feat(debug): port the debugger to FreeBSD

Assisted-by: GLM 5.3 Flash
2026-09-25 21:46:40 +02:00
parent b9015e1c2e
commit b306c210c6
28 changed files with 2444 additions and 15 deletions
@@ -0,0 +1,115 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build freebsd && riscv64
+
+package debug
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/unix"
+)
+
+// GetRegs reads the general-purpose registers of the stopped debuggee and
+// converts the FreeBSD struct reg into the portable layout.  Sstatus rides
+// the kernel's struct but the portable surface carries the GPRs and PC.
+func (s *Session) GetRegs() (Regs, error) {
+	var ur unix.Reg
+	if err := unix.PtraceGetRegs(s.pid, &ur); err != nil {
+		return Regs{}, fmt.Errorf("debug: PT_GETREGS: %w", err)
+	}
+	return Regs{
+		PC:  ur.Sepc,
+		Ra:  ur.Ra,
+		Sp:  ur.Sp,
+		Gp:  ur.Gp,
+		Tp:  ur.Tp,
+		T0:  ur.T[0],
+		T1:  ur.T[1],
+		T2:  ur.T[2],
+		S0:  ur.S[0],
+		S1:  ur.S[1],
+		A0:  ur.A[0],
+		A1:  ur.A[1],
+		A2:  ur.A[2],
+		A3:  ur.A[3],
+		A4:  ur.A[4],
+		A5:  ur.A[5],
+		A6:  ur.A[6],
+		A7:  ur.A[7],
+		S2:  ur.S[2],
+		S3:  ur.S[3],
+		S4:  ur.S[4],
+		S5:  ur.S[5],
+		S6:  ur.S[6],
+		S7:  ur.S[7],
+		S8:  ur.S[8],
+		S9:  ur.S[9],
+		S10: ur.S[10],
+		S11: ur.S[11],
+		T3:  ur.T[3],
+		T4:  ur.T[4],
+		T5:  ur.T[5],
+		T6:  ur.T[6],
+	}, nil
+}
+
+// SetRegs writes the general-purpose registers of the stopped debuggee.
+// Read-modify-write keeps sstatus, which the kernel owns, intact.
+func (s *Session) SetRegs(regs *Regs) error {
+	var ur unix.Reg
+	if err := unix.PtraceGetRegs(s.pid, &ur); err != nil {
+		return fmt.Errorf("debug: PT_GETREGS: %w", err)
+	}
+	ur.Sepc = regs.PC
+	ur.Ra = regs.Ra
+	ur.Sp = regs.Sp
+	ur.Gp = regs.Gp
+	ur.Tp = regs.Tp
+	ur.T = [7]uint64{regs.T0, regs.T1, regs.T2, regs.T3, regs.T4, regs.T5, regs.T6}
+	ur.S = [12]uint64{regs.S0, regs.S1, regs.S2, regs.S3, regs.S4, regs.S5,
+		regs.S6, regs.S7, regs.S8, regs.S9, regs.S10, regs.S11}
+	ur.A = [8]uint64{regs.A0, regs.A1, regs.A2, regs.A3, regs.A4, regs.A5, regs.A6, regs.A7}
+	return unix.PtraceSetRegs(s.pid, &ur)
+}
+
+// FPRegs holds the RISC-V FP register state (32 64-bit FP registers plus
+// fcsr).
+type FPRegs struct {
+	F    [32]uint64 // F0-F31 (64-bit FP registers)
+	FCSR uint32
+}
+
+// GetFPRegs retrieves the FP register state via PT_GETFPREGS.  The FreeBSD
+// struct fpreg carries each 64-bit FP register in a 128-bit slot (fp_x is
+// the flat [64]-word area the x/sys type renders as [32][2]); the low word
+// holds the register, and FCSR rides the tail.
+func (s *Session) GetFPRegs() (FPRegs, error) {
+	var fp FPRegs
+	var fr unix.FpReg
+	if err := unix.PtraceGetFpRegs(s.pid, &fr); err != nil {
+		return fp, fmt.Errorf("debug: PT_GETFPREGS: %w", err)
+	}
+	for i := range 32 {
+		fp.F[i] = fr.X[i][0]
+	}
+	fp.FCSR = uint32(fr.Fcsr)
+	return fp, nil
+}
+
+// VectorRegs holds the FP register state shown by the regs command
+// (riscv64 has 32 64-bit FP registers and fcsr).
+type VectorRegs struct {
+	F    [32]uint64
+	FCSR uint32
+}
+
+// GetVectorRegs retrieves the FP registers.
+func (s *Session) GetVectorRegs() (VectorRegs, error) {
+	fp, err := s.GetFPRegs()
+	if err != nil {
+		return VectorRegs{}, err
+	}
+	return VectorRegs{F: fp.F, FCSR: fp.FCSR}, nil
+}