[RFC PATCH bpf-next 07/13] bpf: Add kernel/bpftool asm support for new instructions

[Yonghong Song <yhs@xxxxxx>]

Add asm support for new instructions so kernel verifier and bpftool
xlated insn dumps can have proper asm syntax for new instructions.

Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
 kernel/bpf/disasm.c | 57 ++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 51 insertions(+), 6 deletions(-)

diff --git a/kernel/bpf/disasm.c b/kernel/bpf/disasm.c
index 7b4afb7d96db..cc46e708df5e 100644
--- a/kernel/bpf/disasm.c
+++ b/kernel/bpf/disasm.c
@@ -87,6 +87,17 @@ const char *const bpf_alu_string[16] = {
 	[BPF_END >> 4]  = "endian",
 };
 
+const char *const bpf_alu_sign_string[16] = {
+	[BPF_DIV >> 4]  = "s/=",
+	[BPF_MOD >> 4]  = "s%=",
+};
+
+const char *const bpf_movs_string[4] = {
+	[0] = "(s8)",
+	[1] = "(s16)",
+	[3] = "(s32)",
+};
+
 static const char *const bpf_atomic_alu_string[16] = {
 	[BPF_ADD >> 4]  = "add",
 	[BPF_AND >> 4]  = "and",
@@ -101,6 +112,12 @@ static const char *const bpf_ldst_string[] = {
 	[BPF_DW >> 3] = "u64",
 };
 
+static const char *const bpf_lds_string[] = {
+	[BPF_W >> 3]  = "s32",
+	[BPF_H >> 3]  = "s16",
+	[BPF_B >> 3]  = "s8",
+};
+
 static const char *const bpf_jmp_string[16] = {
 	[BPF_JA >> 4]   = "jmp",
 	[BPF_JEQ >> 4]  = "==",
@@ -128,6 +145,26 @@ static void print_bpf_end_insn(bpf_insn_print_t verbose,
 		insn->imm, insn->dst_reg);
 }
 
+static void print_bpf_bswap_insn(bpf_insn_print_t verbose,
+			       void *private_data,
+			       const struct bpf_insn *insn)
+{
+	verbose(private_data, "(%02x) r%d = bswap%d r%d\n",
+		insn->code, insn->dst_reg,
+		insn->imm, insn->dst_reg);
+}
+
+static bool is_sdiv_smod(const struct bpf_insn *insn) {
+	u8 op = BPF_OP(insn->code);
+	u16 off = insn->off;
+
+	return (op == BPF_DIV || op == BPF_MOD) && off == 1;
+}
+
+static bool is_movs(const struct bpf_insn *insn) {
+	return BPF_OP(insn->code) == BPF_MOV && insn->off != 0;
+}
+
 void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 		    const struct bpf_insn *insn,
 		    bool allow_ptr_leaks)
@@ -138,7 +175,7 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 	if (class == BPF_ALU || class == BPF_ALU64) {
 		if (BPF_OP(insn->code) == BPF_END) {
 			if (class == BPF_ALU64)
-				verbose(cbs->private_data, "BUG_alu64_%02x\n", insn->code);
+				print_bpf_bswap_insn(verbose, cbs->private_data, insn);
 			else
 				print_bpf_end_insn(verbose, cbs->private_data, insn);
 		} else if (BPF_OP(insn->code) == BPF_NEG) {
@@ -147,17 +184,20 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 				insn->dst_reg, class == BPF_ALU ? 'w' : 'r',
 				insn->dst_reg);
 		} else if (BPF_SRC(insn->code) == BPF_X) {
-			verbose(cbs->private_data, "(%02x) %c%d %s %c%d\n",
+			verbose(cbs->private_data, "(%02x) %c%d %s %s%c%d\n",
 				insn->code, class == BPF_ALU ? 'w' : 'r',
 				insn->dst_reg,
-				bpf_alu_string[BPF_OP(insn->code) >> 4],
+				is_sdiv_smod(insn) ? bpf_alu_sign_string[BPF_OP(insn->code) >> 4]
+						   : bpf_alu_string[BPF_OP(insn->code) >> 4],
+				is_movs(insn) ? bpf_movs_string[(insn->off >> 3) - 1] : "",
 				class == BPF_ALU ? 'w' : 'r',
 				insn->src_reg);
 		} else {
 			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],
+				is_sdiv_smod(insn) ? bpf_alu_sign_string[BPF_OP(insn->code) >> 4]
+						   : bpf_alu_string[BPF_OP(insn->code) >> 4],
 				insn->imm);
 		}
 	} else if (class == BPF_STX) {
@@ -218,13 +258,15 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 			verbose(cbs->private_data, "BUG_st_%02x\n", insn->code);
 		}
 	} else if (class == BPF_LDX) {
-		if (BPF_MODE(insn->code) != BPF_MEM) {
+		if (BPF_MODE(insn->code) != BPF_MEM && BPF_MODE(insn->code) != BPF_MEMS) {
 			verbose(cbs->private_data, "BUG_ldx_%02x\n", insn->code);
 			return;
 		}
 		verbose(cbs->private_data, "(%02x) r%d = *(%s *)(r%d %+d)\n",
 			insn->code, insn->dst_reg,
-			bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+			BPF_MODE(insn->code) == BPF_MEM ?
+				 bpf_ldst_string[BPF_SIZE(insn->code) >> 3] :
+				 bpf_lds_string[BPF_SIZE(insn->code) >> 3],
 			insn->src_reg, insn->off);
 	} else if (class == BPF_LD) {
 		if (BPF_MODE(insn->code) == BPF_ABS) {
@@ -279,6 +321,9 @@ void print_bpf_insn(const struct bpf_insn_cbs *cbs,
 		} else if (insn->code == (BPF_JMP | BPF_JA)) {
 			verbose(cbs->private_data, "(%02x) goto pc%+d\n",
 				insn->code, insn->off);
+		} else if (insn->code == (BPF_JMP32 | BPF_JA)) {
+			verbose(cbs->private_data, "(%02x) gotol pc%+d\n",
+				insn->code, insn->imm);
 		} 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) {
-- 
2.34.1