From d8ad4af78bba1f4bf2bb1ce1ace2b62bc86540fd Mon Sep 17 00:00:00 2001 From: Joel Sing Date: Sat, 4 Jan 2025 03:44:40 +1100 Subject: [PATCH] cmd/internal/disasm: correct instruction length handling for riscv64 disasm_riscv64 currently always returns an instruction length of four, which is not correct if compressed instructions are in use. Return the length of the decoded instruction, defaulting to two bytes if the instruction is unknown. With this change it is possible to correctly objdump a binary that is written in C and includes compressed instructions: $ go tool objdump ./hello TEXT _start(SB) :0 0x5b0 ef002002 CALL 8(PC) :0 0x5b4 aa87 ADD X10, X0, X15 :0 0x5b6 17250000 AUIPC $2, X10 :0 0x5ba 033525a3 MOV -1486(X10), X10 :0 0x5be 8265 MOV (X2), X11 :0 0x5c0 3000 ADDI $8, X2, X12 ... Fixes #71102 Change-Id: Ia99eb114a98c6d535de872ce8a526cd5e6203fff Reviewed-on: https://go-review.googlesource.com/c/go/+/639995 Reviewed-by: Michael Knyszek Reviewed-by: Jorropo LUCI-TryBot-Result: Go LUCI Reviewed-by: Michael Pratt --- src/cmd/internal/disasm/disasm.go | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/cmd/internal/disasm/disasm.go b/src/cmd/internal/disasm/disasm.go index c317effa90..3ae8989b38 100644 --- a/src/cmd/internal/disasm/disasm.go +++ b/src/cmd/internal/disasm/disasm.go @@ -410,14 +410,16 @@ func disasm_ppc64(code []byte, pc uint64, lookup lookupFunc, byteOrder binary.By func disasm_riscv64(code []byte, pc uint64, lookup lookupFunc, byteOrder binary.ByteOrder, gnuAsm bool) (string, int) { inst, err := riscv64asm.Decode(code) var text string + size := inst.Len if err != nil || inst.Op == 0 { + size = 2 text = "?" } else if gnuAsm { text = fmt.Sprintf("%-36s // %s", riscv64asm.GoSyntax(inst, pc, lookup, textReader{code, pc}), riscv64asm.GNUSyntax(inst)) } else { text = riscv64asm.GoSyntax(inst, pc, lookup, textReader{code, pc}) } - return text, 4 + return text, size } func disasm_s390x(code []byte, pc uint64, lookup lookupFunc, _ binary.ByteOrder, gnuAsm bool) (string, int) { -- 2.48.1