99 lines
2.4 KiB
Go
99 lines
2.4 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 freebsd && amd64
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package debug
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// Regs holds the full general-purpose register set of a traced process
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// (the FreeBSD amd64 struct reg layout, sys/x86/include/reg.h). FreeBSD
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// reports segment selectors (FS/GS/ES/DS), not the bases the Linux ptrace
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// surface carries, and has no ORIG_RAX slot.
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type Regs struct {
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R15 uint64
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R14 uint64
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R13 uint64
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R12 uint64
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RBP uint64
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RBX uint64
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R11 uint64
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R10 uint64
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R9 uint64
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R8 uint64
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RAX uint64
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RCX uint64
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RDX uint64
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RSI uint64
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RDI uint64
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RIP uint64
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CS uint64
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RFLAGS uint64
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RSP uint64
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SS uint64
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FS uint64
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GS uint64
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DS uint64
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ES uint64
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}
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// GetPC returns the program counter.
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func (r *Regs) GetPC() uint64 { return r.RIP }
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// SetPC sets the program counter.
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func (r *Regs) SetPC(pc uint64) { r.RIP = pc }
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// GetSP returns the stack pointer.
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func (r *Regs) GetSP() uint64 { return r.RSP }
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// RegValue returns the value of the named register, or false if unknown.
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func (r *Regs) RegValue(name string) (uint64, bool) {
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switch name {
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case "rax", "eax", "ax", "al":
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return r.RAX, true
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case "rbx", "ebx", "bx", "bl":
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return r.RBX, true
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case "rcx", "ecx", "cx", "cl":
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return r.RCX, true
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case "rdx", "edx", "dx", "dl":
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return r.RDX, true
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case "rsi", "esi", "si":
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return r.RSI, true
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case "rdi", "edi", "di":
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return r.RDI, true
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case "rbp", "ebp", "bp":
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return r.RBP, true
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case "rsp", "esp", "sp":
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return r.RSP, true
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case "r8":
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return r.R8, true
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case "r9":
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return r.R9, true
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case "r10":
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return r.R10, true
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case "r11":
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return r.R11, true
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case "r12":
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return r.R12, true
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case "r13":
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return r.R13, true
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case "r14":
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return r.R14, true
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case "r15":
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return r.R15, true
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case "rip", "eip":
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return r.RIP, true
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default:
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return 0, false
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}
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}
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// breakpointInsn is the software breakpoint instruction.
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var breakpointInsn = []byte{0xCC} // INT3
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// breakpointPCAdjust is how far PC is past the breakpoint instruction after
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// a trap. INT3 leaves the hardware PC on the following instruction (Intel
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// SDM vol 3, "Debug Exceptions") and the FreeBSD T_BPTFLT path delivers
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// that frame unmodified (sys/amd64/amd64/trap.c), so the trap address is
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// PC-1, the same correction the Linux side applies.
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const breakpointPCAdjust = 1
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