118 lines
2.6 KiB
Go
118 lines
2.6 KiB
Go
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// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
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// SPDX-License-Identifier: BSD-3-Clause
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//go:build linux && amd64
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package debug
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import (
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"fmt"
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"syscall"
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"unsafe"
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)
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// StopReason describes why the debuggee stopped.
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type StopReason int
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const (
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StopNone StopReason = iota
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StopBreakpoint // INT3 breakpoint hit
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StopWatchpoint // hardware watchpoint triggered
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StopSingleStep // single-step completed
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StopSignal // stopped by a signal
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StopExited // process exited
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)
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// siginfo_t layout (Linux amd64): si_signo, si_errno, si_code, then union.
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type siginfoT struct {
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SiSigno int32
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SiErrno int32
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SiCode int32
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_pad [125]byte
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}
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const (
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trapBRKPT = 1 // INT3 breakpoint
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trapHWBRKPT = 4 // hardware watchpoint
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)
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// StopInfo returns the reason the debuggee stopped and the faulting address
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// (for watchpoints, the watched address that was accessed).
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func (s *Session) StopInfo() (StopReason, uint64) {
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if s.exited {
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return StopExited, 0
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}
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var info siginfoT
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_, _, errno := syscall.Syscall6(
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syscall.SYS_PTRACE,
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uintptr(syscall.PTRACE_GETSIGINFO),
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uintptr(s.pid),
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0,
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uintptr(unsafe.Pointer(&info)),
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0, 0,
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)
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if errno != 0 {
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return StopNone, 0
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}
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if info.SiSigno != int32(syscall.SIGTRAP) {
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return StopSignal, uint64(info.SiCode)
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}
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switch info.SiCode {
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case trapBRKPT:
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return StopBreakpoint, 0
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case trapHWBRKPT:
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// The faulting address is in si_addr (offset 16 in siginfo_t on amd64).
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addr := *(*uint64)(unsafe.Pointer(uintptr(unsafe.Pointer(&info)) + 16))
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return StopWatchpoint, addr
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default:
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return StopSingleStep, 0
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}
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}
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// SetReg modifies a register value in the debuggee.
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func (s *Session) SetReg(name string, value uint64) error {
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regs, err := s.GetRegs()
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if err != nil {
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return err
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}
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switch name {
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case "rax", "eax", "ax", "al":
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regs.RAX = value
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case "rbx", "ebx", "bx", "bl":
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regs.RBX = value
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case "rcx", "ecx", "cx", "cl":
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regs.RCX = value
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case "rdx", "edx", "dx", "dl":
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regs.RDX = value
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case "rsi", "esi", "si":
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regs.RSI = value
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case "rdi", "edi", "di":
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regs.RDI = value
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case "rbp", "ebp", "bp":
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regs.RBP = value
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case "rsp", "esp", "sp":
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regs.RSP = value
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case "r8":
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regs.R8 = value
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case "r9":
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regs.R9 = value
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case "r10":
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regs.R10 = value
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case "r11":
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regs.R11 = value
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case "r12":
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regs.R12 = value
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case "r13":
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regs.R13 = value
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case "r14":
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regs.R14 = value
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case "r15":
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regs.R15 = value
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case "rip", "eip":
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regs.RIP = value
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default:
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return fmt.Errorf("debug: unknown register %q", name)
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}
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return s.SetRegs(®s)
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}
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