Source file src/runtime/signal_darwin_386.go

     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	//go:nosplit
    15	//go:nowritebarrierrec
    16	func (c *sigctxt) regs() *regs32 { return &(*ucontext)(c.ctxt).uc_mcontext.ss }
    17	
    18	func (c *sigctxt) eax() uint32 { return c.regs().eax }
    19	func (c *sigctxt) ebx() uint32 { return c.regs().ebx }
    20	func (c *sigctxt) ecx() uint32 { return c.regs().ecx }
    21	func (c *sigctxt) edx() uint32 { return c.regs().edx }
    22	func (c *sigctxt) edi() uint32 { return c.regs().edi }
    23	func (c *sigctxt) esi() uint32 { return c.regs().esi }
    24	func (c *sigctxt) ebp() uint32 { return c.regs().ebp }
    25	func (c *sigctxt) esp() uint32 { return c.regs().esp }
    26	
    27	//go:nosplit
    28	//go:nowritebarrierrec
    29	func (c *sigctxt) eip() uint32 { return c.regs().eip }
    30	
    31	func (c *sigctxt) eflags() uint32  { return c.regs().eflags }
    32	func (c *sigctxt) cs() uint32      { return c.regs().cs }
    33	func (c *sigctxt) fs() uint32      { return c.regs().fs }
    34	func (c *sigctxt) gs() uint32      { return c.regs().gs }
    35	func (c *sigctxt) sigcode() uint32 { return uint32(c.info.si_code) }
    36	func (c *sigctxt) sigaddr() uint32 { return c.info.si_addr }
    37	
    38	func (c *sigctxt) set_eip(x uint32)     { c.regs().eip = x }
    39	func (c *sigctxt) set_esp(x uint32)     { c.regs().esp = x }
    40	func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
    41	func (c *sigctxt) set_sigaddr(x uint32) { c.info.si_addr = x }
    42	
    43	//go:nosplit
    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.eip())
    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	}
    65	

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