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

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Yonghong Song authored and Alexei Starovoitov committed Jul 28, 2023
1 parent 4cd58e9 commit f835bb6
Showing 1 changed file with 51 additions and 6 deletions.
57 changes: 51 additions & 6 deletions kernel/bpf/disasm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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_movsx_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",
Expand All @@ -101,6 +112,12 @@ static const char *const bpf_ldst_string[] = {
[BPF_DW >> 3] = "u64",
};

static const char *const bpf_ldsx_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] = "==",
Expand Down Expand Up @@ -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)
{
return (BPF_OP(insn->code) == BPF_DIV || BPF_OP(insn->code) == BPF_MOD) &&
insn->off == 1;
}

static bool is_movsx(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)
Expand All @@ -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) {
Expand All @@ -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_movsx(insn) ? bpf_movsx_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) {
Expand Down Expand Up @@ -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_MEMSX) {
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_ldsx_string[BPF_SIZE(insn->code) >> 3],
insn->src_reg, insn->off);
} else if (class == BPF_LD) {
if (BPF_MODE(insn->code) == BPF_ABS) {
Expand Down Expand Up @@ -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) {
Expand Down

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