netdev - [PATCH bpf-next v2 04/16] bpf: disassembler support JMP32

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Date:   Mon, 21 Jan 2019 08:15:41 -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 v2 04/16] bpf: disassembler support JMP32

This patch teaches disassembler about JMP32. There are two places to
update:

  - Class 0x6 now used by BPF_JMP32, not "unused".

  - BPF_JMP32 need to show comparison operands properly.
    The disassemble format is to add an extra "(32)" before the operands if
    it is a sub-register. A better disassemble format for both JMP32 and
    ALU32 just show the register prefix as "w" instead of "r", this is the
    format using by LLVM assembler.

Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
---
 kernel/bpf/disasm.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/kernel/bpf/disasm.c b/kernel/bpf/disasm.c
index d6b7637..de73f55 100644
--- a/kernel/bpf/disasm.c
+++ b/kernel/bpf/disasm.c
@@ -67,7 +67,7 @@ const char *const bpf_class_string[8] = {
 	[BPF_STX]   = "stx",
 	[BPF_ALU]   = "alu",
 	[BPF_JMP]   = "jmp",
-	[BPF_RET]   = "BUG",
+	[BPF_JMP32] = "jmp32",
 	[BPF_ALU64] = "alu64",
 };
 
@@ -136,23 +136,22 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 			else
 				print_bpf_end_insn(verbose, cbs->private_data, insn);
 		} else if (BPF_OP(insn->code) == BPF_NEG) {
-			verbose(cbs->private_data, "(%02x) r%d = %s-r%d\n",
-				insn->code, insn->dst_reg,
-				class == BPF_ALU ? "(u32) " : "",
+			verbose(cbs->private_data, "(%02x) %c%d = -%c%d\n",
+				insn->code, class == BPF_ALU ? 'w' : 'r',
+				insn->dst_reg, class == BPF_ALU ? 'w' : 'r',
 				insn->dst_reg);
 		} else if (BPF_SRC(insn->code) == BPF_X) {
-			verbose(cbs->private_data, "(%02x) %sr%d %s %sr%d\n",
-				insn->code, class == BPF_ALU ? "(u32) " : "",
+			verbose(cbs->private_data, "(%02x) %c%d %s %c%d\n",
+				insn->code, class == BPF_ALU ? 'w' : 'r',
 				insn->dst_reg,
 				bpf_alu_string[BPF_OP(insn->code) >> 4],
-				class == BPF_ALU ? "(u32) " : "",
+				class == BPF_ALU ? 'w' : 'r',
 				insn->src_reg);
 		} else {
-			verbose(cbs->private_data, "(%02x) %sr%d %s %s%d\n",
-				insn->code, class == BPF_ALU ? "(u32) " : "",
+			verbose(cbs->private_data, "(%02x) %c%d %s %d\n",
+				insn->code, class == BPF_ALU ? 'w' : 'r',
 				insn->dst_reg,
 				bpf_alu_string[BPF_OP(insn->code) >> 4],
-				class == BPF_ALU ? "(u32) " : "",
 				insn->imm);
 		}
 	} else if (class == BPF_STX) {
@@ -220,7 +219,7 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 			verbose(cbs->private_data, "BUG_ld_%02x\n", insn->code);
 			return;
 		}
-	} else if (class == BPF_JMP) {
+	} else if (class == BPF_JMP32 || class == BPF_JMP) {
 		u8 opcode = BPF_OP(insn->code);
 
 		if (opcode == BPF_CALL) {
@@ -244,13 +243,18 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 		} else if (insn->code == (BPF_JMP | BPF_EXIT)) {
 			verbose(cbs->private_data, "(%02x) exit\n", insn->code);
 		} else if (BPF_SRC(insn->code) == BPF_X) {
-			verbose(cbs->private_data, "(%02x) if r%d %s r%d goto pc%+d\n",
-				insn->code, insn->dst_reg,
+			verbose(cbs->private_data,
+				"(%02x) if %c%d %s %c%d goto pc%+d\n",
+				insn->code, class == BPF_JMP32 ? 'w' : 'r',
+				insn->dst_reg,
 				bpf_jmp_string[BPF_OP(insn->code) >> 4],
+				class == BPF_JMP32 ? 'w' : 'r',
 				insn->src_reg, insn->off);
 		} else {
-			verbose(cbs->private_data, "(%02x) if r%d %s 0x%x goto pc%+d\n",
-				insn->code, insn->dst_reg,
+			verbose(cbs->private_data,
+				"(%02x) if %c%d %s 0x%x goto pc%+d\n",
+				insn->code, class == BPF_JMP32 ? 'w' : 'r',
+				insn->dst_reg,
 				bpf_jmp_string[BPF_OP(insn->code) >> 4],
 				insn->imm, insn->off);
 		}
-- 
2.7.4