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asm: add support for the may_goto insn and JCOND opcode #1898

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asm: add support for the may_goto insn and JCOND opcode #1898

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12 changes: 11 additions & 1 deletion asm/instruction.go
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Original file line number Diff line number Diff line change
Expand Up @@ -396,9 +396,9 @@ func (ins Instruction) Format(f fmt.State, c rune) {
}

case cls.IsJump():
fmt.Fprintf(f, "%v ", op)
switch jop := op.JumpOp(); jop {
case Call:
fmt.Fprintf(f, "%v ", op)
switch ins.Src {
case PseudoCall:
// bpf-to-bpf call
Expand All @@ -411,13 +411,23 @@ func (ins Instruction) Format(f fmt.State, c rune) {
}

case Ja:
fmt.Fprintf(f, "%v ", op)
if ins.OpCode.Class() == Jump32Class {
fmt.Fprintf(f, "imm: %d", ins.Constant)
} else {
fmt.Fprintf(f, "off: %d", ins.Offset)
}

case JCOND:
switch ins.Src {
case PseudoMayGoto:
fmt.Fprintf(f, "JCond may_goto off: %d", ins.Offset)
default:
fmt.Fprintf(f, "%v", op)
}

default:
fmt.Fprintf(f, "%v ", op)
fmt.Fprintf(f, "dst: %s off: %d ", ins.Dst, ins.Offset)
if op.Source() == ImmSource {
fmt.Fprintf(f, "imm: %d", ins.Constant)
Expand Down
3 changes: 3 additions & 0 deletions asm/instruction_test.go
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Expand Up @@ -393,6 +393,8 @@ func TestISAv4(t *testing.T) {
0xcb, 0x21, 0x00, 0x00, 0x10, 0x01, 0x00, 0x00, // store_release((u16 *)(r1 + 0x0), w2)
0xc3, 0x21, 0x00, 0x00, 0x10, 0x01, 0x00, 0x00, // store_release((u32 *)(r1 + 0x0), w2)
0xdb, 0x21, 0x00, 0x00, 0x10, 0x01, 0x00, 0x00, // store_release((u64 *)(r1 + 0x0), r2)

0xe5, 0x00, 0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, // may_goto +30
}

insns, err := AppendInstructions(nil, bytes.NewReader(rawInsns), binary.LittleEndian, platform.Linux)
Expand Down Expand Up @@ -427,6 +429,7 @@ func TestISAv4(t *testing.T) {
"StXAtomicStRelH dst: r1 src: r2 off: 0",
"StXAtomicStRelW dst: r1 src: r2 off: 0",
"StXAtomicStRelDW dst: r1 src: r2 off: 0",
"JCond may_goto off: 30",
}

for i, ins := range insns {
Expand Down
2 changes: 2 additions & 0 deletions asm/jump.go
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Expand Up @@ -44,6 +44,8 @@ const (
JSLT JumpOp = 0xc0
// JSLE jumps by offset if signed r <= signed imm
JSLE JumpOp = 0xd0
// JCOND is a conditional pseudo jump to encode the may_goto instruction
JCOND JumpOp = 0xe0
)

// Return emits an exit instruction.
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6 changes: 4 additions & 2 deletions asm/jump_string.go
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1 change: 1 addition & 0 deletions asm/opcode_test.go
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Expand Up @@ -44,6 +44,7 @@ func TestGetSetJumpOp(t *testing.T) {
JLE,
JSLT,
JSLE,
JCOND,
} {
test(Jump32Class, op, true)
test(JumpClass, op, true)
Expand Down
1 change: 1 addition & 0 deletions asm/register.go
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Expand Up @@ -40,6 +40,7 @@ const (
PseudoCall = R1 // BPF_PSEUDO_CALL
PseudoFunc = R4 // BPF_PSEUDO_FUNC
PseudoKfuncCall = R2 // BPF_PSEUDO_KFUNC_CALL
PseudoMayGoto = R0 // BPF_MAY_GOTO
)

func (r Register) String() string {
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