1// Copyright 2015 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
5package runtime
6
7import "unsafe"
8
9type sigctxt struct {
10	info *siginfo
11	ctxt unsafe.Pointer
12}
13
14//go:nosplit
15//go:nowritebarrierrec
16func (c *sigctxt) regs() *regs64 { return &(*ucontext)(c.ctxt).uc_mcontext.ss }
17
18func (c *sigctxt) r0() uint64  { return c.regs().x[0] }
19func (c *sigctxt) r1() uint64  { return c.regs().x[1] }
20func (c *sigctxt) r2() uint64  { return c.regs().x[2] }
21func (c *sigctxt) r3() uint64  { return c.regs().x[3] }
22func (c *sigctxt) r4() uint64  { return c.regs().x[4] }
23func (c *sigctxt) r5() uint64  { return c.regs().x[5] }
24func (c *sigctxt) r6() uint64  { return c.regs().x[6] }
25func (c *sigctxt) r7() uint64  { return c.regs().x[7] }
26func (c *sigctxt) r8() uint64  { return c.regs().x[8] }
27func (c *sigctxt) r9() uint64  { return c.regs().x[9] }
28func (c *sigctxt) r10() uint64 { return c.regs().x[10] }
29func (c *sigctxt) r11() uint64 { return c.regs().x[11] }
30func (c *sigctxt) r12() uint64 { return c.regs().x[12] }
31func (c *sigctxt) r13() uint64 { return c.regs().x[13] }
32func (c *sigctxt) r14() uint64 { return c.regs().x[14] }
33func (c *sigctxt) r15() uint64 { return c.regs().x[15] }
34func (c *sigctxt) r16() uint64 { return c.regs().x[16] }
35func (c *sigctxt) r17() uint64 { return c.regs().x[17] }
36func (c *sigctxt) r18() uint64 { return c.regs().x[18] }
37func (c *sigctxt) r19() uint64 { return c.regs().x[19] }
38func (c *sigctxt) r20() uint64 { return c.regs().x[20] }
39func (c *sigctxt) r21() uint64 { return c.regs().x[21] }
40func (c *sigctxt) r22() uint64 { return c.regs().x[22] }
41func (c *sigctxt) r23() uint64 { return c.regs().x[23] }
42func (c *sigctxt) r24() uint64 { return c.regs().x[24] }
43func (c *sigctxt) r25() uint64 { return c.regs().x[25] }
44func (c *sigctxt) r26() uint64 { return c.regs().x[26] }
45func (c *sigctxt) r27() uint64 { return c.regs().x[27] }
46func (c *sigctxt) r28() uint64 { return c.regs().x[28] }
47func (c *sigctxt) r29() uint64 { return c.regs().fp }
48func (c *sigctxt) lr() uint64  { return c.regs().lr }
49func (c *sigctxt) sp() uint64  { return c.regs().sp }
50
51//go:nosplit
52//go:nowritebarrierrec
53func (c *sigctxt) pc() uint64 { return c.regs().pc }
54
55func (c *sigctxt) fault() uintptr { return uintptr(unsafe.Pointer(c.info.si_addr)) }
56
57func (c *sigctxt) sigcode() uint64 { return uint64(c.info.si_code) }
58func (c *sigctxt) sigaddr() uint64 { return uint64(uintptr(unsafe.Pointer(c.info.si_addr))) }
59
60func (c *sigctxt) set_pc(x uint64)  { c.regs().pc = x }
61func (c *sigctxt) set_sp(x uint64)  { c.regs().sp = x }
62func (c *sigctxt) set_lr(x uint64)  { c.regs().lr = x }
63func (c *sigctxt) set_r28(x uint64) { c.regs().x[28] = x }
64
65func (c *sigctxt) set_sigcode(x uint64) { c.info.si_code = int32(x) }
66func (c *sigctxt) set_sigaddr(x uint64) {
67	c.info.si_addr = (*byte)(unsafe.Pointer(uintptr(x)))
68}
69
70//go:nosplit
71func (c *sigctxt) fixsigcode(sig uint32) {
72	switch sig {
73	case _SIGTRAP:
74		// OS X sets c.sigcode() == TRAP_BRKPT unconditionally for all SIGTRAPs,
75		// leaving no way to distinguish a breakpoint-induced SIGTRAP
76		// from an asynchronous signal SIGTRAP.
77		// They all look breakpoint-induced by default.
78		// Try looking at the code to see if it's a breakpoint.
79		// The assumption is that we're very unlikely to get an
80		// asynchronous SIGTRAP at just the moment that the
81		// PC started to point at unmapped memory.
82		pc := uintptr(c.pc())
83		// OS X will leave the pc just after the instruction.
84		code := (*uint32)(unsafe.Pointer(pc - 4))
85		if *code != 0xd4200000 {
86			// SIGTRAP on something other than breakpoint.
87			c.set_sigcode(_SI_USER)
88		}
89	}
90}
91