filter.h       | 20 ++++++++++++++++++++
 kernel/bpf/core.c            | 21 +++++++++++++++++++++
 tools/include/linux/filter.h | 20 ++++++++++++++++++++
 3 files changed, 61 insertions(+)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index be9af6b..e4b473f 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -277,6 +277,26 @@ struct sock_reuseport;
 		.off   = OFF,					\
 		.imm   = IMM })
 
+/* Like BPF_JMP_REG, but with 32-bit wide operands for comparison. */
+
+#define BPF_JMP32_REG(OP, DST, SRC, OFF)			\
+	((struct bpf_insn) {					\
+		.code  = BPF_JMP32 | BPF_OP(OP) | BPF_X,	\
+		.dst_reg = DST,					\
+		.src_reg = SRC,					\
+		.off   = OFF,					\
+		.imm   = 0 })
+
+/* Like BPF_JMP_IMM, but with 32-bit wide operands for comparison. */
+
+#define BPF_JMP32_IMM(OP, DST, IMM, OFF)			\
+	((struct bpf_insn) {					\
+		.code  = BPF_JMP32 | BPF_OP(OP) | BPF_K,	\
+		.dst_reg = DST,					\
+		.src_reg = 0,					\
+		.off   = OFF,					\
+		.imm   = IMM })
+
 /* Unconditional jumps, goto pc + off16 */
 
 #define BPF_JMP_A(OFF)						\
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index bba11c2..a7bcb23 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -949,6 +949,27 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from,
 		*to++ = BPF_JMP_REG(from->code, from->dst_reg, BPF_REG_AX, off);
 		break;
 
+	case BPF_JMP32 | BPF_JEQ  | BPF_K:
+	case BPF_JMP32 | BPF_JNE  | BPF_K:
+	case BPF_JMP32 | BPF_JGT  | BPF_K:
+	case BPF_JMP32 | BPF_JLT  | BPF_K:
+	case BPF_JMP32 | BPF_JGE  | BPF_K:
+	case BPF_JMP32 | BPF_JLE  | BPF_K:
+	case BPF_JMP32 | BPF_JSGT | BPF_K:
+	case BPF_JMP32 | BPF_JSLT | BPF_K:
+	case BPF_JMP32 | BPF_JSGE | BPF_K:
+	case BPF_JMP32 | BPF_JSLE | BPF_K:
+	case BPF_JMP32 | BPF_JSET | BPF_K:
+		/* Accommodate for extra offset in case of a backjump. */
+		off = from->off;
+		if (off < 0)
+			off -= 2;
+		*to++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm);
+		*to++ = BPF_ALU32_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
+		*to++ = BPF_JMP32_REG(from->code, from->dst_reg, BPF_REG_AX,
+				      off);
+		break;
+
 	case BPF_LD | BPF_IMM | BPF_DW:
 		*to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ aux[1].imm);
 		*to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd);
diff --git a/tools/include/linux/filter.h b/tools/include/linux/filter.h
index af55acf..cce0b02 100644
--- a/tools/include/linux/filter.h
+++ b/tools/include/linux/filter.h
@@ -199,6 +199,16 @@
 		.off   = OFF,					\
 		.imm   = 0 })
 
+/* Like BPF_JMP_REG, but with 32-bit wide operands for comparison. */
+
+#define BPF_JMP32_REG(OP, DST, SRC, OFF)			\
+	((struct bpf_insn) {					\
+		.code  = BPF_JMP32 | BPF_OP(OP) | BPF_X,	\
+		.dst_reg = DST,					\
+		.src_reg = SRC,					\
+		.off   = OFF,					\
+		.imm   = 0 })
+
 /* Conditional jumps against immediates, if (dst_reg 'op' imm32) goto pc + off16 */
 
 #define BPF_JMP_IMM(OP, DST, IMM, OFF)				\
@@ -209,6 +219,16 @@
 		.off   = OFF,					\
 		.imm   = IMM })
 
+/* Like BPF_JMP_IMM, but with 32-bit wide operands for comparison. */
+
+#define BPF_JMP32_IMM(OP, DST, IMM, OFF)			\
+	((struct bpf_insn) {					\
+		.code  = BPF_JMP32 | BPF_OP(OP) | BPF_K,	\
+		.dst_reg = DST,					\
+		.src_reg = 0,					\
+		.off   = OFF,					\
+		.imm   = IMM })
+
 /* Unconditional jumps, goto pc + off16 */
 
 #define BPF_JMP_A(OFF)						\
-- 
2.7.4