// Copyright 2013 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package runtime import "unsafe" type sigctxt struct { info *siginfo ctxt unsafe.Pointer } //go:nosplit //go:nowritebarrierrec func (c *sigctxt) regs() *regs64 { return &(*ucontext)(c.ctxt).uc_mcontext.ss } func (c *sigctxt) rax() uint64 { return c.regs().rax } func (c *sigctxt) rbx() uint64 { return c.regs().rbx } func (c *sigctxt) rcx() uint64 { return c.regs().rcx } func (c *sigctxt) rdx() uint64 { return c.regs().rdx } func (c *sigctxt) rdi() uint64 { return c.regs().rdi } func (c *sigctxt) rsi() uint64 { return c.regs().rsi } func (c *sigctxt) rbp() uint64 { return c.regs().rbp } func (c *sigctxt) rsp() uint64 { return c.regs().rsp } func (c *sigctxt) r8() uint64 { return c.regs().r8 } func (c *sigctxt) r9() uint64 { return c.regs().r9 } func (c *sigctxt) r10() uint64 { return c.regs().r10 } func (c *sigctxt) r11() uint64 { return c.regs().r11 } func (c *sigctxt) r12() uint64 { return c.regs().r12 } func (c *sigctxt) r13() uint64 { return c.regs().r13 } func (c *sigctxt) r14() uint64 { return c.regs().r14 } func (c *sigctxt) r15() uint64 { return c.regs().r15 } //go:nosplit //go:nowritebarrierrec func (c *sigctxt) rip() uint64 { return c.regs().rip } func (c *sigctxt) rflags() uint64 { return c.regs().rflags } func (c *sigctxt) cs() uint64 { return c.regs().cs } func (c *sigctxt) fs() uint64 { return c.regs().fs } func (c *sigctxt) gs() uint64 { return c.regs().gs } func (c *sigctxt) sigcode() uint64 { return uint64(c.info.si_code) } func (c *sigctxt) sigaddr() uint64 { return c.info.si_addr } func (c *sigctxt) set_rip(x uint64) { c.regs().rip = x } func (c *sigctxt) set_rsp(x uint64) { c.regs().rsp = x } func (c *sigctxt) set_sigcode(x uint64) { c.info.si_code = int32(x) } func (c *sigctxt) set_sigaddr(x uint64) { c.info.si_addr = x } //go:nosplit func (c *sigctxt) fixsigcode(sig uint32) { switch sig { case _SIGTRAP: // OS X sets c.sigcode() == TRAP_BRKPT unconditionally for all SIGTRAPs, // leaving no way to distinguish a breakpoint-induced SIGTRAP // from an asynchronous signal SIGTRAP. // They all look breakpoint-induced by default. // Try looking at the code to see if it's a breakpoint. // The assumption is that we're very unlikely to get an // asynchronous SIGTRAP at just the moment that the // PC started to point at unmapped memory. pc := uintptr(c.rip()) // OS X will leave the pc just after the INT 3 instruction. // INT 3 is usually 1 byte, but there is a 2-byte form. code := (*[2]byte)(unsafe.Pointer(pc - 2)) if code[1] != 0xCC && (code[0] != 0xCD || code[1] != 3) { // SIGTRAP on something other than INT 3. c.set_sigcode(_SI_USER) } case _SIGSEGV: // x86-64 has 48-bit virtual addresses. The top 16 bits must echo bit 47. // The hardware delivers a different kind of fault for a malformed address // than it does for an attempt to access a valid but unmapped address. // OS X 10.9.2 mishandles the malformed address case, making it look like // a user-generated signal (like someone ran kill -SEGV ourpid). // We pass user-generated signals to os/signal, or else ignore them. // Doing that here - and returning to the faulting code - results in an // infinite loop. It appears the best we can do is rewrite what the kernel // delivers into something more like the truth. The address used below // has very little chance of being the one that caused the fault, but it is // malformed, it is clearly not a real pointer, and if it does get printed // in real life, people will probably search for it and find this code. // There are no Google hits for b01dfacedebac1e or 0xb01dfacedebac1e // as I type this comment. // // Note: if this code is removed, please consider // enabling TestSignalForwardingGo for darwin-amd64 in // misc/cgo/testcarchive/carchive_test.go. if c.sigcode() == _SI_USER { c.set_sigcode(_SI_USER + 1) c.set_sigaddr(0xb01dfacedebac1e) } } }