Source file src/runtime/signal_darwin_arm.go

     1	// Copyright 2014 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) r0() uint32  { return c.regs().r[0] }
    19	func (c *sigctxt) r1() uint32  { return c.regs().r[1] }
    20	func (c *sigctxt) r2() uint32  { return c.regs().r[2] }
    21	func (c *sigctxt) r3() uint32  { return c.regs().r[3] }
    22	func (c *sigctxt) r4() uint32  { return c.regs().r[4] }
    23	func (c *sigctxt) r5() uint32  { return c.regs().r[5] }
    24	func (c *sigctxt) r6() uint32  { return c.regs().r[6] }
    25	func (c *sigctxt) r7() uint32  { return c.regs().r[7] }
    26	func (c *sigctxt) r8() uint32  { return c.regs().r[8] }
    27	func (c *sigctxt) r9() uint32  { return c.regs().r[9] }
    28	func (c *sigctxt) r10() uint32 { return c.regs().r[10] }
    29	func (c *sigctxt) fp() uint32  { return c.regs().r[11] }
    30	func (c *sigctxt) ip() uint32  { return c.regs().r[12] }
    31	func (c *sigctxt) sp() uint32  { return c.regs().sp }
    32	func (c *sigctxt) lr() uint32  { return c.regs().lr }
    33	
    34	//go:nosplit
    35	//go:nowritebarrierrec
    36	func (c *sigctxt) pc() uint32 { return c.regs().pc }
    37	
    38	func (c *sigctxt) cpsr() uint32    { return c.regs().cpsr }
    39	func (c *sigctxt) fault() uintptr  { return uintptr(c.info.si_addr) }
    40	func (c *sigctxt) sigcode() uint32 { return uint32(c.info.si_code) }
    41	func (c *sigctxt) trap() uint32    { return 0 }
    42	func (c *sigctxt) error() uint32   { return 0 }
    43	func (c *sigctxt) oldmask() uint32 { return 0 }
    44	
    45	func (c *sigctxt) set_pc(x uint32)  { c.regs().pc = x }
    46	func (c *sigctxt) set_sp(x uint32)  { c.regs().sp = x }
    47	func (c *sigctxt) set_lr(x uint32)  { c.regs().lr = x }
    48	func (c *sigctxt) set_r10(x uint32) { c.regs().r[10] = x }
    49	
    50	func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
    51	func (c *sigctxt) set_sigaddr(x uint32) { c.info.si_addr = x }
    52	
    53	//go:nosplit
    54	func (c *sigctxt) fixsigcode(sig uint32) {
    55		switch sig {
    56		case _SIGTRAP:
    57			// OS X sets c.sigcode() == TRAP_BRKPT unconditionally for all SIGTRAPs,
    58			// leaving no way to distinguish a breakpoint-induced SIGTRAP
    59			// from an asynchronous signal SIGTRAP.
    60			// They all look breakpoint-induced by default.
    61			// Try looking at the code to see if it's a breakpoint.
    62			// The assumption is that we're very unlikely to get an
    63			// asynchronous SIGTRAP at just the moment that the
    64			// PC started to point at unmapped memory.
    65			pc := uintptr(c.pc())
    66			// OS X will leave the pc just after the instruction.
    67			code := (*uint32)(unsafe.Pointer(pc - 4))
    68			if *code != 0xe7f001f0 {
    69				// SIGTRAP on something other than breakpoint.
    70				c.set_sigcode(_SI_USER)
    71			}
    72		}
    73	}
    74	

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