github.com/4ad/go@v0.0.0-20161219182952-69a12818b605/src/runtime/signal_darwin_amd64.go (about)

     1  // Copyright 2013 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime
     6  
     7  import "unsafe"
     8  
     9  type sigctxt struct {
    10  	info *siginfo
    11  	ctxt unsafe.Pointer
    12  }
    13  
    14  func (c *sigctxt) regs() *regs64   { return &(*ucontext)(c.ctxt).uc_mcontext.ss }
    15  func (c *sigctxt) rax() uint64     { return c.regs().rax }
    16  func (c *sigctxt) rbx() uint64     { return c.regs().rbx }
    17  func (c *sigctxt) rcx() uint64     { return c.regs().rcx }
    18  func (c *sigctxt) rdx() uint64     { return c.regs().rdx }
    19  func (c *sigctxt) rdi() uint64     { return c.regs().rdi }
    20  func (c *sigctxt) rsi() uint64     { return c.regs().rsi }
    21  func (c *sigctxt) rbp() uint64     { return c.regs().rbp }
    22  func (c *sigctxt) rsp() uint64     { return c.regs().rsp }
    23  func (c *sigctxt) r8() uint64      { return c.regs().r8 }
    24  func (c *sigctxt) r9() uint64      { return c.regs().r9 }
    25  func (c *sigctxt) r10() uint64     { return c.regs().r10 }
    26  func (c *sigctxt) r11() uint64     { return c.regs().r11 }
    27  func (c *sigctxt) r12() uint64     { return c.regs().r12 }
    28  func (c *sigctxt) r13() uint64     { return c.regs().r13 }
    29  func (c *sigctxt) r14() uint64     { return c.regs().r14 }
    30  func (c *sigctxt) r15() uint64     { return c.regs().r15 }
    31  func (c *sigctxt) rip() uint64     { return c.regs().rip }
    32  func (c *sigctxt) rflags() uint64  { return c.regs().rflags }
    33  func (c *sigctxt) cs() uint64      { return c.regs().cs }
    34  func (c *sigctxt) fs() uint64      { return c.regs().fs }
    35  func (c *sigctxt) gs() uint64      { return c.regs().gs }
    36  func (c *sigctxt) sigcode() uint64 { return uint64(c.info.si_code) }
    37  func (c *sigctxt) sigaddr() uint64 { return c.info.si_addr }
    38  
    39  func (c *sigctxt) set_rip(x uint64)     { c.regs().rip = x }
    40  func (c *sigctxt) set_rsp(x uint64)     { c.regs().rsp = x }
    41  func (c *sigctxt) set_sigcode(x uint64) { c.info.si_code = int32(x) }
    42  func (c *sigctxt) set_sigaddr(x uint64) { c.info.si_addr = x }
    43  
    44  func (c *sigctxt) fixsigcode(sig uint32) {
    45  	switch sig {
    46  	case _SIGTRAP:
    47  		// OS X sets c.sigcode() == TRAP_BRKPT unconditionally for all SIGTRAPs,
    48  		// leaving no way to distinguish a breakpoint-induced SIGTRAP
    49  		// from an asynchronous signal SIGTRAP.
    50  		// They all look breakpoint-induced by default.
    51  		// Try looking at the code to see if it's a breakpoint.
    52  		// The assumption is that we're very unlikely to get an
    53  		// asynchronous SIGTRAP at just the moment that the
    54  		// PC started to point at unmapped memory.
    55  		pc := uintptr(c.rip())
    56  		// OS X will leave the pc just after the INT 3 instruction.
    57  		// INT 3 is usually 1 byte, but there is a 2-byte form.
    58  		code := (*[2]byte)(unsafe.Pointer(pc - 2))
    59  		if code[1] != 0xCC && (code[0] != 0xCD || code[1] != 3) {
    60  			// SIGTRAP on something other than INT 3.
    61  			c.set_sigcode(_SI_USER)
    62  		}
    63  	}
    64  }